FXUS63 KGID 060450 AAB
AFDGID

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HASTINGS NE
1050 PM CST SAT DEC 5 2009

.AVIATION....FOR THE 06Z KGRI TAF. COMPLEX WEATHER SCENARIO
PLAYING OUT FOR LATE SUNDAY MORNING INTO SUNDAY EVENING AS A
SMALL BUT POTENT UPPER DISTURBANCE SLIPS THROUGH THE REGION.
HOWEVER...THE WEATHER PATTERN WILL STAY QUIET TO START OFF THE
FIRST HALF OF THE PERIOD AS A BROKEN MID TO HIGH CEILING GRADUALLY
LOWERS THROUGH THE NIGHT BUT REMAINS IN A VFR RANGE. ATTENTION
THEN SHIFTS TOWARD EARLY SUNDAY AFTERNOON AS CONDITIONS BEGIN TO
DETERIORATE WITH CEILINGS LOWERING QUICKLY TO AROUND 1-2 KFT AGL.
DEEP LIFT THEN ARRIVES WITH THE UPPER DISTURBANCE DURING THE MID
AFTERNOON HOURS WITH THE THREAT FOR LIGHT TO OCCASIONAL MODERATE
SNOW EXISTING THROUGH EARLY TO MID EVENING. IFR CEILINGS WILL BE
POSSIBLE DURING THIS STRETCH AS WELL...ESPECIALLY WITHIN ANY AREAS
OF HEAVIER SNOW MOVING ACROSS THE TERMINAL. APPEARS SNOW WILL
TAPER SIGNIFICANTLY BY AROUND 9 PM IN THE EVENING AS THE UPPER
WAVE MOVES EAST OF THE REGION...BUT VERY LIGHT SNOW WILL CONTINUE
TO BE A THREAT UNTIL AROUND MIDNIGHT.

&&

.PREV DISCUSSION... /ISSUED 313 PM CST SAT DEC 5 2009/

SHORT TERM...TONIGHT THROUGH MONDAY MORNING.  MAIN CONCERN THIS 
TIME FRAME CONTINUES TO BE CHANCE FOR SNOW ON SUNDAY.

CURRENT WATER VAPOR IMAGERY AND WIND PROFILER DATA SHOWS ONE UPPER 
LOW SPINNING OVER THE NORTHERN GREAT LAKES AND A SECOND LOW DIGGING 
SOUTH ALONG THE ROCKIES AND CURRENTLY OVER SOUTHERN IDAHO. PROFILER 
NETWORK CURRENTLY DEPICTING A 300 MB JET OF 100 KTS OVER NORTHERN 
NEB. VISIBLE IMAGERY SHOWS CLEAR SKIES OVER MUCH OF NEB WITH HIGHER 
CLOUDS STREAMING ACROSS KS.  SURFACE LOW PRESSURE CONTINUES TO 
SLOWLY PUSH ACROSS THE CWA WITH NW WINDS NOW ACROSS THE WESTERN HALF 
OF THE CWA AND SW IN THE EASTERN HALF.

MODELS IN GOOD AGREEMENT WITH FIRST SHORTWAVE TROUGH EJECTING OUT 
FROM THE WESTERN LOW AND INTO OUR CWA ON SUNDAY. WILL HAVE SOME JET 
DYNAMIC HELP HAS WE WILL SIT BETWEEN THE RIGHT ENTRANCE AND LEFT 
EXIT REGIONS FOR A WHILE ON SUNDAY. 500-300 MB Q VECTORS SHOW BROAD 
SCALE LIFT BEGINNING MID MORNING SUNDAY AND CONTINUING INTO SUNDAY 
EVENING BEFORE WAVE MOVES EAST SUNDAY OVERNIGHT.  SPEED OF SYSTEM 
STILL LOOKS FAST ENOUGH TO KEEP US FROM GETTING DUMPED ON.  SHOULD 
BE MORE OF A FLUFFY SNOW WITH COBB METHOD SHOWING A 15 OR 20 TO 1 
RATIO AND ROEBBER METHOD CONFIRMING THIS.  PREVIOUS THINKING OF 1 TO 
3 INCH SNOW STILL SEEMS ON TRACK WITH HIGHER AMOUNTS IN THE NORTH OF 
HIGHWAY 6 IN THE EAST.  ONLY CHANGE I WILL MAKE IS TO PUSH BACK 
TIMING JUST A LITTLE WITH LIGHT SNOW STARING IN THE WEST AROUND 9 AM 
SUNDAY AND ENDING BETWEEN 9 PM AND MIDNIGHT IN THE EAST.

ONE OTHER CONCERN IS THE POSSIBILITY OF FREEZING DRIZZLE IN THE 
SOUTHERN PART OF THE CWA SUNDAY MORNING. BOTH NAM AND GFS HAVE A DRY 
LAYER FROM 750 TO 500 MB WITH PROFILE SATURATED BELOW THAT. HOWEVER 
TEMPS LOOK TO BE FROM -6 TO -9C SO TOUGH TO SAY IF WE DO GET PRECIP 
THERE IN THE MORNING WHETHER IT WILL BE FREEZING DRIZZLE...OR SOME 
LIGHT SNOW.  FOR NOW WILL KEEP LIGHT SNOW GOING AND LET LATER SHIFTS 
ADJUST IF NEED BE.

LONG TERM...12Z MONDAY THROUGH SATURDAY. BIGGEST FORECAST CHALLENGE 
CONTINUES TO BE SNOW AMOUNTS FOR MONDAY NIGHT THROUGH TUESDAY NIGHT 
ASSOCIATED WITH A POTENT WAVE MOVING THROUGH. 

FOR MONDAY...WE SHOULD GET A LULL IN ACTIVITY WITH SHORTWAVE RIDGING 
MONDAY MORNING...BUT IT WILL NOT TAKE LONG FOR ISENTROPIC LIFT TO 
START PRODUCING SOME LIGHT SNOWFALL/FLURRY ACTIVITY...ESPECIALLY IN 
THE SOUTHWESTERN CWA BY LATE AFTERNOON.  THIS SHOWS UP WELL ON THE 
275 K LEVEL. ISENTROPIC LIFT AND MOISTURE INCREASE SIGNIFICANTLY 
MONDAY NIGHT

MONDAY NIGHT THROUGH TUESDAY NIGHT...GOOD INSENTROPIC LIFT OCCURS AT 
THE 275/280K LEVEL MONDAY NIGHT. THERE IS WIDESPREAD AGREEMENT AMONG 
MODELS THAT THIS WILL OCCUR...AND WITH COLD TEMPERATURES LENDING TO 
HIGHER SNOW RATIOS...WE COULD PICK UP A GOOD 2 TO 4 INCHES FROM 
MONDAY NIGHT ALONE. MODELS ADVERTISE STRONG ISENTROPIC LIFT TUESDAY 
MORNING INTO EARLY AFTERNOON BEFORE MODERATE TO STRONG SYNOPTIC LIFT 
TAKES OVER LATER IN THE AFTERNOON INTO THE EVENING. THERE IS 
WIDESPREAD AGREEMENT AND CONSISTENCY AMONG MODELS THAT A CLOSED 700 
MB LOW WILL CROSS TO THE EAST NOT TOO FAR FROM THE STATE LINE. I 
GENERALLY INCREASED SNOW AMOUNTS A COUPLE OF INCHES IN THE SOUTH AS 
MODELS CONTINUE TO FIRM THEIR STANCE ON HIGHER QPF AMOUNTS TO THE 
SOUTH. DIFFICULT TO TELL WHERE EXACTLY THE BEST FRONTOGENETIC BAND 
OR BANDS WILL SET UP ON TUESDAY...BUT IT GENERALLY LOOKS LIKE 
CHANCES ARE BETTER TO THE SOUTH. PUSHED TOTAL SNOW AMOUNTS UP TO 
ABOUT 10 INCHES IN OUR SOUTHEAST. STRONG NORTH WIND LOOKS LIKE A 
GOOD BET ON THE BACKSIDE OF THE SURFACE LOW...ALTHOUGH MODELS HAVE 
TRENDED A BIT FARTHER SOUTH WITH THIS LOW...THUS I EASED OFF WIND 
SPEEDS FROM YESTERDAY BY A COUPLE OF MPH. 

FOR TEMPERATURES...I GENERALLY WENT BELOW GUIDANCE VALUES...AND WENT 
REALLY COLD FOR WEDNESDAY WITH HIGHS STRUGGLING TO MAKE TEENS WITH 
FRESH SNOW PACK AND COLD 850 MB TEMPERATURES...AND THURSDAY MORNING 
NEAR ZERO AS THE CENTER OF THE SURFACE HIGH WILL BE NEARBY. 
TEMPERATURES WILL CONTINUE TO BE ANOMALOUSLY COLD FOR THE ENTIRE  
LONG TERM PERIOD. 

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$