FXUS63 KBIS 262147
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
347 PM CST THU NOV 26 2009

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...

THE MAIN FORECAST PROBLEM TODAY DEALS WITH PRECIPITATION CHANCES
WITH A LOW PRESSURE SYSTEM PUSHING THROUGH THE NORTHERN PLAINS
THIS WEEKEND. 

CURRENTLY...NORTH DAKOTA LIES UNDER NORTHWESTERLY FLOW ALOFT
THANKS TO THE INFLUENCE OF UPPER LEVEL RIDGING CENTERED OVER THE
SOUTHWESTERN CONUS. SOUTHERLY SURFACE FLOW HAS RESULTED IN WARM
ADVECTION...WHICH WHEN COUPLED WITH PLENTY OF INSOLATION THROUGH
MOSTLY THIN CIRRUS...HAS BROUGHT WARMER TEMPERATURES TO THE STATE
THIS AFTERNOON. IN FACT...DICKINSON AND WILLISTON LOOK TO COME
CLOSE TO THEIR RECORD HIGH TEMPERATURES FOR TODAY. 

MODEL GUIDANCE IS IN GOOD AGREEMENT WITH THE OVERALL TREND FROM
THIS POINT...THUS GRIDDED FORECAST IS A GENERAL BLEND OF 12 UTC
NAM/GFS/ECMWF AND 09 UTC SREF MEAN GUIDANCE FOR THE SHORT TERM.

THIN HIGH CLOUDS AND WARMER TEMPS SHOULD CONTINUE THROUGH TONIGHT 
AND FRIDAY. BY FRIDAY EVENING...A FAMILIAR PATTERN EMERGES IN THE 
MODELS AS A PERSISTENT VORTEX SETS UP OVER THE HUDSON BAY AREA. THIS 
SHOULD RESULT IN A MORE ACTIVE PATTERN OVER THE HIGH
PLAINS...WHICH WILL BE CHARACTERIZED BY MORE SOUTHWARD TRANSPORT
OF ARCTIC AIR THAN HAS BEEN SEEN FOR A MONTH. NORTH DAKOTA LOOKS
TO REMAIN UNDER THE SOUTHWEST PERIPHERY OF THE HUDSON VORTEX
INFLUENCE...BUT STRENGTH OF THE VORTEX IS A BIT
QUESTIONABLE...LEADING TO UNCERTAINTY OF DURATION FOR THE ACTIVE
PATTERN. 

AFTER WHAT LOOKS TO BE A DRY COLD FRONTAL PASSAGE LATE FRIDAY...AN
UPPER LEVEL TROUGH...THE RESULT OF A LARGER SCALE SYSTEM THAT
SPLIT AS IT CAME ASHORE EARLY FRIDAY...SHOULD SWEEP ACROSS THE
STATE SATURDAY NIGHT. EXPECT SOME PRECIPITATION AND GUSTY WINDS
FOR THE REGION ON SATURDAY AS THE UPPER LEVEL SYSTEM CAUSES ENOUGH
LIFT TO PRODUCE SOME RAIN AND SNOW BEFORE DISSIPATING
SUNDAY...WITH ONLY LIGHT AMOUNTS EXPECTED.

SUNDAY LOOKS TO BE MUCH COOLER WITH STRONG NORTHERLY FLOW ALOFT AND 
SURFACE HIGH PRESSURE TO THE SOUTHWEST BRINGING A GOOD AMOUNT OF 
COLD AIR FROM CANADA SOUTH INTO THE DAKOTAS.

.LONG TERM...MONDAY THROUGH THURSDAY...
MILD WEATHER ON MONDAY (MAYBE TUESDAY AS WELL) SHOULD NOT BE TAKEN 
FOR GRANTED...AS A MAJOR WEATHER CHANGE IS DEPICTED BY BOTH THE EC 
AND GFS MID-WEEK AS COLD ARCTIC AIR SURGES SOUTH INTO THE NORTHERN 
PLAINS. TIMING DIFFERENCES CONTINUE BETWEEN THE GFS AND EC...WITH 
THE LATER MODEL SLOWER BUT MORE CONSISTENT WITH ITS EARLIER 
VERSIONS. THE GFS ENSEMBLE MEAN ALSO FAVORS MORE OF THE EC THAN THE 
12Z GFS. WITH THIS TEMPERATURE CHANGE COMES PRECIPITATION 
CHANCES...WITH A RAIN/SNOW MIX EARLY ON...QUICKLY CHANGING TO ALL 
SNOW TUES NIGHT AND ONWARD. WILL KEEP CHANCES MINIMAL FOR NOW UNTIL 
DETAILS BECOME MORE CLEAR.  

&&

.AVIATION...
LIGHT SOUTHERLY WINDS EXPECTED TO TURN MORE WEST TO SOUTHWESTERLY AS 
A SURFACE TROUGH WORKS ACROSS THE STATE TONIGHT. SKIES SHOULD REMAIN 
PRETTY CLEAR AT LOWER LEVELS...WITH SCT-BKN HIGH CIRRUS AND SOME 
AREAS OF SCT MID-LEVEL CLOUDS PERSISTING OVER THE AREA THROUGH THE 
NIGHT AND INTO TOMORROW.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...BPN/SCHECK
LONG TERM...NH
AVIATION...BPN/NH