Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 261734
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1134 AM MDT THU MAR 26 2015

.UPDATE...
ISSUED AT 1002 AM MDT THU MAR 26 2015

16Z SURFACE ANALYSIS HAD LOW NEAR KSPF...WHICH IS ALONG WARM
FRONTAL BOUNDARY FROM NORTH CENTRAL MT TO CENTRAL NE. BAND OF
-SHRASN AHEAD OF WARM FRONT UNDER LEFT EXIT REGION OF 140KT JET
STREAK STARTING TO SHIFT EASTWARD AS SHORTWAVE OVER EASTERN
ND/NORTHERN MN TRANSLATES SOUTHEAST. BEHIND IT....DECENT LAPSE
RATES WILL SUPPORT GUSTY NORTHWEST WINDS AS WELL AS DIURNAL SHOWER
ACTIVITY THIS AFTERNOON/EVENING...MAINLY -SHRA...EXCEPT OVER THE
HIGHEST ELEVATIONS OF THE BLACK HILLS.

FORECAST UPDATED TO ACCOUNT FOR THESE TRENDS.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 255 AM MDT THU MAR 26 2015

FRONTAL BOUNDARY WILL REMAIN IN PLACE ACROSS THE REGION...WITH
PERTURBED NW FLOW ALOFT...SUPPORTING UNSETTLED WEATHER THROUGH
TONIGHT. THE FIRST OF TWO MID LEVEL IMPULSES IS IN THE PROCESS OF
ADVECTING SE ACROSS THE NORTHERN PLAINS. THIS FEATURE COUPLED WITH
A POTENT UPPER LEVEL JET STREAK IS SUPPORTING INCREASING COVERAGE
OF PRECIP ACROSS THE NE HALF OF THE FA. THIS WILL CONTINUE THROUGH
MORNING. STEEP LL LAPSE RATES COUPLED WITH PAC MOISTURE WILL
SUPPORT INSTABILITY SHRA OVER MOST OF THE FA THIS AFTERNOON WITH A
SECONDARY IMPULSE SUPPORTING ANOTHER UPGLIDE PUSH TONIGHT...WITH
RESULTING CHANCES FOR MAINLY RAIN SHRA GIVEN WARM BL CONDS PER
ONGOING WAA. MUCH WARMER WEATHER WILL ARRIVE FRIDAY AS THE LL
FRONTAL ZONE SHIFTS EAST...WITH WARM NW PAC FLOW SPREADING OVER
THE FA.

TODAY...FGEN SNOWS WILL CONTINUE THROUGH MORNING ACROSS MAINLY THE
EASTERN HALF OF THE FA. BEST FORCING WILL BE ALONG A NARROW BAND
ACROSS NW SD WHERE A QUICK INCH OR TWO IS POSSIBLE. HOWEVER...GIVEN
INCREASING CONVECTIVE NATURE PER STEEP MID AND LL LAPSE
RATES...DISRUPTION OF BETTER BANDING WILL LIKELY OCCUR LIMITING
SNOW AMOUNTS TO A DEGREE. MAIN LOBE OF UPPER LEVEL FORCING WILL
SHIFT SE OUT OF THE REGION WITH DIURNAL HEATING AND STEEP LL LAPSE
RATES SUPPORTING MORE SHOWERY ACTIVITY THIS AFTERNOON. ESP ACROSS NE
WY/THE BH/AND FAR WESTERN SD. WAA WILL SUPPORT MORE RAIN SHOWER
CHANCES...ESP OUTSIDE THE BH. TEMPS WILL BE A LITTLE WARMER THAN
YESTERDAY WITH 40S AND LOWER 50S FOR HIGHS.

TONIGHT...SCT CONVECTIVE SHRA WILL LINGER INTO THE EVENING...WITH
RENEWED CHANCES FOR PRECIP LATER IN THE EVENING AS THE NEXT MID LEVEL
IMPULSE ARRIVES. WARM PROFILES PER ONGOING WAA WILL SUPPORT MAINLY
RAIN SHOWER CHANCES...SAVE THE HIGHER ELEVATIONS OF THE BH AND
PERHAPS NW SD WHERE COOLER BL CONDS WILL BE IN PLACE. ANY SNOWFALL
WILL BE MINIMAL GIVEN WARM CONDS. LOWS WILL MAINLY BE IN THE 30S.

FRIDAY...LL FRONTAL ZONE WILL FINALLY SHIFT EAST WITH ASSOCIATED
PRECIP CHANCES ENDING. DIURNAL INSTABILITY COUPLED WITH DEEP MIXING
AND MOIST NW FLOW COULD SUPPORT A FEW ISOLD HIGH BASED SHRA FRIDAY
AFTERNOON ON THE SD PLAINS. HOWEVER...GIVEN SUBSIDENT FLOW
ALOFT...LEFT ANY WX MENTION OUT ATTM. MUCH WARMER CONDS EXPECTED
WITH HIGHS IN THE 60S MOST AREAS.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 255 AM MDT THU MAR 26 2015

A VERY WARM START TO THE WEEKEND AS A SHORTWAVE RIDGE PASSES OVER
THE NORTHERN PLAINS. HIGHS ON SATURDAY WILL BE IN THE 70S TO
AROUND 80 DEGREES ACROSS THE PLAINS. THERE IS POTENTIAL FOR FIRE
WEATHER ISSUES ACROSS PARTS OF NORTHEAST WY INTO SOUTHWEST SD IF
WINDS INCREASE ENOUGH IN THE AFTERNOON. A COLD FRONT WILL PASS
THROUGH THE AREA LATE IN THE AFTERNOON AND EVENING...WITH A CHANCE
FOR SHOWERS AND GUSTY WINDS BEHIND IT.

MEDIUM RANGE MODELS IN DECENT AGREEMENT FOR THE REST OF THE EXTENDED
PERIOD. SLIGHTLY COOLER AIR CAN BE EXPECTED FOR SUNDAY INTO EARLY
NEXT WEEK...BUT STILL WELL ABOVE AVERAGE. ANOTHER UPPER LEVEL
DISTURBANCE AND COLD FRONT WILL LIKELY PUSH THROUGH THE REGION LATE
TUESDAY INTO WEDNESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY)
ISSUED AT 1134 AM MDT THU MAR 26 2015

CONDITIONS WILL CONTINUE TO IMPROVE ACROSS CNTRL SD AS THE BAND
OF SNOW PUSHES EAST. VFR CONDITIONS ARE EXPECTED THIS AFTERNOON
ACROSS MOST LOCATION. THE EXCEPTION IS MVFR/IFR CONDITIONS OVER
THE NORTHERN BLACK HILLS AREA WHERE LIGHT RAIN CONTINUES ALONG
WITH SNOW ACROSS HIGHER ELEVATIONS. ANOTHER WEAK DISTURBANCE WILL
MOVE THROUGH THE AREA TONIGHT...WITH AREAS OF LIGHT RAIN/SNOW AND
MVFR CONDITIONS. IFR CIGS ARE EXPECTED OVER THE BLACK HILLS. GUSTY
NW WINDS WILL END THIS EVENING...BUT RETURN FRIDAY MORNING.

&&

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

$$

UPDATE...HELGESON
SHORT TERM...JC
LONG TERM...26
AVIATION...13






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