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Spring severe weather chatter


Ian

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HPC-

...EASTERN OH VALLEY/MID ATLANTIC...

A STRONG SHORT WAVE DROPPING SOUTHEAST OUT OF THE UPPER GREAT

LAKES TO THE MID ATLANTIC STATES ON DAY 1 PARALLELS A FRONTAL

BOUNDARY STRETCHING OVER THE SAME AREA...INDUCING CYCLOGENESIS ON

THE FRONT. MOISTURE AND INSTABILITY AHEAD OF THE LOW WILL FUEL

CONVECTION THAT COULD PRODUCE HEAVY TO EXCESSIVE RAINFALL ACROSS

PORTIONS OF THE MID ATLANTIC...ESPECIALLY AFTER 17/00Z.

CONVECTION WILL BE ONGOING ALONG A FRONTAL BOUNDARY STRETCHED FROM

SOUTHERN MI INTO NORTHERN WV AND NORTHERN VA EARLY IN THE PERIOD.

THE FIRST SHOT OF CONVECTION SHOULD EXIT THE COAST BEFORE 16/18Z.

THE NEXT SHOT OF CONVECTION IS EXPECTED TO DEVELOP AHEAD OF A

SHORT WAVE TRACKING SOUTHEAST CLOSE TO THE SURFACE BOUNDARY FROM

THE UPPER GREAT LAKES TO THE MID ATLANTIC...AS A SURFACE

REFLECTION TRAVELS DOWN THE FRONT AS WELL. INITIALLY...THE

CONVECTION THAT DEVELOPS OVER THE EASTERN OH SHOULD BE MAINLY

OUTFLOW DOMINATED...AS MODEL SOUNDINGS SHOWED A FAIR AMOUNT OF DRY

AIR IN THE MIDDLE LEVELS.

HOWEVER...AFTER 17/00Z...THE LOW LEVEL INFLOW AHEAD OF THE SURFACE

AND MID LEVEL SYSTEMS BACKS TO THE SOUTHEAST...WHICH TAPS A RICH

RESERVOIR OF 1.75 TO 2.00 INCH PRECIPITABLE WATER AIR RESIDING

OVER THE SOUTHEAST AND SOUTHERN MID ATLANTIC EARLY THIS MORNING.

MODEL SOUNDINGS INDICATED THAT THE COLUMN BECOMES INCREASINGLY

MOIST AS THE INFLOW INCREASES...AND WARM RAIN PROCESSES BECOME

MORE IMPORTANT. THE INFLOW ALSO BECOMES ALMOST DIRECTLY OPPOSED TO

THE MOTION OF THE CONVECTION FOR A TIME...CENTERED ON 17/06Z.

BACKBUILDING BECOMES INCREASINGLY LIKELY IN THIS

SCENARIO...RAISING THE SPECTER FOR FLASH FLOODING ACROSS PORTIONS

OF THE MID ATLANTIC.

THERE IS A MULTI MODEL SIGNAL FOR 2.50 TO 3.50 INCH QPF AMOUNTS

EXTENDING FROM WESTERN PA ACROSS THE EASTERN PANHANDLE OF WV INTO

WESTERN MD/NORTHERN VA...WITH THE 00Z WRF ARW SHOWING LOCAL

AMOUNTS OVER 4.00 INCHES. GIVEN THE STRENGTH OF THE INFLOW...AND

THE DEPTH OF THE MOISTURE FUNNELED INTO THE REGION FROM THE

SOUTHEAST STATES...THESE AMOUNTS SEEM PLAUSIBLE. THE CONVECTION

BEGINS TO WEAKEN AS IT STARTS TO EXHAUST ITS INSTABILITY SUPPLY

AFTER 17/06Z...AND THE CONVECTION COMPLEX SHOULD REACH EASTERN MD

THROUGH SOUTHEAST VA BY 17/12Z.

AFTER A RELATIVELY DRY PERIOD OVER PORTIONS OF THE MID

ATLANTIC...THE ONE AHD THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE

FAIRLY HIGH (WITH VALUES ARE LOW AS 1.00 TO 1.50 INCHES ACROSS

SOUTHERN WV). HOWEVER...HIGH RAINFALL RATES IN THE HIGH MOISTURE

CONTENT AIR...AND THE POTENTIAL FOR TRAINING SUGGEST THAT A SLIGHT

RISK AREA WILL BE NEEDED FOR PORTIONS OF EASTERN OH VALLEY INTO

THE MID ATLANTIC.

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The idea of the mid-Atlantic being on the northern periphery of a big ridge with fast WNW flow overhead seems to be dead. Severe chances next week not looking good.

Not sure it's totally dead but that offshore low is messing with the best chance as of now on Tuesday. Prob can still eke something out in the region but doesn't scream big at the moment.
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Not sure it's totally dead but that offshore low is messing with the best chance as of now on Tuesday. Prob can still eke something out in the region but doesn't scream big at the moment.

 

I expect 1 or 2 big time model runs to reel Yoda in. Then as we get close and it falls apart Yoda will somehow reel me in and then we'll both go down with the ship. 

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On the CIPS page for the 0z run if you click the SE sector instead of ours there are some decent analog days showing up. Not so much if you pick our sector though. Really sour severe season for most of us - a few exceptions around the area. 

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On the CIPS page for the 0z run if you click the SE sector instead of ours there are some decent analog days showing up. Not so much if you pick our sector though. Really sour severe season for most of us - a few exceptions around the area. 

 

this season seems somewhat delayed.  it could be that july is our month.

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this season seems somewhat delayed.  it could be that july is our month.

Perhaps - tho usually by July we don't have as much good shear to work with. July tends to be big on high instability but weak speed shear at best. It's always something with our area and severe. 

I'm not sure I want to have a bunch of high instability pulse severe days where a storm goes up - gets super intense for like 15 minutes and then collapses in on itself leaving only outflow. 

Crossing my fingers for something more impressive! Ian is right about that offshore low screwing things up. If only it weren't on the models. 

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I'd settle for some tropical remnants going up to our west and giving us an Ivan type day. That would be exciting. So far it looks pretty boring, though...and our odds at more tropical related stuff don't really start going upwards until August/September. 

Doldrums of DC

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      I had written off the week in a previous post, but I have to admit that the Thursday setup is intriguing.    Heck, even Tuesday late afternoon could have a some sort of squall line if the front waits until later in the day.    The cape/shear combination for Tuesday isn't a show-stopper, but it could be sufficient.

 

 

GFS liking Thurs quite a bit. I think we'll get something interesting in this pattern ahead.

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Random click at 18z on Tue per 12z GFS gave me 5,600 CAPE.

 

I think both Tue and Thurs could work.

 

Two days in one week would be pretty sweet. Both seem pretty conditional though (as it always is). Hopefully the front doesn't clear us too quickly on Tuesday - and hopefully that nice 500 look we've been seeing for Thursday sticks around. Got some crazy soundings on COD website around the area for Thursday despite the maps looking less impressive. 

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Two days in one week would be pretty sweet. Both seem pretty conditional though (as it always is). Hopefully the front doesn't clear us too quickly on Tuesday - and hopefully that nice 500 look we've been seeing for Thursday sticks around. Got some crazy soundings on COD website around the area for Thursday despite the maps looking less impressive. 

Euro and GFS both seem slow enough on Tuesday to keep us in the action. Know NAM and SREF are faster but would perhaps lean on the globals still for timing.

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18z NAM for Tuesday seems to put best instability up near the M/D line. Sim reflectivity doesn't look too impressive but obviously it'll waffle back and forth. 

NAM at range for 06z Thursday has a massive slug of precip moving in from the north and west. But it's the NAM at range. 

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Tomorrows disco -

 

FARTHER E INTO VA...MD AND DE...STRONGER HEATING WILL OCCUR WHICH

WILL RESULT IN AROUND 2000 J/KG MUCAPE BY LATE AFTERNOON. LOW-LEVEL
SHEAR/SRH WILL BE MINIMAL...BUT WINDS WILL CONTINUE TO INCREASE WITH
HEIGHT AND WILL FAVOR LONG-LIVED CELLS CAPABLE OF LARGE HAIL AND
DAMAGING WIND. HAIL TO THE SIZE OF GOLF BALLS APPEARS POSSIBLE.

 

DAY 4 

day4prob.gif?1466431514781

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