Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 271944
SWOMCD
SPC MCD 271944
MTZ000-WYZ000-272145-

MESOSCALE DISCUSSION 1551
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT MON JUL 27 2015

AREAS AFFECTED...PORTIONS OF NRN WY AND ERN MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 271944Z - 272145Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE THREAT FOR DAMAGING WINDS AND LARGE HAIL SHOULD
INCREASE THROUGH THE AFTERNOON. ALTHOUGH NOT IMMEDIATELY LIKELY...WW
ISSUANCE IS POSSIBLE OVER THE NEXT SEVERAL HOURS.

DISCUSSION...SFC ANALYSIS AS OF 19Z SHOWS DUAL LOWS...ONE OVER ERN
MT...AND THE OTHER OVER CNTRL WY. A COLD FRONT EXTENDS SWWD FROM THE
LOW OVER ERN MT...WHILE A WARM FRONT STRETCHES NWD ALONG THE MT/ND
BORDER AND INTO CANADA. THE POST-FRONTAL LOW-LEVEL AIRMASS ACROSS
MUCH OF NRN WY AND ERN MT IS CHARACTERIZED BY NLY WINDS...
TEMPERATURES IN THE MID 70S TO MID 80S...AND DEWPOINTS IN THE LOW
50S TO AROUND 60. VISIBLE/WATER VAPOR SATELLITE LOOPS SHOW AN UPPER
TROUGH WITH ASSOCIATED CLOUDINESS APPROACHING THE MCD AREA FROM THE
W. PARTLY TO MOSTLY SUNNY SKIES OVER MUCH OF NRN WY AND ERN MT
SHOULD ALLOW SFC TEMPERATURES TO CONTINUE TO WARM OVER THE NEXT
SEVERAL HOURS...WITH A CONTINUED INCREASE IN INSTABILITY LIKELY.

AS LARGE-SCALE ASCENT ASSOCIATED WITH THE UPPER TROUGH OVERSPREADS
THE REGION FROM W TO E THIS AFTERNOON...AN INCREASE IN CONVECTIVE
ACTIVITY IS EXPECTED. FORECAST SOUNDINGS FROM THE RAP ALONG WITH A
19Z OBSERVED SOUNDING FROM GLASGOW MT SUGGEST MUCAPE AROUND
1000-2000 J/KG SHOULD GENERALLY BE PRESENT ACROSS MUCH OF THE
AREA...ALONG WITH EFFECTIVE BULK SHEAR OF 40-50 KT. THIS FAVORABLE
COMBINATION OF INSTABILITY AND SHEAR WILL LIKELY ALLOW ANY
THUNDERSTORMS THAT FORM OFF THE HIGHER TERRAIN IN NRN WY/CNTRL MT TO
QUICKLY BECOME ORGANIZED AND POSE A THREAT FOR LARGE HAIL AND
DAMAGING WINDS...PARTICULARLY WITH EWD EXTENT.

MOST CONVECTIVE ALLOWING MODEL GUIDANCE SUGGESTS SCATTERED
CONVECTION SHOULD FORM/MOVE INTO THE MCD AREA BY 22-23Z.
HOWEVER...LATEST RADAR TRENDS SHOW ISOLATED DEVELOPMENT IS ALREADY
OCCURRING IN S-CNTRL MT/NWRN WY. IF THUNDERSTORMS CONTINUE TO
INCREASE IN COVERAGE AND INTENSITY OVER THE NEXT SEVERAL
HOURS...THEN A SEVERE THUNDERSTORM WATCH MAY BE NEEDED.

..GLEASON/GOSS.. 07/27/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...

LAT...LON   47660794 47670631 47260476 46940436 45000496 44040621
            44030793 44350944 45030976 46560921 47660794




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