FXUS63 KLBF 260806
AFDLBF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
206 AM CST THU NOV 26 2009
.DISCUSSION...
DURING THE NEXT 7 DAYS BOTH THE GFS AND ECMWF INDICATE THE
VERY DEEP ALEUTIAN LOW WILL RETROGRADE WEST TOWARD SIBERIA.
THIS REPRESENTS A MAJOR PATTERN SHIFT OVER THE PAST FEW WEEKS.
HEIGHTS ACROSS ALASKA WILL BEGIN TO RISE AND INCREASINGLY COLD HIGH
PRESSURE SYSTEMS FROM CANADA AND THE NORTH BEYOND WILL BEGIN TO DROP
SOUTHWARD TOWARD THE LOWER 48. NO MAJOR COLD FRONTS ARE EXPECTED
ACROSS NEBRASKA UNTIL NEXT WEDNESDAY. TIMING UNCERTAINTIES WITH THIS
FRONTAL PASSAGE MAKE HIGH TEMPERATURES LATE NEXT WEEK UNCERTAIN.
OTHERWISE THE FCST IS VERY STRAIGHT FORWARD. A WARM FRONT MOVES EAST
TODAY FOLLOWED BY A PACIFIC COLD FRONT SATURDAY WITH A WARM FRONT
FOLLOWING ON ITS HEELS MONDAY OR TUESDAY.
VERY SHALLOW COLD AIR IS IN PLACE THIS MORNING. AT 11 PM THE
TEMPERATURE AT KLBF ROSE FROM 21F TO 30F IN ABOUT 1/2 HOUR ATTESTING
TO THE SHALLOWNESS OF THE COLD DOME. THE SFC WARM FRONT IS NEAR KSNY
AND KIML AT 07Z. THE SHALLOW COLD DOME SHOULD ERODE QUICKLY LATER
THIS MORNING WITH TEMPERATURES RISING INTO THE MID AND UPPER 50S
DURING THE AFTERNOON. FRIDAY SHOULD BE WARMER STILL AS HEIGHTS
CONTINUE TO RISE AND A DRY WEST WIND TAKES HOLD OF THE FCST AREA.
HIGHS SHOULD REACH WELL INTO THE 60S. A HYBRID PACIFIC CANADIAN COLD
FRONT IS FCST TO MOVE THROUGH SATURDAY THROUGH EARLY SUNDAY MORNING.
COLD AIR ALOFT AND SUFFICIENT MOISTURE SHOULD BE CAPABLE OF AT LEAST
SOME SNOW SHOWER ACTIVITY. THE ECMWF AND UKMET APPEAR TO BE ABOUT 6
HOURS FASTER THAN THE NAM AND GFS SO LATER FORECASTS MAY REQUIRE A
TIMING ADJUSTMENT. THE COLD FRONT SHOULD LOP OFF ABOUT 20 DEGREES
FROM HIGHS SUNDAY VERSUS HIGHS FRIDAY.
THE HIGH PRESSURE SYSTEM WILL QUICKLY MOVE SOUTH WITH A WARMING
TREND SETTING UP MONDAY AND TUESDAY. HIGH TEMPERATURES BOTH DAYS ARE
FORECAST IN THE 40S BUT COULD BE WARMER DEPENDING ON THE STRENGTH
OF WEST WINDS DEVELOPING IN CONJUNCTION WITH DEEPENING LOW PRESSURE
OVER CANADA. THE POTENTIAL FOR A MAJOR ARCTIC FRONTAL PASSAGE
WEDNESDAY APPEARS TO BE INCREASING. LITTLE OR NO SNOW COVER IS
PRESENT ACROSS THE NRN U.S. WHICH MIGHT SLOW THE SOUTHWARD MOTION OF
THE FRONT OR MODIFY THE AIR MASS BEHIND THE FRONT BUT BOTH THE GFS
AND ECMWF INDICATE A PROTRACTED COLD SPELL DEVELOPING WEDNESDAY AND
BEYOND. LIGHT SNOW OR FLURRIES COULD DEVELOP LATE NEXT WEEK. BOTH
THE GFS AND ECMWF INDICATE 516DM H10-5 THICKNESS AT KLBF AND
514DM THICKNESS AT KVTN NEXT THURSDAY MORNING.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH NEXT 24 HRS WITH WEST WINDS AT
5 TO 15 MPH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
CDC/MP
