Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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075
FXUS63 KFSD 040449
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1049 PM CST WED FEB 3 2016

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 326 PM CST WED FEB 3 2016

WINDS FAR EAST CONTINUE TO DROP OFF AND NO BLOWING SNOW PROBLEMS
REMAIN. TONIGHT WILL BRING A WEAK NORTHWESTERLY SHORT WAVE PASSING
MAINLY NORTH OF THE AREA. AND ASSORTMENT OF MIDDLE AND HIGH CLOUDS
WILL SPREAD OVER THE NORTHERN PART OF THE AREA WITH THIS WAVE LATER
TONIGHT AND SHOULD MOVE MAINLY EAST OF THE AREA WEDNESDAY
AFTERNOON. A LITTLE LIGHT SNOW MAY BRUSH SOUTHWESTERN MINNESOTA
EARLY THURSDAY MORNING. SOME LOWER CLOUDS WILL LIKELY ACCOMPANY THIS
SYSTEM IN THE NORTHEAST...AND HOW EXTENSIVE AND SOLID THEY BECOME
WILL DETERMINE HOW PERSISTENT THEY ARE IN THE AFTERNOON. FOR NOW
EXPECT THESE LOWER CLOUDS...PROBABLY IN THE 2-4K FOOT AGL RANGE...TO
EXIT A LITTLE LATER THAN THE HIGHER CLOUDS BUT MOSTLY BE OUT BY THE
END OF THE DAY AS RIDGING QUICKLY DEVELOPS BEHIND THE WAVE.

LOW TEMPERATURES SHOULD BE AROUND 8 EAST TO THE TEENS WEST TONIGHT
AND WILL DEPEND SOMEWHAT ON CLOUD COVER...THAT IS READINGS COULD
GET A LITTLE COLDER WITH THE FAIRLY LIGHT WINDS. THURSDAY WILL BE A
LITTLE MILDER...UPPER 20S NORTHEAST TO LOWER 30S SOUTHWEST.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 326 PM CST WED FEB 3 2016

THURSDAY NIGHT TEMPERATURES ARE QUITE A CHALLENGE. THIS IS BECAUSE A
FAIRLY STRONG UPPER TROUGH TO THE WEST OF OUR FORECAST AREA WILL
BEGIN TO INCREASE MID AND HIGH LEVEL CLOUDS FROM WEST TO EAST. IN
ADDITION...A DEPARTING SURFACE RIDGE WILL TURN THE WINDS AROUND TO A
SOUTHERLY DIRECTION. AT THIS TIME...THE ECMWF MOS VALUES LOOKED
PRETTY GOOD IN SHOWING PRETTY CHILLY LOWS WHERE FRESH SNOW COVER HAS
FALLEN...BUT MILD READINGS IN THE WEST WHERE MUCH LESS SNOW FELL
COUPLED WITH THE FACT THAT THEIR WINDS WILL BE SHIFTING TO THE SOUTH
FIRST. THAT SAID...WOULD NOT BE SURPRISED IF TEMPERATURES ALONG AND
EAST OF THE I 29 CORRIDOR REACH THEIR LOWS DURING THE OVERNIGHT
HOURS...BEFORE BEGINNING A SLOW CLIMB THROUGH THE PRE DAWN HOURS.
FOR NOW...HAVE SINGLE DIGITS ABOVE ZERO FOR MANY LOCATIONS ALONG AND
EAST OF I 29...WITH 15 TO 20 DEGREES IN OUR WESTERN ZONES.

THIS LEADS INTO FRIDAY AND FRIDAY EVENING WHEN THE AFOREMENTIONED
UPPER TROUGH WILL BE MOVING ACROSS THE FORECAST AREA. THIS TROUGH IS
MAINLY NORTHERN STREAM DOMINATED WITH A DEEP MOISTURE DEPTH.
THEREFORE CLOUD COVER WILL BE ABUNDANT BUT THE OVERALL AIR MASS
REGIME IS QUITE MILD. A CHANCE FOR LIGHT MEASURABLE SNOW EXISTS AS
THE WAVE MOVES EASTWARD WITH AMOUNTS LESS THAN AN INCH...POSSIBLY
WELL LESS THAN AN INCH. WITH HIGHS WELL ABOVE FREEZING IN OUR
WESTERN ZONES...AT FIRST IT APPEARED THAT THERE COULD BE A CHANCE
FOR MIXED PRECIPITATION IN THOSE LOCATIONS. HOWEVER THE PRECIP
CHANCES LOOK TO END IN THE AFTERNOON FOR THOSE AREAS ENDING THE
CHANCE FOR MIXED PRECIP. THEREFORE OUR FORECAST AREA SHOULD BE LIGHT
SNOW. THIS UPPER TROUGH REALLY IS THE LEADING EDGE OF SOME MILDER
AIR WORKING INTO THE REGION FOR THE WEEKEND. SATURDAY LOOKS TO BE A
FAIRLY PLEASANT DAY WITH HIGHS RANGING FROM AROUND 30 EAST OF I
29...TO THE LOWER 40S IN OUR FAR WESTERN ZONES. BOTH ON FRIDAY AND
SATURDAY...PRIMARILY USED WEIGHTED VALUES IN OUR FAR WEST WHICH WERE
BY FAR THE WARMEST READINGS. GIVEN THE 925MB THERMAL FIELD IN THAT
AREA COUPLED WITH A LACK OF SIGNIFICANT NEW SNOW COVER...THEY SHOULD
WARM UP MORE THEN CONSENSUS AND MOS GUIDANCE VALUES. CONVERSELY
TRENDED A BIT LOWER THEN CONSENSUS AND MOS READINGS ALONG AND EAST
OF I 29 FOR BOTH DAYS.

A PATTERN CHANGE ENSUES ONCE AGAIN BEGINNING SATURDAY NIGHT WHEN
ANOTHER UPPER TROUGH STRENGTHENS IN THE NORTHWEST FLOW ALOFT AS IT
DIVES SOUTHWARD FROM CANADA. THE SOUNDING PROFILES ARE ACTUALLY A
BIT UNSTABLE SATURDAY NIGHT THROUGH SUNDAY NIGHT AS A COLDER AIR
REGIME BEGINS TO USHER IN. THEREFORE CHANGED THE LIGHT SNOW CHANCES
TO SNOW SHOWERS BUT THAT IS BASICALLY JUST A COSMETIC CHANGE. HIGHS
ON SUNDAY ARE STILL PRETTY MILD AS THE COLD AIR MOVES IN. HOWEVER
THE SOUNDING TEMPERATURES ARE BELOW FREEZING BEGINNING JUST OFF THE
SURFACE AND ARE IN FACT ABOUT -20C BY 600MB...AND THE SATURATION
DEPTH IS DEEP ESPECIALLY SATURDAY NIGHT AND SUNDAY. THESE
TEMPERATURES UNDERSCORE THE AMOUNT OF INSTABILITY FOR THIS TIME OF
YEAR...AND WHY SUNDAYS PRECIP CHANCES SHOULD REMAIN ALL SNOW DESPITE
SURFACE HIGHS ABOVE FREEZING. SO BY EARLY NEXT WEEK...THE UPPER
STEERING FLOW IS COMING STRAIGHT OUT OF CENTRAL AND NORTHERN CANADA
WHICH WILL COOL TEMPERATURES DOWN FROM SUNDAYS MILD READINGS.
BEGINNING TO WORRY THAT HIGHS ARE TOO WARM MONDAY THROUGH WEDNESDAY
GIVEN THE 925MB TEMPERATURES OFF OF BOTH THE GFS AND ECMWF.
THEREFORE WILL PROBABLY BE PLAYING CATCH UP WITH COLDER HIGHS FOR
NEXT WEEK IN FUTURE FORECASTS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1049 PM CST WED FEB 3 2016

VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD.

&&

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

$$

SHORT TERM...
LONG TERM...MJ
AVIATION...



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