Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 031251
SWODY1
SPC AC 031249

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CST TUE MAR 03 2015

VALID 031300Z - 041200Z

...NO SVR TSTM AREAS FORECAST...

...SUMMARY...
ISOLATED THUNDERSTORMS ARE POSSIBLE MAINLY TONIGHT OVER PARTS OF THE
MID SOUTH TO LOWER OHIO VALLEY...THIS AFTERNOON AND EVENING OVER
WEST TEXAS...AND THIS AFTERNOON FROM NORTHERN ARIZONA TO WESTERN
COLORADO.

...SYNOPSIS...
CONUS UPPER-AIR PATTERN WILL BE DOMINATED BY SLOWLY
PROGRESSIVE...SYNOPTIC-SCALE TROUGH FROM HUDSON BAY AREA SWWD ACROSS
NRN PLAINS AND SWRN STATES...THROUGH WHICH SEVERAL SHORTWAVES WILL
TRANSIT.  STG SHORTWAVE TROUGH -- WITH EMBEDDED LOW EVIDENT IN
MOISTURE-CHANNEL IMAGERY OFFSHORE SRN CA AND NWRN BAJA -- IS
EXPECTED TO PIVOT EWD TO NRN BAJA AND SWRN AZ THROUGH 00Z...THEN
WEAKEN AND ACCELERATE NEWD TO NM...NRN CHIHUAHUA...AND SRN SONORA BY
12Z.  THIS WILL OCCUR AS ANOTHER PERTURBATION -- INITIALLY LOCATED
OVER SRN ID AND NRN NV -- MOVES SEWD TOWARD 4-CORNERS REGION THROUGH
PERIOD.  NRN-STREAM TROUGHS -- NOW OVER NRN MB AND NR SK -- ARE FCST
TO FOLLOW CYCLONICALLY CURVING PATHS TOWARD 12Z POSITIONS OVER FAR
WRN QUE AND ERN ND/NWRN MN RESPECTIVELY.

AT SFC...STG COLD FRONT ASSOCIATED WITH THOSE NRN-STREAM
PERTURBATIONS WAS DRAWN AT 11Z FROM FAR NWRN ONT SWWD ACROSS NWRN
MN...ERN SD...N-CENTRAL/SWRN NEB AND NERN CO.  THIS FRONT IS FCST TO
PROCEED SEWD AND EWD...REACHING UPPER GREAT LAKES...SRN IL...CENTRAL
OK AND NERN NM BY 00Z.  BY END OF PERIOD...FRONT SHOULD EXTEND FROM
NRN NEW ENGLAND SWWD OVER WV...MID TN...SRN AR...AND W-CENTRAL TX.

...AR...MID SOUTH...LOWER OH VALLEY...
CONVECTIVE PRECIP...INCLUDING POTENTIAL FOR SPORADIC...ISOLATED TO
WIDELY SCATTERED EMBEDDED TSTMS...SHOULD INCREASE OVERNIGHT
PRIMARILY N OF AND NEARLY PARALLEL TO SFC COLD FRONT.  BY THIS
TIME...ELEVATED FRONTOGENETIC FORCING WILL AUGMENT LOW-LEVEL WAA
ALONG AND ABOVE STABLE LAYER TO FORCE PARCELS TO LFC. ALTHOUGH
BUOYANCY WILL REMAIN LIMITED -- E.G. MUCAPES GENERALLY BELOW 400
J/KG -- SOME CAPE MAY EXTEND BRIEFLY INTO THERMAL PROFILES SUITABLE
FOR LTG GENERATION.

WIDELY SCATTERED TO SCATTERED SHOWERS ARE EXPECTED THROUGHOUT PERIOD
OVER AREAS FARTHER S ACROSS LOWER MS VALLEY REGION AND CENTRAL/SRN
MS.  FCST SOUNDINGS SUGGEST BRIEF/VERY ISOLATED THUNDER CANNOT BE
RULED OUT.  THOUGH OCCURRING IN ENVIRONMENT CHARACTERIZED BY
SOMEWHAT FAVORABLE DEEP/SPEED SHEAR...AND RELATIVELY MAXIMIZED
LOW-LEVEL MOISTURE...COMBINATION OF CAPE-DEPTH SUPPRESSION BY WEAK
LAPSE RATES ALOFT AND LACK OF SUBSTANTIAL FOCI FOR LIFT INDICATE
THUNDER POTENTIAL IS TOO CONDITIONAL FOR CATEGORICAL OUTLOOK ATTM.

...W TX...
PLUME OF LOW-LEVEL WAA AND WEAK MOISTURE TRANSPORT WILL ENABLE
SPORADIC CONVECTION ACROSS THIS CORRIDOR TODAY AND TONIGHT...AMIDST
GRADUAL HEIGHT FALLS ASSOCIATED WITH APCHG MID/UPPER-LEVEL TROUGH.
SFC HEATING WILL BE MUTED BENEATH PERSISTENT/LONG-FETCH CLOUD PLUME
NOTED ON IR IMAGERY.  DESPITE FAVORABLE DEEP SHEAR...VERY WEAK
INSTABILITY WILL RENDER THIS AREA VERY MARGINAL FOR A THUNDER
OUTLOOK...WITH MUCAPE GENERALLY REMAINING BELOW 400 J/KG.

...NRN AZ TO WRN CO...
ISOLATED TO WIDELY SCATTERED WEAK TSTMS MAY OCCUR WITH CONVECTION
DEVELOPING OVER THIS REGION THIS AFTN.  COMBINATION OF MRGL
LOW-LEVEL MOISTURE...DIABATIC HEATING OF HIGHER TERRAIN...AND
COOLING ALOFT AND RELATED STEEPENING LAPSE RATES RELATED TO
LARGE-SCALE ASCENT...SHOULD YIELD ESSENTIALLY UNINHIBITED 100-300
J/KG MUCAPE EXTENDING AT TIMES INTO FAVORABLE ICING LAYERS FOR LTG
PRODUCTION.  LACK OF STRONGER LOW-LEVEL THETAE WILL SUBSTANTIALLY
LIMIT UPDRAFT INTENSITY.

..EDWARDS/GLEASON.. 03/03/2015




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.