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000
FXUS63 KUNR 072124
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
224 PM MST FRI MAR 7 2014

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 223 PM MST FRI MAR 7 2014

WESTERN NOAM RIDGE WILL CONTINUE TO SPREAD EAST IN THE
PERIOD...AS THE NORTHERN PLAINS SFC RIDGE SHIFTS SE INTO THE
MIDWEST. SHALLOW COLD FRONT HAS PUSHED THROUGH THE FA WITH FLOW
GENERALLY NORTH-NORTH EAST...SUPPORTING UPSLOPE FLOW OVER MUCH OF FAR
WESTERN SD AND NE WY...RESULTING IN AREAS OF LOW CLOUDS AND FOG. A
FEW SNOW SHOWERS WERE PRESENT OVER THE CENTRAL AND SOUTHERN BLACK
HILLS WHERE STEEP LL LAPSE RATES AND LL INSTABILITY IS PRESENT WITH
A SOUTHERN BLKHLS EDDY CONVERGENCE. THIS ACTIVITY IS EXPECTED TO WANE
THIS EVENING. DEEP LAYER WAA WILL ENSUE TONIGHT WITH FLOW EVENTUALLY
BECOMING WESTERLY OVER MUCH OF THE FA BY SAT. HOWEVER...NEAR
SATURATED SFC LAYER WITH INDICATIONS IN FORECAST MODELS FOR
ADDITIONAL LL MOISTURE ADVECTION FROM THE WEST WHEN FLOWS SHIFTS
WESTERLY...SUPPORTS SOME CONCERN FOR THE DEVELOPMENT OF FOG TONIGHT
AS THE BL COOLS. HIRES MODEL SOLUTIONS ALONG WITH MOS GUIDANCE ALSO
SUGGEST THIS IN VIS PROGS. BUFR SOUNDINGS DO INDICATED A MOIST
SUB-INVERISON LAYER WITH STRENGTHENING TENDENCIES PER BL TOP WAA...A
DECENT SETUP FOR STRATUS OR FOG ACROSS THE HIGH TERRAIN OF WY/THE BH
AND EASTERN/NORTHERN BLACK HILLS FOOTHILLS. THERE IS SOME CONFIDENCE
CONCERNS WRT DEVELOPMENT AND POTENTIAL EXPANSIVENESS OF ANY FOG
GIVEN DRIER AIR POTENTIALLY MIXING DOWN WITH DOWNSLOPING WESTERLY
WINDS. HENCE...HAVE OPTED FOR JUST A PATCHY MENTION ACROSS THESE
AREAS. DID RAISE CLOUD COVER OVER THE EASTERN/NORTHERN BH
FOOTHILLS...GIVEN HIGH STRATUS CONFIDENCE PER EASTERLY NEAR
SATURATED FLOW UNDER A GROWING INVERSION. SMALL MIN TEMP ADJUSTMENT
MADE...WITH COLDEST TEMPS EXPECTED ACROSS EASTERN AREAS.

SATURDAY...DEEP LAYER RIDGING/HEIGHT RISES WILL SPREAD OVER THE
AREA...WITH STAUNCH WAA. GENERAL WESTERLY FLOW EXPECTED UNDER
CLEAR/MOSTLY CLEAR SKIES...SUPPORTING STRONG WARMING NEARLY ALL
PLACES. THE ONLY CAVEAT WILL BE THE POTENTIAL FOR EASTERN BH /RAPID
CITY AREA/ EDDY CIRCULATION PER LOW FROUDE...SUPPORTING A LONG
DURATION OF EASTERLY FLOW...WHICH COULD LIMIT T RISES AT FIRST.
STILL THINK THIS AREA WILL MIX OUT BY MID/LATE AFTERNOON GIVEN
INCREASING FLOW PER SFC PRESSURE FALLS AND STRONG INSOLATION.
ADJUSTED MINS SAT NIGHT OPTING FOR THE WARM SIDE OF GUIDANCE GIVEN
CONTINUED THERMAL RIDGING WITH SUSTAINED WESTERLY FLOW. HAVE ESP
WARMED TEMPS OVER THE NORTHERN/EASTERN BH FOOTHILLS WHERE SUSTAINED
WESTERLY DOWNSLOPE FLOW WILL BE IN PLACE.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 223 PM MST FRI MAR 7 2014

THERMAL RIDGE CONTINUES TO BUILD OVER THE AREA INTO
SUNDAY WITH TEMPERATURES CLIMBING WELL ABOVE AVERAGE. NEXT COLD
FRONT AND UPPER WAVE PUSH INTO THE AREA LATE MONDAY BRINGING PRECIP
CHANCES ALONG WITH A COOLING TREND. THE BEST CHANCES WILL BE MONDAY
NIGHT INTO TUESDAY MORNING WITH RAIN CHANGING TO SNOW AS COLDER AIR
PUSHES IN FROM THE NORTH. UPPER RIDGING WILL BUILD BACK IN FOR THE
SECOND HALF OF THE WEEK BRINGING DRIER CONDITIONS AND WARMING TEMPS.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING
ISSUED AT 223 PM MST FRI MAR 7 2014

LOW CIGS WILL CONTINUE ACROSS THE FORECAST AREA TONIGHT.
FOG ACROSS PORTIONS OF THE BLACK HILLS AND SOUTHWEST SD WILL ALSO
CONTINUE TONIGHT...WHILE FOG REDEVELOPS ACROSS PORTIONS OF NORTHEAST
WYOMING AND FAR WESTERN SD INCLUDING THE FOOTHILLS. THEREFORE
WIDESPREAD IFR/MVFR CONDITIONS ARE EXPECTED. CONDITIONS WILL
GRADUALLY IMPROVE TO VFR LATE TONIGHT AND EARLY SATURDAY MORNING AS
DRIER AIR PUSHES IN FROM THE WEST.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

SHORT TERM...JC
LONG TERM...13
AVIATION...13