Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 250544
SWODY1
SPC AC 250542

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1242 AM CDT MON JUL 25 2016

VALID 251200Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE OH
VALLEY INTO THE NRN MIDDLE ATLANTIC...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE OH VALLEY INTO WRN NEW
ENGLAND...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE NRN/CNTRL HIGH
PLAINS...

...SUMMARY...
ISOLATED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE
OHIO VALLEY INTO THE NORTHERN MIDDLE ATLANTIC AND DELMARVA REGION.
DAMAGING WIND GUSTS ARE POSSIBLE WITH THESE STORMS.  ISOLATED
STRONG/SEVERE STORMS MAY ALSO DEVELOP ACROSS PARTS OF THE NORTHERN
AND CENTRAL HIGH PLAINS.

...OH VALLEY/NRN MIDDLE ATLANTIC...

DIFFLUENT HIGH-LEVEL FLOW WILL DEVELOP ACROSS THE NERN U.S. AS GREAT
LAKES SHORT-WAVE TROUGH EJECTS ACROSS ERN ON INTO WRN QC.  500MB
FLOW IS EXPECTED TO INCREASE WITHIN THE BASE OF THIS FEATURE WITH
SPEEDS ON THE ORDER OF 35KT EXPECTED ACROSS PA DURING THE AFTERNOON
HOURS.  LARGE-SCALE ASCENT AHEAD OF THE SHORT WAVE SHOULD ENCOURAGE
CONVECTION EARLY IN THE PERIOD AND THIS MAY INHIBIT SFC HEATING
ACROSS MUCH OF NEW YORK AND NEW ENGLAND AS WARM SECTOR STRUGGLES TO
RECOVER DURING THE DAY.

OF MORE CONCERN IS THE SRN FRINGE OF STRONGER WLY FLOW FORECAST TO
EXTEND ACROSS OH/PA INTO NJ.  LATEST GUIDANCE SUGGESTS THIS CORRIDOR
WILL RECEIVE STRONG BOUNDARY-LAYER HEATING AND SFC TEMPERATURES
SHOULD SOAR INTO THE 90S ACROSS MUCH OF PA...POSSIBLY NEAR 100F IN
PARTS OF THE DELMARVA.  CONVECTIVE TEMPERATURES SHOULD BE BREACHED
BY EARLY-MID AFTERNOON AND SCT TSTMS ARE EXPECTED TO EVOLVE WITHIN
DEEPENING WLY FLOW WITHIN THE BASE OF THE TROUGH.  THIS ACTIVITY
WILL DEVELOP WITHIN A PLUME OF NEAR 2 INCH PW WHERE SUB-CLOUD RH
WILL BE SEASONALLY LOW DUE TO THE INTENSE HEAT.  DAMAGING DOWNBURST
POTENTIAL SHOULD BE ENHANCED BY HIGH PW STORMS THAT WILL PROPAGATE
SEWD TOWARD THE DELMARVA INTO THE EARLY EVENING HOURS.

...NRN/CNTRL HIGH PLAINS...

EARLY-MORNING WV IMAGERY SUGGESTS A MID-LEVEL SHORT-WAVE TROUGH WAS
LOCATED OVER ERN ORE...SHIFTING EAST IN LINE WITH LATEST MODEL
GUIDANCE.  THIS FEATURE SHOULD EJECT ACROSS ID INTO NRN WY LATE IN
THE PERIOD...FLATTENING THE CNTRL ROCKIES RIDGE.  IN RESPONSE TO
THIS FEATURE...NRN HIGH PLAINS LEE SFC LOW SHOULD SETTLE INTO THE
NRN BLACK HILLS REGION BY LATE AFTERNOON.  STRONG HEATING ACROSS
THIS REGION SHOULD WEAKEN THE CAP AND A FEW TSTMS MAY DEVELOP OVER
THE HIGHER TERRAIN.  HOWEVER...LLJ WILL STRENGTHEN AFTER DARK IN
ADVANCE OF THE SHORT WAVE AND CONVECTION COULD INCREASE ALONG THE
NOSE OF THIS FEATURE AS BOUNDARY LAYER DECOUPLES.  WILL MAINTAIN
MRGL RISK TO ACCOUNT FOR HAIL/WIND WITH ISOLATED SEVERE STORMS
ACROSS THIS REGION DURING THE LATTER HALF OF THE PERIOD.

..DARROW/LEITMAN.. 07/25/2016

$$



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