Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 201850 AAC
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1250 PM CST THU NOV 20 2014

.UPDATE...
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.

HAVE MADE JUST A FEW MINOR MODIFICATIONS TO THE MAX TEMPERATURE
AND SKYCOVER GRIDS/FORECAST. GENERALLY-SPEAKING...THE FORECAST
HIGH TEMPERATURES SHOULD SUFFICE FOR TODAY WHILE SHALLOW COLD AIR
REMAINS IN PLACE. 850HPA AND LATER ON 925HPA LAYERS BEGIN TO
EXPERIENCE WAA...WHICH OCCURRING OVER A SNOW FIELD SHOULD YIELD
EITHER SOME SCATTERED COVERAGE OF FOG AND/OR LOW STRATUS PROBABLY
NOT TODAY...BUT LATER TONIGHT INTO FRIDAY. UPDATES ARE OUT.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...THROUGH SATURDAY

SURFACE HIGH PRESSURE CENTERED OVERHEAD WITH STRATUS TRAPPED IN
THE LOW LEVELS...MAINLY ALONG THE MISSOURI VALLEY. AS THE HIGH
PRESSURE SYSTEM SHIFTS OFF TO THE SOUTHEAST...SOUTH/SOUTHWESTERLY
LOW LEVEL FLOW WILL ADVECT THE STRATUS NORTHEAST. WITH POOR MIXING
CONDITIONS...TEMPERATURES WILL STRUGGLE...PARTICULARLY IN THE
NORTHEAST DESPITE AMPLE SUNSHINE.

WHILE DAYTIME HEATING WILL BE LESS EFFICIENT THANKS TO THICK
MID/HIGH CLOUDS ASSOCIATED WITH AN UPPER TROF...WARM AIR ADVECTION
WILL BE IN FULL GEAR FOR FRIDAY...WITH H925 TEMPERATURES OF +1 TO
+3C. A SECOND SURFACE TROF DEVELOPS FOR SATURDAY...WITH H925
TEMPERATURES INCREASING TO +1 TO +5C.

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY

A FAIRLY ACTIVE LONG TERM IN THE OFFING. DURING THE PERIOD ENERGY
FROM THE SOUTH AND FROM THE WEST IS EXPECTED TO PHASE INTO A
PROGRESSIVE TROF OVER THE CENTRAL US. SOME LIGHT PCPN MAY OCCUR
OVER THE WEEKEND WITH NORTHERN STREAM ENERGY...BUT FOR NOW THE
MAIN PLAYER WILL BE THE SOUTHERN STREAM ENERGY HEADED TOWARD THE
GREAT LAKES. BEHIND THE DEVELOPING MID LEVEL TROF WILL BE THE
AREAS GREATEST CHANCE FOR MEASURABLE PCPN AND MAINLY SNOW AT THAT
TIME SINCE COLD AIR WILL BE DIVING IN BEHIND THE SYSTEM. ALTHOUGH
SNOW AMOUNTS ARE EXPECTED TO BE RATHER LIGHT...THE ADDITION OF
STRONG WINDS MAY PROVIDE FOR BLOWING/DRIFTING SNOW ON MONDAY.
TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL AT THE START OF THE
FORECAST...BUT THEN DROP BACK TO NORMAL OR EVEN BELOW FOR THE
LATTER PART OF THE LONG TERM.


&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

KMBG HAS BEEN IN BETWEEN VFR/MVFR CIGS THIS MORNING AND BASED OFF
SATELLITE DATA...WILL PROBABLY SLIDE OVER TO THE VFR SIDE OF THE
FENCE THROUGH LATE THIS AFTERNOON. HOWEVER...IFR FREEZING
FOG/STRATUS WAITS JUST OFF TO THE WEST AND SHOULD MOVE INTO THE
KMBG TERMINAL BY 00Z. THERE IS A RELATIVELY HIGH PROBABILITY OF
AIRPORT CLOSING IFR CONDITIONS SETTING UP OVERNIGHT TONIGHT AT
KMBG. BE ADVISED.

KPIR IS SITTING UNDER AN MVFR STRATUS DECK...WHICH MAY CLEAR OFF
BY 22Z/23Z THIS AFTERNOON...LEAVING KPIR VFR HEADING INTO THE
EVENING HOURS. HOWEVER...ALL THE AVAILABLE MODEL
GUIDANCE/SOUNDINGS SUGGESTS THAT KPIR WILL LIKELY FREEZING FOG-UP
OR DEVELOP A LOW STRATUS DECK BY 03Z TONIGHT. THERE IS A
RELATIVELY HIGH PROBABILITY OF IFR CONDITIONS DEVELOPING TONIGHT
AT KPIR.

THERE IS RELATIVELY HIGH CONFIDENCE THAT KABR/KATY TERMINALS WILL
REMAIN VFR THROUGH THE REST OF TODAY. AFTER 00Z THOUGH...THE
PROBABILITY OF IFR CONDITIONS AND FREEZING FOG/LOW STRATUS REALLY
STARTS TO INCREASE...ESPECIALLY AT/AFTER 06Z. GOOD LOW LEVEL WAA
SIGNAL OVER A SNOWFIELD UNDER PRESUMABLY A MOSTLY CLEAR SKY NIGHT
AND THE SYNOPTIC SCALE PATTERN OF LIGHT SOUTHERLY WINDS. ALL THE
EARMARKS OF AN IFR FOG/LOW STRATUS EVENT.




&&

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

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

WEATHER.GOV/ABERDEEN





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