MESO: Mesoscale Discussion 1070

ACUS11 KWNS 051746
SWOMCD
SPC MCD 051746
WYZ000-UTZ000-IDZ000-052015-

MESOSCALE DISCUSSION 1070
NWS STORM PREDICTION CENTER NORMAN OK
1246 PM CDT TUE JUN 05 2012

AREAS AFFECTED...NERN UT...SWRN WY...FAR SERN ID

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 051746Z - 052015Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A VERY ISOLATED SVR WIND THREAT WILL EXIST WITH A FEW
THUNDERSTORMS THIS AFTERNOON...AND A WW IS NOT NEEDED.

DISCUSSION...RECENT WATER VAPOR LOOP REVEALS A STRONG DEEP TROUGH
OVER THE WRN U.S. THAT IS BECOMING INCREASINGLY NEGATIVELY TILTED.
STRONG DEEP MERIDIONAL FLOW LEADS THE TROUGH AXIS ACROSS PARTS OF
THE CNTRL GREAT BASIN...WITH SALT LAKE CITY VWP DATA INDICATING
30-50 KT OF SLY FLOW WITHIN THE 2-4-KM-AGL LAYER. NEAR AND AHEAD OF
THE SFC COLD FRONT ATTENDANT TO THE TROUGH...ABUNDANT
INSOLATION/DIABATIC HEATING IS SUPPORTING STEEPENING
LOW-TO-MID-LEVEL LAPSE RATES AS SFC TEMPERATURES WARM THROUGH THE
70S. THIS IS BEING MANIFESTED AS SFC GUSTS REACHING/EXCEEDING 40 MPH
PER AREA OBSERVATIONS.

STRONG LARGE-SCALE FORCING FOR ASCENT ASSOCIATED WITH THE
TROUGH...MARKED BY 500-MB HEIGHT FALLS IN EXCESS OF 90 GEOPOTENTIAL
METERS PER 12 HRS...AND THE AFOREMENTIONED DIABATIC HEATING WILL AID
IN FURTHER DESTABILIZATION INTO THE AFTERNOON.
WHILE DEEP MOISTURE IS VERY SCARCE...WITH PW VALUES OF 0.3-0.4 INCH
PER GPS DATA...WATER VAPOR IMAGERY DEPICTS THE SRN EXTENT OF THE
DCVA-RELATED LOBE OF ASCENT ACCOMPANYING THE TROUGH ENTERING NWRN UT
AND S-CNTRL ID. AS VERTICAL MIXING ALLOWS SOME OF THIS MOISTURE TO
BE DISTRIBUTED THROUGH THE WELL MIXED BOUNDARY LAYER...SBCAPE VALUES
OF 150-250 J/KG SHOULD DEVELOP WITHIN A ZONE NEAR AND JUST AHEAD OF
THE FRONT. AND...WITH FRONTAL ASCENT COMBINED WITH OROGRAPHIC
EFFECTS -- E.G. INVOF THE WASATCH RANGE AND UINTA MOUNTAINS --
MESOSCALE ASCENT WILL EXIST TO SUPPORT THE POTENTIAL INITIATION OF
VERY ISOLATED...SHALLOW...PULSE CONVECTION AFTER 1900Z.

WHILE CONVECTION MAY CONTAIN LITTLE...IF ANY...LIGHTNING...ITS
ACCOMPANYING CONVECTIVE MASS TRANSPORT PROCESSES AUGMENTED BY
EVAPORATIVE COOLING PROCESSES WITHIN THE DEEP BOUNDARY LAYER
COMBINED WITH THE STRONG BACKGROUND FLOW/TIGHT SFC PRESSURE GRADIENT
WILL SUPPORT A THREAT FOR VERY ISOLATED SVR WIND GUSTS WITH DRY
MICROBURSTS THIS AFTERNOON. THE THREAT IS EXPECTED TO REMAIN TOO
ISOLATED TO WARRANT A SVR TSTM WATCH IN THE ABSENCE OF GREATER
MOISTURE/BUOYANCY.

..COHEN/MEAD.. 06/05/2012

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

ATTN...WFO...RIW...GJT...SLC...PIH...

LAT...LON 42391173 42861068 42640965 41820956 40850996 39961073
39611156 40241223 42391173

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