Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 061735
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1135 AM MDT WED MAY 6 2015

.UPDATE...
ISSUED AT 912 AM MDT WED MAY 6 2015

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE CENTERED OVER
NORTHEAST CO. A INVERTED TROF STRETCHES NORTH FROM THE LOW INTO
FAR WESTERN SD. A COLD FRONT LIES FROM FAR NORTHEASTERN MT INTO
WESTERN WY. UPPER LEVEL ANALYSIS SHOWS LOW ALSO CENTERED OVER FAR
NORTHEAST CO...WITH WATER VAPOR IMAGERY SHOWING PLENTY OF MOISTURE
STREAMING NORTHWARD AHEAD OF THE LOW INTO NEB AND SD. DEFORMATION
ZONE APPEARS TO BE IN PLACE OVER WESTERN PORTIONS OF THE CWA. 12Z
KUNR SOUNDING SHOWS VERY MOIST SOUNDING TO 300 MB...WITH
PRECIPITABLE WATER VALUE OF 1 INCH...WELL ABOVE AVERAGE FOR THIS
TIME OF YEAR. KUDX RADAR SHOWS WIDESPREAD AREA OF MOSTLY LIGHT
SHOWERS COVERING MUCH OF FAR WESTERN SD INTO FAR NORTHEAST
WY...WITH MORE SCATTERED ACTIVITY FURTHER EAST INTO CENTRAL SD.
REGIONAL RADARS SHOW MORE ACTIVITY DEVELOPING OVER CENTRAL
NEB...ROTATING NORTHWESTWARD TOWARD SOUTH CENTRAL SD. TEMPS ARE ON
THE MILD SIDE EARLY THIS MORNING WITH VERY MOIST AIRMASS IN
PLACE...50S AND LOWER 60S.

HAVE UPDATED FORECAST TO MAKE SOME MINOR ADJUSTMENTS TO POPS AND
WEATHER THROUGH THE AFTERNOON...ALSO ADDING SOME FOG OVER THE
BLACK HILLS FOR THIS MORNING. SHOWERS WILL CONTINUE THROUGH THE
AFTERNOON. SOME THUNDERSTORMS ARE ALSO EXPECTED TO DEVELOP INTO THE
AFTERNOON AS ATMOSPHERE DESTABILIZES...ESPECIALLY TO THE SOUTH AND
EAST OF THE BLACK HILLS. FORECAST INSTABILITY WOULD SUGGEST MAIN
CHANCES FOR STRONGER STORMS WILL STAY SOUTHEAST OF THE CWA LATER
TODAY. HOWEVER...WOULD NOT BE SURPRISED TO SEE A STRONG STORM OR
TWO TOWARD SOUTH CENTRAL SD THIS AFTERNOON...WITH SMALL HAIL BEING
THE MAIN THREAT. WILL KEEP FORECAST HIGHS AS IS FOR NOW...ABOUT 5 TO
10 DEGREES HIGHER THAN CURRENT TEMPS. WINDS WILL GRADUALLY SWITCH
TO THE NORTHWEST FROM NORTHEAST WY INTO FAR WESTERN SD LATE THIS
MORNING AND AFTERNOON AS THE COLD FRONT SLOWLY MOVES EAST INTO THE
WESTERN DAKOTAS. ADDITIONAL MINOR ADJUSTMENTS TO THE FORECAST MAY
BE NEEDED INTO THE AFTERNOON...DEPENDING ON HOW ACTIVITY DEVELOPS.

&&

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 235 AM MDT WED MAY 6 2015

WATER VAPOR IMAGES SHOW THE UPPER LOW IS NOW LOCATED OVER
NERN CO WITH ABUNDANT MID AND HIGH LEVEL MOISTURE STREAMING
NORTHWARD TOWARD THE FORECAST AREA. AT THE SURFACE...LOW PRESSURE
IS CENTERED OVER SERN WY WITH AN INVERTED TROUGH EXTENDING
NORTHWARD ACROSS ERN WY AND ERN MT.

THE SFC LOW AND THE INVERTED TROUGH WILL MOVE SLOWLY EASTWARD
ACROSS THE CENTRAL AND NORTHERN PLAINS OVER THE NEXT COUPLE OF
DAYS AS THE UPPER LOW EJECTS TO THE NORTHEAST. AS THE UPPER LOW
APPROACHES THE FORECAST AREA TODAY...ABUNDANT MOISTURE AND LARGE
SCALE FORCING WILL BRING WIDESPREAD PRECIPITATION TO THE AREA.
SHOWERS...AND ISOLD-SCT TSTMS WILL OCCUR ACROSS THE AREA DUE TO
INCREASING SYNOPTIC SCALE LIFT...DIURNAL HEATING AND ABUNDANT
MOISTURE. COOLER AIR WILL WRAP AROUND THE SFC LOW THIS AFTN AND
WILL PUSH IN TO THE WESTERN PARTS OF THE FA. THE FRONTAL PASSAGE
WILL BRING THE BEST CHANCE OF PRECIP FOR THIS EVENT AS HEAVIER
SHOWERS AND SOME THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF THE
FRONT. SHOWERS WILL CONTINUE OVERNIGHT. HAVE RAISED POPS ON
THURSDAY AS CYCLONIC FLOW AROUND THE UPPER LOW WILL KEEP A CHANCE
OF SHOWERS ACROSS THE AREA AT LEAST THROUGH THE MORNING. DRIER AIR
WILL BEGIN WORKING ON FROM THE NORTHWEST ON THURSDAY AFT.

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 235 AM MDT WED MAY 6 2015

AS THE NEXT UPPER LOW SPINS OVER CALIFORNIA...WEAK ENERGY
WILL EJECT INTO THE NORTHERN PLAINS AND WILL KEEP CHANCES OF SHOWERS
AROUND FOR FRIDAY...MAINLY ACROSS THE SW CWA. PRECIP CHANCES
INCREASE ON SATURDAY AS CALIFORNIA CLOSED LOW MOVES INTO THE CENTRAL
PLAINS. COLD AIR WILL WRAP AROUND THE LOW AS IT MOVES
NORTHEASTWARD...WITH BOTH THE ECM AND GFS SHOWING 850MB TEMPS AROUND
0C. SOME PRECIP MAY FALL AS SNOW ACROSS THE HIGHER ELEVATIONS OF THE
BLACK HILLS...BUT STILL MUCH UNCERTAINTY EXISTS WITH THE TRACK OF
THIS STORM. PRECIP WILL CONTINUE INTO MONDAY...AND THEN MODELS ARE
HINTING AT A WEAK RIDGE BUILDING INTO THE REGION FOR EARLY NEXT
WEEK...BRINGING A SLIGHT WARMING TREND AND DRIER WEATHER.
TEMPERATURES FOR THE END OF THIS WEEK INTO EARLY NEXT WEEK WILL BE
SLIGHTLY BELOW AVERAGE...GENERALLY IN THE 50S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY)
ISSUED AT 1135 AM MDT WED MAY 6 2015

SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE AREA TODAY INTO
TONIGHT BEFORE GRADUALLY DECREASING THROUGH THE NIGHT INTO THU
MORNING. MVFR/IFR CONDITIONS WILL CONTINUE INTO THURSDAY.

&&

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

$$

UPDATE...26
SHORT TERM...10
LONG TERM...POJORLIE
AVIATION...13


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