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March, 2019


snowman19
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The few models that have the wave show it coming through early morning. Low level temps and thicknesses are plenty cold for accumulating snow should there be a narrow fronto/defo band just N of the low. Not unlike the system early last April...
Maybe it's my location? Central Long island.
High 43 degrees Monday.8d48ff939a152f4872a636fc57f8b844.jpg

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Looking more and more likely a few of these storms could become severe this evening. We're getting 925mb moisture advection timed with a weakening of the stout cap that's been in place all day.  The surface heating really helped out low level lapse rates (to achieve some potential downbursts), but a number of features are coming together at the right time. Mid-level lapse rates have weakened a bit from those observed on this morning's soundings, but they're more than enough. Wind fields easily support gusts of 40-50KT and the shear present also may support a few rotating (elevated) storms with small hail.

Most of the hi-res shows these isolated individual cells joining up into a squall line this evening. Should at least get a good light show this evening.

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26 minutes ago, purduewx80 said:

Looking more and more likely a few of these storms could become severe this evening. We're getting 925mb moisture advection timed with a weakening of the stout cap that's been in place all day.  The surface heating really helped out low level lapse rates (to achieve some potential downbursts), but a number of features are coming together at the right time. Mid-level lapse rates have weakened a bit from those observed on this morning's soundings, but they're more than enough. Wind fields easily support gusts of 40-50KT and the shear present also may support a few rotating (elevated) storms with small hail.

Most of the hi-res shows these isolated individual cells joining up into a squall line this evening. Should at least get a good light show this evening.

 

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2 hours ago, purduewx80 said:

Looking more and more likely a few of these storms could become severe this evening. We're getting 925mb moisture advection timed with a weakening of the stout cap that's been in place all day.  The surface heating really helped out low level lapse rates (to achieve some potential downbursts), but a number of features are coming together at the right time. Mid-level lapse rates have weakened a bit from those observed on this morning's soundings, but they're more than enough. Wind fields easily support gusts of 40-50KT and the shear present also may support a few rotating (elevated) storms with small hail.

Most of the hi-res shows these isolated individual cells joining up into a squall line this evening. Should at least get a good light show this evening.

Nice call. Severe thunderstorm warning for here in Westchester County.

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Courtesy of the combination of breaks of sunshine and an exceptionally warm air mass aloft, today saw the warmest readings since last autumn. In a few locations, the mercury approached or reached the daily record high temperature.

Some highlights:

Albany: 72° (tied record set in 1989) -- warmest reading since October 11, 2018 (72°)
Allentown: 74° -- warmest reading since October 11, 2018 (79°)
New York City: 75° -- warmest reading since October 11, 2018 (77°)
Newark: 77° -- warmest reading since October 11, 2018 (81°) 
Philadelphia: 77° -- warmest reading since October 11, 2018 (83°)
Poughkeepsie: 72° -- warmest reading since October 11, 2018 (75°)
Teterboro: 76° -- warmest reading since November 2, 2018 (79°)
Trenton: 74° (old record: 72°, 1971 and 2002) -- warmest reading since October 11, 2018 (82°)
Wilmington, DE: 79° -- warmest reading since October 11, 2018 (83°)

The ENSO Region 1+2 anomaly was +0.50°C and the Region 3.4 anomaly was +1.00°C for the week centered around March 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.50°C and the ENSO Region 3.4 anomaly has averaged +0.69°C. Similar ENSO conditions will likely persist through much of March.

The SOI was -8.33 today. It has been negative for 37 out of the last 38 days.

Today's preliminary value of the Arctic Oscillation (AO) was +1.381. The AO has now been positive for 36 consecutive days. The last time the AO was positive for at least that long was during the April 13, 2018 through June 3, 2018 period when the AO was positive for 52 consecutive days. Historic probabilities favor the continuation of a predominantly positive AO through the remainder of March.

On March 14, the MJO moved into Phase 3 with at a low amplitude, 0.809 (RMM). The amplitude was lower than the March 13-adjusted figure of 1.063. The MJO will likely remain in Phase 3 at a low amplitude for at least several days.

Following today's warmth, a brief shot of cooler air will move into the East. There is even the possibility of some light rain or snow across parts of the northern Middle Atlantic region on Monday morning. However, by late next week temperatures could again be rising to levels above seasonal norms.

In part, the forecast strongly positive PNA will contribute to that outcome. Unlike during January and the first half of February, shorter wave lengths now result in the PNA's having a direct relationship with regional temperatures and an inverse relationship with snowfall prospects.

During the March 16-31, 1950-2018 period, the mean temperature in New York City was +1.1° above climatology when the PNA was +1.000 or above. The mean temperature was 0.5° below climatology when the PNA was negative. In terms of snowfall, the frequency of measurable snow events in New York City was somewhat less than half of climatology when the PNA was +1.000 or above while that frequency was just over 40% above climatology when the PNA was negative.

Based on the latest guidance, New York City's average temperature for the March 16-31 period could be approximately 1.6° above normal. As a result, the implied probability of a colder than normal March in New York City has decreased to 55%.

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