FXUS63 KGID 051120
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
520 AM CST SAT DEC 5 2009

.AVIATION...12Z TAF. A COLD FRONT WILL MOVE THROUGH THE KGRI
TERMINAL AREA TODAY TURNING WINDS FROM SOUTH TO NORTHWEST
GRADUALLY THROUGH THE DAY. CIRRUS CLOUDS SHOULD START TO MOVE INTO
THE AREA DURING THE DAY. CONDITIONS WILL REMAIN VFR THROUGH THE
PERIOD. 

&&

.PREV DISCUSSION... /ISSUED 246 AM CST SAT DEC 5 2009/ 

DISCUSSION...THE MAIN FORECAST ISSUES ARE TWO SNOW EVENTS...ONE
LIGHT EVENT ON SUNDAY...AND THE OTHER POTENTIALLY MUCH HEAVIER ON
TUESDAY/TUESDAY NIGHT.

BRIEF SHORTWAVE RIDGE TODAY WILL RESULT IN A PRETTY DECENT DAY
WITH HIGHS CLIMBING UP ABOVE 40 ACROSS THE SOUTHERN 1/2 OF THE
CWFA.

LATE TONIGHT...THE FIRST SIGNS OF SUNDAY/S LIGHT SNOWFALL EVENT 
START WITH FLURRIES OVER THE WESTERN CWFA. ALL THE MODELS HAVE 
BEEN CONSISTENT IN A LIGHT QPF SNOW EVENT WITH SHORT WAVE AND 
ASSOCIATED JET ENERGY MOVING ACROSS THE SUNDAY. TRENDS SEEM TO 
BE A TOUCH FURTHER NORTH...AND A BIT STRONGER SYNOPTICALLY WITH
THE SYSTEM. WITH SNOW RATIOS OF AT LEAST 15 TO 1 LIKELY...THIS
LOOKS A SWATH OF ABOUT 2 INCHES OF SNOW ON AVERAGE SUNDAY. ITS NOT
A HEAVY SNOW EVENT...BUT A STEADY SNOW EVENT FOR ABOUT 9 HOURS.
HAVE INCREASED SNOWFALL CHANCES TO NEAR 100 PERCENT...WITH SNOW
TOTALS IN THE 1.5 TO 3 INCH RANGE. PROBABLY GOING TO BE A
BORDERLINE ADVISORY EVENT...AS A FEW AREAS IN THE NORTHEAST CWFA
COULD PICK UP MORE THAN 3 INCHES. WINDS LOOKS STEADY AS WELL...BUT
NOT OVERLY STRONG AND IN THE 15 TO 20 MPH RANGE. 
 
ANOTHER SHORTWAVE RIDGE MONDAY SHOULD KEEP MOST OF THE PRECIPITATION 
AT BAY. MAY HAVE BEEN A BIT OPTIMISTIC IN PULLING ALL SNOW CHANCE
FOR THE DAY...BUT IT APPEARS TIMING OF NEXT SYSTEM WILL BE SO CLOSE
TO THE EVENING THAT I THOUGHT I COULD GET AWAY WITH IT. 

ALL SIGNS POINTING TOWARD A SIGNIFICANT SNOWSTORM BEGINNING LATE 
MONDAY NIGHT THROUGH TUESDAY NIGHT. CANADIAN/GFS/ECWMF ALL HAVE SOME 
DIFFERENCES...BUT SIMILARITIES ARE MORE IMPORTANT. A STRONG...SLIGHTLY
NEGATIVE TILT TROUGH WILL QUICKLY ROLL ACROSS THE CWFA TUESDAY. 
AHEAD OF THAT...BROAD ISENTROPIC LIFT WILL SPREAD LIGHT SNOW ACROSS 
THE CWFA TO THE TUNE OF 1 TO 3 INCHES MONDAY NIGHT AND EARLY
TUESDAY. THIS FIRST SNOW IS A KEY IN GETTING HEAVIER STORM TOTAL
SNOW AMOUNTS...AS WE OFTEN SEE THE ISENTROPIC/WARM ADVECTION SNOW
AHEAD OF THE MAIN SYNOPTIC SYSTEM. AFTER A SHORT LULL IN THE
SNOWFALL RATES TUESDAY MORNING...STRONG SYNOPTIC SCALE LIFT WITH
THE MAIN WAVE WILL MOVE INTO THE AREA DURING THE AFTERNOON.
MOISTURE STREAMING NORTH WILL BE ALMOST TWO STANDARD DEVIATIONS
ABOVE NORMAL IN TERMS OF PRECIPITABLE WATER IN THE SOUTHEAST CWFA.
THAT SOUTHEAST 1/3 OF THE CWFA COULD BE REALLY UNDER THE GUN LATE
TUESDAY AFTERNOON/EARLY EVENING...DEPENDING UPON JUST WHERE THE
MAIN FRONTOGENETIC SNOW BAND SETS UP. STRONG NORTH WINDS OF 20 TO
30 MPH /GUSTS OF 35+ MPH/ WILL WRAP UP ON THE BACK OF THE LOW
TUESDAY EVENING...CREATING SOME FAIRLY TREACHEROUS TRAVEL ISSUES.
FORTUNATELY...THIS SYSTEM IS PRETTY QUICK HITTING AND SNOW FALL
WILL TAPER OFF BY MIDNIGHT... BUT WINDS WILL CONTINUE THROUGH MOST
OF THE DAY WEDNESDAY. FINALLY...ADD ON THE FACT WEDNESDAY/S
TEMPERATURES WILL LIKELY NOT REACH 20 DEGREES WITH THAT GUSTY
NORTH WIND. IT WILL BE ONE WINTRY WEEK.

THE PREVIOUS FORECAST SHIFT WAS ON TARGET BY INCREASING ALL
ASPECTS OF PRECIPITATION AND ACCUMULATION. RIGHT NOW...CONFIDENCE
IS ALSO INCREASING REGARDING THE LIKELIHOOD OF THIS EVENT AND ITS
IMPACTS ON THE AREA. SNOW AMOUNTS RANGING FROM 4 TO 5 INCHES IN THE
NORTHWEST CWFA...TO 8+ INCHES IN THE SOUTHEAST CWFA LOOK QUITE
REASONABLE. IT APPEARS THE AREA ALONG AND SOUTH OF HIGHWAY 6 IN
NEBRASKA...AND NEARLY ALL OF NORTH CENTRAL KANSAS ARE THE MOST
LIKELY REGIONS TO BE IMPACTING BY HEAVIER SNOW TOTALS. 

&&

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

$$