Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 171125
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
625 AM CDT FRI APR 17 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 347 AM CDT FRI APR 17 2015

DEEP UPPER LEVEL LOW WILL CONTINUE TO CHURN OVER THE FOUR CORNERS
THIS MORNING THEN BEGIN TO SLOWLY LIFT NORTHEAST INTO THE CENTRAL
ROCKIES THROUGH TONIGHT. MID LEVEL FRONTOGENESIS LIFTS A LITTLE
NORTHWARD INTO NORTHERN NEBRASKA THROUGH THE DAY TODAY. MID LEVEL
CLOUDS WILL INCREASE FROM THE SOUTH TODAY...HOWEVER DESPITE THE
CLOUDS...TEMPERATURES SHOULD BE SIMILAR TO YESTERDAY OR A FEW
DEGREES WARMER. NUDGED TOWARDS THE WARMER END OF GUIDANCE SIMILAR TO
THE BCCONSALL. RELATIVELY MOIST DEWPOINTS REMAIN PRIMARILY IN THE
40S EARLY THIS MORNING BUT WILL INCREASE INTO THE LOWER 50S IN THE
MISSOURI VALLEY BY THIS AFTERNOON. WITH ISENTROPIC LIFT APPROACHING
THE MISSOURI VALLEY...SCATTERED RAIN SHOWERS WILL EXPAND INTO THIS
REGION MID MORNING AND BECOME LIKELY IN OUR FAR SOUTHWESTERN
COUNTIES IN THE AFTERNOON. MODELS DEVELOPS AROUND 50 TO 100 J/KG OF
ELEVATED CAPE WHICH SHOULD SUPPORT SOME ISOLATED THUNDERSTORMS IN
ADDITION TO THE SHOWERS. NOT EXPECTING ANY SEVERE STORMS IN OUR
FORECAST AREA. NORTH OF A STORM LAKE TO MITCHELL LINE LOOKS TO
REMAIN DRY THROUGH THE AFTERNOON.

THE LIFT APPEARS TO WANE SLIGHTLY THIS EVENING...SO DECREASED POPS
EVER SO SLIGHTLY...HOWEVER AS THE UPPER LEVEL LOW ARRIVES IN THE
CENTRAL HIGH PLAINS LATE TONIGHT...A STRONGER PUSH OF SHOWER AND
ISOLATED STORMS INTO THE MISSOURI VALLEY AND AREAS WEST OF THE JAMES
RIVER VALLEY. RAINFALL WILL GENERALLY BE AROUND A TENTH OF AN INCH
OR LESS TODAY...FOLLOWED BY UP TO A HALF INCH TONIGHT...HIGHEST
AMOUNTS NEAR THE MISSOURI VALLEY. LOWS TONIGHT WILL MAINLY BE IN THE
50S.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 347 AM CDT FRI APR 17 2015

ISENTROPIC LIFT AND PWAT VALUES WILL INCREASE SATURDAY AHEAD OF THE
UPPER LOW AS IT MOVES EAST INTO THE CENTRAL PLAINS. SOME MINOR
TIMING ISSUES...BUT IN GENERAL MODELS IN GOOD AGREEMENT ON THE
EVOLUTION OF THE SYSTEM THIS WEEKEND. SHOWERS ONGOING SATURDAY
MORNING ALONG THE MISSOURI RIVER WILL PUSH NORTH AND ENCOMPASS THE
WHOLE CWA BY EARLY AFTERNOON. BEST CHANCE OF SEEING SOME EMBEDDED
THUNDER WILL BE ALONG THE MISSOURI RIVER CORRIDOR WHERE STABILITY IS
LOWER...BUT CAN NOT RULE OUT A RUMBLE OF THUNDER ANYWHERE. NOT
EXPECTING ANYTHING STRONG AS INSTABILITY AND SHEAR REMAIN TOO WEAK.
AN APPROACHING NORTHERN STREAM WAVE WILL HELP PUSH A COLD FRONT
THROUGH THE AREA SATURDAY NIGHT. THIS SHOULD HELP KEEP THE RAIN
MOVING OFF TO THE EAST...AND WHILE WE COULD STILL SEE A FEW SHOWERS
AROUND...EXPECT INTENSITY TO DECREASE SATURDAY NIGHT BEHIND THIS
FRONT AS WE LOSE BOTH FORCING AND THE BETTER MOISTURE. SAME GOES FOR
SUNDAY...WITH THE BETTER RAIN THREAT AHEAD OF THE FRONT AND THUS
MAINLY EAST OF OUR CWA. SUNDAY WILL STILL BE MOSTLY CLOUDY WITH
MAYBE A FEW LIGHT SHOWERS...BUT CURRENTLY NOT EXPECTING ANY STEADY
RAINFALL...OTHER THAN MAYBE IN THE MORNING IN NORTHWEST IOWA
DEPENDING ON TIMING OF THE FRONT.

HIGHS SATURDAY A BIT TRICKY...AS WILL BE QUITE WARM ALOFT. HOWEVER
QUESTION BECOMES HOW MUCH WE WILL BE ABLE TO MIX INTO THAT WARMER
AIR...WHICH WILL BE DETERMINED IN PART BY THE ARRIVAL AND END OF THE
STEADIER RAIN. CURRENT TIMING SUGGESTS WE WILL PROBABLY JUST SEE MID
60S ACROSS THE AREA...BUT IF A SLOWER START OCCURRED IT COULD ALLOW
SOME LOCATIONS TO GET A BIT WARMER. SUNDAY WILL BE COOLER BEHIND THE
FRONT...WITH 50S TO AROUND 60 EXPECTED. WILL ALSO BECOME WINDY AGAIN
BY SUNDAY WITH NORTHWESTERLY WINDS GUSTING 30 TO 40 MPH.

THE STORY NEXT WEEK WILL BE THE CONTINUED COOLER TEMPERATURES.
MONDAY LOOKS THE COOLEST WITH HIGHS ONLY IN THE 40S AND 50S. THEN WE
SHOULD SEE A SLOW WARMING TREND AS THE UPPER LOW PUSHES OFF TO THE
EAST. UPPER RIDGING IS SLOW TO BUILD IN THOUGH...SO ONLY LOOKS LIKE
WE WILL SEE HIGHS IN THE 50S AND 60S INTO MID WEEK. LOWS WILL BE
RIGHT AROUND FREEZING MONDAY NIGHT INTO THURSDAY NIGHT AS
WELL...WITH 20S POSSIBLE AT LEAST ONE OF THE NIGHTS DEPENDING ON
HIGH PRESSURE PLACEMENT AND THUS RADIATIONAL COOLING IMPACTS.

IT GENERALLY LOOKS DRY INTO MID WEEK...WITH JUST A FEW SHOWERS
POSSIBLE MONDAY AS THE UPPER TROUGH AXIS SWINGS THROUGH. OTHER THING
TO WATCH NEXT WEEK WILL BE THE WINDS ON MONDAY...WITH GOOD AGREEMENT
AMONG THE ECMWF AND GFS ON STRONG WIND SPEEDS ALOFT. BOTH WOULD
SUGGEST WE SEE NEAR ADVISORY SPEEDS...WITH GUSTS AROUND 45 MPH...SO
SOMETHING TO KEEP AN EYE ON. HUMIDITY LEVELS WILL ALSO DECREASE NEXT
WEEK...AND GIVEN THE STRONG WINDS SUNDAY AND MONDAY...MAY HAVE SOME
FIRE WEATHER CONCERNS. ALTHOUGH THIS IS DEPENDENT ON HOW MUCH RAIN
FALLS THIS WEEKEND AND ITS IMPACT ON FUELS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 622 AM CDT FRI APR 17 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. MID CLOUDS
WILL BE ON THE INCREASE TODAY...WITH SOME SCATTERED SHOWERS AND
ISOLATED TSRA POSSIBLE NEAR THE MISSOURI RIVER. SHOWER CHANCES
SLOWLY INCREASE TONIGHT...BUT CHANCES IN KHON AND KFSD SHOULD
REMAIN TOO LOW FOR MENTION AT THIS POINT.

&&

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

$$

SHORT TERM...
LONG TERM...CHENARD
AVIATION...



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