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Sunday/Monday AM storm threat


free_man

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looks like no TOR watch for wizzy based on that MCD.

I really am not sure what to make of the svr threat today. There's definitely been more sun than I expected... even from 10z this morning. Instability and shear look good but I'm still pretty hesitant to pull the trigger on a big event given some of the negatives still floating around.

Looka like that lead s/w is firing off a few storms right near in the Hudson Valley. I even have a few shwrs popping sw of BOS now.

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What are you concerned about the most as far as negatives go?

The models showed us mixing down drier air as the boundary layer grows this morning and cutting off instability fairly dramatically. So I'm not sure how that will play off. Also the convection is firing pretty early to our west... so between clouds and poorly timed convection... not sure what to expect for later on.

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The models showed us mixing down drier air as the boundary layer grows this morning and cutting off instability fairly dramatically. So I'm not sure how that will play off. Also the convection is firing pretty early to our west... so between clouds and poorly timed convection... not sure what to expect for later on.

Hopefully with the southwesterly flow in the lower levels of the atmosphere and with the LLJ potentially increasing later on this will help to continue pumping in moisture into the lower levels making in more difficult for that drier air to mix down.

Convection firing early is definitely a huge concern. With virtually no capping in place and moderate instability any weak s/w will fire something up...hopefully this doesn't kill lapse rates any and doesn't become an issue.

Agree though, tough call on today on what to really expect.

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OKX doing a special 18z balloon sounding!

Yuppers.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE NEW YORK NY

1206 PM EDT SUN AUG 21 2011

.NEAR TERM /THIS AFTERNOON AND THIS EVENING/...

-- Changed Discussion --PLEASE NOTE THAT WE WILL BE TAKING A SPECIAL 18Z UPPER AIR

OBSERVATION IN SUPPORT OF SEVERE WEATHER OPERATIONS. FORECAST STILL

BASICALLY ON TRACK. STRONG TO POSSIBLY SEVERE THUNDERSTORMS

ANTICIPATED WITH SBCAPES UP TO 2500 J/KG AS PER LAPS ANALYSIS OVER

THE WESTERN ZONES AND A PRE-FRONTAL TROUGH DEVELOPING JUST TO OUR

WEST.

MODELS CONTINUE TO PROG TSTMS THIS AFTERNOON EVOLVING INTO

WIDESPREAD TSTMS THIS EVENING AND THROUGH THE OVERNIGHT AS A COLD

FRONT AND INCREASING DYNAMICS APPROACH US.

PARAMETERS REMAIN IN PLACE FOR A SEVERE OUTBREAK. 00Z NAM CAME IN

A BIT HIGHER WITH THE BRN...RESULTING IN A TENDENCY TOWARDS

MULTICELLULAR. SYNOPTIC LOW LEVEL DIRECTIONAL SHEAR IS

LIMITED...HOWEVER AS STORMS DEVELOP ALLOWING FOR LOW LEVEL

INFLOW...EXPECT THIS SHEAR TO BE ENHANCED RESULTING IN AN

ENVIRONMENT MORE SUPPORTIVE OF SUPERCELLS.

ALTHOUGH THERE ISN/T A WARM FRONT IN THE VICINITY OF THE CWA WITH

THIS EVENT...EHI STILL IN THE 1-2 RANGE SUPPORTING A TOR

POTENTIAL. INFLOW MAY ENHANCE THESE NUMBERS AS WELL BUT

COMPUTATION IS BASED ON SRH SO CONFIDENCE NOT AS HIGH AS IN THE

BRN. ANY OUTFLOW BOUNDARIES WILL ELEVATE THE SPIN UP RISK...AND

AS THE CONVECTION CONSOLIDATES TONIGHT THE RISK COULD SHIFT TO LI

WITH COASTAL BOUNDARY DEVELOPMENT.

PW/S STILL ON TRACK TO REACH JUST UNDER 2 INCHES SO HEAVY RAIN HAS

BEEN INCLUDED IN THE FCST. SEE HYDRO SECTION FOR ADDITIONAL INFO.

:popcorn:

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It's always extremely difficult pinpointing down convection to a specific location or small area but NW MA is in the threat area for severe storms; the numbers are about as good there as anywhere else as far as instability/shear is concerned.

12z NAM coming in and actually it doesn't look all too bad...although it is on the weak side with the ML lapse rates it definitely isn't showing any issues with instability or shear. Actually it developes the strongest helicity values right in western/central MA and CT...east of where the SPC has the 5% TOR risk.

Thanks, Paul. I know the 'hits' can't be really forecasted, but it's nice to know that I'm not beyond the scope of the good parameters.

75.1/71. humid, eh?

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such a tropical looking sky out here again today. LCLs are ridiculously low. it's like watching a strat. cu deck bust through vertically...so funky. huge fat towers that look like a fog deck. with deep blue sky mixed in. and they are so moisture rich each cloud can drop a shower.

LCL heights are around 750-850 meters!!

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