Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 282335
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
635 PM CDT SUN SEP 28 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 309 PM CDT SUN SEP 28 2014

A FEW SHOWERS CONTINUE ALONG THE MISSOURI RIVER...BUT THESE SHOULD
DISSIPATE THIS EVENING. OTHERWISE WILL BE A SUNNY AND WARM REST OF
THE AFTERNOON. BOUNDARY NORTH OF THE CWA WILL PUSH SOUTH TONIGHT.
STRONG CONVERGENCE AND FRONTOGENESIS ALONG THIS LOW LEVEL
FRONT...ESPECIALLY AS THE SOUTHERLY LOW LEVEL JET GETS GOING TONIGHT
SOUTH OF THE BOUNDARY. LOOKS LIKE WE SHOULD GET ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS DEVELOP JUST ON THE COOL SIDE OF THIS
FRONT...BASED AROUND 900 TO 925 MB. MODELS IN DISAGREEMENT ON
PLACEMENT OF THIS BOUNDARY...AND THUS BEST PRECIPITATION THREAT.
CONSENSUS SEEMS TO SUGGEST SOMEWHERE BETWEEN HIGHWAY 14 AND
INTERSTATE 90 IS WHERE IT WILL END UP AND THUS KEPT HIGHEST POPS
THERE. LARGE SCALE SUPPORT NOT GOOD WITH UPPER RIDGING STILL
OVERHEAD...WHICH SHOULD LIMIT STORM DEPTH AND THUNDER POTENTIAL. BUT
WEAK HEIGHT FALLS MIGHT BE ENOUGH TO ALLOW A FEW LIGHTNING
STRIKES...SO KEPT LOW THUNDER MENTION IN THE GRIDS. LOW STRATUS WILL
ALSO WORK SOUTH BEHIND THE FRONT...GETTING AS FAR SOUTH AS AROUND
INTERSTATE 90. LOOKING AT LOWS IN THE 50S.

BOUNDARY WILL NOT MOVE MUCH ON MONDAY...AS THE WAVE EJECTING INTO
THE ROCKIES WILL SLOW ITS PROGRESSION SOUTH. IT MAY EVEN BEGIN TO
LIFT BACK NORTH AS A WARM FRONT. ELEVATED SHOWER AND THUNDERSTORM
THREAT MENTIONED ABOVE SHOULD CONTINUE INTO MONDAY...AGAIN MAINLY
ALONG THE INTERSTATE 90 CORRIDOR AND POINTS NORTH...EVENTUALLY
SHIFTING EAST INTO PORTIONS OF SOUTHWEST MINNESOTA AND NORTHWEST
IOWA. AGAIN NOTHING STRONG EXPECTED AND ACTIVITY SHOULD ONLY BE
ISOLATED TO SCATTERED. LOW STRATUS WILL SLOWLY LIFT AND RETREAT
NORTH THROUGH THE DAY. TRICKY TEMPERATURE FORECAST AS WILL LIKELY BE
A TIGHT GRADIENT NEAR THE BOUNDARY...WITH 60S AND 70S TO THE NORTH
AND 80S TO THE SOUTH. STAYED CLOSE TO RAW CONSENSUS FOR HIGHS...BUT
THEN DID BUMP AREAS TO THE SOUTH UP SEVERAL DEGREES...AS THEY SHOULD
BE JUST AS WARM IF NOT WARMER THAN TODAY BASED ON THERMAL
PROFILES.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 309 PM CDT SUN SEP 28 2014

THE MID AND LONG RANGE WILL BE DOMINATED BY MUCH COOLER AND WETTER
CONDITIONS AS TROUGHING SETTLES INTO THE NORTHERN PLAINS MID TO LATE
WEEK. MODELS CONTINUE TO SHOW GOOD CONSENSUS ON THE TIMING AND TRACK
OF THE INITIAL NEGATIVELY TILTED UPPER LOW. TIMING CONTINUES TO SLOW
THE SYSTEM SLIGHTLY...THE RESULT OF THE DEEPENING OF THE FEATURE AS
IT LIFTS NORTHWARD ACROSS THE CENTRAL AND NORTHERN HIGH PLAINS
MONDAY NIGHT AND TUESDAY AND THE BLOCKING RIDGE PATTERN IN THE
EASTERN PLAINS. SHOWERS AND THUNDERSTORMS WILL REMAIN LARGELY WEST
OF THE FORECAST AREA MONDAY NIGHT...PERHAPS CREEPING INTO OUR SOUTH
CENTRAL SOUTH DAKOTA COUNTIES LATE. SURFACE LOW DEEPENS OVER THE
BLACK HILLS AREA TUESDAY MORNING AND LIKEWISE LIFTS TO THE NORTH
NORTHEAST...REACHING THE CENTRAL NORTH DAKOTA AND CANADA BORDER
WEDNESDAY MORNING.

STRONG SOUTHERLY WINDS DEVELOPING MONDAY NIGHT AND TUESDAY WILL TAP
INTO SOME INCREASED MOISTURE AND CREATE SOME MODEST INSTABILITY.
WITH MARGINALLY STEEP MID LEVEL LAPSE RATES AND DECENT SHEAR...SOME
ISOLATED SEVERE CONVECTION WILL BE POSSIBLE ON TUESDAY...
PARTICULARLY DURING THE PEAK HEATING OF THE AFTERNOON AND EVENING
WHEN INSTABILITY WILL BE GREATEST. SHOWERS AND STORMS PUSH TO THE
EAST OF THE AREA TUESDAY WHICH WILL RESULT IN A LULL IN
PRECIPITATION. THE TRAILING COLD FRONT FINALLY SAGS ACROSS THE
REGION DURING THE DAY ON WEDNESDAY...WITH SCATTERED SHOWERS AND
THUNDERSTORMS AGAIN POSSIBLE...MAINLY EAST OF INTERSTATE 90.

WITH THE BROAD UPPER LEVEL TROUGH DIGGING INTO THE PLAINS WEDNESDAY
NIGHT AND THURSDAY...MUCH COOLER TEMPERATURES ARRIVE. A FEW
ADDITIONAL SCATTERED SHOWERS WILL BE POSSIBLE IN THE SOUTHEAST HALF
OF THE FORECAST AREA THURSDAY AND THURSDAY NIGHT BEFORE DRIER
NORTHWEST FLOW ARRIVES FRIDAY AND THE WEEKEND. HIGHS WILL BE IN THE
60S ON THURSDAY AND WILL ONLY REACH THE MID 50S TO LOWER 60S ON
FRIDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 628 PM CDT SUN SEP 28 2014

FRONT CONTINUES TO SLOWLY SAG SOUTHEAST THIS EVENING AND WILL PASS
THROUGH HURON IN THE NEXT 1-2 HOURS. A FEW SCATTERED SHOWERS WILL
BE POSSIBLE ALONG THE BOUNDARY AND ALONG A SEPARATE NW-SW ALIGNED LOW-
LVL THETA-E GRADIENT. GENERALLY THIS ACTIVITY WILL BE TOO
SCATTERED TO MENTION...BUT WILL MONITOR FOR AMENDMENTS.

THE PRIMARY CONCERN INTO MONDAY WILL BE WITH THE DEVELOPMENT OF
STRATUS THROUGH THE NIGHT. MODELS COULD BE A LITTLE SLOW IN
ADDITIONAL STRATUS DEVELOPING BEHIND THE BOUNDARY...BUT STILL
POINT TO LOW LEVEL CLOUDS REACHING FSD TOWARDS 12Z. HOW FAR SOUTH
AND THE EXTENT OF CLOUDS IS IN QUESTION...SO FOR NOW WILL ONLY
MENTION A TEMPO GROUP. CLOUDS SHOULD MIX TO HIGH MVFR OR VFR
LEVELS BY LATE MORNING.

&&

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

$$

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



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