Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 212049
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
349 PM CDT MON APR 21 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 347 PM CDT MON APR 21 2014

STRONG NORTHWEST WINDS WILL DIMINISH AROUND SUNSET AS HIGH PRESSURE
BUILDS INTO THE AREA. THIS WILL ALLOW WINDS TO GO LIGHT THIS EVENING
THEN GRADUALLY TURN TO THE SOUTHEAST. WILL KEEP TOWARDS THE COOL
SIDE OF GUIDANCE WITH THE LIGHT WINDS AND MOSTLY CLEAR SKIES. LOWS
MAINLY IN THE 30S.

TUESDAY SHOULD PROVE TO BE A PRETTY NICE DAY FOR MOST LOCATIONS EAST
OF THE JAMES RIVER VALLEY AS WINDS ONLY GRADUALLY INCREASE. THE LOW
LEVEL THERMAL FIELD HAS COME IN JUST A TOUCH WARMER THAN YESTERDAY
BUT WITH CONCERNS ABOUT A FAIRLY DENSE MID CLOUD DECK IN THE
AFTERNOON WILL NOT RAISE HIGHS FROM GOING FORECAST...EXPECT A LITTLE
IN SOUTH CENTRAL SD WHERE THE CLOUDS SHOULD CLEAR BY MID AFTERNOON.
HIGHS SHOULD RANGE FROM THE MID 60S IN SOUTHWEST MN TO 70 TO 75 IN
SOUTH CENTRAL SD. WHILE A FEW SHOWERS MAY BE POSSIBLE AS THE MID
LEVEL MOISTURE MOVES THROUGH THE APPROXIMATE 700MB CAPE VALUES ARE
VERY LOW AND CAPPED A BIT JUST ABOVE SO NOT GOING TO INCLUDE ANY
MENTION.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 347 PM CDT MON APR 21 2014

FAIRLY ACTIVE PATTERN MID WEEK WITH STRONG LOW LEVEL JET DEVELOPING
ACROSS THE PLAIN.  LOW LEVEL JET COULD RESULT IN THE DEVELOPMENT OF
A FEW STORMS...BUT INSTABILITY IS AND MOISTURE IS PRETTY LIMITED.
HAVE FOLLOWED THE EASTERN EDGE OF THE LOW LEVEL JET FOR POPS...BUT
CONFIDENCE IS NOT ALL THAT HIGH ON MEASURABLE PRECIP. WITH STRONG
WINDS...TEMPERATURES SHOULD BE FAIRLY MILD...THOUGH GRADIENT TAKES A
LITTLE WHILE TO WORK INTO THE EASTERN CWA SO LOWERED LOWS SLIGHTLY
THERE.

WEDNESDAY IS AN INTERESTING DAY WITH VERY STRONG SHEAR PROFILE FOR
SEVERE WEATHER...HOWEVER LACK OF MOISTURE LEADS TO A LACK OF
INSTABILITY.  STEEP LAPSE RATES ABOVE 700 MB RESULTS IN A MEAGER
AMOUNT OF INSTABILITY...BUT DOESN/T APPEAR TO BE MUCH MORE THAN A
FEW HUNDRED J/KG.  WITH SHEAR PROFILE...CERTAINLY COULD GET STORMS
TO ROTATE IF SHEAR ITSELF DOESN/T SHEAR THUNDERSTORMS APART.  UPPER
LEVEL LOW GENERALLY REMAINS TO THE WEST...SO LACK OF FOCUS MECHANISM
MAY ALSO BE A CONCERN.

WITH UPPER LOW SLOWING DOWN EVER SO SLIGHTLY...HAVE SLOWED
PROGRESSION OF COLD FRONT MOVING THROUGH THE AREA WEDNESDAY NIGHT.
HAVE THEREFORE KEPT LOWS RELATIVELY MILD IN THE UPPER 40S TO LOWER
50S.

SHOWERS WORK OUT OF THE AREA ON THURSDAY AND IT APPEARS TO BE A VERY
MIXY DAY WITH BOUNDARY LAYER DEVELOPING TO NEAR 700 MB.  WITH
UNIDIRECTIONAL FLOW AND DRY AIR ALOFT...HAVE LOWERED DEWPOINTS AND
INCREASED WINDS TO NEAR EXTREME FIRE WEATHER CONDITIONS.

SECONDARY COLD FRONT WORKS THROUGH THE AREA FRIDAY WITH MUCH COOLER
CONDITIONS TO FOLLOW.  WITH DRY NORTHEAST TO EASTERLY FLOW SETTING
UP WITH HIGH PRESSURE TO THE NORTH AND STRENGTHENING MID LEVEL
RIDGE...DECREASED POPS AS MUCH AS POSSIBLE SATURDAY INTO SATURDAY
NIGHT.

BETTER CHANCES FOR PRECIPITATION CREEP INTO THE FORECAST ON SUNDAY
AS UPPER LOW MOVES INTO THE REGION. IN GENERAL...MUCH OF THE FORCING
REMAINS TO THE SOUTH OF THE FORECAST AREA...SO HAVE KEPT HIGHEST
CONCENTRATION OF POPS ACROSS THE SOUTH.

WITH COOL EAST TO NORTHEAST FLOW...KEPT TEMPERATURES AT OR BELOW
NORMAL THROUGH THE END OF THE FORECAST PERIOD. HAVE LOW TEMPERATURES
NEAR FREEZING...WHICH MAY CAUSE SOME PROBLEMS WITH EARLY SURFACING
VEGETATION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 145 PM CDT MON APR 21 2014

NORTHWEST WINDS WILL GUST TO AROUND 35 MPH AT TIMES THROUGH 0Z
THIS AFTERNOON. OTHERWISE VFR THROUGH THE PERIOD.


&&

.FIRE WEATHER...
ISSUED AT 347 PM CDT MON APR 21 2014

NORTHWEST WINDS OF 20 TO 40 MPH WILL CONTINUE THROUGH THE AFTERNOON
WITH RELATIVE HUMIDITY VALUES AROUND 25 PERCENT. THE WINDS WILL
RAPIDLY DIMINISH AROUND SUNSET BRINGING AN END TO THE RED FLAG
CONDITIONS. VERY HIGH FIRE CONDITIONS WILL AGAIN BE LIKELY ALONG AND
WEST OF THE JAMES RIVER VALLEY AS SOUTHEAST WINDS DEVELOP TUESDAY
AFTERNOON. AT THIS TIME THE RELATIVE HUMIDITY VALUES SHOULD STAY
JUST ABOVE RED FLAG CRITERIA. THE NEXT DAY OF CONCERN WILL BE ON
THURSDAY WHERE A POTENTIALLY VERY WELL MIXED ENVIRONMENT WILL
DEVELOP WITH STRONG WEST WINDS AND POTENTIALLY VERY LOW HUMIDITIES.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR SDZ256>258.

MN...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR MNZ900.

IA...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR IAZ300-301.

NE...RED FLAG WARNING UNTIL 7 PM CDT THIS EVENING FOR NEZ249.

&&

$$

SHORT TERM...08
LONG TERM...
AVIATION...08
FIRE WEATHER...08








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