Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 190511
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1111 PM MDT MON AUG 18 2014

.UPDATE...
ISSUED AT 806 PM MDT MON AUG 18 2014

00Z KUNR SOUNDING SHOWED A BIT OF MUCAPE. COUPLE OF WEAK
SHORTWAVES OVER SOUTH CENTRAL MT/NORTHWEST WY WILL MOVE EAST
THROUGH THE SOUTHWEST THIRD OF THE CWA OVERNIGHT BRINGING WITH IT
ISOLATED TSRA. LATEST HRRR SEEMS TO PICK UP ON THIS AS WELL AS
CURRENT RADAR TRENDS TO OUR WEST. WILL SPREAD POPS FROM CURRENT
RADAR RETURNS THROUGH SOUTHWEST THIRD OF CWA TO ACCOUNT WITH UPDATE.

&&

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 300 PM MDT MON AUG 18 2014

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER FAR NORTHERN MN
WITH HIGH PRESSURE OVER CENTRAL MT. UPPER LEVEL ANALYSIS SHOWS
TROF OVER SOUTH CENTRAL CANADA...WITH NORTHWESTERLY FLOW OVER MOST
OF THE NORTHERN HIGH PLAINS. DRIER AIR IS IN PLACE ACROSS THE AREA
FOR TODAY...WITH DEWPOINTS MOSTLY IN THE UPPER 40S AND 50S.
SHOWERS AND STORMS THIS AFTERNOON HAVE STAYED TO THE NORTH AND
SOUTH OF THE CWA...WITH A FEW STRONG STORMS OVER THE NEB PANHANDLE
RIGHT NOW. TEMPS ARE IN THE UPPER 79S TO UPPER 80S WITH BRISK
NORTHWESTERLY WINDS ACROSS MUCH OF THE PLAINS. THESE WINDS WILL
BEGIN TO DIMINISH BY EARLY EVENING.

UNSETTLED WEATHER WILL RETURN LATER ON TUESDAY AND PERSIST AT TIMES
THROUGH THE END OF THE WEEK AS HIGH PRESSURE ALOFT MOVES INTO THE
SOUTHEASTERN CONUS AND A BROAD TROF DEVELOPS OVER THE WESTERN
STATES. DAILY CHANCES FOR SHOWERS AND STORMS CAN BE EXPECTED...
ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS.

FOR TONIGHT...SKIES WILL BE CLEAR TO PARTLY CLOUDY. A WEAK
DISTURBANCE IN NORTHWEST FLOW COULD PRODUCE A FEW SHOWERS AND
POSSIBLY A STORM LATE TONIGHT INTO EARLY TUESDAY OVER THE BLACK
HILLS AREA. WINDS WILL BECOME LIGHT THIS EVENING AND THEN SWITCH TO
THE SOUTHEAST OVERNIGHT INTO TUESDAY MORNING AS HIGH PRESSURE PASSES
OVER AND EVENTUALLY EAST OF THE AREA.

WARMER AIR WILL RETURN ON TUESDAY AS SOUTH-SOUTHEAST WINDS INCREASE.
HIGHS WILL BE IN THE MID 80S TO AROUND 90 DEGREES ACROSS THE
PLAINS...MOSTLY 80S OVER THE BLACK HILLS. A MORE WIDESPREAD CHANCE
FOR STORMS WILL RETURN LATE TUESDAY AND ESPECIALLY TUESDAY NIGHT AS
FLOW ALOFT TURNS SOUTHWESTERLY OVER THE HIGH PLAINS. THE
SOUTH-SOUTHEAST WINDS WILL ALSO BRING LOW LEVEL MOISTURE BACK INTO
THE AREA...WITH INCREASING INSTABILITY INTO TUESDAY NIGHT. WILL
GENERALLY KEEP POPS AS IS LATE TUESDAY INTO TUESDAY NIGHT. THE
THREAT FOR SEVERE STORMS STILL LOOKS RELATIVELY LOW. HOWEVER...WITH
SUFFICIENT INSTABILITY AROUND...ISOLATED STRONG TO MARGINALLY SEVERE
STORMS WITH HAIL AND GUSTY WINDS ARE CERTAINLY POSSIBLE LATE IN THE
AFTERNOON INTO THE EVENING.

&&

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 300 PM MDT MON AUG 18 2014

MEAN WESTERN NOAM TROUGHING WILL PERSIST IN THE PERIOD...WITH
MASSIVE EASTERN NOAM RIDGING ENSUING TOWARD THE END OF THE WEEK.
THIS WILL SUPPORT A LOCAL PATTERN CHANGE AS LOWER HEIGHTS AND MUCH
COOLER TEMPS SPREAD OVER THE NORTHERN PLAINS BY THIS WEEKEND...PER
THE WESTERN CONUS TROUGH PHASING WITH A LONG WAVE NORTHERN STREAM
TROUGH. ACTIVE SW FLOW CAN BE EXPECTED TO SUPPORT NEAR DAILY
CHANCES FOR PRECIP THROUGH THE PERIOD...WITH THE WESTERN CONUS
TROUGH SHIFTING EAST OVER THE NORTHERN PLAINS BY LATE THIS
WEEKEND.

HAVE RETAINED DAILY CHANCES FOR SHRA/TS WITH A WAVERING FRONTAL ZONE
OVER THE REGION THROUGH THUR. COLD FRONT WILL SHIFT SE TROUGH THE
REGION FRIDAY...WITH CAA SPREADING ACROSS THE REGION VIA GUSTY NW
WINDS. CYCLONIC DISTURBED SW FLOW WILL PERSIST THROUGH THE WEEKEND.
HOWEVER...GIVEN SIGNALS FOR THE BEST LSA BEING NW OF THE FA...WITH
MORE DIURNALLY DRIVEN CHANCES FOR CONVECTION...HAVE BIASED POPS MORE
TOWARD CLIMO NUMBERS THIS WEEKEND..ESP GIVEN CONVECTIVE NATURE TO
PRECIP.

AS FOR TEMPS...SEASONAL NUMBERS WILL PERSIST THROUGH THURS...WITH
COOLING CONDITIONS FRI-SUN. TEMPERATURES ARE PROGGED TO BE 5 TO 15
DEGREES BELOW SEASONAL NORMS BY SUNDAY AND MONDAY...ESP HIGH
TEMPERATURES. HAVE CONTINUED TO ADD A NEGATIVE BIAS PER HIGHS
SAT-MONDAY...WITH MANY PLACES LIKELY STRUGGLING TO REACH 70 ACROSS
THE NORTHERN HALF SUNDAY AND MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1109 PM MDT MON AUG 18 2014

MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. A
WARM FRONT WILL SHIFT NORTH TONIGHT AND POSSIBLY SUPPORT ISOLATED
TSRA. ADDITIONAL TSRA WILL DEVELOP LATER TUESDAY AFTERNOON INTO
TUESDAY NIGHT WITH LOCAL MVFR CIGS/VSBYS IN THE STRONGEST STORMS.

&&

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

$$

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




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