National Weather Service Weather Forecast Office

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

000
FXUS63 KUNR 101003
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
403 AM MDT MON MAR 10 2014

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 323 AM MDT MON MAR 10 2014

WATER VAPOR SHOWS UPPER RIDGE EXTENDING FROM THE NRN/CNTRL ROCKIES
INTO THE PLAINS...WITH UPPER TROF MOVING ONSHORE THE PAC NW. AT
THE SFC...MILD PAC AIR STILL IN PLACE ACROSS THE CWFA WITH TEMPS
MOSTLY IN THE 40S. FCST CONCERN CENTERED AROUND SNOW AMOUNTS LATE
TONIGHT/TUESDAY MRNG AS UPPER TROF WORKS QUICKLY THROUGH THE PAC
NW/NRN ROCKIES.

TODAY...ANOTHER MILD DAY IN STORE WITH THERMAL RIDGE
OVERHEAD...ALTHOUGH NOT QUITE AS WARM AS SUNDAY. THE COOLEST TEMPS
WILL BE ACROSS NWRN SD AS SFC LOW DEVELOPS OVER ERN WY IN RESPONSE
TO JET STREAK ROUNDING THE UPPER TROF AND NOSING INTO WRN WY.
COULD SEE SOME RAIN DEVELOPING IN OUR WRN/NRN ZONES LATE IN THE
DAY.

TONIGHT/TUESDAY MRNG...CONDITIONS WILL DETERIORATE RAPIDLY FROM
NORTH TO SOUTH AS UPPER TROF TRANSLATES QUICKLY FROM THE NRN
ROCKIES INTO THE NRN PLAINS BY LATE TONIGHT. BAND OF DEEP
FRONTOGENESIS WILL PUSH SWD ACRS THE CWFA WITH BROAD MID/UPR LEVEL
DIVERGENT FLOW ALOFT AND RESULT IN WDSPRD RAIN/SNOW ACROSS THE
CWFA. A BURST OF HEAVY PCPN POSSIBLE AROUND THE NRN
BLKHLS/FOOTHILLS AREA AS CLOSED CIRCULATION FROM 700-500MB PASSES
FROM FAR NERN WY INTO SWRN LATE TONIGHT/EARLY TUE MRNG AND DEEP
LOW LEVEL NE WINDS (LOWER FROUDE NUMBERS) FLOWING INTO THE HILLS.
THE BIGGEST QUESTION REMAINS THE RAIN TO SNOW CONVERSION...WITH
COLD AIR LOOKING TO BE A LITTLE MORE DELAYED THAN THE PREVIOUS
FCST. THE LATEST THERMAL PROFILES DON`T SHOW A TRANSITION TO SNOW
ACROSS FAR NWRN SD UNTIL ABOUT MID EVENING...AND ABOUT 06Z FROM
KGCC INTO THE NRN BLKHLS...AND 09Z FOR THE KRAP AREA. CONVECTIVE
SNOW IS ALSO SOME CONCERN...BUT IT LOOKS AS IF BEST LAPSE RATES
MAY BE MORE ON THE LIQUID SIDE OF THE PCPN.

AT THIS TIME...IT APPEARS THE BEST SNOW ACCUMULATIONS SHOULD OCCUR
IN THE NRN BLKHLS/FOOTHILLS AREA. GIVEN THE POSITION OF THE CLOSED
700-500MB LOW AND LOWER TROPOSPHERIC FLOW FROM THE NE...TARGET
AREA LOOKS TO FROM LEAD/DEADWOOD TO SPEARFISH AND STURGIS WHERE
SNOW ACCUMS OF 6-10 INCHES ARE POSSIBLE...WITH LESSER AMOUNTS AS
YOU HEAD FURTHER SW THROUGH THE BLKHLS. WITH THAT IN MIND...HAVE
EXPANDED THE WINTER STORM WATCH TO INCLUDE THE NRN FOOTHILLS AND
STURGIS/PIEDMONT ZONES...BUT HAVE PUSHED BACK THE START UNTIL 06Z.
AREAS JUST NORTH/EAST OF THE WATCH...SUCH AS BELLE FOURCHE AND
RAPID CITY (AND POSSIBLY EVEN GILLETTE) COULD END UP WITH ADVISORY
TYPE SNOW...BUT THIS WILL BE HEAVILY DEPENDENT ON WHEN THE RAIN
TRANSITIONS TO SNOW. WILL ALLOW DAY SHIFT TO MONITOR ANOTHER A
COUPLE MODEL RUNS BEFORE MAKING THAT DECISION.

TUESDAY AFTN...SNOW SHOULD END RATHER QUICKLY FROM NORTH TO SOUTH
BY TUE AFTN...WITH SOME RESIDUAL SNOW SHOWERS POSSIBLE IN THE NRN
BLKHLS AREA. HAVE UNDERCUT GUIDANCE TEMPS A BIT GIVEN THERMAL
PROFILES AND EXPECTED SNOW COVER.

&&

.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 323 AM MDT MON MAR 10 2014

UPPER RIDGING WILL BRING DRY CONDITIONS AND ABOVE
AVERAGE TEMPERATURES THROUGH THE END OF THE WORK WEEK. THE NEXT WAVE
DIVES THRU NWRLY FLOW FOR THE UPCOMING WEEKEND BRINGING CHANCES FOR
RAIN/SNOW AND SLIGHTLY COOLER TEMPERATURES.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING
ISSUED AT 323 AM MDT MON MAR 10 2014

VFR CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON.
CONDITIONS WILL DETERIORATE TONIGHT AS RAIN MOVES IN AND CHANGES
OVER TO SNOW FROM NORTH TO SOUTH BRINGING AREAS OF IFR CIGS/VIS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR
     SDZ024-025-028-072.

WY...WINTER STORM WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR
     WYZ057.

&&

$$

SHORT TERM...JOHNSON
LONG TERM...77
AVIATION...77