Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 282001
SWODY1
SPC AC 281959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SAT MAY 28 2016

VALID 282000Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF SCNTRL AND
SWRN TX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE UPPER MS
VALLEY AREA...

...THERE IS A MRGL RISK OF SVR TSTMS FROM SRN THROUGH NCNTRL TX...

...THERE IS A MRGL RISK OF SVR TSTMS OVER A PORTION OF THE MIDDLE
THROUGH UPPER MS VALLEY AND GREAT LAKES REGIONS...

...THERE IS A MRGL RISK OF SVR TSTMS FROM A PORTION OF IND...NWRN OH
AND SRN LOWER MI...

...THERE IS A MRGL RISK OF SVR TSTMS OVER A PORTION OF THE COASTAL
CAROLINAS...

...SUMMARY...
A FEW SEVERE THUNDERSTORMS ARE EXPECTED LATER THIS AFTERNOON AND
EVENING OVER A PORTION OF SOUTH CENTRAL AND SOUTHWEST TEXAS.  A
THREAT FOR STRONG TO SEVERE STORMS WILL PERSIST INTO THE EVENING
OVER PARTS OF THE MID AND UPPER MISSISSIPPI VALLEY. A MARGINAL
THREAT FOR A COUPLE OF STRONG WIND GUSTS AND AN ISOLATED BRIEF
TORNADO WILL EXIST TONIGHT AND EARLY SUNDAY ALONG A PORTION OF THE
SOUTH CAROLINA AND SOUTHERN NORTH CAROLINA COAST.

...DISCUSSION...

HAVE INTRODUCED LOW TORNADO PROBABILITIES OVER SCNTRL TX.
THUNDERSTORMS INCLUDING A FEW SUPERCELLS WITH LARGE HAIL ARE
EXPECTED TO DEVELOP BY EARLY EVENING IN THIS AREA. REF SWOMCD 770
FOR MORE INFORMATION. HAVE ALSO INTRODUCED LOW WIND PROBABILITIES
OVER A PORTION OF NRN IND...NWRN OH AND SRN MI. OTHERWISE ONLY MINOR
ADJUSTMENTS HAVE BEEN MADE TO ONGOING FORECAST.

..DIAL.. 05/28/2016

.PREV DISCUSSION... /ISSUED 1142 AM CDT SAT MAY 28 2016/

...SYNOPTIC SETUP...
NEB/IA SHORTWAVE TROUGH EXPECTED TO FURTHER WEAKEN AS IT CONTINUES
SLOWLY ENEWD...REACHING SW WI EARLY SUN. IN ITS WAKE...WEAK
SHORTWAVE RIDGING WILL PREVAIL OVER THE SRN AND CNTRL
PLNS...DOWNSTREAM FROM SRN STREAM LOW APPROACHING THE SRN CA CST.
OVER THE SOUTHEAST...WITH RIDGE REMAINING QSTNRY OFF THE
MID-ATLANTIC CST...TD #2 EXPECTED TO CONTINUE NWWD...POSSIBLY
DECELERATING WITH TIME PER NHC.

FEATURES WILL REMAIN WEAK AT LWR LVLS. A WEAK LOW WILL TRACK NE
ACROSS NW IA ATTENDANT TO NEB-IA UPR VORT. THE LOW SHOULD TURN MORE
ENEWD ALONG STALLED FRONT OVER SRN MN/CNTRL WI TNGT. ACROSS THE SRN
PLNS...RELAXATION OF LOW-LVL DRYING/COOLING IN WAKE OF NEB-IA
SYSTEM...AND STRENGTHENING OF LEE TROUGH DOWNSTREAM FROM E PAC
LOW...WILL BACK LOW-LVL FLOW TO SELY...ALLOWING MOISTURE TO RETURN
NWWD ACROSS SW AND WRN TX.

...MID/UPR MS VLY TODAY...
POCKETS OF MODERATE WARM SECTOR HEATING WILL OCCUR TODAY OVER
NRN/ERN IA AND ADJACENT NW IL/SW WI AND FAR SRN MN...S OF STALLED
FRONT IN MN/WI...AND W OF RESIDUAL TSTM DEBRIS IN IL. SATELLITE
SUGGESTS THAT ASCENT WITH WRN IA VORT LOBE WILL OVERSPREAD NRN AND
ERN IA FOLLOWING MAX HEATING...WITH ASSOCIATED 500 MB TEMPS AOB
MINUS 14C CONTRIBUTING TO AREAL DESTABILIZATION. ALTHOUGH GRADUAL
WEAKENING OF UPR SYSTEM WILL KEEP MEAN FLOW COMPARATIVELY MODEST
RELATIVE TO RECENT DAYS...RESIDUAL BAND OF 40+ KT SWLY 700-500 MB
FLOW ON E SIDE OF VORT LOBE WILL SUPPLY AMPLE DEEP SHEAR FOR SHORT
LINES OF SUSTAINED/ORGANIZED STORMS WITH HAIL/LOCALLY DMGG WIND.
AND...ALTHOUGH WIND PROFILES WILL ONCE AGAIN EXHIBIT VERTICAL
VEER-BACK PATTERNS...WITH SFC DEWPOINTS IN THE MID 60S F AND
ENHANCED LOW-LVL DIRECTIONAL SHEAR NEAR STALLED FRONT...CANNOT RULE
OUT THE RISK OF A TORNADO OR TWO GIVEN SOME POTENTIAL FOR FAVORABLE
STORM-BOUNDARY INTERACTION. THE SVR THREAT SHOULD DIMINISH AFTER
SUNSET.

...S CNTRL/SW TX TO SW KS/WRN OK THIS AFTN INTO TNGT...
STRONG SFC HEATING AND INFLOW OF RICH MOISTURE RETURNING NWWD ACROSS
THE BIG BEND REGION AND HILL COUNTRY WILL YIELD CONSIDERABLE
SFC-BASED CAPE /VALUES AOA 4000 J PER KG/ ACROSS S CNTRL TX THIS
AFTN. ALTHOUGH WEAK SHORTWAVE RIDGING WILL PREVAIL...SATELLITE
SUGGESTS PRESENCE OF WEAK DISTURBANCES EMANATING NRN CHIHUAHUA
THAT...COUPLED WITH TERRAIN CIRCULATIONS AND/OR LOCALIZED ASCENT
ALONG RESIDUAL OUTFLOW BOUNDARIES FROM YESTERDAY`S MCS...COULD BOOST
PARCELS TO THEIR LFCS. GIVEN STRENGTH OF BUOYANCY...IF EML CAP IS
INDEED BREACHED...25-30 KT WLY MID-LVL FLOW WILL BE SUFFICIENT FOR
HP-TYPE SUPERCELLS WITH A RISK FOR VERY LARGE HAIL...LOCALLY DMGG
WIND AND PERHAPS A TORNADO. THESE MAY MERGE INTO A SLOWLY-MOVING
CLUSTER OVER THE HILL COUNTRY TNGT.

FARTHER N...CANNOT RULE OUT THE POSSIBILITY FOR AN ISOLD STORM OR
TWO WITH LARGE HAIL FORMING IN NOCTURNALLY-STRENGTHENED WAA/MOISTURE
TRANSPORT ZONE OVER THE TX/OK PANHANDLES AND ADJACENT PARTS OF OK/SW
KS EARLY SUN. THE COVERAGE OF ANY SUCH ACTIVITY...HOWEVER...APPEARS
TOO LOW TO WARRANT ADDITION OF PROBABILITIES ATTM.

...CSTL CAROLINAS/TD 2 TNGT/EARLY SUN...
TD 2 IS EXPECTED TO CONTINUE GENERALLY NWWD THROUGH THE PERIOD
...GIVEN STRENGTH/ORIENTATION OF RIDGE OFF THE MID-ATLANTIC CST.
SATELLITE/LIGHTNING DATA AND COMPARATIVELY COOL MID-LVL TEMPS
SUGGEST THAT AN ENVELOPE OF SUFFICIENTLY BUOYANT AIR WILL REMAIN
PRESENT ON THE NWRN EDGE OF THE SYSTEM TO SUPPORT ADDITIONAL
SEMI-DISCRETE STORM DEVELOPMENT. WITH SYSTEM NOT EXPECTED TO
APPRECIABLY DEEPEN /PER NHC/...HODOGRAPHS LIKELY WILL REMAIN FAIRLY
SMALL. NEVERTHELESS...PRESENCE OF ENHANCED LOW-LVL DIRECTIONAL SHEAR
INVOF DISCRETE CELLS SUGGESTS A NON-ZERO BRIEF TORNADO RISK ALONG
PARTS OF THE SC AND SRN NC CSTS LATE TNGT AND EARLY SUN.

$$



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