FXUS63 KDVN 262059
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
259 PM CST SAT DEC 26 2009
.SYNOPSIS...
MASSIVE UPPER LEVEL LOW PRESSURE SYSTEM CONTINUES TO ROTATE SLOWLY
ACROSS THE UPPER MIDWEST AND GREAT LAKES. NUMEROUS SURFACE AND
UPPER LEVEL WAVES PINWHEELING AROUND SAID SYSTEM CONTINUE TO AFFECT
THE REGION. WV AND IR SATELLITE LOOPS DEPICT NICELY THE WAVE
CURRENTLY SUPPORTING LIGHT TO MODERATE SNOW ACROSS THE SERVICE
AREA...AS WELL AS THE NEXT WAVE OF INTEREST DROPPING SOUTH ACROSS
CENTRAL MN.
&&
.SHORT TERM...TONIGHT AND SUNDAY
MAIN SLUG ...AND FINAL ROUND...OF ENERGY SWINGS ACROSS THE SERVICE
AREA OVERNIGHT TONIGHT THROUGH TOMMORROW MORNING BRINGING ANOTHER
ROUND OF SNOW. SOUTHERN HALF TO TWO-THIRDS OF THE AREA SHOULD SEE
THE HIGHER SNOWFALL AMOUNTS...1 TO 2 INCHES...AND HAVE ADJUSTED POPS
AND QPF ACCORDINGLY. SNOW TO LIQUID RATIOS AGAIN LIKELY TO BE HIGH
AND THUS A LIGHT FLUFFY SNOW EXPECTED. FORTUNATELY A WEAK PRESSURE
GRADIENT AND RELATIVELY LIGHT WINDS SHOULD KEEP BLOWING TO A MINIMUM.
UPPER LOW FINALLY PROGGED TO BEGIN TO OPEN UP AND MOVE EAST INTO
INDIANA SUNDAY. WITH FRESH SNOWCOVER...TEMPS WILL REMAIN BELOW
GUIDANCE THROUGH THE PERIOD.
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
ALL MODELS KEEP CONDENSATION PRESSURE DEFICITS SOMEWHAT LOW WITH
SOME FORCING AROUND SUNDAY NIGHT. THUS FLURRIES ARE EXPECTED BUT I
WOULD NOT BE SURPRISED IF SOME LINGERING -SN ALSO OCCURS. THE LOW
CONDENSATION PRESSURE DEFICITS ALSO LINGER TO SOME DEGREE INTO
MONDAY MORNING DEPENDING UPON WHICH MODEL ONE FOLLOWS. HOWEVER...
THERE IS LITTLE IF ANY FORCING PRESENT. SO...IT IS NOT OUT OF THE
REALM OF POSSIBILITY THAT FLURRIES MAY BEEN SEEN OVER PARTS OF THE
AREA FOR PART OF MONDAY MORNING.
QUIET WX IS THEN EXPECTED MONDAY NIGHT/TUESDAY AS HIGH PRESSURE
MOVES THROUGH THE AREA. ATTENTION THEN TURNS TO THE MID WEEK SYSTEM.
CONDENSATION PRESSURE DEFICITS REMAIN HIGH TUESDAY EVENING SO DRY
CONDITIONS ARE EXPECTED. MODELS DIFFER ON THE OVERALL TIMING OF THE
SYSTEM. GFS IS THE FASTEST WHILE THE ECMWF DELAYS PRECIP UNTIL
WEDNESDAY. FOLLOWED THE GEM SINCE IT WAS IN BETWEEN WITH PRECIP
ARRIVING AFTER MIDNIGHT IN THE SOUTH. ALL MODELS INDICATE THE
NORTHERN STREAM SYSTEM WILL FEED OFF SOME MOISTURE FROM THE SOUTHERN
STREAM SYSTEM AND PRODUCE SN ACROSS THE AREA ON WEDNESDAY. SO CHC
POPS RIGHT NOW LOOK GOOD BUT WILL LIKELY NEED TO BE RAISED OVER THE
NEXT FEW DAYS. SN WILL CONTINUE INTO WEDNESDAY NIGHT AND END PRIOR
TO DAWN ON THURSDAY.
QUICK SHOT OF HIGH PRESSURE SHOULD KEEP THURSDAY/THURSDAY NIGHT DRY.
DEPENDING UPON THE TIMING OF THE MID WEEK SYSTEM...THE POSSIBILITY
EXISTS THAT SOME -SN OR FLURRIES MAY LINGER INTO THURSDAY MORNING.
FRIDAY/SATURDAY IS INTERESTING. ALL MODELS DROP A RESPECTABLY STRONG
NORTHERN STREAM SHORTWAVE INTO THE GREAT LAKES AS A NEW LONGWAVE
TROF DEVELOPS OVER THE EASTERN CONUS. CONDENSATION PRESSURE DEFICITS
LOWER ON FRIDAY WITH THE LEAD SHORTWAVE AND LOW LEVEL LAPSE RATES
BECOME QUITE STEEP. THUS EXPECT SHSN OR -SN TO DEVELOP DURING THE
DAY. DUE TO SMOOTHING OF MODEL FEATURES...HAVE OPTED TO GO WITH SCHC
POPS FOR FRIDAY BUT BELIEVE THESE WILL EVENTUALLY BE RAISED TO CHC.
CURRENTLY DRY CONDITIONS ARE FCST FOR FRIDAY NIGHT THROUGH SATURDAY
NIGHT. HOWEVER...POTENTIAL EXISTS FOR ADDITIONAL PRECIP AS WEAKER
SHORTWAVES MOVE THROUGH THE AREA IN THE FLOW ALOFT.
...08...
&&
.AVIATION...
RECYCLING STORM SYSTEM WILL BRING ANOTHER ROUND OF SNOW TONIGHT.
WIDESPREAD MVFR CONDITIONS WILL PREVAIL MUCH OF THE PERIOD...WITH
OCCASIONAL PERIODS OF IFR VSBYS AND CIGS IN THE MORE INTENSE
SNOWBANDS...MAINLY FROM 6Z THROUGH 18Z SUNDAY.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR BUREAU-
CARROLL-HENRY IL-PUTNAM-WHITESIDE.
MO...NONE.
&&
$$
33/08/33
