Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 231706
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1206 PM CDT THU APR 23 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT THU APR 23 2015

IN THE IMMEDIATE TERM...WILL BE CANCELING A PORTION OF THIS
MORNINGS FREEZE WARNING...AS MID CLOUD DECK WHICH DEVELOPED EARLY
THIS MORNING HAS BECOME FAIRLY WIDESPREAD AND PERSISTENT. THIS IS
PREVENTING TEMPERATURES FROM FALLING TO NEAR FREEZING...LET ALONE
TO 28 OR COLDER. REALIZE ANY PRECAUTIONS TO PROTECT SENSITIVE
PLANTS FROM A FREEZE WILL HAVE ALREADY BEEN TAKEN...BUT MAKES NO
SENSE TO KEEP THE HEADLINE IN PLACE WHEN THE THREAT IS NO LONGER
THERE.

BEYOND THAT...HIGH RES MODELS DO SHOW THE MID CLOUD DECK DIMINISHING
THROUGH THE MORNING...BUT SOME SCATTERED REDEVELOPMENT POSSIBLE IN
OUR WEST THROUGH THE AFTERNOON AS MOISTURE BEGINS TO INCREASE AHEAD
OF APPROACHING WAVE. SHOULD STILL SEE ENOUGH SUNSHINE TO HELP WARM
TEMPERATURES INTO THE LOWER-MID 60S AS WARMER AIR BEGINS TO SPREAD
INTO THE WESTERN AND SOUTHERN PARTS OF THE FORECAST AREA. NORTHEAST
AREAS WILL REMAIN IN THE MID-UPPER 50S...AND WILL ALSO MAINTAIN THE
LOWEST DEW POINTS THROUGH THE AFTERNOON. AS A RESULT...HUMIDITY
VALUES ARE AGAIN EXPECTED TO DROP INTO THE 15-20 PERCENT RANGE OVER
PARTS OF SOUTHWEST MINNESOTA. HOWEVER THE WINDS WILL BE MUCH LIGHTER
THAN YESTERDAY AS THE SURFACE RIDGE SLOWLY PULLS TO THE EAST...SO NO
FIRE WEATHER CONCERNS THERE TODAY. HUMIDITY LEVELS FROM 20-25
PERCENT WILL STRETCH FROM THE MIDDLE JAMES RIVER VALLEY INTO MUCH OF
NORTHWEST IOWA...BUT AGAIN RELATIVELY LIGHT WINDS WILL KEEP FIRE
DANGER IN MODERATE-HIGH RANGE MOST AREAS. ONLY A SMALL AREA OF VERY
HIGH FIRE DANGER EXPECTED IN PARTS OF OUR FAR WEST AT THIS POINT...
WHERE STRONGER WINDS WILL COUPLE WITH HUMIDITY VALUES FROM 20 TO 30
PERCENT. ELSEWHERE IN SOUTH CENTRAL SOUTH DAKOTA...STRONGER SOUTH
WINDS SHOULD DRAW HIGHER MOISTURE INTO THE REGION AND HOLD HUMIDITY
LEVELS ABOVE 30 PERCENT.

BY TONIGHT...LOW LEVEL JET WILL CONTINUE TO AID IN LOW-MID LEVEL
MOISTURE TRANSPORT...WITH BROAD WARM ADVECTION/ISENTROPIC LIFT
LEADING TO EXPANDING CLOUDS. LIFT WILL INITIALLY HAVE TO OVERCOME
FAIRLY DRY AIR BELOW 850MB...BUT SHOULD STILL SEE SOME ISOLATED TO
SCATTERED LIGHT SHOWERS DEVELOP EAST OF THE JAMES BY LATE TONIGHT.
ALTHOUGH PLACEMENT VARIES AMONG THE MODELS...ALL SHOWING SOME WEAK
ELEVATED INSTABILITY. GREATEST AGREEMENT IS IN OUR SOUTH...SO WILL
CONTINUE MENTION OF ISOLATED THUNDER IN THE SOUTH CENTRAL PORTIONS
OF THE FORECAST AREA. MOISTURE INCREASE...CLOUDS AND WINDS WILL ALL
WORK TO KEEP TEMPERATURES MUCH WARMER THAN THE PAST COUPLE OF NIGHTS
WITH LOWS IN THE 40S EXPECTED MOST AREAS.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 408 AM CDT THU APR 23 2015

WAVE COMING UP FRIDAY ON A PATH TO THE SOUTH AND SOUTHEAST OF OUR
FORECAST AREA WILL BE MOST EVIDENT...AT LEAST AT MID LEVELS AND WITH
THE RAIN THREAT...OVER THE EASTERN PART OF THE AREA. LOW LEVEL
MOISTURE WILL REACH ACROSS THE AREA ON A DEVELOPING EASTERLY FLOW.
AFTER SHOWERS/RAIN WITH MODEST AMOUNTS...PRECIPITATION SHOULD END
SATURDAY BUT CLOUDS WILL LINGER UNTIL CLEARING OUT SUNDAY...UNDER A
STRENGTHENING UPPER RIDGE AND A DRYING LOW LEVEL EASTERLY FLOW
DRIVEN BY A NORTHERLY UPPER FLOW OVER THE UPPER GREAT LAKES.

RAINFALL AMOUNTS ARE SOMEWHAT UNCERTAIN AND WILL KEEP THEM MODEST
FOR NOW...EVEN THOUGH MODELS ARE SHOOTING FOR SOME FAIRLY HEALTHY
RAINFALL IN SOUTHWEST MN AND NORTHWEST IA. THINK THESE ARE OVERDONE
GIVEN THE MAIN SYSTEM STAYS SOUTH/SOUTHEAST OF THE AREA.

DAYTIME TEMPERATURES WILL BE GENERALLY COOL FRIDAY AND SATURDAY THEN
SHOULD WARM SOME EARLY NEXT WEEK. UPPER LOW DIGGING INTO THE ROCKIES
SEEMS DESTINED TO STAY WELL SOUTH OF THE AREA. WE ARE SILL LOOKING
AT AN UNCERTAIN THREAT OF SHOWERS MONDAY THROUGH TUESDAY AS THE
NORTHERN STREAM WAVE AFFECTS THE AREA. FOR NOW WILL COMPROMISE THE
EC WITH BOTH THE GFS AND CANADIAN OVER SHARP DIGGING OF A SHORT WAVE
THE LATTER MODELS HAVE INTO A SMALL UPPER LOW OVER THE AREA ABOUT
TUESDAY. EITHER WAY THE OUTLOOK FOR THE POST EXTENDED PERIOD IS
LOOKING PRETTY MILD OR WARM UNDER STRONG RIDGING. THE EC WOULD
SIMPLY GIVE AN EARLIER AND STRONGER START TO THE WARMING AT THE END
OF THE FORECAST PERIOD...BRINGING SOME 70S TUESDAY AND WEDNESDAY
INSTEAD OF THE 60S WE WILL HAVE IN FOR NOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1201 PM CDT THU APR 23 2015

VFR CONDITIONS THROUGH LATER TONIGHT...THEN LOWERING CEILINGS
AFTER 08Z WITH A CHANCE OF SHOWERS BY FRIDAY MORNING. CONFIDENCE ON
TIMING AND LOCATION OF SHOWERS NOT VERY HIGH...THOUGH BETTER
CHANCES LOOK TO BE AROUND KSUX AND KFSD BETWEEN 12Z AND 15Z.

&&

.FIRE WEATHER...
ISSUED AT 408 AM CDT THU APR 23 2015

MUCH LIGHTER WINDS WILL BRING A DECREASE IN GRASSLAND FIRE DANGER
ACROSS MINNESOTA AND IOWA TODAY...DESPITE HUMIDITY LEVELS AGAIN
DROPPING TO 15 TO 25 PERCENT THIS AFTERNOON. INCREASING SOUTH TO
SOUTHEAST WINDS ARE EXPECTED WEST OF INTERSTATE 29...WITH THE
STRONGEST WINDS OF 15 TO 30 MPH WEST OF THE JAMES RIVER VALLEY.
THIS WILL BEGIN TO INCREASE THE HUMIDITY IN PARTS OF THE LOWER
BRULE REGION IN SOUTH CENTRAL SOUTH DAKOTA...WHICH SHOULD HOLD THE
GRASSLAND FIRE DANGER IN CHECK THERE. HOWEVER THE MOISTURE WILL BE
SLOWER TO REACH NORTHERN PORTIONS OF FIRE ZONE 255...AND A SMALL
AREA OF VERY HIGH FIRE DANGER IS ANTICIPATED NEAR AND WEST OF A
LINE FROM KIMBALL TO WESSINGTON SPRINGS.

&&

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

$$

SHORT TERM...JH
LONG TERM...
AVIATION...JM
FIRE WEATHER...JH



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