FXUS63 KLBF 272054
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
254 PM CST FRI NOV 27 2009

.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT.
MOISTURE CHANNEL IMAGERY AT 18Z CONFIRMS THAT THE TROUGH ENTERING 
THE WEST COAST IS IN THE PROCESS OF SPLITTING...WHICH WILL SEND A 
MODEST FRONT OF PACIFIC ORIGINS ALL THE WAY ACROSS THE HIGH PLAINS 
BY THIS TIME SATURDAY. BASED ON THE 00Z GFS ENSEMBLE RMOP 500-HPA 
HEIGHT PROBABILITIES...THE MOST PREDICABLE PART OF THE SPLIT WILL BE 
THE SRN STREAM WAVE. HOWEVER...THERE/S BEEN LITTLE SPREAD BTWN NAM 
AND GFS DETERMINISTIC SOLUTIONS ACROSS NE SINCE AT LEAST 00Z LAST 
NIGHT...SO THE GOING FCST WAS NUDGED TWD A BLEND OF BOTH THRU 12Z 
MON. CONTINUITY ACTUALLY RULES MUCH OF THE SHORT TERM THOUGH.

HEIGHTS SLOWLY FALL THE NEXT 24 HRS...WHICH WILL TAKE 850-HPA TEMPS 
FROM THEIR 11-14 DEG C LVLS TODAY TO 3-7 DEG C SAT. EVEN SO...PROG 
SOUNDINGS VALID 17-22Z SAT STILL MIX TO NEAR THAT 850-HPA LEVEL. 
THAT IMPLIES MAX TEMPS IN THE MID 50S F...AND THE GUIDANCE THAT FITS 
THOSE NUMBERS BEST IS THE LAST FEW CYCLES OF THE MAV OUTPUT. RECENT 
VERIFICATION SUGGESTS THAT THE LACK OF SNOW COVER AND DRY BNDRY 
LAYER IS MAKING FOR WARMER-THAN-EXPECTED DAYS...SO WITH THAT IN MIND 
THE MAX TEMPS THRU THE WEEKEND WERE DEVELOPED USING A BLEND OF THE 
06Z AND 12Z MAV...BUT WEIGHTED 2/3RDS OF THE WAY TO THE LATTER. THIS 
MEANT INCREASING TEMPS JUST A BIT...EVEN AFT THE SLIGHTLY STRONGER 
CAA TAKES PLACE SAT NIGHT AND 850-HPA TEMPS GO BLO 0 C. RADIATIONAL 
COOLING WILL STILL BE POTENT AT TIMES...ESPECIALLY TONIGHT GIVEN 
LACK OF DENSE CIRRUS AND THE BNDRY LAYER MIXING THAT/S DROPPING SFC 
TD/S INTO THE 15-20 F RANGE THIS AFTN.

THE ENTRANCE REGION OF AN 85KT 250-HPA JET SEGMENT PASSES THRU THE 
AREA BTWN 00Z AND 12Z SUN. CONCEPTUAL MODELS SUGGEST MINOR IF ANY 
MOISTURE WILL FOLLOW THESE PACIFIC FRONTS...AND Q-VECTORS IMPLY ONLY 
A BRIEF WINDOW OF OMEGA. HOWEVER...BASED ON THE MODEST JET-INDUCED 
VERTICAL MOTION...PWATS OF 0.40+ INCHES...AND LACK OF A DISTINCT DRY 
LAYER ON PROG SOUNDINGS...WE WILL CONTINUE WITH SLGT CHANCE POPS IN 
THAT PERIOD. BTWN 00Z AND 06Z SUN...THE LOW-LVLS REMAIN AOA 3 C...SO 
WE ALSO INTRODUCED SOME -RA INTO THE MIX...WHICH IS EXACTLY WHAT 
HAPPENED WITH THE NOCTURNAL EVENT THIS PAST WEEK. 

.LONG RANGE...MONDAY THROUGH FRIDAY.
EARLY IN THE WEEK /MONDAY AND TUESDAY/ CONDITIONS LOOK QUITE 
PLEASANT...WITH WESTERLY DOWNSLOPE WINDS EXPECTED AHEAD OF 
APPROACHING SHORTWAVE DIVING SOUTHEAST INTO THE NORTHERN ROCKIES. 
SKIES SHOULD BE CLEAR...AS VERY LOW RH VALUES NOTED IN THE MID AND 
UPPER LEVELS. FOLLOWED THE ECMWF ON TEMPS...AS GFS SEEMS TO BE 
PLAYING CATCH UP TO THE EC/S WESTERLY DOWNSLOPE SCENARIO. EC HAS 
H925 TEMPS WARMING TO AROUND 12C MONDAY ACROSS WESTERN NEB...AND 
AROUND 8C FURTHER EAST. SHOULD SEE HIGHS NEAR 50 NORTHEAST...AND MID 
50S WEST. TUESDAY IS RATHER TRICKY...WITH COLD FRONT EXPECTED TO 
ARRIVE BY TUESDAY AFTERNOON. HIGHS SHOULD BE REACHED AROUND 
NOON...WITH STEADY OR SLOWLY FALLING TEMPS THEREAFTER.    

COLD ARCTIC AIR STILL ARREARS IT WILL FILTER INTO THE CENTRAL PLAINS 
BY WEDNESDAY BEHIND COLD FRONT...AND THEN LINGER INTO NEXT 
WEEKEND. CONFIDENCE IS LOWER TODAY HOWEVER...AS THE GFS AND IT/S 
ENSEMBLES KEEP MUCH OF THE COLD AIR NORTHEAST OF THE AREA. THE NEW 
12Z ECMWF CONTINUES GOOD RUN TO RUN CONTINUITY...AND BRINGS MORE OF 
THE ARCTIC AIR INTO CENTRAL AND WESTERN NEB. WITH THE DIFFERENCES IN 
THE MODELS...WILL NOT GO TO LOW WITH TEMPS...AND KEEP THEM ABOUT 
THE SAME OR JUST SLIGHTLY WARMER FROM THE PREVIOUS FORECAST. WILL 
ALSO MAINTAIN THE SLGT CHANCE POPS FOR WED AND THURS...AS AREA IN 
COLD UNSTABLE CYCLONIC FLOW AROUND GREAT LAKES UPPER LEVEL LOW.   
&&

.AVIATION...
FLIGHT CONDITIONS LOOK TO REMAIN AT VFR THROUGH THE NEXT 24 HOURS 
WITH CIGS EXPECTED TO BE AOA 120KT AGL AND LOWER CLOUDS IN THE SCT 
CATEGORY. WINDS WILL MOST LIKELY DECOUPLE TO LIGHT AND VARIABLE IN 
THE PLATTE RIVER VALLEY...BUT FRONT PUSHING THOUGH THE SANDHILLS 
OVERNIGHT SHOULD KEEP LIGHT NORTHWEST WIND IN PLACE AT KVTN. FAIRLY 
LIGHT WINDS ALOFT WILL PREVENT LLWS AS WELL.  
&&

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

$$
SHORT RANGE...SCHULTZ
LONG RANGE...TAYLOR
AVIATION...PHILLIPS