Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 102003
SWODY1
SPC AC 102002

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0302 PM CDT THU JUL 10 2014

VALID 102000Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN SC ACROSS ERN NC AND
SERN VA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM EXTREME ERN WY INTO
WRN/SRN SD AND NRN/CENTRAL NEB...

...THERE IS A SLGT RISK OF SVR TSTMS OVER NRN ND...

...SUMMARY...
SEVERE STORMS ARE POSSIBLE OVER PARTS OF THE NORTHERN AND CENTRAL
GREAT PLAINS DURING THE LATE AFTERNOON AND EVENING. LARGE HAIL AND
SEVERE WIND GUSTS ARE THE PRIMARY THREATS.  IN ADDITION...A FEW
SEVERE STORMS ARE ALSO POSSIBLE MAINLY THIS AFTERNOON AND EARLY
EVENING FROM EASTERN SOUTH CAROLINA AND EASTERN NORTH CAROLINA INTO
SOUTHEAST VIRGINIA.

...ERN SC/NC INTO SERN VA...
THE SLIGHT RISK AND ATTENDANT SEVERE PROBABILITIES HAVE BEEN
ADJUSTED TO ACCOUNT FOR ONGOING CONVECTIVE TRENDS...WITH FORECAST
SCENARIO REMAINING ON TRACK FOR THIS REGION.  FOR ADDITIONAL SHORT
TERM DETAILS...REFER TO ANY VALID MESOSCALE DISCUSSIONS FOR THIS
REGION.

...CENTRAL/NERN PA AND NRN NJ...
THIS OUTLOOK HAS EXPANDED THE 5% SEVERE WIND/HAIL PROBABILITIES NWD
SOME...GIVEN THE PRESENCE OF EFFECTIVE BULK SHEAR OF 30-35 KT
FAVORING SOME STORM ORGANIZATION.  HOWEVER...MARGINAL INSTABILITY
SHOULD LIMIT THE OVERALL COVERAGE OF THE SEVERE WEATHER THREAT.

...ERN OK/AR TO THE MID SOUTH...
LOW SEVERE WIND/HAIL PROBABILITIES HAVE BEEN EXPANDED SOME ACROSS AR
AND WWD INTO ERN OK WHERE MODERATE INSTABILITY FAVORS...AT LEAST A
MARGINAL SEVERE WEATHER THREAT ALONG THE LEADING EDGE OF FORWARD
PROPAGATING MCS...NOW IN CENTRAL AR.  A VEERING WIND PROFILE PER VAD
DATA IN CENTRAL/ERN OK TO WRN AR SUGGESTS A 2% TORNADO PROBABILITY
IS WARRANTED...IF STORMS CAN BECOME SURFACE BASED AS THEY DEVELOP
AND/OR MOVE SSEWD FROM NRN/NERN OK.  MEANWHILE...THE GENERAL TSTM
OUTLOOK HAS BEEN EXPANDED SOME ACROSS THE MID SOUTH AS THE CENTRAL
AR MCS TRACKS ESEWD ALONG AN INSTABILITY GRADIENT TOWARD NRN/CENTRAL
MS.

..PETERS.. 07/10/2014

.PREV DISCUSSION... /ISSUED 1129 AM CDT THU JUL 10 2014/

...NRN ND...
A STRONG UPPER TROUGH IS MOVING EWD ACROSS WRN CANADA TOWARD THE
PRAIRIE PROVINCES.  A COLD FRONT EXTENDING SWWD FROM THE SURFACE LOW
IS FORECAST TO MOVE ACROSS ND THROUGH TONIGHT...HOWEVER...THE
PRIMARY DYNAMIC FORCING FOR LARGE SCALE ASCENT IS EXPECTED TO REMAIN
NORTH OF THE INTERNATIONAL BORDER.  THE ENVIRONMENT IS EXPECTED TO
DESTABILIZE IN THE WAKE OF AN EWD MOVING SHORT WAVE TROUGH OVER WRN
ND...AND A FEW STORMS MAY DEVELOP SWD ALONG THE FRONT INTO FAR NRN
ND LATE THIS AFTERNOON AND EVENING.  WLY FLOW ALOFT ALONG THE SRN
PERIPHERY OF THE CANADIAN TROUGH WILL CONTRIBUTE TO SUFFICIENT
VERTICAL SHEAR TO ENHANCE STORM ORGANIZATION AND INTENSITY FOR ANY
PERSISTENT UPDRAFTS THAT CAN DEVELOP.  STRONGER CELLS WILL BE
CAPABLE OF PRODUCING LARGE HAIL AND STRONG WIND GUSTS.

...EXTREME ERN WY/WRN/SRN SD INTO NRN/CENTRAL NEB...
AN AREA OF CLOUDS AND WEAK CONVECTION EXTENDING SWD INTO SD IS
EXPECTED TO PROGRESS EWD AND PERMIT STRONG DIABATIC HEATING TO OCCUR
FROM PARTS OF NEB INTO SRN/CENTRAL SD.  A DIFFERENTIAL HEATING
BOUNDARY MAY DEVELOP ALONG THE SRN EDGE OF MORE PERSISTENT CLOUDS
FROM EXTREME NERN WY EWD ACROSS CENTRAL SD BY LATER THIS AFTERNOON.
LATEST NAM OPERATIONAL/PARALLEL RUNS AND GFS ARE CONSISTENT FOCUSING
CONVECTIVE DEVELOPMENT LATER THIS AFTERNOON AND EVENING ACROSS SRN
SD/NRN NEB...ALTHOUGH CONVECTION-ALLOWING MODELS INCLUDING NAM NESTS
ARE LESS AGGRESSIVE IN EXPLICIT SIMULATIONS OF CONVECTIVE
DEVELOPMENT IN THIS REGION.  GIVEN POTENTIAL FOR MODERATE-STRONG
INSTABILITY LATER THIS AFTERNOON AMIDST STEEP LAPSE RATES ALONG THE
WRN PART OF THE LOW LEVEL MOISTURE AXIS...COUPLED WITH VEERING WIND
PROFILES WITH HEIGHT...A FEW SEVERE STORMS ARE EXPECTED DURING THE
LATE AFTERNOON AND EVENING HOURS.  THE ACTIVITY MAY GROW UPSCALE
INTO ONE OR MORE SMALL CLUSTERS THIS EVENING AS THE LOW LEVEL JET
STRENGTHENS FROM WRN KS INTO WRN/CENTRAL NEB...WITH SOME SEVERE
THREAT CONTINUING TOWARD 06Z.  LARGE HAIL AND DAMAGING WIND GUSTS
WILL BE THE PRIMARY THREATS.

...ERN SC INTO ERN NC AND SERN VA...
VISIBLE IMAGERY SHOWS A CORRIDOR OF LIMITED/THINNING CLOUDS ACROSS
THIS AREA AHEAD OF A COLD FRONT.  STRONGER DIABATIC
HEATING/DESTABILIZATION IS OCCURRING OVER THIS AREA WITH MLCAPE OF
2000-2500 J/KG EXPECTED THIS AFTERNOON.  STORMS ARE EXPECTED TO
CONTINUE DEVELOPING WITHIN A WEAKLY CAPPED ENVIRONMENT AND
SPREAD/DEVELOP NEWD ALONG THE SRN EDGE OF MODEST SWLY WINDS ALOFT.
STRONG INSTABILITY/HIGH PW CONTENT WILL PROMOTE STRONG WIND GUSTS
WITH STRONGER STORMS DURING THE AFTERNOON AND EVENING.

...LOWER CO RIVER VALLEY...
WATER VAPOR IMAGERY SHOWS A CYCLONIC CIRCULATION LIFTING SLOWLY NWD
ALONG THE NORTH-SOUTH MID/UPPER LEVEL MOISTURE DISCONTINUITY.
CLOUDS ARE THINNING AHEAD OF THIS FEATURE WHICH WILL ENHANCE
DIABATIC HEATING RESULTING IN STEEPENING OF DEEPER LAYER LAPSE
RATES.  THIS WILL SUPPORT POTENTIAL FOR A FEW STRONGER STORMS TO
DEVELOP WITHIN A MOIST AIR MASS /PW OF 1.50-1.75 INCHES/ AND A FEW
WET MICROBURSTS WILL BE POSSIBLE THIS AFTERNOON AND EVENING.



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