As the pattern over North America shifts, an extended period of potential severe thunderstorms targets the central U.S. Although this update covers May 6-10, thunderstorms are ongoing today (May 5th) and were prevalent in prior days as well. The difference here is that we are gradually starting to see more and more potentially potent setups on the horizon.
Wednesday, May 6th: This day has been on the radar for a while and things are coming into somewhat better focus. As shortwave energy pivots
As the calendar passes deeper into June, there is typically a steady drop-off in the frequency of severe weather threats across the U.S. Last year featured a grand finale to the severe weather season with a fairly significant sequence or tornado events across portions of the north-central U.S. from June 16th to 18th. While this year will likely not see quite an intense show as June 2014, there could very well still be some respectable severe activity with tornadoes.
Mid-June of this year has be
Here is a snowfall map using reports from various sources. Many of the reports came from this forum and the National Weather Service. Only social media reports that passed through quality control were considered. All reports gathered were carefully considered and compared before being included.
Snow reached southern Connecticut during the predawn hours on January 23rd. The snow gradually moved inland, dropping the most persistent bands of moderate to heavy snow on an axis from Fairfield Coun
April is seen as a transition month during the severe weather season, as the frequency of tornadoes typically picks up rather quickly through the month. Despite what the calendar has to say, tornado activity has been fairly lackluster so far this month. In fact, after moving well above the average to-date tornado count in late February, the U.S. has steadily been losing ground. As it stands now, through April 18, the U.S. is near average this year for tornadoes, but with a relatively quiet rest
I see this event as a widespread 2-4 incher across most of interior SNE. The tough call comes along I-95 for BOS-PVD-GON, as often is the case. I do think most areas even along the South Shore get a thump of snow/sleet at the beginning.
I'm not really all that confident on widespread 4"+ amounts, but I've outlined an area with a black dotted line that could see locally 5-6 inches.
I also expect precipitation to quickly shut off in the morning (by 7 or 8 a.m. across much of Connecticut) and ta
A strong low pressure system is forecast to move up into the Great Lakes by Thursday and eventually into southeastern Canada late Friday into Saturday. A potent cold front associated with this storm will move towards the Appalachians by the second half of Friday. (For Wednesday and Thursday, severe thunderstorm activity is probable for the Mississippi Valley and portions of the western Ohio River Valley.
I see a marginal setup for severe storms from Central N.Y. into the middle Appalachians. Ev
An early season storm is expected to bring a heavy, wet snow to the interior hills of the upper mid-Atlantic region and New England on Wednesday into very early Thanksgiving morning. While the big cities from Philadelphia to New York and Boston can expect some snow, the greatest amounts will be to their north and west.
Low pressure will develop along the Carolina coast this morning and ride up the East Coast. With the low passing close to, if not over Cape Cod, no strong high pressure center in
Here is a final snowfall forecast for the upper mid-Atlantic region and southern New England for the Blizzard of 2015. No major changes were made to the forecast, but the western fringe was trimmed somewhat.
It's becoming a nowcast situation, as the computer models are relatively all over the place. The 12z Euro is one extreme (heavy west), with the 00z RGEM further east and much less impressive. Based on radar trends, the previous forecast map and a consideration to the model consensus, here i
A pattern change is soon underway that will leave much of the U.S., especially the eastern two thirds, feeling spring fever. Unlike patterns in recent years, a prevalent ridge of high pressure off or near the East Coast (“Southeast ridge”) will maintain generally at or above average temperatures for the region. The only exception may be parts of the Northeast, where some backdoor cold fronts could keep temperatures cooler. To the west, troughing across the West Coast should help keep a much-need
The final few days of April finished on the quiet side in terms of severe and that continued into May 1st. With that said, a larger-scale pattern change is likely to be accompanied by multiple threats of severe weather in the coming days.
Saturday 5/2: Not seeing anything major here. Although we should finally see some modest instability up into the central Plains, dew-points are only expected to rise into the upper 40s to lower 50s across the area with some weak forcing during the evening. One
Map above is based on reports from various sources, including this board, the National Weather Service and data viewers from across the state sent in.
Event Summary:
Scattered snow showers reached portions of western Connecticut by late morning on the 29th. This snow was associated with weakening low pressure over Pennsylvania.
The main storm began to develop east of Virginia during the afternoon.
Steady precipitation overspread the state from southwest to northeast between about 1 and 3 p.m
Outside of the hilly terrain across the interior, this snow event does not look like a big deal. I expect 3-6"+ across the east slopes of the Berkshires and much of Worcester County. Connecticut only sees a brief period of rain, with generally 1-3" across the northern hills.
The boundary layer temperatures are simply too marginal for much to change, especially with dew-points in the upper 20's as of early Tuesday evening. Downstream observations don't indicate that cold air damming across New E
A cold front is forecast to move from west to east across the East Coast on Wednesday. The result could mean scattered thunderstorms along the front, along with a few severe thunderstorms.
(Marginal threat)
Middle Appalachians into DE, PA, inland NJ and interior NY.
A similar setup to this past Friday is expected on Wednesday, with a cold front moving across the area during the afternoon and evening hours. The only difference here is that the cold front is not as strong as that scenario (last
A tornado outbreak appears likely on Tuesday into Tuesday night across portions of Alabama, Mississippi and Tennessee. Over a broad area from the lower Mississippi Valley to the Tennessee and lower Ohio valleys, scattered severe thunderstorms are expected to develop Tuesday afternoon, continuing into Tuesday evening. The threat will shift east overnight, gradually lessening, especially after midnight. The setup looks favorable for several tornadoes, including at least one or two strong tornadoes
What a challenging forecast and I still think the models have more to resolve, mainly on Sunday with respect to enhancement of snow along a trough.
Essentially, a light mixture of rain and snow overspreads the region through later today. Across the lower Hudson Valley, Connecticut, Rhode Island and southeastern Massachusetts, I expect virtually no daytime snow accumulation. Low pressure develops south of the area tonight, but the heaviest precipitation and best lift also stays south.
Some snow
A notable threat of severe thunderstorm activity in early February has been showing up in the models for several days now. As the event gets closer, confidence is increasing that a setup favorable for severe weather is likely to occur. However, there still are a lot of details left to be nailed down. The broad pattern involves a vigorous trough in the jet stream digging across the Four Corners region on Monday, February 1st and swinging east to northeast across the United States into Groundhog D
As a warm front lifts into the Northeastern United States on Wednesday, a warmer, more humid air-mass floods into the Northeast. Some thunderstorm development is forecast and some of those storms may be capable of reaching severe limits, particularly across portions of New York and west-central New England.
Low threat (Conditions are somewhat favorable for severe thunderstorms)
Interior New England, New York, northwestern New Jersey and norther Pennsylvania:
As a warm front clears, an increas
As a warm front lifts into the Northeastern United States on Wednesday, some thunderstorm development is forecast and some of those storms may be capable of reaching severe limits.
Low threat (Conditions are somewhat favorable for severe thunderstorms)
Central Pennsylvania and portions of Maryland:
A warm front is expected to lift into the Northeast on Wednesday. The focus is across the warm sector where some strong wind shear combines with surface/low-level instability to enhance the severe
As a cold front moves towards the East Coast on Saturday, some thunderstorm development is possible during the afternoon and early evening hours.
Low threat (Conditions are somewhat favorable for severe thunderstorms)
Mid-Atlantic region (east of Appalachians), lower Hudson Valley and SW New England.
Conditions will destabilize in a warm, somewhat moist air-mass before an approaching cold front swings from west to east through the area. The biggest question mark is how much daytime heating wi
There have been no major changes to the previous forecast. Some of the snowfall totals have been trimmed back ever so slightly. A fairly widespread area of 5 to 10 inches of snow is expected, with a jackpot across much of interior Massachusetts, where most or all of the precipitation should fall as snow.
Snow becomes heavy at times early Monday morning and begins to mix with sleet and freezing rain by the morning rush around New York City. The mixing then spreads into southern New England by mi
Another vigorous through is forecast to sweep through the south-central states over the next few days, bringing a threat of thunderstorms to the region. Although this threat looks substantially less impressive than the event in mid-November, there still exists the potential for at least a few severe thunderstorms, especially Saturday.
The setup for Saturday has had a lot of question marks and red flags from the start, but now that the event is approaching, things are coming into better focus
The threat for severe thunderstorms, including tornadoes, continues for Tuesday. The area of focus is the lower Mississippi Valley into portions of the Tennessee Valley and lower Ohio Valley. Nothing significant has changed from the computer models, suggesting that a severe weather event is still probable Tuesday into Tuesday night with at least a few tornadoes possible. There are still details to nail down, but at least a few key ingredients are in place for tornadoes across the region.
Thi
A strong cold front approaches the Appalachians Friday afternoon and evening. Along that cold front, a squall line with thunderstorms is currently expected is develop.
(Marginal threat)
Middle Appalachians into Pennsylvania, northwestern New Jersey and interior New York:
Daytime heating is expected to push temperatures into the low to mid-70's in the valley locations with mid to upper 60's in the higher elevations. Low and mid-level clouds will likely limit just how unstable the atmosphere c
I've been creating daily 6-day forecasts for the better part of this year, with a focus on inland Connecticut. Before making any forecast, I take a close look at the computer model forecasts through Day 6, including a few forecast techniques to see how verification pans out. In April, I had 29 days worth of data, out of a possible 30, to measure forecast accuracy.
As expected, forecast error generally increases with time. It is interesting to note a spike at Day 5 and a decrease at Day 6. That
For the fourth year in a row, overall severe thunderstorm activity, including tornadoes, finished below average across the Lower 48. This graphic shows the severe thunderstorm watch departure from the 13-year average. The vast majority of the U.S. saw at or below average numbers of severe thunderstorm watches. The greatest departures from average were across the central Plains into parts of the Midwest. The only state with more severe thunderstorm watches than average was Texas, with a higher in
