Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 061300
SWODY1
SPC AC 061258

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CDT MON JUL 06 2015

VALID 061300Z - 071200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE MID AND UPR
MS VLYS...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE SRN RCKYS/SRN PLNS NE
INTO THE UPR GRT LKS...

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE SOUTHEAST...

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE
MID-ATLANTIC...

...SUMMARY...
STRONG TO SEVERE THUNDERSTORMS WILL OCCUR THIS AFTERNOON AND EVENING
FROM THE SOUTHERN ROCKIES AND SOUTH-CENTRAL PLAINS NORTHEAST INTO
THE UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES; A FEW STRONG TO
SEVERE STORMS ALSO MAY OCCUR OVER FLORIDA AND THE MID-ATLANTIC
STATES.

...SYNOPTIC SETUP...
MODERATE CYCLONIC FLOW WILL PREVAIL OVER THE N CNTRL STATES THIS
PERIOD...ON SRN SIDE OF PROGRESSIVE...POSITIVE-TILT TROUGH OVER
MB/ONT. WITHIN THIS FLOW...IMPULSE NOW OVER NW ND EXPECTED TO
CONTINUE EWD TO PHASE WITH A DISTURBANCE AMPLIFYING SE FROM MB. THE
COMBINED FEATURES SHOULD REACH WRN LK SUPERIOR EARLY TUE AS A WEAKER
LEAD IMPULSE NOW OVER CNTRL NEB TRACKS ENE INTO WI/ERN IA BY THIS
EVE. ELSEWHERE...SRN APPALACHIANS TROUGH EXPECTED TO FURTHER WEAKEN
AS IT CONTINUES SLOWLY NE AND BECOMES ABSORBED WITHIN STRENGTHENING
SW FLOW AHEAD OF MB/ONT TROUGH. AT THE SAME TIME...A WEAK TROUGH
WILL MOVE SLOWLY E/SE FROM NM INTO W TX.

COLD FRONT AND PRE-FRONTAL OUTFLOW BOUNDARIES ASSOCIATED WITH MB/ONT
SYSTEM SHOULD CONTINUE GENERALLY SSE ACROSS THE
UPR GRT LKS...UPR MS VLY...LWR MO VLY...AND S CNTRL PLNS
TODAY/TNGT...AND WILL BE THE MAIN FOCUS FOR DIURNALLY-ENHANCED TSTMS
THROUGH THE PERIOD.

...IA/UPR MS VLY TODAY INTO TNGT...
MODEST FORCING FOR ASCENT WILL OVERSPREAD IA AND THE UPR MS VLY
TODAY...ASSOCIATED WITH LEAD UPR IMPULSE NOW OVER NEB. 30-40 KT DEEP
WSWLY SHEAR ON SRN FRINGE OF MB/ONT TROUGH WILL BE SUFFICIENT FOR
ORGANIZED/SUSTAINED STORMS...WITH AMPLE MOISTURE /PW 1.75-2.00
INCHES/ FOR STRONG UPDRAFTS. MID-LVL LAPSE RATES...HOWEVER...WILL BE
FAIRLY WEAK...AND DEBRIS FROM OVERNIGHT PRE-FRONTAL STORMS WILL
LIMIT DIURNAL WARM SECTOR DESTABILIZATION. NEVERTHELESS...STORMS
SHOULD REDEVELOP/INTENSIFY ALONG COLD FRONT THIS AFTN AND
EVE...POSING SOME THREAT FOR SVR WIND/HAIL ESPECIALLY OVER IA AND
SRN WI. MORE WDLY SCTD ACTIVITY ALSO COULD STRENGTHEN ALONG
PRE-FRONTAL OUTFLOW BOUNDARY FARTHER E ACROSS NRN IL AND WRN LWR MI.


...SRN RCKYS/S-CNTRL PLNS INTO LWR MO VLY/OZARKS THIS AFTN/EVE...
SFC HEATING AND LOW-LVL UPLIFT SHOULD OVERCOME EML CAP AND PROMOTE
SCTD TSTM DEVELOPMENT BY LATE AFTN ALONG COLD FRONT FROM THE CO/NM
MOUNTAINS THROUGH THE TX PANHANDLE AND NW OK INTO NRN/WRN MO. THIS
ACTIVITY SHOULD INCREASE IN COVERAGE THROUGH THE EVE AS SWLY LLJ
NOCTURNALLY STRENGTHENS. ALTHOUGH NM UPR TROUGH MAY ENHANCE
POTENTIAL FOR STORMS OVER THE SRN RCKYS AND ADJACENT HIGH
PLNS...MOST OF THE REGION WILL EXPERIENCE VERY LIMITED FORCING FOR
ASCENT/DEEP SHEAR. BUT VERY WARM/MOIST PRE-FRONTAL ENVIRONMENT COULD
SUPPORT A FEW STORMS WITH LOCALLY DMGG WIND AND MARGINALLY SVR HAIL.
AHEAD OF THE FRONT...ISOLD PULSE-TYPE SVR STORMS MAY OCCUR IN MOIST
AXIS OVERLYING THE OZARKS/MID-MS VLY.

...MID-ATLANTIC THIS AFTN...
A BELT OF ENHANCED /25 KT/ SSWLY MID-LVL FLOW WILL PERSIST OVER THE
CHESAPEAKE BAY REGION TODAY...ON ERN SIDE OF APPALACHIANS TROUGH.
DIFFUSE NW-SE WARM FRONT NOW OVER SRN VA SHOULD FURTHER WEAKEN AS IT
CONTINUES NWD THROUGH THE DAY. LOW-LVL DESTABILIZATION AND
TERRAIN/DIFFERENTIAL HEATING CIRCULATIONS SHOULD PROMOTE
SLOWLY-MOVING CLUSTERS/BANDS OF AFTN STORMS OVER PARTS OF
DE-MD-VA-WV/SRN PA. THIS ACTIVITY COULD INCLUDE A FEW SUSTAINED
UPDRAFTS/WEAK SUPERCELLS GIVEN SLIGHTLY-BACKED FLOW NEAR WARM FRONT.
MODEST MID-LVL LAPSE RATES/DEEP SHEAR SHOULD LIMIT OVERALL SVR
THREAT...BUT THE STORMS COULD YIELD ISOLD INSTANCES OF DMGG WIND
AND/OR A WEAK TORNADO.

...FL AND ADJACENT SE STATES THIS AFTN...
THERMODYNAMIC ENVIRONMENT ON SRN FRINGE OF APPALACHIANS TROUGH
EXPECTED TO BE AT LEAST MARGINALLY FAVORABLE FOR SCTD STRONGER
STORMS THIS AFTN...WITH A FEW WET MICROBURSTS POSSIBLE IN AREAS OF
GREATEST LOW-LVL HEATING/UPLIFT OVER FL AND ADJACENT PARTS OF
AL/GA/CSTL SC.

..CORFIDI/SMITH.. 07/06/2015




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