000
FXUS63 KABR 060951
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
351 AM CST TUE JAN 6 2009
.SHORT TERM...TODAY THROUGH THURSDAY
FORECAST CHALLENGES INCLUDE SHORTWAVES IN NW FLOW AND TEMPERATURES
THURSDAY.
CURRENTLY...A WEAK CLIPPER LOW IS MOVING ALONG THE BORDER OF
MANITOBA AND NORTH DAKOTA...WITH THE SURFACE LOW REFLECTION
WORKING THROUGH THE EASTERN FORECAST ZONES OF THIS CWA. STILL JUST
DEALING WITH MAINLY SOME MID AND HIGH CLOUDS STREAMING OVER THE
REGION. IN FACT...A SEARCH FOR ANY CLOUDS WITH A CEILING BELOW
5000 FT AGL FINDS THEM ALL BOTTLED UP ACROSS CENTRAL AND SOUTHERN
CANADA.
AS THE DAY PROGRESSES...SHOULD SEE THIS CURRENT CLIPPER LOW WORK
EAST INTO MINNESOTA WITH LITTLE FAN-FARE FROM IT FOR THIS AREA
TODAY. WILL LIKELY SEE SOME MVFR TO VFR STRATUS CLOUDS FORM
BEHIND THE SLOW-TO-WORK-SOUTH POLAR COLD FRONT THAT STRETCHES
NORTHWEST INTO SASKATCHEWAN AT THIS TIME. PULLED ANY MENTION OF
MEASURABLE SNOW /EVEN FLURRIES/ FROM THE TODAY PERIOD...BUT
DECIDED TO LEAVE A MENTION OF SCATTERED FLURRIES ACROSS THE
FORECAST AREA FOR TONIGHT WHEN THE BETTER LOW LEVEL CAA AND
STRATUS CLOUDS ARE EXPECTED TO PUSH THROUGH.
THE NEXT IN A SERIES OF NW FLOW UPPER WAVES LOOKS TO PRODUCE SOME
LIGHT SNOWFALL ACROSS WESTERN SOUTH DAKOTA /PERHAPS INTO PORTIONS
OF THE MISSOURI RIVER VALLEY/ WEDNESDAY AFTERNOON AND EVENING. DID
NUDGE POPS UP MAINLY ACROSS PORTIONS OF THE WEST RIVER COUNTIES
WHERE THE STRONGEST LOW LEVEL SPEED CONVERGENCE /AND LOW LEVEL
FRONTOGENESIS/ COMBINED WITH THE BEST 850-500HPA SYNOPTIC SCALE
LIFT. THE END RESULT CAME OUT TO BE A 6 TO 12 HOUR BANDED LIGHT
SNOW EVENT ACROSS THE FAR WESTERN/SOUTHWESTERN FORECAST
ZONES...WITH AROUND 0.5 TO 1.5 INCHES OF SNOWFALL FORECAST ACROSS
THAT AREA BY LATE WEDNESDAY NIGHT.
WAS NOT SURE WHAT TO DO WITH THE THURSDAY DAY PERIOD...WHEN THE
ONSET OF LOW LEVEL WAA AND LOW TO MID LEVEL THETA-E ADVECTION IS
PROGGED TO BEGIN. SURFACE WINDS ARE EXPECTED TO TAKE ON MORE OF A
SOUTHEASTERLY DIRECTION...WHICH IS NOT THE BEST WIND FOR WARMING
THE BOUNDARY LAYER. ALSO...DESPITE THE EXPANSIVE
SNOWFIELD...THERE IS A SMALL PORTION OF THE FAR SOUTHWESTERN CWA
WHERE ALOT OF SNOW HAS MELTED. IF ANY NEW SNOW FALLS THERE
WEDNESDAY AFTERNOON AND EVENING...THE THURSDAY MAX T FORECAST
ACROSS THE SWRN FORECAST ZONES MAY BE A LITTLE OVERLY OPTIMISTIC.
IN FACT...SNOW OR NO SNOW...THE ENTIRE THURSDAY MAX T FORECAST MAY
BE A LITTLE OVERLY OPTIMISTIC WITH THAT SOUTHEASTERLY SURFACE
WIND. THE ECMWF...GFS AND NAM ALL WOULD SUGGEST THAT ANY
WAA/OVER-RUNNING TYPE PRECIPITATION THAT CAN GET GOING ON
THURSDAY IS WELL NORTH OF THIS CWA...FOUND MAINLY ACROSS THE
BISMARK FORECAST AREA. HAD A NOTION TO ELIMINATE THE SLIGHT CHANCE
POPS FOR THURSDAY...BUT DECIDED TO WAIT ONE OR TWO MORE MODEL RUNS
TO SEE IF THE TREND CONTINUES TO BE TOWARD DRY WEATHER FOR
THURSDAY.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MODELS AND GFS ENSEMBLES CONTINUE TO BE CONSISTENT AND AGREE THAT
A SHORT WAVE TROUGH WILL SLIDE ACROSS THE REGION THURSDAY NIGHT
AND FRIDAY WITH COLD HIGH PRESSURE BUILDING IN BEHIND THROUGH
SATURDAY. WITH WAA IN ADVANCE OF THE INCOMING UPPER
TROUGH...COULD SEE SOME FZRA ACROSS MAINLY THE NORTHERN CWA
THURSDAY NIGHT AS THE SURFACE AIR REMAINS BELOW FREEZING WITH MUCH
WARMER AIR MOVING IN ALOFT. THUS...HAVE IN CHANCES OF FZRA/SN FOR
MUCH OF THE CWA INTO FRIDAY MORNING. FOR FRIDAY AS THE UPPER LEVEL
TROUGH AXIS PASSES...SUBISDENCE...CAA...A TIGHTENING SURFACE
PRESSURE GRADIENT AND INCREASING LOW LEVEL WINDS...SHOULD RESULT
IN WINDY CONDITIONS ACROSS THE CWA FRIDAY. DEPENDING ON HOW MUCH
SNOW OR FREEZING RAIN FALLS...THESE STRONG WINDS COULD RESULT IN
WIDESPREAD BLOWING SNOW OF THE EXISTING SNOW COVER ON FRIDAY.
INCREASED CHANCES OF PRECIPITATION FOR BOTH THURSDAY NIGHT AND
FRIDAY MAINLY NORTH AND EAST IN THE CWA. THE MODELS AND GFS
ENSEMBLES CONTINUE WITH THE UPPER RIDGE/WESTERN US/UPPER
TROUGH/EASTERN US THROUGH THE REST OF THE FORECAST PERIOD WITH
SOUTHEAST MOVING SHORT WAVES DROPPING ACROSS THE REGION. LEFT IT
DRY AT THIS POINT. ONLY MADE SMALL ADJUSTMENTS TO THE
TEMPERATURES.
&&
.AVIATION...
MAINLY VFR SKIES AND VISIBILITIES ARE EXPECTED THROUGH TODAY AND
TONIGHT AT ALL TAF SITES. MAINLY MID AND HIGH LEVEL CLOUDS WILL
MOVE OVER THE TAF SITES. THERE MAY BE SOME MVFR CEILINGS AFFECT
SOME OF THE TAF SITES TONIGHT. OTHERWISE...NO SIGNIFICANT WEATHER
IS EXPECTED THROUGH TONIGHT.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...DORN
LONG TERM...MOHR
AVIATION...MOHR
WEATHER.GOV/ABERDEEN
