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2014 Severe Storm season


downeastnc

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From the AFD this afternoon (RAH)

MON/MON NIGHT: A STRONG COLD FRONT APPROACHING FROM THE NORTHWEST WILL CROSS THE CWA ON MONDAY AS ADDITIONAL SHORTWAVE ENERGY DIVES THROUGH THE BACKSIDE OF THE UPPER TROUGH.  UNSEASONABLY STRONG 40-60M HEIGHT FALLS OVERSPREADING WHAT IS EXPECTED TO BE A MOIST AND MODERATELY UNSTABLE AIRMASS WILL AID IN THE DEVELOPMENT OF STORMS ALONG AND AHEAD OF THE FRONT.  BASED ON 40-50KT OF 0-6KM BULK SHEAR ASSOCIATED WITH THE DEEP PUSH OF THE STRONG WESTERLIES AND LONG...THERE IS GOOD CONFIDENCE THAT SUPERCELLS WITH A LARGE HAIL AND DAMAGING WIND THREAT WILL BE POSSIBLE.  THE BIGGEST QUESTION WILL BE EXACTLY WHERE THE LEE TROUGH SETS UP AND HOW MUCH DEWPOINTS MIX OUT AS WEST-SOUTHWESTERLY LOW-LEVEL FLOW STRENGTHENS.  EAST OF THE TROUGH...MOST LIKELY FROM US HWY 1 EAST...MODERATE INSTABILITY IS EXPECTED WITH FAIRLY STEEP MID-LEVEL LAPSE RATES OF -6C/KM TO MAYBE EVEN -7C/KM.  FORECAST SOUNDINGS ALSO SHOW RATHER DRY MID-LEVEL AIR...THOUGH THE FORCING AND INSTABILITY SHOULD BE ABLE TO OVERCOME THIS...AND THE DRY AIR WILL LIKELY ENHANCE DAMAGING WIND THREAT.  AT THE MOMENT...CONFIDENCE IS STRONG THAT SEVERE WEATHER WILL BE POSSIBLE...BUT THE UNCERTAINTY LIES HOW FAR EAST STORMS WILL DEVELOP AND THE OVERALL COVERAGE.  HIGHS MONDAY WILL BE IN THE LOW TO MID 90S. -BLS
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30% probs for eastern nc on Monday, how are the models looking?

Good....mostly a hail threat but wouldn't be surprised to see a 5% risk for tornadoes along the coast or maybe even a 10% risk come Monday with the sea breaze involved, assuming models stay trending the way they are...timing is a bit off..if models can back up a bit and instead of making this an 11pm-2pm even for the coast, being a 8-11pm even would help a lot for severe...or maybe even back it up more than that.

 

Jacksonville, NC has had some interesting curvature to some hodographs in bufkit, best maxed out sounding I've seen is PGV seen below on 06z NAM. should be interesting to see how this trends today and tomorrow...

 

18EtaJo.png

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Our high for Monday is supposed to be 95, I'm sure we'll have some pretty strong instability if we don't get cloud debris from any left over mcs; Morehead's write up says sb cape on the order of 4000 with li's -9 to -10, the ingredients are definitely there with shear >35 knts. 

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Yeah, the longer the storms hold off, the more heat and instability they will have to work with. If we do get to 95 without any storms in the morning or early afternoon, things could get interesting.

Have to see what it does out west the next two days, too. They could get hit pretty hard in the Mississippi and Ohio Valley.

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Looks pretty unstable for sure, latest from SPC

 

   ...ERN CAROLINAS INTO EXTREME SERN VA...
   STRONG INSTABILITY WILL DEVELOP AHEAD OF THE FRONT...AND BENEATH
   40-60 KT MID TO UPPER LEVEL WLY FLOW AT THE BASE OF THE UPPER
   TROUGH. GIVEN THE FOCUSED FORCING FOR ASCENT...PERHAPS AIDED BY A
   SEA-BREEZE NEAR THE COAST...A ZONE OF VIGOROUS CONVECTION IS LIKELY
   IN THE FORM OF SUPERCELLS OR SMALL CLUSTERS. THE STRONGEST CELLS
   SHOULD BE CAPABLE OF DAMAGING WINDS AND LARGE HAIL UP TO GOLF
   BALL/HEN EGG SIZE.

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Lots of uncertainty in the RAH afternoon discussion for Monday's severe threat in Central NC.

THE GFS AND ECMWF HAVE COME INTO BETTER AGREEMENT WITH THE TIMING AND LOCATION OF THE FRONT...HOWEVER THE CHANCES FOR CONVECTION HAVE DECREASED SOMEWHAT. THE BEST CHANCES ARE STILL MAINLY ALONG AND EAST OF I-95 FROM 18Z MONDAY THROUGH 06Z TUESDAY. IN THIS FAVORED REGION...MODELS ARE FORECASTING MUCAPE IN THE 1500-2500 J/KG RANGE...0-6 KM BULK SHEAR OF 40-50 KTS...LOW LEVEL LAPSE RATES OF 8-8.5 DEG/KM...AND MID LEVEL LAPSE RATES OF 6.5-7 DEG/KM. LOW LEVEL SHEAR REMAINS WEAK. GIVEN THAT ENVIRONMENT...EXPECT CONVECTION... WHERE IT DEVELOPS...TO BE STRONG TO SEVERE...WITH THE MAIN THREATS BEING LARGE HAIL AND DAMAGING WINDS. THERE CONTINUES TO BE UNCERTAINTIES WITH RESPECT TO COVERAGE OF CONVECTION AND WHETHER THERE WILL BE MUCH OVER CENTRAL NC. SOME OF THE MODELS INDICATE THAT THE CONVECTION WILL FALL APART AS IT CROSSES THE APPALACHIANS... WITH SOME REDEVELOPMENT ALONG THE COAST LATE MONDAY AND/OR REMAIN NORTH OF THE NC/VA BORDER. THE GFS CONTINUES TO FORECAST THE BEST UPPER LEVEL FORCING WELL TO THE NORTH OF THE AREA. THUS...ALTHOUGH THE CHANCE FOR CONVECTION DEFINITELY EXISTS AND SHOULD IT DEVELOP ITS LIKELY THAT STORMS WILL BE STRONG/SEVERE...CONFIDENCE IS DECREASING WITH REGARD TO WHETHER STORMS WILL DEVELOP OVER THE AREA. ALSO...RESIDUAL CLOUDINESS AND OUTFLOW BOUNDARIES FROM CONVECTION SUNDAY/SUNDAY NIGHT (SHOULD IT OCCUR) MAY ALSO PLAY A ROLE IN LIMITING CONVECTION. HIGHS WILL BE MAINLY IN THE UPPER 80S NW TO MID 90S SE WITH OVERNIGHT LOWS...DEPENDING ON THE PROGRESSION OF THE FRONT...MAINLY IN THE LOW 60S NW TO UPPER 60S SE. -KC
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I wouldn't look past tomorrow night in NC...hodographs and severe indices look maxed over eastern NC, especially PGV, and the 18z 4km nam just dropped a big one on central NC, went from completely dry to severe stroms over central NC at 11pm. Big change, and could mean an upgrade from SPC for tomorrow if trend continues.

 

12z was dry, here's the 18z 4km

F8qKz2s.png

 

Tomorrow 7pm RDU..

QyGO2Ge.png

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That is a huge change for tomorrow night. Have to keep an eye out.

As far as Monday goes, sounds like more of the same from RAH with uncertainty about the coverage. That's been the case all summer. Of course, watch us all be focusing on Monday and something surprise us tomorrow.

 

00z 4km nam keeps with the idea that Jon was mentioning.  Large cell sort of backdooring central NC around 10-11pm and moving east, turning into a line later..  Looks like it misses Wake Forest though. sigh.  Could be interesting to watch this unfold, the 4km nam did pretty well with the most recent fropa and where it fired convection.  

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Yeah that's a bit surprising to see this morning,.....the clearing out in front of this line should help boost instability as it rolls along.....

Yeah SPC expanding slight risk quite a bit!

ymu9age4.jpg

 

 

Some pretty decent shear also with that current line.  35kt in central nc & 40kt on the nc/va border.  This front is pretty stout.

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