Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 211825
SWOMCD
SPC MCD 211825
WYZ000-MTZ000-IDZ000-212100-

MESOSCALE DISCUSSION 1417
NWS STORM PREDICTION CENTER NORMAN OK
0125 PM CDT MON JUL 21 2014

AREAS AFFECTED...PORTIONS OF SRN ID...NWRN WY...SRN MT

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 211825Z - 212100Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...STORMS WILL CONTINUE TO INCREASE IN COVERAGE AND INTENSITY
ACROSS PARTS OF THE NRN GREAT BASIN AND NRN ROCKIES DURING THE NEXT
FEW HOURS. A FEW STORMS MAY BECOME SEVERE...THOUGH WW ISSUANCE IS
NOT ANTICIPATED.

DISCUSSION...VISIBLE SATELLITE AND MOSAIC RADAR IMAGERY SUGGEST
CONVECTIVE INITIATION UNDERWAY -- LIKELY BOLSTERED BY STRENGTHENING
OROGRAPHIC CIRCULATIONS AND DIFFERENTIAL-HEATING-INDUCED
BAROCLINICITY ON THE PERIPHERY OF A MID-LEVEL CLOUD BAND EXTENDING
NEWD ACROSS CNTRL ID INTO SW MT. MEANWHILE...A BAND OF MODERATE
MID-LEVEL WSWLYS/SWLYS OVERLYING THE REGION CONTINUES TO SUSTAIN A
PLUME OF ENHANCED MID-LEVEL MOISTURE ACROSS THE AREA. IN TURN...SFC
DEWPOINTS ARE HOLDING IN THE MIDDLE 40S TO LOWER 50S AS PBL
CIRCULATIONS DIURNALLY DEEPEN...WHILE THE MOISTURE ALOFT FACILITATES
SHELTERING OF INCIPIENT UPDRAFTS. AS SUCH...WITH MANY AREAS OF AMPLE
INSOLATION -- PARTICULARLY S OF THE MT BORDER -- THUNDERSTORMS ARE
EXPECTED TO INCREASE IN COVERAGE AND INTENSITY DURING THE NEXT FEW
HOURS.

MODIFICATIONS TO AREA 12Z RAOBS TO ACCOUNT FOR CURRENT SFC
CONDITIONS SUGGEST SBCAPE AROUND 500-1500 J/KG...AIDED BY STEEP
TROPOSPHERIC LAPSE RATES SUPERIMPOSED WITH MODEST LOW-LEVEL
MOISTURE. AND...WITH 30-40 KT OF EFFECTIVE BULK SHEAR ATTENDANT TO
THE ENHANCED FLOW ALOFT...SUSTAINED AND LOCALLY ORGANIZED CONVECTIVE
STRUCTURES -- INCLUDING POSSIBLE MARGINAL/TRANSIENT SUPERCELLS --
MAY OCCUR. ISOLATED DMGG WIND GUSTS WILL BE POSSIBLE WITH THE MOST
INTENSE STORMS. HOWEVER...WITH A MID-LEVEL RIDGE BUILDING NWD INTO
THE REGION AND ATTENDANT HEIGHT RISES THROUGH PEAK HEATING...THE
COVERAGE OF SVR STORMS SHOULD BE TOO MINIMAL FOR WW ISSUANCE --
ESPECIALLY WITHOUT STRONGER BUOYANCY.

..COHEN/HART.. 07/21/2014

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

ATTN...WFO...BYZ...RIW...TFX...PIH...MSO...BOI...

LAT...LON   42151184 42381528 45441263 46601044 46250806 44370770
            43200944 42151184



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