Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 301625
SWODY1
SPC AC 301623

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1123 AM CDT MON MAY 30 2016

VALID 301630Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE NRN AND CNTRL
PLNS...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE SRN HIGH PLNS NNE INTO
THE NRN PLNS/UPR MS VLY...

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

...SUMMARY...
ISOLATED TO WIDELY SCATTERED SEVERE STORMS WILL OCCUR OVER PARTS OF
THE NORTHERN AND CENTRAL PLAINS...MAINLY THIS AFTERNOON AND EVENING.
THE MAIN HAZARDS SHOULD BE HAIL AND DAMAGING WIND.

...SYNOPSIS...
TWO-STREAM FLOW WILL CONTINUE OVER THE LWR 48. THE PRIMARY BAND OF
THE WLYS WILL REMAIN ACROSS THE NRN TIER OF STATES...WITH THE SRN
STREAM EXTENDING FROM NRN MEXICO ENE ACROSS THE SRN PLNS AND LWR MS
VLY TO THE S ATLANTIC CST. WITH NRN STREAM JET STREAK NOW ENTERING
THE NRN RCKYS...EXPECT THAT AB/MT TROUGH/LOW WILL SOMEWHAT DEEPEN AS
IT CONTINUES ESE INTO ERN MT THIS EVE...AND INTO THE ERN DAKOTAS
EARLY TUE. TO THE SOUTH...WEAK SHORTWAVE RIDGING SHOULD PERSIST OVER
THE SRN PLNS...DOWNSTREAM FROM QSTNRY LOW OVER THE LWR CO VLY.

AT THE SFC...EXISTING NRN PLNS LEE LOW EXPECTED TO CONSOLIDATE NEAR
THE BLACK HILLS LATER TODAY. THE LOW SHOULD MOVE E INTO CNTRL SD
THIS EVE...BEFORE TURNING NE TO THE ND-MN BORDER EARLY TUE.
DEVELOPING COLD FRONT NOW IN MT SHOULD ACCELERATE SEWD AS THE SFC
LOW STRENGTHENS...WITH THE NRN PORTION OVERTAKING LEE TROUGH/DRY
LINE OVER SD/WRN NEB EARLY TNGT. E OF THE LOW...PERSISTENT
FRONTOGENESIS SHOULD RESULT IN A FAIRLY WELL-DEFINED NW/SE-ORIENTED
WARM FRONT OVER MN BY THE END OF THE PERIOD.

...CNTRL/NRN PLNS AFTN THROUGH TNGT...
SFC HEATING AND ASCENT WITH APPROACHING UPR TROUGH SHOULD PROMOTE
SCTD AREAS OF STRONG AFTN/EVE TSTMS FROM THE DAKOTAS SSW THROUGH
CNTRL NEB INTO NW KS. STORMS SHOULD BE MOST CONCENTRATED NEAR THE
SFC LOW AND ALONG COLD FRONT/LEE TROUGH SEGMENTS. ACTIVITY ALSO
COULD ARISE ALONG OUTFLOW/DIFFERENTIAL HEATING ZONES PRODUCED BY
ELEVATED CONVECTION NOW OVER ND/NRN SD.

GIVEN STEEP LOW TO MID-LVL LAPSE RATES...WITH SFC DEW POINTS MAINLY
IN THE 50S F AND PW AROUND 1 INCH...PRIMARY EARLY-STAGE SVR THREAT
SHOULD BE HAIL AS HEATING BOOSTS MLCAPE TO 1000-1500 J/KG AMID 30-35
KT WSWLY DEEP SHEAR. HOWEVER...SETUP ALSO SHOULD SUPPORT STRONG
CONVECTIVE GUSTS...ESPECIALLY AS STORM OUTFLOWS ENCOURAGE UPSCALE
DEVELOPMENT INTO CLUSTERS/BANDS. STORMS MAY PERSIST INTO THE NGT
ACROSS ERN SD AND WRN MN...WHERE NOCTURNALLY-ENHANCED WAA WILL BE
FOCUSED ALONG DEVELOPING WARM FRONT...BUT WITH A MUCH DIMINISHED
RISK FOR SVR WEATHER. A SEPARATE AREA OR TWO OF OVERNIGHT STORMS
ALSO MAY LINGER OVER NEB/KS...WHERE SOMEWHAT GREATER LOW-LVL
MOISTURE WILL RESIDE.

...SRN PLNS AFTN/EVE...
THE LARGE-SCALE PATTERN OVER THE SRN PLNS REMAINS SIMILAR TO
YESTERDAYS...WITH WEAK TO MODERATE WSWLY SRN STREAM FLOW ATOP
WEAK/ADEQUATELY MOIST LOW-LVL SLY FLOW. ALTHOUGH SFC DEWPOINTS ARE
SOMEWHAT REDUCED IN WAKE OF WIDESPREAD CONVECTIVE OVERTURNING
YESTERDAY...STRONG SFC HEATING SHOULD SUPPORT ISOLD TO SCTD STORMS
OVER THE HIGHER TERRAIN AND ALONG LEE TROUGH/DRYLINE SEGMENTS FROM
ERN CO AND ERN INTO WEST TX BY EVE. SVR HAIL/WIND MAY OCCUR WITH
SOME STORMS...ESPECIALLY IN SW/W CNTRL TX...WHERE SOMEWHAT ENHANCED
/40+ KT/ DEEP SHEAR WILL EXIST BENEATH SRN STREAM JET...AND MOISTURE
AVAILABILITY SHOULD BE GREATEST.

...NERN U.S. AFTN/EARLY EVE...
WEAK COLD FRONT THAT CROSSED THE UPR GRT LKS YESTERDAY WILL CONTINUE
E ACROSS THE LWR LKS AND NRN APPALACHIANS LATER TODAY. THIS
FEATURE...AND SW/NE-ORIENTED CONFLUENCE ZONE AHEAD OF IT...WILL
SERVE AS MODEST SOURCES OF LOW-LVL UPLIFT. LARGE-SCALE FORCING FOR
ASCENT WILL BE WEAK...JUDGING FROM CURRENT SATELLITE AND MODEL DATA
SHOWING A SERIES OF MINOR DISTURBANCES IN LOW-AMPLITUDE CYCLONIC
FLOW ALOFT. BUT AREA FROM CNTRL/ERN PA NEWD INTO VT/NH/WRN ME WILL
EXPERIENCE STRONG HEATING...WITH AMPLE MOISTURE FOR STORMS. ALTHOUGH
MODEST MID-LVL LAPSE RATES WILL TEMPER UPDRAFT STRENGTH...30-40 KT
UNIDIRECTIONAL WSWLY 700-500 MB FLOW COULD FOSTER DEVELOPMENT OF
SMALL BOWING SEGMENTS IN EXPECTED AFTN/EARLY EVE STORMS. THESE COULD
YIELD LOCALLY STRONG GUSTS AND...MAINLY IN NRN NEW
ENGLAND...MARGINALLY SVR HAIL.

...S CNTRL/SE NC THIS AFTN...
SFC HEATING OF MOIST/CONFLUENT FLOW NE OF REMNANT CIRCULATION OF
TROPICAL SYSTEM BONNIE MAY YIELD A FOCUSED AREA OF AFTN SHOWERS/WEAK
STORMS IN S CNTRL/SE NC. AREA VWP DATA SHOW THAT SOME DEGREE OF
LOW-LVL DIRECTIONAL SHEAR PERSISTS...BUT WEAK FLOW SHOULD KEEP
MAGNITUDE OF 0-1 KM SRH QUITE WEAK.

..CORFIDI/COOK.. 05/30/2016

$$



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