Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 241534 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
934 AM CST WED DEC 24 2014

.UPDATE...
ONLY SOME MINOR ADJUSTMENTS TO THE TODAY PERIOD FORECAST. NUDGED
TEMPERATURES UP A COUPLE DEGREES GIVEN DAYTIME HEATING THROUGH
CLOUDY CONDITIONS BUT NEUTRAL LOW LEVEL THERMAL ADVECTION AND
LIGHT BOUNDARY LAYER WINDS GRADUALLY BECOMING SOUTH SOUTHWESTERLY.
MADE A TWEAK TO THE SKYCOVER GRIDS TO KEEP HIGHER AMOUNTS OF
SKYCOVER IN GIVEN THE COMBINATION OF THICK JET-LEVEL CIRRUS
STREAMING INTO THE REGION AND WIDESPREAD LOW LEVEL STRATUS CLOUDS
AROUND. ALSO...PER AREA OBS AND WEBCAMS...GOT SOME PATCHY COVERAGE
OF FOG ONGOING THIS MORNING AND SOME OF IT APPEARS RATHER DENSE.
SO ADDED IN SOME PATCHY/DENSE FOG TO THE WX GRIDS THROUGH NOON
CST TODAY...AND HIGHLIGHTED MORE DENSE FOG COVERAGE ON THE COTEAU
AND OVER ALONG THE MISSOURI RIVER. UPDATES ARE OUT.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH FRIDAY
SNOWFALL AMOUNTS THURSDAY THROUGH FRIDAY WILL BE THE MAIN FORECAST
CHALLENGE.

TODAY WILL FEATURE CLOUDY SKIES WITH HIGHS GENERALLY IN THE 30S.
OUR NEXT SYSTEM CURRENTLY DIVING SOUTHWARD ALONG THE COAST OF
BRITISH COLUMBIA WILL KEEP CLOUDY SKIES THROUGH TONIGHT AS WELL.
OVERNIGHT LOWS WILL RANGE IN THE 20S.

SIGNIFICANT CHANGES HAVE BEEN MADE TO THE PREVIOUS FORECAST WITH
MOST OF THE SNOWFALL OCCURRING THURSDAY AND THURSDAY NIGHT FOR
THIS CWA. VIRTUALLY ALL MODELS SHOW A BAND OF SNOW DEVELOPING
EAST/WEST...AFFECTING MOST OF THIS CWA BY 18Z THURSDAY. PWATS ARE
SHOWN TO INCREASE THROUGH THE AFTERNOON HOURS...PEAKING OVER A
HALF INCH. WHILE THE AMOUNT OF AVAILABLE MOISTURE IS GOOD...THERE
APPEARS TO BE A LACK OF SIGNIFICANT LIFT. OMEGA IN THE SNOW GROWTH
REGION IS ONLY 5 TO 10 MICRO-BARS AT THE MOST...WHICH SHOULD LEAD
TO MINOR SNOWFALL TOTALS. THE 21Z AND 03Z SREF SUGGEST LOW
PROBABILITIES/10 TO 20%/ OF THIS CWA SEEING FOUR PLUS INCHES OF
SNOW BY FRIDAY MORNING. THE 20 PERCENT PROB IS LOCATED FROM MILLER
TO KENNEBEC.

MUCH DRIER AIR PUSHES INTO THE REGION FROM THE NORTHWEST FOR FRIDAY
WITH PWATS DROPPING BELOW TENTH OF AN INCH. MODELS SUGGEST ONLY
THE SOUTHEAST PORTION OF THE CWA...OR THE WATERTOWN AREA...WILL
SEE ACCUMULATING SNOWFALL ON FRIDAY. SNOWFALL AMOUNTS WILL RANGE
FROM 1 TO 3 INCHES WITH ISOLATED HIGHER AMOUNTS.


.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY

THE MAIN CHALLENGE IN THE LONG TERM WILL BE TEMPERATURES. THE MID
LEVEL PATTERN AT THE BEGINNING OF THE PERIOD STARTS OFF WITH A
SPLIT FLOW TROF OVER THE CENTRAL CONUS. THIS FEATURE IS EXPECTED
TO SHIFT EAST BUT GET REPLACED WITH A BROADER AND DEEPER MID LEVEL
TROF THAT IS EXPECTED TO COVER MUCH OF THE CONUS NEXT WEEK. THIS
SPELLS A RETURN TO MUCH COLDER TEMPERATURES TOWARD THE END OF THE
PERIOD AS FLOW RIGHT OFF THE POLE BRINGS A VERY COLD AIRMASS SOUTH
INTO THE NORTHERN PLAINS. SOME LIGHT SNOW MAY ACCOMPANY THAT COLD
AIR...BUT NOTHING SIGNIFICANT IS EXPECTED AT THIS TIME.
HOWEVER...THERE WILL BE A MARKED CHANGE IN TEMPERATURES...WITH
MUCH BELOW NORMAL TEMPERATURES EXPECTED BY THE EARLY AND MIDDLE
PART OF NEXT WEEK.


&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

IFR/MVFR CIGS ARE LIKELY TO CONTINUE REGION WIDE THROUGH THE
MORNING. HOWEVER THE BACK EDGE OF THE LOW CLOUDS SHOULD SLOWLY
ADVECT EAST WITH KPIR/KMBG THE FIRST TO LOSE THE LOW CLOUDS. KABR
AND ESPECIALLY KATY MAY HAND ONTO THE LOW CLOUDS THROUGH MUCH OF
THE DAY.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

$$
UPDATE...DORN
SHORT TERM...SD
LONG TERM...TDK
AVIATION...TDK

WEATHER.GOV/ABERDEEN




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