Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 141259
SWODY1
SPC AC 141257

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0657 AM CST SUN FEB 14 2016

VALID 141300Z - 151200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
FOR A FEW MORE HOURS...ISOLATED TO WIDELY SCATTERED THUNDERSTORMS
MAY ACCOMPANY A PLUME OF FREEZING AND FROZEN PRECIPITATION OVER THE
OZARKS REGION AND NEARBY MISSISSIPPI VALLEY.  THIS ACTIVITY WILL
WEAKEN AS IT SHIFTS EAST OF THE MISSISSIPPI RIVER.  AFTER ABOUT A
12-HOUR LULL...ANOTHER PLUME OF THUNDERSTORMS SHOULD DEVELOP FROM
PARTS OF NORTH-CENTRAL AND NORTHEAST TEXAS TO WESTERN TENNESSEE
OVERNIGHT.  SEVERE WEATHER IS NOT ANTICIPATED IN EITHER EVENT.

--- TECHNICAL DISCUSSION ---

...SYNOPSIS...
MID/UPPER-LEVEL PATTERN WILL REMAIN PROGRESSIVE THROUGH PERIOD
ACROSS CONUS.  BROAD SWATH OF GRADUAL HEIGHT FALLS IS FCST TO SHIFT
EWD ACROSS PLAINS STATES AND ACROSS MUCH OF MS RIVER VALLEY AS
SEVERAL SHORTWAVES TRAVERSE CYCLONICALLY CURVING FLOW REGIME IN
THOSE REGIONS.  LEADING SHORTWAVE TROUGH -- NOW APPARENT IN
MOISTURE-CHANNEL IMAGERY FROM SRN MN SSWWD TO ERN KS -- SHOULD
WEAKEN AND MOVE EWD TO PA BY 12Z.  SERIES OF NEARLY PHASED...LOW-
AMPLITUDE VORTICITY MAXIMA NOW OVER NRN ROCKIES AND NRN GREAT BASIN
SHOULD MOVE ESEWD TO SEWD...CONTRIBUTING TO AFOREMENTIONED
CENTRAL-CONUS HEIGHT FALLS.

AT SFC...12Z ANALYSIS SHOWED COLD FRONT ORIENTED SW-NE ACROSS OK AND
EXTENDING WWD OVER SRN PANHANDLE OF TX.  FRONT IS FCST TO MOVE
SLOWLY SEWD...REACHING TO NEAR DYR-TXK-DRT LINE BY END OF PERIOD.
WEAK SFC LOW SHOULD DEVELOP SOON ALONG FRONT INVOF SW OK/NW TX RED
RIVER REGION AND MIGRATE GENERALLY ESEWD TOWARD ARKLATEX.

GEN-TSTM OUTLOOK REPRESENTS SPATIAL OVERLAP OF TWO TEMPORALLY
DISPARATE REGIMES DESCRIBED BELOW.

...SRN MO REGION...
SWATH OF ELEVATED CONVECTION WITH EMBEDDED TSTMS WILL CONTINUE TO
POSE THREAT FOR MIXED WINTER PRECIP FOR ANOTHER FEW HOURS WHILE
MOVING EWD ACROSS SRN MO.  THUNDER POTENTIAL THEREAFTER SHOULD
DIMINISH...AS IT MOVES EWD PAST MS RIVER VALLEY...AND AS SUPPORTIVE
LLJ ASSOCIATED WITH MN-KS SHORTWAVE TROUGH WEAKENS SOMEWHAT AND
EJECTS AWAY FROM MOISTURE SOURCE.  REF SPC MESOSCALE DISCUSSION 95
FOR MORE NEAR-TERM METEOROLOGICAL DETAILS.

...N TX TO MID TN...
TSTMS SHOULD DEVELOP TONIGHT IN 03-08Z TIME FRAME OVER PARTS OF N TX
AND/OR ARKLATEX REGION...AND BUILD NEWD ACROSS PARTS OF MID SOUTH
BEFORE 12Z.  THIS ACTIVITY WILL BE SUPPORTED BY
1. WEAK LIFT PRODUCED DIRECTLY BY LOW-LEVEL BAROCLINIC ZONE...BUT AT
LEAST AS IMPORTANTLY...
2. STEEPENING OF LAPSE RATES AND DEVELOPING ELEVATED BUOYANCY...
RELATED TO JUXTAPOSITION OF INCREASING HEIGHT FALLS AND COOLING
ALOFT WITH LOW-LEVEL WAA AND MOISTURE TRANSPORT.

MUCAPE MAY REACH NEAR 500 J/KG IN THIS SETTING.  SOME MODEL-FCST
SOUNDINGS INDICATE NOMINALLY SFC-BASED EFFECTIVE-INFLOW PARCELS FOR
TEMPS IN UPPER 50S TO LOWER 60S F...AND LOW-LEVEL HODOGRAPHS DO
CONTAIN APPRECIABLE CURVATURE.  HOWEVER...THESE FACTORS SHOULD BE
OFFSET BY LIKELIHOOD OF MESSY/BANDED CONVECTIVE MODE...SHALLOW/
DIABATICALLY COOLED STABLE LAYER NEAR SFC...WEAK LOW-MIDDLE LEVEL
LAPSE RATES...AND RELATED NARROW BUOYANT PROFILES WITH SMALL CAPE
DENSITY.

WWD EXTENT OF TSTM POTENTIAL IS NOT SHARPLY DEFINED...WITH MIXED
SIGNALS IN BOTH SYNOPTIC AND CONVECTION-ALLOWING GUIDANCE REGARDING
DEVELOPMENT BACK TOWARD DFW METROPLEX.  THIS IS RELATED TO
DISCREPANCIES IN WRN RIM OF MOST FAVORABLE MOISTURE-TRANSPORT PLUME.
GIVEN PROG TRENDS THAT WAY WITH TIME...WILL EXTEND GEN-TSTM/10%
THUNDER LINE A FEW COUNTIES WWD ACROSS N-CENTRAL TX FOR OVERNIGHT.

..EDWARDS/COHEN.. 02/14/2016

$$


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