FXUS63 KLBF 280847
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
245 AM CST SAT NOV 28 2009

.SYNOPSIS...
    AT 08Z...SURFACE ANALYSIS SHOWED A FRONT DRAPED FROM A LOW IN 
NORTHEAST NEBRASKA THROUGH NORTHWEST KANSAS TO ANOTHER LOW IN 
SOUTHEAST COLORADO. IN THE UPPER LEVELS...A DEVELOPING WAVE WAS 
APPARENT IN THE 6.7 MICRON IMAGERY OVER SOUTHEAST NEVADA. MID TO 
UPPER LEVEL MOISTURE CONTINUED STREAMING ACROSS THE ROCKIES AND OVER 
THE NORTHERN PLAINS. 
&&

.SHORT...TODAY THROUGH SUNDAY NIGHT.
    AS THE FRONT CONTINUES THROUGH NEBRASKA TODAY...COLD ADVECTION 
WITH IT WILL BRING SOME BREEZY CONDITIONS. BY ABOUT MIDDAY...WIND 
WILL INCREASE TO 15 TO 20 MPH WITH GUSTS OVER 25 MPH.
    BEHIND THE FRONT...THE ADVANCE OF THE COLDER AIR TONIGHT WILL 
GENERATE SOME PRETTY DECENT SYSTEM RELATIVE ISENTROPIC LIFT IN THE 
290-300K LAYER...BUT THE LOWEST CONDENSATION DEFICITS OF 10-20MB ARE 
EXPECTED TO BE AT OR ABOVE THE 600MB PRESSURE LEVEL. THEREFORE...THE 
PROBABILITY OF MEASURABLE PRECIPITATION IS VERY LOW AND WE WILL KEEP 
IT BELOW 20 PERCENT. THE PRIMARY EFFECT WILL BE TEMPERATURES BY 
SUNDAY MUCH COLDER THAN THEY WERE YESTERDAY. TEMPERATURE DIFFERENCES 
BETWEEN YESTERDAY AND TODAY WILL BE ON THE ORDER OF 10-15F...AND ON 
SUNDAY THEY WILL BE ANOTHER 10F COLDER.            

.MEDIUM RANGE...MONDAY THROUGH WEDNESDAY.
    SLIGHTLY WARMER TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY AS 
AN UPPER RIDGE BUILDS BACK OVER THE CENTRAL ROCKIES. 
    THE POSSIBILITY OF AN ARCTIC OUTBREAK WEDNESDAY IS STILL THE 
BIGGEST CHALLENGE WITH THE MEDIUM RANGE FORECAST. THERE IS GENERAL 
AGREEMENT AMONG THE 28/00Z CANADIAN GLOBAL...THE 28/00Z EUROPEAN AND 
THE 28/00Z NCEP GLOBAL MODELS THAT A TRAJECTORY FROM THE FAR 
NORTHERN REACHES OF NORTH AMERICA IS LIKELY WEDNESDAY AND BEYOND. 
THAT SAID...THE SNOW FIELD IN THE PRAIRIE REGIONS OF ALBERTA AND 
SASKATCHEWAN IS NORTH OF LAT-55N...SO THERE IS STRONG POTENTIAL FOR 
SIGNIFICANT MODIFICATION OF THE ARCTIC AIRMASS AS IT COMES ACROSS 
THE PRAIRIE PROVINCES AND INTO THE NORTHERN HIGH PLAINS OF THE U.S. 
THIS WOULD INDICATE THAT IT WILL NOT BE QUITE AS COLD AS ONE WOULD 
EXPECT. STILL...THE MEDIUM RANGE MODELS ARE SHOWING A SLIGHT CHANCE 
OF SIGNIFICANT SNOWFALL IN THOSE AREAS TUESDAY NIGHT AND WEDNESDAY 
BUT...BY THEN...THE COLDEST OF THE AIR MASS IS LIKELY TO BE IN THE 
CENTRAL U.S. ALREADY. HOWEVER...THAT MAY BECOME A FACTOR TOWARD THE 
END OF THE WEEK IF THE TRAJECTORY FROM THE FAR NORTH CONTINUES OR 
DEVELOPS AGAIN. 
    ANOTHER PLAYER IN THIS FORECAST PERIOD IS A FAIRLY STRONG 
CYCLONE DEVELOPING OVER SOUTHERN CALIFORNIA AND THE NORTHERN BAJA 
PENINSULA TRACKING ACROSS THE SOUTHWEST U.S. AND THROUGH SOUTH 
TEXAS. THAT FEATURE WILL PULL GULF MOISTURE WESTWARD TO THE SOUTHERN 
HIGH PLAINS...THUS KEEPING IT OUT OF THE CENTRAL AND NORTHERN HIGH 
PLAINS. THE RESULT WILL BE THAT THERE IS LITTLE TO NO CHANCE OF 
MEASURABLE PRECIPITATION WITH THE ARCTIC FRONT TUESDAY NIGHT AND 
WEDNESDAY.     
&&

.AVIATION...
    FOR MOST OF THE DAY...UNRESTRICTED CEILING AND VISIBILITY IS 
LIKELY IN CENTRAL AND WESTERN NEBRASKA. IN THE WAKE OF THE FRONT... 
TIGHTENING PRESSURE GRADIENT AND COLD ADVECTION MIXING OF THE 
BOUNDARY LAYER WILL ALLOW WIND TO INCREASE TO MORE THAN 12KT 
SUSTAINED WITH GUSTS IN THE 20-24KT RANGE. DIRECTION WILL BE 
340-360. LATE THIS EVENING...SOME VFR CEILINGS ARE LIKELY AS AIR 
LIFTS UP OVER THE SHALLOW ARCTIC AIR MASS MOVING IN FROM THE 
NORTHERN HIGH PLAINS. 
&&

.LBF 
WATCHES/WARNINGS/ADVISORIES...NONE. 
&&

$$
SPRINGER