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000
FXUS63 KDVN 092041
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
240 PM CST TUE FEB 9 2010


..SYNOPSIS...
ANALYSIS AT 2 PM ILLUSTRATES LARGE...DIFFUSE SURFACE OCCLUSION MOVING
EAST.  LIGHT SNOW BASED ON NOWCAST TOOLS WILL END FROM NW TO SE NEXT
3 TO 5 HOURS WITH SOME LINGERING FLURRIES UNTIL LATE EVENING. EDGE OF
CLOUDS SUPPLEMENTED BY SUBSIDENCE INDICATES CLEARING TO MOVE ACROSS
REGION LATE EVENING AND ESPECIALLY OVERNIGHT. PRESSURE RISES ALLOWING
FOR NW WINDS OF 15 TO 25+ MPH WITH SOME MINOR BLOWING SNOW ACROSS
IOWA.  WINDS SHOULD DECREASE ACROSS AREA AS ISALLOBARIC RIDGE MOVES
EAST BETWEEN 9 AND 12 PM.  UPPER AIR ANALYSIS SHOWS NW UPPER AIR FLOW
AND QUIET WEATHER WEDNESDAY WITH SFC HIGH OVERHEAD BY LATE PM. AREA
WILL END UP WITH WIDESPREAD 4 TO 8 INCHES OF NEW SNOW FROM DEPARTING
SYSTEM WHICH WILL PRODUCE A DECENT NEGATIVE FEEDBACK TO AREA TEMPS
THE NEXT SEVERAL DAYS.

&&

.SHORT TERM...TONIGHT AND WEDNESDAY...
WILL KEEP ADVISORY UNTIL 06Z TO WALK OUT LINGERING SNOW AND WINDS FOR
EVENING SHIFT TO DECIDE WHEN TO PULL.  TRENDS SUGGEST CONDITIONS TO
IMPROVE FROM WEST TO EAST BETWEEN 7 AND 11 PM.

TONIGHT...CLOUDY WITH FLURRIES AND LIGHT SNOW...WITH MINOR TO NO
ACCUMULATIONS IN IOWA AND MISSOURI.  IN ILLINOIS...ADDITIONAL SNOW
AMOUNTS TO BE LESS THAN INCH. AS DISCUSSED ABOVE...CONDITIONS TO
IMPROVE BY LATE EVENING AND CLEARING OVERNIGHT.  LOCAL TOOLS SUGGEST
IF CLEARING IS FASTER...MINS MAY NEED LOWERING WITH NEAR ZERO
READINGS POSSIBLE IN NW SECTIONS.

WEDNESDAY...FAIR SKIES AND MODERATE NW WINDS AND SNOW COVER TO KEEP
HIGHS BELOW GUIDANCE.  KEPT HIGHS TEMPS IN THE UPPER TEENS NW TO
LOWER 20S SE 2/3. SOME LOCAL TECHNIQUES SUGGEST MAX TEMPS MAY NEED
TRIMMING A FEW DEGREES IN SOME LOCATIONS FOR LATER SHIFTS. WIND
CHILLS TO NEAR 10 BELOW IN MORNING HOURS IN NW SECTIONS WILL MAKE FOR
ANOTHER VERY COLD MORNING.   ..NICHOLS..

.LONG TERM...WEDNESDAY NIGHT THROUGH NEXT TUESDAY...
ARCTIC HIGH MOVES ACROSS THE AREA WED NIGHT/THURSDAY KEEPING
TEMPERATURES WELL BELOW NORMAL. SOME QUESTIONS REMAIN REGARDING
TEMPERATURES. IF NO CI MOVES INTO THE AREA TEMPERATURES MAY NOT BE
COLD ENOUGH GIVEN THE FRESH SNOW FIELD. IF CI DOES MOVE IN...
TEMPERATURES ARE PROBABLY TOO COLD. WAA DEVELOPS THURSDAY NIGHT
AHEAD OF THE NEXT SYSTEM.

FRIDAY THROUGH SUNDAY WILL BE INTERESTING AS SIGNALS ARE PRESENT
INDICATING TWO SEPARATE WINTER WEATHER EVENTS HAPPENING IN QUICK
ORDER. THE QUESTION IS WHETHER OR NOT THERE WILL BE A LULL BETWEEN
EVENTS. A HYBRID CLIPPER TYPE SYSTEM MOVES THROUGH THE AREA
FRIDAY/FRIDAY NIGHT BRINGING SOME SNOW ACCUMULATION TO THE AREA. A
TREND TOWARD HIGHER POPS HAS BEEN INITIATED BUT FORCING SIGNALS
INDICATE MUCH HIGHER POPS WILL BE NEEDED.

SAT/SUN IS IN QUESTION. ANOTHER SYSTEM WILL BE ON THE HEELS OF THE
HYBRID CLIPPER SYSTEM. DEPENDING UPON THE MODEL...THIS SECOND EVENT
EITHER STARTS SATURDAY OR STARTS SAT NIGHT AND CONTINUES INTO
SUNDAY. MODELS SUGGEST SOME WEAK CONVERGENCE WITH LOW CONDENSATION
PRESSURE DEFICITS AND FORCING. SO...WILL INCREASE POPS TO CHC FOR
SAT/SAT NIGHT WHILE CONTINUING THE SCHC POPS FOR SUNDAY. FORCING
SIGNALS INDICATE HIGHER POPS WILL EVENTUALLY BE NEEDED WITH THE
SECOND EVENT AS WELL.

MONDAY/TUESDAY LOOKS DRY AS THE NEXT CANADIAN/ARCTIC HIGH BUILDS
INTO THE MIDWEST.  ..08..

&&

.AVIATION...
MVFR FLYING CONDITIONS DUE TO 1-3K AGL CIGS AND VSBYS 2-4 MILES IN
SNOW TO INCREASE TO VFR CONDITIONS BETWEEN 23Z AND 05Z ALL
TERMINALS AS SNOW ENDS AND SKIES CLEAR.  CLEAR SKIES AND VSBYS AOA 7
MILES AFTER 08Z ALL TERMINALS INTO LATE WEDNESDAY.   ..NICHOLS..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT CST TONIGHT
     FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DES MOINES-
     DUBUQUE-HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-JONES-
     KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.

IL...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT CST TONIGHT
     FOR BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-
     MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-
     WHITESIDE.

MO...WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT CST TONIGHT
     FOR CLARK-SCOTLAND.

&&

$$

NICHOLS/08