Severe Storm Outlook Narrative (AC)
Issued by NWS

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587
ACUS01 KWNS 141950
SWODY1
SPC AC 141948

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CST SUN FEB 14 2016

VALID 142000Z - 151200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
SCATTERED THUNDERSTORMS EXPECTED TONIGHT AND EARLY MONDAY FROM PARTS
OF NORTH TEXAS NORTHEAST INTO THE LOWER TENNESSEE VALLEY.

...20Z OUTLOOK UPDATE...
THE 10 PERCENT THUNDERSTORM PROBABILITY LINE HAS BEEN ADJUSTED ON
ITS NORTHEASTERN EDGE...ACROSS PARTS OF WESTERN KENTUCKY AND
TENNESSEE...NORTHEASTERN ARKANSAS AND SOUTHEASTERN MISSOURI...IN
LINE WITH EARLIER EXPECTATIONS.  A SLIGHT ADJUSTMENT HAS ALSO BEEN
MADE TO LOWER PROBABILITIES ACROSS PARTS OF CENTRAL LOUISIANA...
WHERE FORECAST SOUNDINGS...INCLUDING THE LATEST /18Z/ RAPID REFRESH
APPEAR INCREASINGLY SUGGESTIVE THAT MID-LEVEL INHIBITION MAY
SUPPRESS DEEP CONVECTION THROUGH 15/12Z.

SOME LIGHTNING HAS RECENTLY BEEN DETECTED WITH ONGOING LOW-TOPPED
CONVECTIVE DEVELOPMENT ACROSS THE HIGHER TERRAIN TO THE SOUTHEAST OF
BILLINGS MT.  THIS ACTIVITY HAS BEEN AIDED BY FORCING ASSOCIATED
WITH A DIGGING MID-LEVEL JET STREAK...WHICH IS EXPECTED TO CONTINUE
TO SPREAD ACROSS AND SOUTHEAST OF THE BIGHORN MOUNTAINS DURING THE
NEXT FEW HOURS.  OCCASIONAL ADDITIONAL LIGHTNING MAY NOT BE OUT OF
THE QUESTION WITH CONVECTION ACROSS THE NEARBY HIGH PLAINS AND BLACK
HILLS REGION THIS AFTERNOON.  HOWEVER...COVERAGE IS STILL EXPECTED
TO REMAIN GENERALLY BELOW 10 PERCENT.

..KERR.. 02/14/2016

.PREV DISCUSSION... /ISSUED 1018 AM CST SUN FEB 14 2016/

...SYNOPTIC SETUP...
DOWNSTREAM FROM DOMINANT E PAC RIDGE AND IN WAKE OF DEPARTING E CST
TROUGH...A BROAD TROUGH WILL EVOLVE OVER THE CNTRL U.S AS A SERIES
OF SMALL-SCALE DISTURBANCES PROGRESS SEWD FROM THE RCKYS INTO THE
PLNS/MS VLY. LEAD IMPULSE IN THIS PATTERN...NOW OVER IA...SHOULD
DEAMPLIFY IN CONFLUENT FLOW OVER THE OH VLY LATER TODAY...WHILE JET
STREAK NOW IN WRN MT CONTINUES SE INTO KS/OK BY 12Z MON...ENHANCING
DCVA ACROSS THE OZARKS/LWR MS VLY.

AT THE SFC...ARCTIC SFC RIDGE WILL ADVANCE E INTO THE WRN
ATLANTIC...ALLOWING FOR STRENGTHENING LOW-LVL WAA/MOISTURE TRANSPORT
ATOP RESIDUAL SFC-BASED COLD LAYER FROM E TX NEWD INTO THE TN AND OH
VLYS.

...SE MO/NE AR/WRN TN/WRN KY THIS MORNING...
CORRIDOR OF ELEVATED WAA/MOISTURE TRANSPORT BENEATH STEEP MID-LVL
LAPSE RATE PLUME DRAWN EWD IN BASE OF IA UPR IMPULSE SHOULD FURTHER
NARROW TODAY AS THE DISTURBANCE CONTINUES ENE AWAY FROM MARGINAL
MOIST AXIS. AS A RESULT...ASSOCIATED CONVECTIVE BAND AND POTENTIAL
FOR OCCASIONAL THUNDER SHOULD FURTHER DIMINISH.

...N TX TO LWR TN VLY TNGT/EARLY MON...
ELEVATED WAA EXPECTED TO STRENGTHEN OVER A BROAD SWATH OF THE S
CNTRL/SE U.S. TNGT AND EARLY MON AS DISTURBANCES NOW OVER THE RCKYS
REACH THE CNTRL AND SRN PLNS...AND AS SFC RIDGE MOVES OFF THE E CST.
THIS WILL FOSTER INCREASED SWLY 925-850 MB FLOW FROM E TX ENE INTO
THE TN VLY/CAROLINAS. RECENT COLD-AIR INTRUSION AND CURRENT SFC/STLT
MOISTURE OBSERVATIONS IN THE GULF OF MEXICO SUGGEST THAT ASSOCIATED
MOISTURE TRANSPORT WILL REMAIN COMPARATIVELY MODEST...ALTHOUGH PW
MAY INCREASE TO AOA 1 INCH BY THE END OF THE PERIOD FROM THE
ARKLATEX NEWD INTO W TN. COUPLED WITH INCREASING/NOT STRONGLY
FOCUSED HEIGHT FALLS AND STEEPENING MID-LVL LAPSE RATES...EXPECT A
FAIRLY EXTENSIVE BAND OF CONVECTION TO DEVELOP AFTER 00-03Z FROM N
TX ENE INTO THE LWR TN VLY. THIS ACTIVITY SHOULD INCREASE IN
COVERAGE DURING THE NIGHT AND PERSIST BEYOND 12Z MON. WHILE THE SRN
END OF THE CONVECTIVE BAND MAY INCLUDE A FEW PATCHES OF NEARLY
SFC-BASED ACTIVITY OVER NE TX...NEITHER THE NEAR-SFC BUOYANCY NOR
LOW-LVL WIND FIELD ARE LIKELY TO BE SUFFICIENTLY STRONG TO POSE AN
APPRECIABLE SVR THREAT.

...SE LA 09-12Z MON...
A SEPARATE AREA OF CONVECTION SHOULD DEVELOP LATE IN THE PERIOD
ALONG LOW-LVL CONFLUENCE ZONE EXTENDING NNE FROM THE N CNTRL GULF OF
MEXICO INTO SE LA. THE ONSHORE PORTION OF THIS ACTIVITY LIKELY WILL
REMAIN SLIGHTLY ELEVATED...AND RESIDUAL WARM LAYER ALOFT SHOULD KEEP
THE UPDRAFTS FAIRLY SHALLOW. THUS...THE POTENTIAL FOR LIGHTNING OVER
THE REGION APPEARS LIMITED THROUGH 12Z.

$$



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