National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
ACUS11 KWNS 221912
SWOMCD
SPC MCD 221912
UTZ000-AZZ000-NVZ000-222115-

MESOSCALE DISCUSSION 1729
NWS STORM PREDICTION CENTER NORMAN OK
0212 PM CDT THU SEP 22 2016

AREAS AFFECTED...ERN NV/WRN UT/NWRN AZ

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 221912Z - 222115Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...SLOWLY INCREASING CONVECTION ACROSS THE DISCUSSION AREA
SUGGESTS CORRESPONDING INCREASE IN MARGINAL SEVERE POTENTIAL.
HOWEVER...WW NOT ANTICIPATED ATTM DUE TO MARGINAL/ISOLATED RISK.

DISCUSSION...LATEST WV LOOP SHOWS AN UPPER CENTER-OF-CIRCULATION
MOVING SLOWLY SEWD INTO NWRN NV...WITH THE ZONE OF STRONGEST IMPLIED
ASCENT OVER THE ERN HALF OF NV AND NOSING INTO WRN UT -- I.E. JUST W
OF THE N-S BAND OF CLOUD COVER OVER ERN UT REPRESENTING
EARLIER/REMNANT PRECIPITATION.

DIURNAL HEATING W OF THE AFOREMENTIONED CLOUDINESS IS RESULTING IN
MODEST DESTABILIZATION...WITH UP 500 J/KG MIXED-LAYER CAPE NOW
INDICATED PER OBJECTIVE ANALYSIS.  THIS HAS PROVEN SUFFICIENT FOR AN
INCREASE IN CONVECTION/LIGHTNING IN THE ERN NV/NWRN UT AREA...AND
EXPECT THIS TREND TO CONTINUE -- BOTH ACROSS THIS AREA AND SWD
TOWARD NWRN AZ -- OVER THE NEXT FEW HOURS AS ADDITIONAL
HEATING/DESTABILIZATION CONTINUE.

AS STORMS INCREASE ALONG/AHEAD OF THE SURFACE FRONT...INCREASING SLY
LOW-LEVEL FLOW BENEATH STRONG MID-LEVEL WINDS /SSWLY H5 FLOW IN
EXCESS OF 50 KT/ IS RESULTING IN SHEAR SUPPORTIVE OF ORGANIZED
UPDRAFTS AND/OR BANDS OF STORMS.  AIDED BY SOME LOW-LEVEL
EVAPORATION/MIXING...SOME OF THE STRONGER FLOW ALOFT COULD BE
TRANSPORTED TO THE SURFACE YIELDING ISOLATED/LOCALLY DAMAGING WIND
GUSTS.  HAIL UP TO 1" IN DIAMETER MAY ALSO OCCUR WITH A COUPLE OF
THE STRONGER CELLS.

ATTM...THE EXPECTED ISOLATED/MARGINAL NATURE OF THE RISK PRECLUDES
ANY IMMEDIATE NEED FOR WW ISSUANCE.  SHOULD CONVECTION GROW UPSCALE
INTO SMALL BANDS -- AS IS HINTED AT OVER NWRN
UT...RESULTING/POTENTIAL INCREASE IN WIND RISK COULD EVENTUALLY
REQUIRE WW CONSIDERATION.

..GOSS/THOMPSON.. 09/22/2016

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

ATTN...WFO...SLC...VEF...LKN...

LAT...LON   41441167 40661138 38871171 37761230 36611317 35241379
            35201454 35921481 36961448 38181489 39091507 39961433
            40991373 41151247 41441167