Mesoscale Discussion 844

Issued

Jun 8, 2016, 1:16 PM PDT (20:16 UTC)

Expired

Jun 8, 2016, 3:45 PM PDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

The Spokane radar (KOTX), 150 km from the middle of the area, began a volume at 20:18 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

• Severe Thunderstorm Watch 238Jun 8, 2:05 PM PDT

406 
ACUS11 KWNS 082016
SWOMCD
SPC MCD 082016 
MTZ000-IDZ000-ORZ000-WAZ000-082245-

MESOSCALE DISCUSSION 0844
NWS STORM PREDICTION CENTER NORMAN OK
0316 PM CDT WED JUN 08 2016

AREAS AFFECTED...PORTIONS OF NERN ORE...NRN ID...NWRN/N-CNTRL MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 082016Z - 082245Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THERE IS INCREASING POTENTIAL FOR ISOLATED TO PERHAPS
WIDELY SCATTERED SEVERE THUNDERSTORMS TO BEGIN AFFECTING PORTIONS OF
THE NRN GREAT BASIN...NRN ROCKIES...AND IMMEDIATELY ADJACENT HIGH
PLAINS OF N-CNTRL MT WITHIN THE NEXT FEW HOURS...AND CONTINUE INTO
THE EVENING. WHILE NOT IMMEDIATELY LIKELY...THERE MAY BE SOME
POTENTIAL FOR SEVERE THUNDERSTORM WATCH ISSUANCE LATER TODAY.

DISCUSSION...AS OF MID-DAY...VISIBLE SATELLITE LOOPS HAVE INDICATED
A CONCENTRATED AREA OF DEEPENING CUMULUS OVER PARTS OF N-CNTRL/NERN
ORE...GIVING RISE TO TSTM DEVELOPMENT OVER CROOK COUNTY. THIS
ACTIVITY LIES ALONG THE ERN PERIPHERY OF A PERSISTENT MULTI-LAYERED
CLOUD BAND THAT EXTENDS FROM CNTRL ORE TO ERN WA AND NRN ID. AREAS
OF INSOLATION E OF THE MOST PERSISTENT PORTION OF THE CLOUD BAND ARE
FACILITATING DESTABILIZATION AS TEMPERATURES HAVE CLIMBED INTO THE
80S IN MANY OF THE LOWER ELEVATIONS. WHILE BOUNDARY-LAYER MOISTURE
REMAINS QUITE MARGINAL -- E.G. DEWPOINTS IN THE UPPER 40S TO THE
LOWER 50S IN MANY AREAS -- STEEP TROPOSPHERIC LAPSE RATES ARE
SUPPORTING MLCAPE AROUND 250-1000 J/KG WHERE MOSTLY SUNNY SKIES
EXIST. SOME ADDITIONAL INCREASE IN BUOYANCY MAY YET STILL OCCUR
OWING TO CONTINUED DIABATIC SFC-LAYER HEATING. AS SUCH...THE
AFOREMENTIONED CONVECTION WILL LIKELY CONTINUE TO INCREASE IN
INTENSITY ACROSS PARTS OF ORE...WITH DEVELOPMENT POSSIBLE DOWNSTREAM
INTO SERN WA AND NRN ID...ON THE EDGES OF THE CLOUD BAND. TSTMS WILL
SPREAD NEWD/ENEWD INTO/ACROSS PARTS OF NWRN/N-CNTRL MT THROUGH LATE
AFTERNOON AND INTO THIS EVENING.

IN ADDITION TO MESOSCALE BAROCLINIC CIRCULATIONS ON THE FRINGES OF
THE CLOUD BAND...THE ADDITIONAL INCREASE IN CONVECTIVE COVERAGE WILL
ALSO BE ENCOURAGED BY STRENGTHENING DCVA/DEEP ASCENT AHEAD OF A
SHORTWAVE TROUGH EMERGING OVER THE PACIFIC NW PER WATER VAPOR LOOPS.
THIS ASCENT IS LIKELY ENHANCING THE AFOREMENTIONED CROOK COUNTY ORE
ACTIVITY...AND IS EXPECTED TO CONTINUE OVERSPREADING THE AREA. GIVEN
THE PRESENCE OF AROUND 50-60 KT OF 0-6-KM BULK SHEAR SAMPLED BY
OTX/PDT VWPS...TSTMS THIS AFTERNOON MAY BECOME ORGANIZED...WITH
SUPERCELL STRUCTURES AND SMALL BOWING SEGMENTS. ISOLATED TO PERHAPS
WIDELY SCATTERED SVR WIND/HAIL MAY OCCUR WITH THIS ACTIVITY...WITH
DMGG WIND POTENTIAL PERHAPS BECOMING LOCALLY ENHANCED IF COLD-POOL
AMALGAMATION WERE TO FOSTER A MORE ORGANIZED CONVECTIVE CLUSTER
SPREADING ENEWD ACROSS THE HI-LINE OF NRN MT.

THERE IS ULTIMATELY SUBSTANTIAL UNCERTAINTY REGARDING THE NEED FOR A
WW. THE STRONGEST FORCING FOR ASCENT AND STRONGEST DEEP SHEAR
ATTENDANT TO THE SHORTWAVE TROUGH MAY TEND TO REMAIN DISPLACED TO
THE W OF THE STRONGEST BUOYANCY. FURTHERMORE...THE OVERALL LIMITED
DEGREE OF TROPOSPHERIC MOISTURE...AND THE POTENTIALLY DELAYED
ARRIVAL OF STRONGER ASCENT RELATIVE TO PEAK HEATING...COULD LIMIT
SVR COVERAGE. THERE MAY BE A MODEST INCREASE IN THE SVR RISK
SHORTLY...BUT SVR COVERAGE UNCERTAINTY THROUGH THE NEXT SEVERAL
HOURS CASTS DOUBT ON OVERALL PROSPECTS FOR WW ISSUANCE.
REGARDLESS...CONVECTIVE AND OBSERVATIONAL TRENDS WILL CONTINUE TO BE
MONITORED. IF A MORE WIDESPREAD/SUBSTANTIAL SVR RISK WERE TO BECOME
EVIDENT...WW ISSUANCE MAY BECOME REQUIRED.

..COHEN/DIAL.. 06/08/2016

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

ATTN...WFO...TFX...MSO...BOI...OTX...PDT...

LAT...LON   44752001 46811843 48481641 48981356 48941145 48321118
            46501445 44171897 44752001

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.