FXUS63 KLBF 262045
AFDLBF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
245 PM CST THU NOV 26 2009
.SYNOPSIS...
THE 20Z SURFACE ANALYSIS SHOWED A WARM FRONT DRAPED FROM A LOW
CENTERED JUST NORTH OF THE ALBERTA-NORTHWEST TERRITORY BORDER
THROUGH SASKATCHEWAN...THE DAKOTAS AND WESTERN NEBRASKA...TO WESTERN
KANSAS AND THE TEXAS/OKLAHOMA PANHANDLE. IN THE UPPER LEVELS...THE
6.7 MICRON IMAGERY SHOWED HIGH LEVEL MOISTURE STREAMING AROUND THE
CREST OF THE UPPER RIDGE ACROSS THE ROCKIES AND OVER THE DAKOTAS AND
NEBRASKA.
&&
.SHORT/MEDIUM RANGE...TONIGHT THROUGH SUNDAY NIGHT.
WITH 850MB TEMPERATURES 12-16C SOUTHWEST TO 9-14C IN NORTH
CENTRAL NEBRASKA...HIGHS FRIDAY SHOULD HAVE NO TROUBLE GETTING INTO
AT LEAST THE LOWER 60S. ALTHOUGH THERE IS SOME ISENTROPIC LIFT
TONIGHT WITH THE WARM FRONT...THE AIR IS VERY DRY AND UNLIKELY TO
PRODUCE MUCH IN THE WAY OF LOW AND MIDDLE CLOUDS...MUCH LESS
PRECIPITATION. SOME HIGH CLOUDS ARE LIKELY WITH THE HIGH LEVEL
MOISTURE STREAMING ACROSS THE MOUNTAINS THIS AFTERNOON.
AFTER FRIDAY...THERE ARE SOME SIGNIFICANT DIFFERENCES AMONG THE
FORECASTS WITH THE TIMING OF THE COLD AIR. OF THE GFS...NAM AND
EURO...THE GFS AND THE EURO INDICATE STEADY OR FALLING TEMPERATURES
SATURDAY AFTERNOON. THE NAEFS APPEARS TO SUPPORT THE NAM SOLUTION.
LEANING TOWARD THE GFS/EURO...WE HAVE PUT THE HIGH SATURDAY NEAR
MIDDAY INSTEAD OF MID-AFTERNOON. THE COLD AIR THEN PERSISTS THROUGH
AT LEAST SUNDAY NIGHT. AS THE COLD FRONT PUSHES THROUGH...ITS
STRENGTH AND SPEED WILL GENERATE PLENTY OF SYSTEM-RELATIVE
ISENTROPIC LIFT. THE AIR IN THE 290-300K LAYER IS NEARLY SATURATED
WITH CONDENSATION DEFICITS AT OR BELOW 50MB BEHIND THE FRONT...SO WE
HAVE INCLUDED SOME MENTION OF SNOW SHOWERS IN WESTERN NEBRASKA BUT
WITH PROBABILITY 35 PERCENT OR LOWER.
.LONG RANGE...MONDAY THROUGH WEDNESDAY.
MODELS STILL ADVERTISING AN ARCTIC PLUNGE OF COLD AIR INTO THE
CENTRAL AND NORTHERN PLAINS WEDNESDAY OF NEXT WEEK AND BEYOND.
BEFORE THE COLD AIR INTRUSION...MONDAY AND TUESDAY SHOULD BE QUITE
MILD...WITH WESTERLY DOWNSLOPE WINDS AND CLEAR SKIES ALLOWING
TEMPERATURES TO REACH THE UPPER 40S TO MID 50S. BOTH THE ECMWF AND
GFS HAVE BACKED OFF ON THE COLD AIR WEDNESDAY AND THURSDAY JUST A
TOUCH...BUT H925 TEMPS STILL SUPPORT HIGHS OF ONLY LOWER TO MID 30S
WEDNESDAY AND AROUND 30 ON THURSDAY. LOWS WILL BE 10 TO 15 DEGREES.
NORTH WINDS WILL BE RATHER STRONG...AND WIND CHILLS NEAR ZERO APPEAR
LIKELY...ESPECIALLY AT NIGHT.
PRECIP CHANCES LOOK MINIMAL AT THIS POINT...BUT SHOULD BE ABLE
TO SQUEEZE OUT SOME LIGHT SNOW SHOWERS AND FLURRIES. WILL MAINTAIN
THE CURRENT 20 POP ON WEDNESDAY...AND EXTEND INTO THURSDAY.
&&
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR THE NEXT 24 HRS
ACROSS WESTERN AND CENTRAL NEB. SCT CIRRUS IS THE ONLY EXPECTED
CLOUD COVER...AND WINDS WILL BE FROM THE WEST TO 10 KTS.
&&
.LBF
WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT/MEDIUM RANGE...SPRINGER
AVIATION/LONG RANGE...TAYLOR