Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 182335
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
635 PM CDT MON MAY 18 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 400 PM CDT MON MAY 18 2015

STRONG NORTHWEST FLOW AND STRATOCUMULUS ON BACKSIDE OF EXITING LOW
PRESSURE HAVE KEPT VERY COLD CONDITIONS IN PLACE FOR MUCH OF THE
AREA. CLOUDS ARE GRADUALLY ERODING FROM WEST TO EAST WITH WHAT LOOKS
TO BE LIKE THE BACKSIDE OF THE MORE ORGANIZED STRATUS FROM ABOUT DE
SMET TO IDA GROVE AT 2PM. TO THE WEST OF THIS MUCH OF THE CUMULUS
LOOKS DIURNALLY DRIVEN AND SUSPECT THAT IT WILL QUICKLY ERODE AROUND
SUNSET. MODEL SOUNDINGS REALLY WANT TO HANG ON TO STRATUS ALL NIGHT
BUT SUBSIDENCE AND CURRENT EROSION SUGGEST OTHERWISE. DID SLOW DOWN
EROSION OF CLOUDS INTO SW MN THIS EVENING BUT STILL HAVE SOME
CLEARING LATE TONIGHT. WILL LEAVE THE FREEZE WARNING AS IS BUT ALSO
ADD A LAYER OF FROST ADVISORY TO THE SOUTH OF THE WARNING. MUCH OF
SOUTHWEST MN AND NORTHWEST IA WILL SEE WINDS REMAIN ABOUT 5 TO 10
MPH THROUGH TOMORROW MORNING WHICH SHOULD KEEP TEMPERATURES IN THE
MID 30S AND FROST FROM DEVELOPING.

AFTER A COLD START TO THE MORNING TEMPERATURES WILL ONLY WARM INTO
THE 50S ACROSS THE CWA BECAUSE OF A COMBINATION OF EXISTING COOL AIR
AND INCREASING MID AND HIGH CLOUDS. HOWEVER EVEN WITH THESE COOLER
TEMPERATURES WINDS MAINLY LESS THAN 15 MPH WILL REALLY HELP IT FEEL
MUCH BETTER THAN TODAY. UPPER AND MID LEVEL SUPPORT SPREADS NORTH
LATE TUESDAY AFTERNOON AND WILL HAVE A SMALL CHANCE FOR SHOWERS IN
THE FAR SOUTHERN CWA...BUT THE BETTER THREAT FOR RAIN WILL BE ON
TUESDAY NIGHT.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 400 PM CDT MON MAY 18 2015

ISENTROPIC LIFT ON THE 290 AND 295 SURFACE INCREASES THROUGH THE
EVENING HOURS TUESDAY NIGHT EXPANDING FROM THE SOUTH TO THE NORTH.
HAVE INCREASED POPS ALONG THE MISSOURI RIVER VALLEY THROUGH THE
OVERNIGHT...WITH LINGERING POPS THROUGH AT LEAST THE MORNING HOURS
ON WEDNESDAY. LIFT WILL BE FIGHTING DRY AIR IN THE NEAR SURFACE
LAYER...BUT EXPECT DYNAMICS TO WIN OUT SOUTH OF I-90.

SHEARED UPPER LEVEL SUPPORT WORKS EAST WEDNESDAY AFTERNOON LEADING
TO CLEARING SKIES ACROSS THE REGION. SHOULD BE WARMER AND MORE
PLEASANT THURSDAY INTO FRIDAY AS SURFACE HIGH PRESSURE REMAINS IN
CONTROL.  EXPECT TO SEE SOME DIURNAL CUMULUS CLOUDS...ESPECIALLY ON
THURSDAY ACROSS THE EASTERN CWA.

A SERIES OF WAVES APPROACH FROM THE SOUTHWEST IN A PIECEMEAL FASHION
THIS WEEKEND LEADING TOWARDS CHANCES OF RAIN AND STORMS.  MOISTURE
LOOKS TO BE A LIMITING FACTOR WITH MOISTURE NOT REALLY WORKING NORTH
OF THE TEXAS BOARDER TILL FRIDAY.  APPEARS AS THOUGH MOISTURE REALLY
DOESN/T ARRIVE TILL SATURDAY NIGHT INTO SUNDAY.  MODELS SUGGEST
STALLED FRONT ACROSS THE AREA THEN COULD BE THE FOCUS FOR SHOWERS
AND STORMS.  HAVE CONTINUED THE MENTION OF SHOWERS WEST ON
SUNDAY...AND THUNDERSTORMS EAST OF THE JAMES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 632 PM CDT MON MAY 18 2015

STRATUS REMAINS SITUATED ACROSS THE SIOUX FALLS FORECAST AREA
GENERALL ALONG AND EAST OF A HURON SD...TO MITCHELL SD TO STORM
LAKE IA LINE. CEILINGS ARE IN THE MVFR TO LOWER END VFR CATEGORY.
MODELS INDICATE THAT THE CEILINGS WILL SCOUR OUT BUT LOOKING AT
THE SATELLITE LOOP AM NOT SO SURE THEY WILL EVAPORATE TOO QUICKLY.
THEREFORE KEPT MVFR TO LOWER END VFR CEILINGS INTO THE OVERNIGHT
HOURS FOR KFSD AND KHON AND WILL CONTINUE TO MONITOR FOR CLEARING
OR LACK OF IT.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...FROST ADVISORY FROM 3 AM TO 8 AM CDT TUESDAY FOR SDZ061-062-
     065>071.

     FREEZE WARNING FROM 3 AM TO 8 AM CDT TUESDAY FOR SDZ038>040-050-
     052>060-063-064.

MN...FROST ADVISORY FROM 3 AM TO 8 AM CDT TUESDAY FOR MNZ098.

     FREEZE WARNING FROM 3 AM TO 8 AM CDT TUESDAY FOR MNZ071-097.

IA...FROST ADVISORY FROM 3 AM TO 8 AM CDT TUESDAY FOR IAZ001-012-020-
     031.

NE...FROST ADVISORY FROM 3 AM TO 8 AM CDT TUESDAY FOR NEZ013-014.

&&

$$

SHORT TERM...08
LONG TERM...
AVIATION...MJ



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