Summer Arrives (in the East)! Winter’s Back (in the Rockies)!

The current weather pattern across the country is one that is fairly typical of Spring. However, the results of that pattern are Winter in the Rockies and Summer in the East. In between, there is plenty of severe weather, which is fairly typical of Spring.

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A ridge in the East, a trough in the West. Not that uncommon of a pattern. Image provided by College of DuPage.

An upper-level low pressure area will move out of the Pacific Northwest and into the nation’s midsection over the next few days. While one storm system moves into the Upper Midwest today, a second one will develop east of the Rockies and move into the Plains states on Thursday. With cold air moving in behind these systems, and warm, moist air flowing northward from the Gulf of Mexico ahead of them, strong to severe thunderstorms are likely again for the next few days across the Plains states.

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Thursday could be a very active day for severe weather in the Central and Southern Plains. Image provided by the Storm Prediction Center.

Severe weather has plagued the Plains states and Great Lakes for the past few days, with over 500 reports of severe weather between Monday and Tuesday. Nearly 30 tornadoes were reported, along with hail as large as softballs, and hundreds of reports of wind damage from gusts as high as 85 mph.

 

Behind the low pressure area, a late-season snowstorm is expected across the Rocky Mountains. Heavy snow will continue across portions of Montana and Idaho today, spreading into Wyoming and Colorado for Thursday into Friday. Across the higher elevations, totals of 1-3 feet are expected, which will keep the ski season going for a while longer. Snow may also spread into the High Plains of eastern Colorado and western Nebraska, with some minor accumulations possible. In Denver, it looks a couple of slushy inches may fall, though at least 1 model is forecasting much heavier amounts. In a normal year, Denver averages 1.7″ of snow, and the city has seen measurable snow during the month of May in 11 out of the last 16 years, so snow in May is not uncommon, though a heavy snowstorm, if it materializes, would be. Denver has only received 10 or more inches of snow in the month of May 6 times in a 135 years of records, with a record total of 15.5″ set back in May of 1898.

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A late-season snowstorm may drop up to 3 feet of snow in the higher elevations of the Rockies. Image provided by WeatherBell.

Meanwhile, in the East, an early taste of summer is ongoing, thanks to a ridge of high pressure aloft, and a surface high pressure area off the East Coast. Temperatures soared into the 80s and lower 90s on Wednesday, setting several records, but the hottest day for many locations will be Thursday. High temperatures will climb into the lower to middle 90s in many locations, likely breaking records across much of the region. When you combine the heat with dewpoints well into the 60s, it will definitely feel like a mid-summer afternoon across the region. A cold front will move through the area of Friday, possibly triggering a few showers and thunderstorms, but also sending temperatures back to where they should be in the middle of May.

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A lot of record high temperatures may be broken across the Northeast on Thursday. Image provided by WeatherBell.

Severe Weather in the South Today, but a Bigger Threat Looms for Friday

Severe weather is likely across portions of the Gulf Coast and Mississippi Valley today, but another, perhaps more widespread, outbreak is possible at the end of the week. While that is happening, a snowstorm might also be brewing in the Rockies. Spring can feature a little bit of everything across the nation.

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Severe weather is expected across portions of the Mississippi Valley today. Image provided by NOAA.

A strong cold front is moving into the Mississippi Valley and Texas this afternoon, and it is helping to trigger strong to severe thunderstorms across portions of the region. Ahead of the front, temperatures are into the 70s and lower 80s, with dewpoints in the upper 60s and 70s, so there’s plenty of warm, moist air in place. Behind the front, temperatures quickly drop into the 40s and 50s. Thunderstorms will continue to develop in the unstable airmass ahead of the front, with some of the storms containing large hail, heavy downpours, damaging winds, and possibly some tornadoes. Earlier this morning, some storms produced baseball-sized hail and wind gusts in excess of 70 mph in portions of Missouri, Arkansas, and Oklahoma. The threat should start to diminish across the region as we head into the overnight hours.

 

A more significant severe weather outbreak is possible later Friday into Saturday from the Southern Plains and Texas into portions of the Mississippi and Tennessee Valleys. Low pressure will move out of Texas and head northeastward, drawing warm, moist air northward from the Gulf of Mexico once again. North and west of the system, much cooler air will be in place (more on that in a moment).

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Lifted index values of -10 and lower across Texas and the Lower Mississippi Valley show that the airmass will be very unstable on Friday. Image provided by Pivotal Weather.
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CAPE values of 4000 J/kg and higher across Texas and the Lower Mississippi Valley show that the airmass will be very unstable on Friday. Image provided by Pivotal Weather.

As low pressure rides along the boundary between the two airmasses, it will help to trigger strong to severe thunderstorms across the region. The threat will continue into the overnight hours Friday night, shifting into the Mississippi and Tennessee Valleys on Saturday as the system continues to progress northeastward. Some of the storms may produce torrential downpours that could trigger flash flooding, large hail, damaging winds, and tornadoes.

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The GFS model shows the potential for 5-10 inches of rain (or more) in parts of the Mississippi Valley through Sunday. Flooding is likely. Image provided by WeatherBell.

Behind the storm, as colder air settles into the region, a different threat is evolving – heavy snow. While it’s getting late in the season, heavy snow is not uncommon in the Central and Southern Rockies at this time of year. Some of the higher elevations in Colorado and New Mexico could receive 1-2 feet of snow Friday into Saturday. East of the Continental Divide, especially in the High Plains, snow is also possible, especially from eastern Colorado and western Kansas into portions of the Oklahoma and Texas Panhandles. In Denver, there is still a big question as to whether to precipitation falls mainly as rain, snow, or a wintry mix. Some snow accumulation seems likely at this point, but it’s still a little too early to tell whether there will be heavy snow in the city itself. The heavy snow threat will expand into the portions of the Upper Midwest and southern Canada Sunday into Monday as the storm moves into that region.

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GFS model forecast for snowfall in the Rockies and High Plains through Sunday. Winter is definitely not over there. Image provided by WeatherBell.

Severe weather outbreaks are not uncommon at this time of year. In fact, from late March into early May is when they are most likely. The largest tornado outbreak on record occurred 6 years ago this week. Between April 25 and 28, 2011, a total of 362 tornadoes were observed from Texas to New York and portions of southern Canada, resulting in 324 fatalities, 317 of them on April 27, the most active day.

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Map showing tracks of all 362 tornadoes from the April 2011 “Super Outbreak”. Image provided by Encyclopedia Brittanica.

As for our part of the country – the clouds and rain and cool temperatures will eventually move out. Things will start to improve on Thursday with some sunny breaks possible and temperatures into the 60s. By Friday, there will be more sunshine and temperatures getting into the 70s. Saturday looks like the best day, as temperatures could get into the lower 80s in some spots. We will have to watch out for some late-day showers and maybe a thunderstorm. Sunday looks to be significantly cooler thanks to a northeast wind off of the still-chilly Atlantic.

In Like a Lion…

The old saying is that March comes in like a lion and goes out like a lamb. We’ll see about how it goes out, but it certainly looks like it’s going to come in like a lion this year, but not in the usual way.

We’ve got some unseasonably mild air already in place, but it’s going to get even warmer as a warm front moves across the region tonight. It’ll be accompanied by some showers, and maybe even a rumble of thunder when it moves through. Some of the rain overnight may be locally heavy, but since most of you will be sleeping when it comes through, you won’t even notice. Also, with the warm front coming through, we’ll have our low temperatures this evening instead of in the morning, as temperatures will slowly rise overnight.

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Plenty of record highs are expected across the Northeast on Wednesday. Image provided by WeatherBell.

 

This brings us to Wednesday. Once that warm front moves across the area, even warmer air will flood into the region, with highs again soaring well into the 60s. The only limiting factor for tomorrow will be cloud cover, which there will likely be plenty of. If we can get some breaks of sunshine, it wouldn’t be a surprise if temperatures made a run at 70 in spots.

Warm temperatures aren’t the only story for Wednesday though. A strong cold front will be approaching from the west. While this front will bring an end to our warmth Thursday morning, it’s what happens ahead of it that is a bigger concern.

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A slight risk for severe weather exists across parts of southwestern New England on Wednesday, with a marginal risk for most of the remainder of Southern New England. Image provided by the Storm Prediction Center.

 

As is usually the case during the warmer months, with a warm and relatively humid airmass in place, the atmosphere will become unstable. Add in some lift ahead of the front and you get showers and thunderstorms. The bigger the clash in airmasses, but stronger the storms. That’s what will happen tomorrow. Thunderstorms will develop ahead of the front during the afternoon and evening hours and may even continue into the nighttime ahead of the front. Some of the storms could become quite strong, with heavy downpours, frequent lightning, and damaging winds. There is even the chance for an isolated tornado. Just last week, a tornado touched down in Goshen and Conway, Massachusetts – the first confirmed tornado ever during the month of February in the Commonwealth.

 

New England isn’t the only place where severe weather is expected though. In fact, what’s expected up here is minor compared to the Ohio and Mississippi Valleys. As that cold front moves into those areas later today into early Wednesday, widespread severe weather is expected to develop. Large hail, heavy downpours, damaging winds and several tornadoes are expected. This is more typical of April than the last day of February.

After this front moves offshore, things quiet down a bit, and we get back into weather that is more typical of early March, especially here in the Northeast. We do need to keep an eye on Friday though. An Alberta Clipper will be diving southeastward from the Great Lakes. It will pass south of New England during the day on Friday and into Friday morning. While the majority of the forecast models keep the system far enough south of have little to no impact on us, not all of them do. So, there is the chance for some light snow, especially south of the Mass Pike, on Friday. We’ll have more on this later in the week if the threat materializes.

Record Highs, Blizzard Conditions, and Severe Weather – February in the Nation’s Midsection

“In the Spring, I have counted 136 different kinds of weather inside of 24 hours.” – Mark Twain

It’s not quite spring yet, but this quote is still appropriate. Much of the nation’s midsection has been enjoying temperatures more typical of April than February for the past week, with a few hundred record high temperatures broken. That is about to change, as Mother Nature will remind the region that is still February.

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Numerous record highs are expected across the Plains and Midwest again today. Image provided by WeatherBell.

Of course, they will still have one more warm day today, with highs well into the 60s and 70s likely setting more records. However, a cold front will sweep across the region, bringing an end to the record heat, and setting the stage for a snowstorm.

The low pressure system that brought more rain to California over the past couple of days will head eastward, bringing some snow into the Rockies today. As that system moves into the Plains on Thursday it will start to strengthen, drawing moisture northward from the Gulf of Mexico while cold air flows southward on the backside of the storm into the Northern Plains. Where these airmasses meet, snow will develop across the Central Plains states. The snow will be accompanied by winds of 20-30 mph, gusting to 40 mph or more at times, resulting in near-blizzard conditions across portions of South Dakota, Nebraska, southeastern Wyoming, and eastern Colorado on Thursday.

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More than a foot of snow may fall in a swath from the Plains into the Upper Midwest. A lot of these same places are going to be in the 60s and 70s today. Image provided by Pivotal Weather.

As the system heads eastward, snow will move into portions of the Mississippi Valley and the Upper Midwest on Friday. The heaviest snow looks to stay just south of the Twin Cities, but even there, moderate to heavy snow is likely. By the time the storm moves out on Saturday, a foot or more of snow is possible in a swath from the Central Plains into the Great Lakes.

Snow isn’t the only threat from this system. As the storm moves eastward, record warmth will remain in place across the Midwest. With warm, moist air in place and a strong cold front approaching from the West, strong to severe thunderstorms are possible across portions of the Lower Great Lakes and Ohio Valley on Friday. Some of the stronger storms that form may contain damaging winds, hail, and possibly tornadoes.

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The Storm Prediction Center has already highlighted the Midwest as an area to watch for severe weather on Friday. Image provided by NOAA.

The system will continue to move eastward, bringing some rain to the East Coast on Saturday, which may cause problems for hockey fans in the Steel City. The next NHL Stadium Series game (Ed – Enough with the outdoor games already. It jumped the shark a long time ago), is scheduled for Saturday at 8pm between the Pittsburgh Penguins and Philadelphia Flyers. The daytime hours will likely be mild with rain, but the rain may change to snow late in the day as temperatures tumble. Either way, it won’t be a pleasant night for fans to be sitting in the stands at Heinz Field. Here at Storm HQ, we despise the Flyers, so we hope their fans not only have to sit through the weather, but watch their team get thumped too.

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That’s former UMass-Lowell RiverHawk (and StormHQ favorite) Scott Wilson hoisting the Stanley Cup last June. Image provided by Toronto Star.

Once it gets past Pittsburgh, that front will head eastward, bringing some rain to us here in New England. It probably won’t be a lot of rain, but temperatures will be in the 50s and possibly 60s ahead of the front on Saturday. Once the front comes through, Sunday will be windy and colder.

After 2 Days of Severe Weather, The East Will Be Quiet This Weekend

Severe weather has been widespread across the eastern half of the nation for the past 2 days, but high pressure will bring much quieter conditions this weekend.

A cold front has been slowly dropping southward over the past 2 days, replacing warm and humid air with cooler and drier conditions. Ahead of the front, strong to severe thunderstorms have cut a large swath of damage.

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Reports of severe weather from Thursday June 16. Image provided by the Storm Prediction Center.

On Thursday, severe weather was widespread across the Mid-Atlantic states from mid-afternoon through the late evening hours. There were over 250 reports of damage from wind gusts as high as 77 mph, with a majority of the reports concentrated in West Virginia, Virginia, and Maryland, including the Washington, DC metropolitan area, where thunderstorms dropped 2.58″ of rain in just a couple of hours at Dulles Airport. In addition to the wind damage and heavy rain, hail as large as baseballs was observed with some of the strong storms. One tornado was also confirmed in Barnes Gap, Pennsylvania.

While most of activity quieted down in the evening, thunderstorms flared up across North Dakota and Minnesota. A cluster of storms moved across the state early in the morning, producing baseball-sized hail near Bismarck. Wind gusts as high as 80 mph were also reported across the region.

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By Friday afternoon, activity started to flare up again across the Southeast ahead of the cold front. A line of strong to severe thunderstorms quickly developed from Mississippi to South Carolina and began to march southward. Widespread wind damage was reported across the region as wind gusted as high as 70 mph in some of the stronger storms. These storms also produced torrential rainfall, with 2.32″ falling in one hour in Columbus, Mississippi.

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Reports of severe weather from Friday June 17. Image provided by the Storm Prediction Center.

Across the Plains states, under sunny skies temperatures soared well into the 90s and lower 100s on Friday.  Another cold front moving into the Western Plains provided the necessary lift to trigger thunderstorms across portions of Kansas and Nebraska. Once the activity got going, it quickly exploded into a large cluster of strong to severe thunderstorms. In McCook, Nebraska, the temperature reached 99 degrees during the afternoon with a dewpoint in the upper 60s to lower 70s. As a severe thunderstorm moved into the region, it produced a wind gust to 72 mph and dropped over 2 inches of rain on the area. It also sent temperatures tumbling into the middle 60s.

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Radar loop for Kansas and Nebraska from Friday afternoon June 17. Loop provided by the College of Dupage.

Much quieter conditions are expected over the weekend as a large area of high pressure builds into the eastern half of the nation. Sunshine and seasonably warm temperatures are expected for most of the region, with thunderstorm activity mostly confined to the Gulf Coast, near the dying frontal boundary that produced severe weather over the past few days, and the Northern Plains, where a strong cold front will slowly move through this weekend.

Here in New England, we’re looking at plenty of sunshine right through Monday. Temperatures will be mainly in the middle 70s to lower 80s on Saturday, and well into the 80s for Sunday and Monday, with a few places possibly topping 90 degrees. The cold front crossing the Northern Plains this weekend will move into New England at some point on Tuesday. With a warm and humid airmass in place, the front will likely trigger showers and thunderstorms as it moves through. However, the timing of the front will be the key to determining whether we just have a few showers and thunderstorms, or more widespread strong to severe storms. The details on that will be come clearer as we get closer to Tuesday.

Severe Weather on Saturday? Maybe.

For the second weekend in a row, there is a threat for severe weather across parts of the Northeast. Unlike last weekend, when the threat was centered on areas from the Delmarva Peninsula southward to the Carolinas, the threat on Saturday is focused on the Northeast.

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Strong to severe thunderstorms moved across the Midwest Friday evening. Loop provided by College of DuPage NexLab.

Low pressure is moving across Lake Superior this evening, with a warm front extending east and southeast from the system across the eastern Great Lakes and into Virginia. A cold front trails the system into the Dakotas and Wyoming. South of these two fronts a very warm and humid airmass is in place, with temperatures well into the 80s and 90s on Friday. Dewpoints were in the 60s to lower 70s across much of the region as well. As the cold front moved into the Upper Midwest, it helped ignite a line of strong to severe thunderstorms. These storms produce golfball-sized hail and wind gusts as high as 76 mph as they cross Minnesota and Wisconsin Friday afternoon and evening.

Usually, strong to severe thunderstorms diminish during the evening hours as they lose the heating of the sun. However, with the warm and humid air in place across the Midwest, these storms will likely continue to march eastward overnight ahead of the cold front.

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Radar loop predicted by the NAM Model from Friday night into Sunday night. Loop provided by College of DuPage NexLab

Forecast models indicate that this line of thunderstorms will move across portions of New York and Pennsylvania Saturday morning and afternoon before moving into portions of New England. How far north and east the warm front moves will help determine where the best chance for severe weather will be located.

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High temperature forecast for Saturday afternoon based on the NAM model. Image provided by WeatherBell.
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Dewpoint forecast for Saturday afternoon based on the NAM model. Image provided by WeatherBell.

Right now, it looks like the warm front will only make it into New York and southwestern New England before the cluster of showers and thunderstorms arrives. Some of the stronger storms could produce downpours, strong winds, and hail across portions of New York, Pennsylvania, and New Jersey.

Across New England, the threat for the afternoon seems less, with more typical showers and thunderstorms expected. However, this does not mean that the threat is zero. If the warm front were to make progress farther northward, the threat would increase. The bigger threat in this region could come at night. The warm front should eventually push through during the evening, allowing the warm and humid air to move into Southern New England. As the cold front continues it eastward march, another round of showers and thunderstorms will likely develop along and ahead of it. As these storms move across New England overnight, some of those storms could produce heavy downpours and strong winds.

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Forecast for 500mb heights and winds based on the NAM model. Image provided by Pivotal Weather.

After the cold front moves through Saturday night, skies should become partly to mostly sunny across the Northeast on Sunday with near-to-below normal temperatures expected. An upper-level low will slowly move across the Gulf of Maine early next week, keep temperatures near or below seasonal normals while heat and humidity dominate the remainder of the eastern two-thirds of the nation.

Here Comes the Heat (Except for You New England)

A large ridge of high pressure will shift from the West Coast into the Nation’s midsection over the next few days, bringing with it some of the hottest weather so far this year to the Plains states.

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Temperature anomalies for the past 30 days across the nation. Image provided by WeatherBell.

A persistent ridge of high pressure has been anchored across the West for the past few weeks, keeping temperatures well above normal for much of May and early June. Numerous records were set across the region, even in normally hot locations like the Desert Southwest, where temperatures exceeded 110 degrees several times. In Death Valley, California, which is frequently the nation’s hotspot, the first 8 days of June have averaged 10.6 degrees above normal, with high temperatures exceeding 115 degrees each day.

While the West has been baking, temperatures across the Plains states have been 1 to 3 degrees below normal for the past month. That is about to change as the ridge slides eastward. By the end of the week and the weekend, the ridge will be centered across the Plains and doesn’t look to move that much right through next week.

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Map showing heights at the 500mb level across the United states on Sunday June 12. Image provided by Pivotal Weather.

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With the ridge of high pressure in place, temperatures will soar well into the 90s across the Plains states and adjacent portions of the Mississippi Valley for much of the remainder of the week, with some triple-digit heat possible across parts of the Dakotas, especially Friday and Saturday.

Some relief will settle into the Northern Plains in the form of a cold front early next week, but the heat will continue from the Southern Plains and Texas eastward into the Southeast. Across these areas, humidity levels will be higher, with dewpoints rising into the 60s and 70s. The result will be heat index values well over 100 degrees across parts of these areas.

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High temperature forecast based off of the GFS model for Saturday June 11. Image provided by WeatherBell

The ridge will also act to suppress thunderstorm activity across the Plains states for much of the remainder of the week. Cluster of thunderstorms may develop across the Northern Rockies and ride over the Ridge and into the Great Lakes and eventually the Northeast later in the week. One of these clusters could produce some severe weather across the Eastern Great Lakes and Mid-Atlantic states on Saturday.

While the heat settles in across the Plains temperatures will remain cool across the Northeast. An upper-level low pressure system will only slowly move eastward across southern Canada over the next few days, moving into the Gulf of Maine by early next week. While temperatures surge into the 90s and lower 100s across the Dakotas on Friday, temperatures will only be in the 60s to lower 70s across the Northeast, with parts of Northern New England staying in the 50s. A few showers may pop up during the afternoon, and across some of the higher peaks of the region, some wet snowflakes could mix in with the rain.

There are signs that things could change in New England, but not until the end of next week. Some of the forecast models are indicating the possibility that the upper-level low finally moves out, allowing the heat to finally spread eastward. The latter half of June could feature much warmer conditions if this does come to pass.

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Temperature anomalies forecast by the GFS Ensemble for the period June 19 through June 24. Image provided by WeatherBell.

Colin (or what’s left of it) is Hitting Florida, Severe Weather on Tuesday in New England?

Often, you’ll hear meteorologists say not to focus on the center of a tropical system, because its effects can be felt far from the center. Tropical Storm Colin is a terrific example of this.

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Satellite loop of Tropical Storm Colin from Monday afternoon. Loop provided by NOAA.

The “center” of Tropical Storm Colin is about to cross the coast of the Big Bend of Florida this evening. As of 11pm, the center was about 70 miles east of Apalachicola, Florida, moving northeast at 22 mph. Maximum sustained winds are near 50 mph. While the center is about to cross the coast, most of the thunderstorm activity is located east and northeast of the center. Heavy rain has been falling for most of the day across much of Florida as well as parts of Georgia and the Carolinas, but there have only been a few reports of tropical-storm force winds.

Tropical Storm Warnings remain in effect for the Gulf Coast of Florida from Indian Pass to Englewood, and along the Atlantic coast from Sebastian Inlet, Florida northward to Oregon Inlet, North Carolina. The current forecast from the National Hurricane Center calls for Colin to cross northern Florida and southern Georgia overnight, then move back into the Atlantic on Tuesday. Colin will likely have lost tropical characteristics by then (some would that it is already doing that), but it may still strengthen a bit as it passes offshore of the Carolinas. The main impact will be heavy rain and flooding near the coast. Flood watches are in effect for much of the region.

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Expected rainfall between Monday evening and Thursday evening. Image provided by WeatherBell.

Once Colin or its remains pull away from the Carolinas it will head out into the open Atlantic. Aside from impacting the fish and marine traffic, the system could pass close enough to Newfoundland to bring some gusty winds and rainfall to the island later this week.

Meanwhile, the first tropical depression of the season has formed in the Eastern Pacific Ocean. As of 11pm EDT, Tropical Depression One-E was centered about 125 miles south-southwest of Salina Cruz, Mexico, heading towards the northeast at 7 mph. A Tropical Storm Watch has been posted for the coast of Mexico from Puerto Escondido to Boca De Pijijiapan.

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Computer model forecasts for the intensity of Tropical Depression One-E. Image provided by Tropical Tidbits.
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Computer model forecasts for the track of Tropical Depression One-E. Image provided by Tropical Tidbits.

The system is expected to remain weak while drifting towards the northeast over the next day or two. The system could dissipate before making landfall. One thing it will do is produce very heavy rainfall across southern Mexico and adjacent Central America. Rainfall totals of 5-10 inches are expected with heavier amounts possible. This will lead to flash flooding and mudslides across the region.

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GFS model forecast for rainfall across Mexico for the next 4 days. Image provided by Pivotal Weather.

Closer to home, we have a possibility of severe weather around here on Tuesday. A cold front will cross the region during the afternoon, likely producing some showers and thunderstorms. Before that, we’ll have some cloud cover and showers around in the morning. If we can get enough sunshine to develop during the afternoon, it could help produce instability for another round of showers and thunderstorms, some of which could be strong to severe. Right now, it looks like the best chance for and strong storms will be from western and central Massachusetts into southern Vermont and southern New Hampshire, but again, this is dependent on how much sunshine we get. Any storms that do form may contain heavy downpours, gusty winds, and hail.

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NAM model forecast of CAPE values for 4pm Tuesday. Notice that the higher values are across central and western Massachusetts. Image provided by Pivotal Weather.
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NAM model forecast of Lifted Index values for 4pm Tuesday. Notice that the higher values are across central and western Massachusetts. Image provided by Pivotal Weather.

After the front moves through, cooler weather will settle in for Wednesday, but a secondary cold front may produce another round of showers and thunderstorms Wednesday afternoon. With much cooler air aloft, there’s a better chance that any storms that form on Wednesday may contain small hail, but widespread severe weather isn’t expected.

A Classic “Good News/Bad News” Weekend is Coming Up

Sunday isn’t looking that great around here, but things could be worse. Severe weather is likely across the Mid-Atlantic states on Sunday. Meanwhile, Tropical Storm Bonnie will head out into the open Atlantic this weekend, but another area is being watched for development near the Yucatan Peninsula.

We’re starting the weekend off with a fantastic Saturday here in New England, but big changes are coming. High pressure builds in today, so after some morning fog burns off we’ll have a mix of sunshine and clouds this afternoon. High temperatures will get into the upper 60s and 70s near the coastline, but away from the water, highs will be in the lower to middle 80s, with a few spots possibly reaching the upper 80s. Make sure you get outside and enjoy it because clouds will stream in late in the day ahead of a cold front moving across the Midwest.

Ahead of that front, with a warm, humid airmass in place, showers and thunderstorms will develop, some of which will become strong to severe. Widespread severe weather isn’t expected on Saturday, but there is a risk for some strong to severe storms from the Great Lakes into the Ohio Valley.  Sunday will be a different story. The ingredients will be in place for a severe weather outbreak from the Mid-Atlantic states into the Carolinas.

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GFS forecast of Lifted Index values for Sunday afternoon. Image provided by Pivotal Weather
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GFS forecast of CAPE values for Sunday afternoon. Image provided by Pivotal Weather

As temperatures rise into the 80s to lower 90s, the airmass will become increasingly unstable. CAPE, which is short for Convective Available Potential Energy, is a measure of instability through the atmosphere. CAPE values of 1000-3000 J/kg are expected from the Delmarva Peninsula into the Carolinas Sunday afternoon. These values are indicative of moderate instability in the atmosphere. The “Lifted Index” is the difference in temperature between the atmosphere at 500mb (about 18,000 feet up) and a parcel of air from the surface that is lifted to 500mb. A negative value is indicative of unstable conditions. On Sunday, forecast models are showing values between -4 and -9 across the Mid-Atlantic states.

While Sunday may start off cloudy with showers across parts of the region, breaks of sunshine should develop by early afternoon, with showers and thunderstorms developing along the eastern slopes of the Appalachians. Thunderstorm activity will likely organize into a line that will march eastward, reaching the Washington/Baltimore area by late afternoon, and the Richmond/Norfolk area towards evening. The main threats with any storms that do develop are strong winds, hail, and heavy downpours, with a few tornadoes also possible.

Up here in New England, we won’t have to worry too much about severe weather. That doesn’t mean we’ll have a great day. Rain will likely develop Sunday morning and continue for much of the day, ending late Sunday night or early Monday morning. We’re looking at an inch to an inch and a half of rain across the region, which we really need, as it’s been dry for the past few months. If you’ve got outdoor plans for Sunday, we’d start looking for alternate ideas. While the day may not be a complete washout, it’ll be cloudy, relatively cool (60s to lower 70s), and raining off and on for much of the day.

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Most recent update on drought conditions across the Northeast. Image provided by NOAA.

Meanwhile, Tropical Storm Bonnie has redeveloped east of North Carolina this evening. As of 5pm Friday, Bonnie was centered about 285 miles east of Cape Hatteras, NC, moving towards the east at 13 mph. Maximum sustained winds are near 40 mph. Bonnie is expected to head out into the open waters of the Atlantic over the weekend while steadily weakening.

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Satellite loop of Tropical Storm Bonnie from Friday afternoon. Loop provided by NOAA.

While June is usually quiet in the tropics, another area of disturbed weather in the western Caribbean is being monitored for development this weekend. A cluster of showers and thunderstorms will head towards the Yucatan Peninsula this weekend and then turn more towards the north and head into the Gulf of Mexico. For several days now, forecast models have been indicating that this system could become a tropical depression or tropical storm over the Gulf early next week.

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Computer model forecasts for the strength of a potential tropical system in the Gulf of Mexico. Image provided by Tropical Tidbits
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Computer model forecasts for the track of a potential tropical system in the Gulf of Mexico. Image provided by Tropical Tidbits

Most forecasts are for the storm to turn more toward the northeast early next week and cross the Florida Peninsula as a tropical depression or weak tropical storm. While winds aren’t expected to be strong, the main impact will be heavy rainfall. The storm could drop as much as 4-8 inches of rain on the Sunshine State next week, especially the southern half of the state. Heavy rain fell on portions of the region during May, so additional heavy rain could lead to flooding in parts of the area.

After all that, we didn’t even talk about the potential tropical system in the Eastern Pacific, the record heat in the West, the flooding in Paris and parts of western Europe, or the powerful storm impacting southeastern Australia. Yup, things are pretty busy in the weather office.