Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 270930 CCA
AFDFSD

AREA FORECAST DISCUSSION...CORRECTED THURSDAY NIGHT WORDING
NATIONAL WEATHER SERVICE SIOUX FALLS SD
410 AM CDT WED APR 27 2016

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 410 AM CDT WED APR 27 2016

WET AND COOL FORECAST TODAY AS UPPER LOW CHURNS ACROSS THE CENTRAL
PLAINS.  WATER VAPOR SUGGESTS UPPER LOW IS CURRENTLY CENTERED ACROSS
WESTERN KANSAS...AND IS EXPECTED TO WORK NORTHWARD THROUGHOUT THE
DAY INTO EASTERN NEBRASKA.  AS THIS SYSTEM LIFTS NORTH..THE LOBE OF
ENERGY RESPONSIBLE FOR THE PRECIPITATION ACROSS EASTERN NEBRASKA
THIS MORNING IS EXPECTED TO LIFT TO THE NORTH AND WEST.  EXPECT BAND
OF RAIN TO LIFT NORTH THROUGH THE MORNING HOURS ACROSS THE FORECAST
AREA...AND WILL BE MOST PREVALENT ACROSS CENTRAL SOUTH DAKOTA NEAR
INVERTED TROUGH TYPE FEATURE.  EXPECT PRECIPITATION TO BECOME MORE
SCATTERED ACROSS THE SOUTHERN HALF OF THE FORECAST AREA THIS
AFTERNOON. THE BREAK IN PRECIPITATION MAY ALLOW FOR TEMPERATURES TO
RISE SLIGHTLY.  ELSEWHERE...EXPECT TEMPERATURES TO REMAIN STEADY IF
NOT FALL SLIGHTLY AS SLIGHTLY COOLER AIR WORKS IN ALOFT. MAY SEE A
FEW LIGHTNING STRIKES ACROSS THE SOUTHERN EDGE OF THE FORECAST AREA
ON WEDNESDAY AFTERNOON AND EVENING AS LIFTING FROM WARM LAYER NEAR
850 YIELDS SOME MARGINAL CAPE.  CERTAINLY NOT EXPECTING ANYTHING IN
TERMS OF SEVERE WEATHER.

FOR TONIGHT...EXPECT PRECIPITATION TO BE MOST COMMON ACROSS THE
HIGHWAY 14 CORRIDOR INTO CENTRAL SOUTH DAKOTA AS UPPER WAVE PIVOTS
BACK TO THE NORTHWEST.  TEMPERATURES ARE ALSO EXPECTED TO FALL
THROUGH THE NIGHT...AND COULD SEE SOME SNOW MIX IN WITH RAIN ALONG
HIGHWAY 14 CORRIDOR.  SOUNDING PROFILES ARE ACTUALLY QUITE
INTERESTING...AS SATURATION IN THE DENDRITIC LAYER IS QUESTIONABLE
AT TIMES. IN ADDITION...THERE IS A SATURATE SUBFREEZING LAYER JUST
ABOVE THE SURFACE...BUT IS NOT COOL ENOUGH TO REFREEZE PRECIPITATION
PARTICLES.  THEREFORE...EXPECT RAIN TO CONTINUE TO BE DOMINANT
PRECIPITATION TYPE...BUT COULD HAVE SOME SNOW MIXED IN IF ICE
CRYSTAL IS ABLE TO SURVIVE FROM ALOFT.


.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 410 AM CDT WED APR 27 2016

ON THURSDAY...OUR UPPER LOW FINALLY FILLS A BIT AND MOVES
EASTWARD...AS A WELL ADVERTISED SECOND UPPER LEVEL LOW MOVES CLOSER
TO THE FOUR CORNERS AREA GIVING THIS CURRENT LOW THE BOOT. BUT
THURSDAY WILL CONTINUE TO BE A LITTLE UNSETTLED...CERTAINLY CLOUDY
WITH SOME LIGHT SHOWERS. THE MORE WIDESPREAD SHOWER ACTIVITY WILL
FAVOR THE NORTHERN HALF OF OUR FORECAST AREA IN THE MORNING...WITH
THE PRECIP BECOMING SKITTISH IN THE AFTERNOON. THE NORTHERN HALF
OF OUR FORECAST AREA HAS THE FORCING...WITH SOME DECENT MID AND
UPPER LEVEL QG FORCING NORTH OF INTERSTATE 90. THE GFS IS A LITTLE
FASTER WITH THE MOVEMENT OF THE LOW EASTWARD...BUT ALL MODELS ARE
ALSO SHOWING A SUBTLE VORT FILAMENT EXTENDING WESTWARD THROUGH OUR
FORECAST AREA...AND CONNECTING INTO A WEAK LOW IN WESTERN MT. THIS
HELPS THE MOISTURE PROFILE REMAIN SATURATED BETWEEN 850 AND 700MB.
WITH THE CLOUDS AND OFF AN ON LIGHT RAIN...TRENDED TOWARD THE COOLER
GUIDANCE READINGS FOR HIGHS...WHICH WAS A BLEND OF THE RAW MODEL
VALUES INCLUDING THE ECMWF. BUT STRAIGHT ECMWF LOOK TOO COLD. WOULD
NOT RULE OUT A CHANCE FOR SNOW IN OUR NORTHERN ZONES MIXED WITH THE
RAINFALL THURSDAY MORNING. THE SOUNDING PROFILES ARE HOVERING A
COUPLE OF DEGREES EITHER SIDE OF FREEZING IN THE LOWEST LAYERS...BUT
WITH SURFACE TEMPERATURES IN THE MID 30S AND LIGHT PRECIP RATES...ANY
SNOWFALL WILL LIKELY NOT STICK.

THINGS FINALLY DRY OUT SOME THURSDAY NIGHT AND FRIDAY...PERHAPS WITH
A SLIGHT CHANCE OF LIGHT RAIN IN OUR MO RIVER VALLEY ZONES FRIDAY.
THE NAM IS A FAST OUTLIER WITH THE ONSLAUGHT OF RAINFALL ON FRIDAY
COMPARED TO THE ECMWF...GFS AND GEM GLOBAL. THEREFORE THE NAM WAS
NOT FOLLOWED. BELIEVE THE LATTER THREE MODELS ARE CAPTURING THE
DRIER PROFILE DUE TO THE UPPER RIDGE STILL IN THIS AREA AHEAD OF THE
ADVANCING UPPER LOW TO THE SOUTHWEST. DUE TO ANTICIPATED LINGERING
CLOUD COVER THURSDAY NIGHT...TEMPERATURES SHOULD REMAIN COMFORTABLY
ABOVE FREEZING...FOLLOWED BY A CHILLY DAY ON FRIDAY WITH HIGHS IN
THE 50S. AGAIN...TRENDED TOWARD THE COOLER RAW MODEL GUIDANCE VALUES
AS THERE STILL COULD BE A FAIR AMOUNT OF CLOUD COVER. AT ANY RATE...
EVEN WITHOUT CLOUD COVER...IT IS CHILLY FROM 925-850MB.

THIS WEEKEND...THE GFS AND ECMWF ARE IN PRETTY GOOD AGREEMENT WITH
THE TIMING AND PLACEMENT OF THE AFOREMENTIONED NEXT UPPER LEVEL LOW.
RAIN WILL OVERSPREAD FROM SOUTH TO NORTH FRIDAY NIGHT AND SATURDAY.
HIGHS ON SATURDAY WILL BE MISERABLY CHILLY FOR THIS TIME OF YEAR...
AS MIXING FROM 925MB YIELDS MID 40S TO LOWER 50S ACROSS THE FORECAST
AREA. IN ADDITION...EAST TO NORTHEAST WINDS WILL BE AVERAGING 15 TO
30 MPH ADDING A CHILL TO THE AIR. SUPERBLEND LOOKS TOO MILD AND WAS
NOT FOLLOWED. USED ECMWF AND RAW MODEL VALUES ONCE AGAIN. LIGHT
SHOWERS WILL LINGER SATURDAY NIGHT AND SUNDAY AS THE UPPER LOW
WEAKENS AND MOVES EASTWARD. BUT AFTER THAT...THERE IS UPPER RIDGING
THAT BEGINS TO INFLUENCE OUR WEATHER WHICH WILL DRY OUT THE FORECAST
AREA BY MONDAY WITH MUCH WARMER TEMPERATURES.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1047 PM CDT TUE APR 26 2016

WIDESPREAD MVFR-IFR CONDITIONS EXPECTED THROUGH THIS TAF PERIOD AS
RAIN AND ISOLATED THUNDERSTORMS OVERSPREAD THE REGION. CONFIDENCE
IN TIMING OF THUNDER THREAT AT ANY ONE LOCATION IS LOW...AND THUS
OPTED TO NOT MENTION IN TAFS AT THIS TIME.

GUSTY EAST WINDS WILL ACCOMPANY THE RAIN THROUGH THE DAY WEDNESDAY
WITH GUSTS AT OR ABOVE 25KT AT TIMES.


&&

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

$$

SHORT TERM...BT
LONG TERM...MJ
AVIATION...JH


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