FXUS63 KBIS 272138
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
338 PM CST FRI NOV 27 2009

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...

THE MAIN FORECAST PROBLEM IN THE SHORT TERM FORECAST DEALS WITH 
PRECIPITATION CHANCES WITH AN UPPER LEVEL SHORTWAVE TROUGH MOVING 
ACROSS THE NORTHERN PLAINS TONIGHT AND SATURDAY.

ECMWF AND GFS DEPICT A GENERALLY PROGRESSIVE PATTERN FOR THE 
NORTHERN PLAINS...BRINGING A SHORTWAVE TROUGH AND COLD FRONT THROUGH 
THE REGION TONIGHT. I DONT SEE MUCH IN THE WAY OF PRECIPITATION AS 
THE SURFACE FEATURES TOO FAR AHEAD OF UPPER SHORTWAVE. THIS IS 
FOLLOWED BY A BROAD RIDGE SUNDAY THROUGH MONDAY. I WILL KEEP A 20 TO 
30 PERCENT CHANCE OF RAIN AND SNOW SHOWERS BEGINNING LATER TONIGHT 
NORTHWEST AND TRACKING EAST ACROSS THE REGION SATURDAY. SURFACE HIGH 
PRESSURE BUILDS INTO THE REGION SUNDAY AND EXPECT A FEW DEGREES 
COOLER THAN SATURDAY...OR NEAR NORMAL. A LITTLE WARMER AND DRY 
MONDAY. THIS SHOULD KEEP NOVEMBER IN THE TOP 5 TO 10 WARMEST 
MONTHS.  

.LONG TERM...TUESDAY THROUGH FRIDAY...
A MAJOR WEATHER CHANGE IS DEPICTED BY BOTH THE EC AND GFS MID-WEEK 
AS COLD NORTHERN CANADIAN AIR SURGES SOUTH INTO THE NORTHERN PLAINS. 
DAYTIME AND NIGHTTIME TEMPERATURES WILL TREND NORMAL TO SLIGHTLY 
BELOW SEASONAL AVERAGES MID TO LATE WEEK. 

A 500 HPA RIDGE PUSHES EAST DURING THE DAY ON MONDAY WITH SEVERAL 
DISTURBANCES TOPPING THE WESTERN RIDGE OUT OF A GULF OF ALASKA 
TROUGH. A STRONG DISTURBANCE EJECTING OUT OF THE TROUGH BEGINS TO 
PUSH DOWN THE RIDGE LATE MONDAY INTO TUESDAY AS A STRONG COLD FRONT 
DIVES SOUTHWARD OUT OF CANADA. THE COLD FRONT MOVES THROUGH NORTH 
DAKOTA LATE TUESDAY WITH GUSTY WINDS. THE DISTURBANCE CONTINUES TO 
DROP SOUTHWARD DURING THE DAY WED CARVING OUT A TROUGH OVER THE 
CENTRAL UNITED STATES WHICH LOOKS TO PERSIST THROUGH FRIDAY.

TIMING DIFFERENCES CONTINUE HOWEVER BETWEEN THE GFS AND EC...WITH 
THE LATER MODEL STILL SLOWER. ALONG WITH THIS TEMPERATURE CHANGE 
COMES PRECIPITATION CHANCES...WITH A RAIN/SNOW MIX EARLY ON WITH THE 
INITIAL COLD FROPA TUESDAY...QUICKLY CHANGING TO ALL SNOW TUES NIGHT 
AND ONWARD. WILL KEEP CHANCES MINIMAL FOR NOW UNTIL DETAILS BECOME 
MORE CLEAR.  

&&

.AVIATION...
SURFACE TROUGH EXITING TO THE WEST TODAY HAS LEFT MID/HIGH BKN 
CLOUDS AND 5 TO 10 KT NORTHWEST WINDS ACROSS THE FORECAST AREA. AS 
UPPER LEVEL TROUGH APPROACHES FROM THE WEST THIS AFTERNOON AND 
EVENING...EXPECT LOW CLOUDS TO DEVELOP AND BRING MVFR CONDITIONS TO 
MOST OF THE STATE BY SATURDAY MORNING. RAIN/SNOW SHOWERS AND LOW OVC 
SKIES ARE POSSIBLE THIS EVENING AND TOMORROW...SO WILL NOT RULE OUT 
PERIODS OF IFR WHERE THESE SHOWERS RESIDE. WINDS SHOULD GENERALLY 
INCREASE SATURDAY MORNING TO 10 TO 20 KTS.

&&

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

&&

$$

SHORT TERM...WAA
LONG TERM...NH
AVIATION...BN/NH