PM Update: Warm, stormy end to the work week

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Unsettled weather has gripped the area over the past day or so — after a prolonged period of pleasant and dry weather. Over 2 inches of rain fell in New York City on Wednesday as an upper level low moved near the area and moisture streamed into the area. Thursday featured some rain as well, but it was more spotty and scattered as opposed to the synoptic type heavy rain which fell along the warm front Wednesday. The forecast will remain unsettled through the end of the work week and into the weekend, but a warming trend will also be noticeable. This will be especially true on Friday, ahead of a cold front, when temperatures could warm into the upper 70’s to lower 80’s throughout much of New Jersey towards New York City.

The catch, however, will be the disturbance approaching aloft — and the cold front approaching at the surface. Showers and thunderstorms will become scattered by Friday afternoon over Pennsylvania and Western New Jersey and could move into the area overnight Friday into Saturday. Although Saturday will likely be warm as well, thunderstorms and periods of rain appear likely with the frontal boundary near the area. The Storm Prediction Center has placed the area in a 5% risk of severe thunderstorms (a tier below the 15% that would trigger a “Slight Risk). Clearing is expected by Sunday with colder temperatures moving into the area behind the front.

Stay tuned over the next day or so for updates on the approaching disturbance and cold front, as well as any potential thunderstorms and associated watches and warnings.

For a day-by-day breakdown of the forecast, check out our Forecast Brief. If you’re looking to get more details and technical reasoning, check out our Technical Forecast Discussion. Have a great night!

Potential for Late Season Freeze

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One of the coldest springs in recent history nationwide continues to roll forward with the potential for one more shot of winter across the Mid-west and Northeast. Since February 1st, we have seen a dramatic reversal in temperature anomalies from the blowtorch Dec-Jan period to the very cold Feb-Mar-April of 2013. The only mild areas have been northeastern New England and the SW US – all other locations have been feeling the chill. The epicenter of this cold has been the Mid-west and northern Plains, where many stations experienced over a 20 degree decrease in mean temperature from March 2012 to March 2013:

Last3mTDeptUS

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Chicago  IL:    -27.7º

2012: 64.0º

2013: 36.3º

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Des Moines IA: -26.0º

2012: 64.4º

2013: 38.4º

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Indianapolis IN: -25.3º

2012: 66.5º

2013: 41.2º

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La Crosse WI: -27.5º

2012: 59.4º

2013: 31.9º

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Marquette MI: -24.3º

2012: 50.6º

2013: 26.3º

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Milwaukee WI: -26.3º

2012: 59.1º

2013: 32.8º

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Minneapolis MN: -25.2º

2012: 56.3º

2013: 31.1º

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St. Louis MO: -22.1º

2012: 70.4º

2013: 48.3º

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The month of May began with similar magnitude of cold in the same areas that have been targeted over recent months. Brutal, recording breaking cold encompassed the Plains, with the historic event of snow flakes flying as far south as Arkansas. The coastal Northeast has been near normal with a northeasterly flow off the Atlantic, but surface high pressure made the airmass a beautiful, dry, sunny one for us. The interior Northeast and OH Valley have been much warmer the past week, though that will change for a time next week.

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Pleasant pattern will come to an end next week

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[alert type=”info”]Don’t Forget! The Eta Aquarid meteor shower peaks Saturday Night through Sunday Morning. Good viewing conditions are expected with clear skies. Up to 30 meteors per hour possible. Let us know if you see any![/alert]

Blocking patterns often produce anomalous weather somewhere in the United States — and frequently, it occurs in the Eastern 1/3 of the United States. Not this time. The blocking pattern, which became anomalous late this past week, drove a cutoff low into the Central United States that produced an amazing late-season snowfall across parts of the United States. The unsettled weather, however, has remained over the Central United States thus far and has not made much progress to the east — as the block has actually collapsed overhead and high pressure in association with it has settled over the Northeast US.

This will change next week. Until then, however, a few more days of pleasant weather can be expected through the weekend and into early next week. The game changer will occur once the decaying cutoff low, once responsible for historic late season snow over the Central US, drifts up the Eastern seaboard. Forecast models are in good agreement that it will bring increased chances of showers and thunderstorms as well as cooler temperatures. In addition, a slightly cooler and more unsettled pattern looks likely through the medium to long term forecast period.

For a day-by-day breakdown of the forecast, check out our Forecast Brief. If you’re looking to get more details and technical reasoning, check out our Technical Forecast Discussion. Have a great Saturday night!

Blocking sends disturbance south from Greenland

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High latitude blocking, which we discussed earlier this week as an important predictor in summer temperature patterns around our area, is at it again. A large and anomalous blocking ridge, building north from Canada towards the higher latitudes into Newfoundland and Southeastern Greenland, is forcing a disturbance and upper level low to shift southward. The disturbance will track southward today — and can be seen on water vapor and visible satellite imagery early this afternoon. The feature won’t directly impact our area, nor will it cause any widespread unsettled weather on the east coast, but it could reinforce east/southeasterly winds as it passes later this week.

The track of the disturbance is the most unusual. To see an upper level low or disturbance track southward from Greenland all the way to a point just a few hundred miles off of the US East Coast is exceedingly rare. However, one glance at the blocking pattern aloft tells you the story — the disturbance had nowhere else to go, being forced into a small window between the trough over the Atlantic and the blocking ridge to the west over Canada. (Click read more for more imagery).

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