000
FXUS63 KABR 011137
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
537 AM CST SUN DEC 1 2013

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

&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH MONDAY NIGHT
A RATHER CHALLENGING FORECAST WITH REGARDS TO PLACEMENT AND TIMING
OF PRECIPITATION CHANCES AND PRECIPITATION TYPE HAS LED TO A LOW
FORECASTER CONFIDENCE. THERE IS A FAIR AGREEMENT AMONG THE HIGH
RESOLUTION MODELS FOR THE PRECIPITATION EVENT FOR TODAY.

MODELS HAVE SIGNIFICANTLY WEAKENED THE MID LEVEL TROUGH AND SURFACE
BOUNDARY AFFECTING THE REGION TODAY. HI-RES VERSIONS OF THE
ARW/MNN AND THE NSSL WRF SHOW VERY LITTLE PCPN FOR THIS CWA AS THE
LOWER LEVELS ARE RATHER DRY. ALSO...MODELS BY AND LARGE LACK
SIGNIFICANT LIFT AS WELL. WILL MAINTAIN A SLIGHT CHANCE POP/LOW
END CHANCE POP FOR NOW HOWEVER. VIRTUALLY ALL HI-RES MODELS HAVE
PCPN EAST OF THE JAMES RIVER VALLEY BY 0Z MONDAY...AND EAST OF THE
CWA BY 3Z.

HOWEVER ANOTHER SHORT WAVE WILL QUICKLY PUSH INTO NORTHWESTERN
SOUTH DAKOTA BY 6Z...AND PERHAPS REACHING THIS CWA BY 9Z. THE NSSL
WRF IS A LITTLE FASTER AND FURTHER SOUTH WITH THIS SHORT
WAVE...THUS HAVE INCREASED POPS A BIT FURTHER SOUTH. THIS BAND OF
PCPN SHOULD TRACK NORTHEASTWARD AND INTO CENTRAL MINNESOTA BY 0Z
TUESDAY.

BY 6Z TUESDAY...A SURFACE LOW PRESSURE SYSTEM AND LARGE UPPER LEVEL
TROUGH OF LOW PRESSURE WILL BEGIN AFFECTING THE REGION. AS THE
INVERTED SURFACE LOW PRESSURE TRACKS ACROSS THE REGION IT WILL
DRAW COLDER AIR INTO THE CWA...WITH PERHAPS ACCUMULATING SNOWFALL
OVER THE NW PORTION OF THE CWA. TIMING AND PLACEMENT OF THE
ACCUMULATING SNOWFALL IS A LITTLE UNCLEAR AT THIS TIME HOWEVER.

AS FOR PRECIPITATION TYPE...SOME HI-RES MODELS SUGGEST RAIN AND
SNOW WILL BE POSSIBLE FOR ALL THREE PCPN TIME PERIODS. THEY ALSO
SHOW BRIEF PERIODS OF FREEZING RAIN AND SLEET AS WELL. WILL FORGO
ADDING ADDITIONAL MIXED P-TYPE FOR NOW AS THE PROBABILITY IS
RATHER LOW PER THE 3Z SREF.



.LONG TERM...TUESDAY THROUGH SATURDAY

THE LONG RANGE PERIODS FORECAST IS RIDDLED WITH CONCERNS AND LOW
FORECASTER CONFIDENCE. TO START...MODELS CONTINUE TO HAVE ISSUES
RESOLVING THE TRACK AND INTENSITY OF AN AREA OF LOW PRESSURE THAT
MOVES ACROSS THE REGION DURING THE START OF THE PERIOD. NO MODEL
HAS SHOWN CONSISTENCY OR SIGNIFICANT TRENDS OVER THE LAST SEVERAL
RUNS. THE BEST CHANCE FOR HEAVY SNOW REMAINS ACROSS NORTH
DAKOTA...AS HIGHLIGHTED BY THE SREF...THOUGH 1...4...AND EVEN 8
INCH PROBABILITIES COME DOWN TO/JUST OVER THE SOUTH DAKOTA STATE
LINE AT POINTS.

FRONTAL PASSAGE WILL ALSO RESULT IN WINDY CONDITIONS...THOUGH
ITS DIFFICULT TO NAIL DOWN HOW WINDY AND WHETHER WE WILL HAVE
SNOW TO BLOW. GUIDANCE HAS FLIPPED SEVERAL TIMES ON THE INTENSITY
OF THE LOW AND THUS WIND STRENGTH. MODELS RANGE BETWEEN A 16 TO
26MB PRESSURE GRADIENT ACROSS THE STATE AND A POTENTIAL PRESSURE
BUBBLE OF +8 TO +12MB/6 HOURS ON TOP OF THE STRONG COLD ADVECTION.

BOTH THE DETERMINISTIC ECMWF AND GFS/GFS ENSEMBLES ARE CONSISTENT
IN THE INTENSITY AND LONGEVITY OF THE ARCTIC AIRMASS THAT WILL
REMAIN OVER THE FORECAST AREA FROM MID WEEK ON. DURING THAT
TIME...H85 TEMPERATURES WILL RANGE BETWEEN -20 AND -25C TO
POSSIBLY AS LOW AS -28C. THE SURFACE HIGH WILL MOVE SLOWLY...SO
SOME MIXING THURSDAY AND POSSIBLY FRIDAY WILL HELP LIMIT
TEMPERATURE DROPS AT NIGHT. THE LINCHPIN WILL BE THE QUANTITY AND
QUALITY OF SNOW COVER AND ITS INFLUENCE ON TEMPERATURES.



&&

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

AN AREA OF IFR VISBY AND CIGS WILL EVENTUALLY MOVE INTO KABR/KATY
THIS MORNING WITH A NORTHEAST WIND. AS WINDS SHIFT TO SOUTH...THIS
AREA OF LOW CIGS/FOG WILL DISSIPATE AND SHIFT NORTH. A FEW SHOWERS
WILL PASS THROUGH THE KMBG/KABR TERMINALS LATER TODAY...THOUGH
CIGS AND VISBY ARE EXPECTED TO REMAIN VFR.



&&

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

$$
UPDATE...CONNELLY
SHORT TERM...SD
LONG TERM...CONNELLY
AVIATION...CONNELLY

WEATHER.GOV/ABERDEEN