Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 280848
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
348 AM CDT THU MAY 28 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 346 AM CDT THU MAY 28 2015

COMPLEX FORECAST IN THE SHORT TERM WITH SEVERAL PLAYERS COMING INTO
PLAY LEADING TO A POTENTIAL ACTIVE FORECAST PERIOD.  IN THE NEAR
TERM...BAND OF 850 HPA THETA-E ADVECTION LIFTING NORTH INTH THE
FORECAST AREA.  WITH THE INCREASED MOISTURE...COULD SPARK A
THUNDERSTORM OR TWO ACROSS THE WESTERN CWA. CONFIDENCE IS FAR FROM
HIGH ON THIS...SINCE MOISTURE RETURN IS JUST BEGINNING ACROSS THE
AREA.  SHORT TERM HIGH RES MODELS HAVE BEEN FAIRLY CONSISTENT WITH
CONVECTION...BUT WITH CONFIDENCE ONLY IN THE MID-RANGE...KEPT POPS
IN THE CHANCE CATEGORY.  AS PREVIOUS FORECASTER MENTIONED...MESSY
FORECAST TODAY BUT IN- GENERAL...POPS CENTERED AROUND SHORT WAVE
LIFTING NORTHEAST ACROSS NORTHWEST IOWA LATE THIS AFTERNOON...AND
THE FRONT APPROACHING FROM THE WEST.  WITH STORMS AHEAD OF THE
FRONT...COULD SEE AN OUTSIDE CHANCE OF A STRONG WIND GUST OR TWO
WITH FAIR AMOUNT OF DRY AIR ALOFT INITIALLY...HOWEVER...INSTABILITY
IS QUITE LIMITED AND IS VERY THIN LIMITING SEVERE POTENTIAL.

FOR TONIGHT...STRONG COLD FRONT MOVES ACROSS THE AREA AND HAVE
CONCENTRATED LIKELY POPS ALONG THE FRONT.  LOWS WILL BE MILD AHEAD
OF THE FRONT...BUT IN THE 50S BEHIND THE FRONT AS COLD PUSH OF AIR
STARTS TO WORK IN FROM THE NORTH.


.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU MAY 28 2015

ON FRIDAY...THE GFS CONTINUES TO BE THE MOST AGGRESSIVE MODEL IN
BRINGING THROUGH A SHORT WAVE FRIDAY MORNING ASSOCIATED WITH THE
NORTHERN JET STREAM. THIS WAVE AT 12Z FRIDAY AT 500MB EXTENDS FROM
NORTHEAST SD TO NORTHWEST MN ON THE GFS...WHICH IS THE POSITION OF
THE ECMWF AT 18Z FRIDAY. THE NAM AND GEM GLOBAL ARE CLOSER TO THE
ECMWF POSITION AT 18Z FRIDAY...ALBEIT THE NAM LOOKS LIKE A BIT OF A
SLOW OUTLIER. BEHIND THIS WAVE IS A SHORT WAVE ASSOCIATED WITH THE
SOUTHERN JET WHICH EXTENDS ACROSS THE NEB PANHANDLE AND EASTERN CO
AT 18Z FRIDAY...MOVING INTO THE CENTRAL PLAINS FRIDAY AFTERNOON AND
EVENING. BELIEVE AT THIS TIME THE ECMWF AND GEM GLOBAL SOLUTIONS ARE
LIKELY THE MOST CORRECT AND CERTAINLY A COMPROMISE BETWEEN THE GFS
AND NAM...ALTHOUGH AGAIN STRESSING THAT THE NAM IS NOT A LOT SLOWER
THAN THE ECMWF AND GEM GLOBAL. THEREFORE FOR PRECIPITATION TRENDS
AND ASSOCIATED SURFACE TO 850MB WIND SHIFT TIMING...PRIMARILY
FOLLOWED THE GEM GLOBAL AND ECMWF. LIKELY POPS ARE WARRANTED FRIDAY
MORNING ACROSS MOST OF OUR FORECAST AREA MINUS OUR NORTHWEST
ZONES...ALTHOUGH THE HANG BACK OF THE ECMWF 6 HOUR QPF FRIDAY
MORNING IN OUR NORTHERN ZONES ASSOCIATED WITH THE NORTHERN STREAM
SHORT WAVE IS RATHER DISTURBING. THEREFORE THIS WILL HAVE TO BE
WATCHED FOR A POSSIBLE RAISING OF THE STRONG CHANCE POPS AROUND
HURON TO LIKELY POPS IN FUTURE FORECASTS. ON FRIDAY AFTERNOON... THE
LIKELY POPS WILL SHOVE SOUTHWARD INTO OUR SOUTHERN ZONES. THAT SAID
RAIN AMOUNTS WILL PROBABLY NOT BE VERY HIGH AT ALL BY FRIDAY
AFTERNOON. LOOKS LIKE THE 850MB FRONT IS PUSHING THROUGH WAY TOO
FAST TO WORRY ABOUT ANY SEVERE POTENTIAL ON FRIDAY...BUT IT WILL BE
QUITE WINDY BEHIND THE FRONTAL PASSAGE. IN FACT LOCATIONS FROM
AROUND MITCHELL...TO BROOKINGS AND THE NORTHERN SECTIONS OF
SOUTHWEST MN MAY PUSH WIND ADVISORY CRITERIA AS THEY ARE IN THAT
SWEET SPOT OF STRONGEST GRADIENT...STRONGEST WINDS ALOFT AND TIME OF
DAY ALL COMING TOGETHER.

SMALL RAIN CHANCES WILL MOVE SOUTHWARD ACROSS NORTHWEST IA DURING
FRIDAY EVENING. AFTER THAT AND THROUGH THE WEEKEND...NOT A LOT GOING
ON FOR A CHANGE. IT WILL STILL BE QUITE BREEZY FRIDAY NIGHT FOR MANY
LOCATIONS...HOWEVER THE COLD AIR ADVECTION PUSH IS ABNORMALLY STRONG
FOR THIS TIME OF YEAR. SO LOOKING AT LOWS FROM 40 AROUND HURON TO 50
AT STORM LAKE. QUITE CHILLY FOR THIS TIME OF YEAR. THIS WILL BE
FOLLOWED BY HIGHS ONLY IN THE 60S ON SATURDAY WITH A WELL MIXED DAY
ALLOWING TEMPERATURES TO MIX TO ABOUT 800MB. SUNDAYS HIGHS WILL BE 5
TO 10 DEGREES WARMER THAN SATURDAYS.

IN THE EXTENDED...A STRONG SOUTHERLY FLOW OF AIR WILL SETUP SHOP ON
MONDAY AND TUESDAY...LINGERING ACROSS OUR EASTERN ZONES ON
WEDNESDAY. THEREFORE INCREASED THE SUPERBLEND WINDS AS THEY WERE TOO
LIGHT. THIS WILL ALLOW FOR A WARMUP MORE COINCIDENT WITH EARLY
SUMMER/LATE SPRING TYPE HIGHS...WITH TUESDAY LOOKING THE WARMEST AT
80 TO 85 DEGREES. RIGHT NOW...RAINFALL CHANCES LOOK SKITTISH UNTIL
POSSIBLY WEDNESDAY AND WEDNESDAY NIGHT...WHEN BOTH THE ECMWF AND GFS
SHOW A SERIES OF SHORT WAVES MOVING THROUGH AN UPPER TROUGH.


&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 718 PM CDT WED MAY 27 2015

VFR THROUGH THE NIGHT. ISOLATED SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE WEST OF THE JAMES RIVER THROUGH ABOUT 10 PM...THEN A
SMALL THREAT WILL SHIFT EAST THROUGH THE NIGHT...BUT COVERAGE WILL
BE MINIMAL.


&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

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



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