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June 10-14 Severe/Flooding Wx - Obs, Radar, Warnings, Dmg. rpts


wxmeddler

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SREF definitely trended more bullish.. pulled the low back to NW of HGR at 18z thur compared to NE MD at 18z prior run.  Lines up big parameters in teh same general area from N/NE MD into SE PA especially but broadly the larger area. 

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00z GFS has a 1000 L in W OH Thursday at 09z... 18z THUR broad-ish 1000 L in SW PA (though the 2m maps has it at 997mb)

850s seem a bit warm but WV might cash in on backlash

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00z GFS soundings are pretty decent... not the disturbing 00z NAM kind... but they still look pretty good for us severe weather weenies.  Not sure I buy 5000+ SBCAPE at 2pm on Thursday at BWI and DCA and ~4000 at IAD... but still nice soudings

 

With that strong of a low, pumping in cape values that high doesn't seem unreasonable. 

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Not that I should be forecasting SPC's ways, but I'd expect for DC proper, 0/5/15 (T/H/W respectively, though the 15 may go to JYOish), and a MDT should definitely be in place for DC on the d2 but I agree with your 30% hatched call. 

 

Just having a lil fun predicting what SPC will say in the next few mins ;)

 

I see the MOD risk coming at the 1730z outlook... allowing SPC to digest the 12z suite and see what goes on in the Plains

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45% hatched is MOD risk region for Day 2 aka Thursday

 

post-397-0-38203900-1371018111_thumb.gif

 

Disco:

 ...MID-ATLANTIC REGION SWWD INTO THE GULF COAST STATES...   POTENTIALLY SUBSTANTIAL/WIDESPREAD SEVERE WEATHER EVENT IS FORECAST   DAY 2/THURSDAY -- FOCUSED ON THE MID-ATLANTIC REGION.   CLOUDS AND PRECIPITATION -- AND LIKELY AN ONGOING MCS -- ARE   EXPECTED AT THE START OF THE PERIOD ACROSS THE UPPER OH VALLEY   REGION INCLUDING MUCH OF PA AND LIKELY WV.  WHILE THIS MCS MAY BE   DECAYING AND GENERALLY SUB-SEVERE EARLY IN THE PERIOD...CLOUDS AND   CONVECTIVE OUTFLOW WILL LIKELY AFFECT DESTABILIZATION AND EVENTUAL   LOCATION OF NEW CONVECTIVE DEVELOPMENT INTO THE MID-ATLANTIC REGION.   HAVING SAID THAT...AS THE STRONG UPPER SYSTEM DIGS SEWD AND THE COLD   FRONT SHIFTS E OF THE MOUNTAINS...DIURNAL HEATING/DESTABILIZATION   COMBINED WITH STRONG UVV FOCUSED INVOF THE FRONT AND POSSIBLY   CONVECTIVE OUTFLOW WILL ALLOW STORMS TO REDEVELOP/REINTENSIFY ACROSS   THE AREA.  SHEAR WILL BE VERY SUPPORTIVE OF UPDRAFT ROTATION...AND   THUS SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL...DAMAGING   WINDS...AND ISOLATED TORNADOES CAN BE EXPECTED.  ATTM...THE GREATEST   TORNADO RISK APPEARS TO EXIST WITHIN A ZONE FROM NRN VA/MD/DE NWD   INTO CENTRAL AND ERN PA AND NJ...WHERE STRONGEST LOW-LEVEL SHEAR IS   FORECAST JUST AHEAD OF THE SURFACE LOW AND INVOF THE WARM FRONT   EXTENDING E FROM THE LOW.
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Day 1 (today) 2/15/15 (added the WV/WRN PA disco with ours since 30 hatched wind/hail is bordering LWX CWA in NW portions and I believe we have some WV posters in our forum)

 ...SRN MI INTO OH...WV...WRN PA LATE AFTERNOON...   ALTHOUGH THE MAIN SURFACE LOW WILL BE OVER IL AT THIS TIME...A BROAD   AREA OF CONVERGENCE WILL EXIST NEAR A DIFFUSE WARM FRONT FROM SRN   LOWER MI INTO OH. FORECAST SOUNDINGS SHOW EXTREME   INSTABILITY...STEEP LAPSE RATES...AND VEERING WINDS WITH HEIGHT   WHICH WILL FAVOR SUPERCELLS CAPABLE OF VERY LARGE HAIL AND   TORNADOES.   ...VA INTO THE DELMARVA - AFTERNOON...   BRIEF SHORTWAVE RIDGING WILL OCCUR DURING THE DAY WELL AHEAD OF THE   OH VALLEY SYSTEM...WITH STRONG HEATING AND INSTABILITY DEVELOPING.   WEAK CONVERGENCE WITHIN THE SFC TROUGH MAY BE ENOUGH FOR ISOLATED   STORMS CAPABLE OF HAIL OR WIND DURING THE AFTERNOON. THEN   OVERNIGHT...INSTABILITY AND SHEAR PROFILES WILL CONDITIONALLY BE   FAVORABLE FOR SEVERE WEATHER...BUT THE MAIN CONVECTIVE COMPLEX MAY   REMAIN MAINLY NW OF THE AREA AS THE MAIN SURGE IS EXPECTED ACROSS OH   AND WRN PA. HOWEVER...SUBSEQUENT OUTLOOKS WILL REASSESS AS NEW DATA   INCLUDING SPECIAL SOUNDINGS BECOME AVAILABLE.
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Are there any good examples of a similar summertime setup with a strengthening surface low passing thru PA? I've done a slightly more than cursory look and haven't found any.

 

I went back through some Mid Atlantic tornado/severe weather events and I couldn't find anything like what the 12z and 00z suites had either. This bombing surface low with such a vigorous s/w trough this time of year is bound to cause problems somewhere, it's just a matter of how big that problem becomes.

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LWX AFD

 

...POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT AND FLASH
FLOODING THURSDAY...

THURSDAY BEGINS WITH SOME UNCERTAINTY REGARDING THE FATE OF A
MESOSCALE CONVECTIVE SYSTEM AFFECTING THE OHIO VALLEY TONIGHT. IT IS
UNCLEAR WHAT THE STRENGTH OF THIS SYSTEM WILL BE AT THE BEGINNING OF
THURSDAY...WHETHER IT MAY STILL BE SEVERE AND AFFECT THE WESTERN
PORTION OF THE CWA EARLY THURSDAY MORNING /WITH DAMAGING WINDS AND
HEAVY RAINFALL/ OR WHETHER IT WILL BE IN A WEAKENING/DECAYING STATE
DURING THE MORNING. WILL NEED TO FURTHER ADDRESS THIS ISSUE AS THE
MCS DEVELOPS TODAY AND THE MODELS ARE BETTER ABLE TO RESOLVE DETAILS
OF THIS MCS AND ITS EVOLUTION THROUGH THE DAY AND NIGHT.

MEANWHILE...THERE IS A GOOD CONSENSUS THAT REGARDLESS OF THE FATE OF
AN EARLY MORNING MCS...THE ATMOSPHERE ACROSS THE MID-ATLANTIC WILL
SUFFICIENTLY DESTABILIZE AND BE PRIMED FOR WHAT COULD BE A
SIGNIFICANT SEVERE WEATHER EVENT DURING THE AFTERNOON AND EARLY
EVENING.

AN UNSEASONABLY STRONG SURFACE LOW WILL MOVE FROM THE OHIO VALLEY
INTO SOUTHERN PENNSYLVANIA THURSDAY AFTERNOON. WARM FRONTAL BOUNDARY
LOOKS BE DRAPED ACROSS NORTHEAST MARYLAND...WHILE A COLD FRONT
APPROACHES THE APPALACHIANS. MODELS SHOW STRONG SYNOPTIC LIFT
ACROSS THE CWA...JOINED BY DECENT DESTABILIZATION DURING THE
AFTERNOON AND LIKELY CONTRIBUTING TO STRONG LAPSE RATES AND CAPE
AOA 2000 J/KG. MODELS ALSO INDICATE STRONG VERTICAL WIND SHEAR
ACROSS THE CWA /BULK SHEAR GTE 50 KT/. THESE FACTORS WILL RESULT
IN WIDESPREAD THUNDERSTORMS DURING THE AFTERNOON...SOME PRODUCING
DAMAGING/DESTRUCTIVE WIND GUSTS...LARGE HAIL AND ALSO A FEW
TORNADOES.


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