Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

July 9 tornado watch and slight/enh risk


yoda

Recommended Posts

  • Replies 118
  • Created
  • Last Reply
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
252 PM EDT THU JUL 9 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTHEAST ACROSS THE REGION TONIGHT. THE
FRONT WILL STALL OUT IN NORTH CAROLINA AS HIGH PRESSURE BUILDS IN
OVER OUR AREA FRIDAY. THE FRONT WILL THEN REVERSE AND SLOWLY PUSH
BACK NORTH AS A WARM FRONT EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
POTENT TROUGH MOVING THROUGH LATE THIS AFTERNOON AND EARLY THIS
EVENING ACCOMPANIED BY A SURFACE COLD FRONT AS A WAVE OF LOW
PRESSURE PUSHES EASTWARD TO OUR NORTH. ALREADY A BROKEN LINE OF
THUNDERSTORMS HAS DEVELOPED TO THE WEST AND IS MOVING TOWARDS US.
CAPE IS FAIRLY ROBUST WITH VALUES ABOVE 2K J/KG...SHEAR IN THE
VICNITY OF 30 KNOTS WITH SIGNIFICANT LOW- LEVEL HELICITY...AND A
FAVORABLE JET STREAK POSITION ALOFT. SHOULD HAVE NO TROUBLE
GETTING STORMS INTO THE NORTHERN PORTION OF OUR FORECAST
AREA...WITH DAMAGING WINDS BEING THE PRIMARY THREAT AND AN
ADDITIONAL POSSIBILITY...GIVEN ROBUST LOW LEVEL HELICITY AND
DIRECTIONAL SHEAR...OF AN ISOLATED TORNADO. BEST TIMING FOR STORM
PASSAGE ALONG THE I-95 CORRIDOR IS AROUND 6 PM GIVE OR TAKE AN
HOUR OR TWO. ODDS FAVOR NORTHERN AREAS INCLUDING BALTIMORE...HENCE
THE WATCH NOW IN EFFECT THERE. HOWEVER...SOME RISK EXISTS FURTHER
SOUTH...AND IT IS NOT IMPOSSIBLE THE WATCH COULD GET EXTENDED
FURTHER SOUTH
OR THAT WARNINGS MAY BE ISSUED AS FAR SOUTH AS DC
PROPER.
Link to comment
Share on other sites

There could be an F5 on the ground mowing down I-66 and Eskimo would meh the parameters.

Yea no.  Ian and ERS are right in that climatology usually isn't on our side here and I noticed our best days for severe weather is when the mid level lapse rates and shear coincide with on another.  We saw that back in June when Montgomery, Baltimore and Fairfax got hit really hard with 4" hail and several microbursts.  The latest meso from SPC underscores why the tornado watch is justified, but I'm having my doubts for anyone outside of the mountains.

 

Looking at the RAP point forecast soundings...what strikes me is that a layer of warm temperatures exist around 700 mb (seems about +11 *C) and only a narrow ribbon of SB instability in the lee of the mountains.  If we have strong insolation we'd see an environment primed for action but that isn't the case.  Again, I meh 9.9/10 things so just disregard what I say.

Link to comment
Share on other sites

18z -- 2000 MLCAPE and 3000 SBCAPE in N VA/DC/C MD... LI's -5 to -6...

 

19z -- -4 to -7 LI's... 1500 to 3000 MLCAPE... 2000-3500 SBCAPE.... sup composite parameter 4-8... sig tor effective and fixed layer are both at 1... 30 kts bulk shear with 30 kts effective shear as well... derecho composite 4 to 6... 30-50 in Craven SigSvr

Link to comment
Share on other sites


mcd1341.gif

 

MESOSCALE DISCUSSION 1341   NWS STORM PREDICTION CENTER NORMAN OK   0209 PM CDT THU JUL 09 2015   AREAS AFFECTED...PA/MD/NORTHERN WV TO NORTHERN VA AND DE/NJ   CONCERNING...TORNADO WATCH 397...   VALID 091909Z - 092045Z   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 397 CONTINUES.   SUMMARY...DAMAGING WIND/ISOLATED TORNADO POTENTIAL IS EXPECTED TO   INCREASE/SPREAD EASTWARD THROUGH LATE AFTERNOON ACROSS PARTS OF PA   AND NEARBY NORTHERN WV/MD. TORNADO WATCH 397 CONTINUES UNTIL 01Z. AN   ADDITIONAL WATCH IS LIKELY BY LATE AFTERNOON /APPROX 20-21Z/   ESPECIALLY FOR PORTIONS OF EASTERN PA AND NJ/DE/NORTHEAST MD.   DISCUSSION...18Z SUBJECTIVE SURFACE ANALYSIS FEATURES AN   EASTWARD-MOVING SURFACE LOW ACROSS FAR WESTERN NY/NORTHWEST   PA...WITH PRECEDING 2-3 MB TWO-HOURLY PRESSURE FALLS ACROSS   SOUTH-CENTRAL NY/NORTH-CENTRAL PA. A WAVY/NORTHWARD-SHIFTING WARM   FRONT EXTENDS EAST-SOUTHWARD FROM THE SURFACE LOW ACROSS ACROSS   NORTH-CENTRAL/EASTERN PA INTO NJ.   AS OF 19Z/3PM EDT...A NARROW/BOWING CONVECTIVE LINE CONTINUES TO   GRADUALLY GROW UPSCALE AND MOVE EASTWARD ACROSS SOUTHWEST PA/FAR   WESTERN MD...WHILE FARTHER NORTH...WITH OTHER LOWER-TOPPED   SEMI-DISCRETE STORMS INCLUDING A COUPLE OF SUPERCELLS CONTINUE TO   FLUCTUATE INTENSITY-WISE ACROSS WEST-CENTRAL PA. AHEAD OF THIS   ACTIVITY...VISIBLE SATELLITE IMAGERY SUGGESTS THAT THE CUMULUS FIELD   CONTINUES TO BECOME INCREASING AGITATED/DEEPEN WITHIN THE WARM   SECTOR PARTICULARLY ACROSS PA/NJ WHERE MLCAPE IS ESTIMATED TO BE AT   LEAST 500-1000 J/KG COINCIDENT WITH UPPER 60S/LOWER 70S F SURFACE   DEWPOINTS.    SIMILAR TO PREVIOUSLY DESCRIBED CONVECTIVE TRENDS...LATEST THINKING   IS THAT THE EASTWARD-MOVING BAND OF STORMS WILL CONTINUE TO GROW   UPSCALE/ACCELERATE EASTWARD ACROSS EASTERN/NORTHERN WV AND   MD/SOUTHERN PA...WITH OTHER SEMI-DISCRETE STORMS/SUPERCELLS   REMAINING A DISTINCT POSSIBILITY FARTHER NORTH /AND POSSIBLY EAST   AHEAD OF THE LINE/ ACROSS ADDITIONAL PORTIONS OF PA/NJ AND DELMARVA   VICINITY. WHILE DAMAGING WINDS ARE LIKELY TO BE THE MOST PREVALENT   RISK...TORNADO POTENTIAL WILL EXIST...PARTICULARLY WITH ANY   SUPERCELLS INTERACTING WITH THE WARM FRONT ACROSS PA/NJ. LATEST   WSR-88D VWP DATA FROM STATE COLLEGE IS SAMPLING 0-1 KM SRH OF   APPROXIMATELY 200 M2/S2...WITH LOCALLY HIGHER VALUES WHERE LOW-LEVEL   WINDS ARE BACKED TO MORE SOUTHEASTERLY /SUCH AS THE THE WILLIAMSPORT   VICINITY AS OF 18Z-19Z/.   ..GUYER.. 07/09/2015   ATTN...WFO...OKX...PHI...BGM...CTP...LWX...PBZ...RLX...
Link to comment
Share on other sites

Bulk shear seems to peak out ahead of the line per models around 5 and isn't too impressive with it. Storms are going thru a low instability environment right now so they could certainly increase in intensity upon leaving it.

Link to comment
Share on other sites

Bulk shear seems to peak out ahead of the line per models around 5 and isn't too impressive with it. Storms are going thru a low instability environment right now so they could certainly increase in intensity upon leaving it.

 

Would agree that they should intensify... MLCAPE and SBCAPE are 2000-3000 just east of the mts

Link to comment
Share on other sites

Most of the stuff out west is lining out.

That should be the case overall I think. Best shear is not super well collocated to instability ... Better in PA.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...