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000
FXUS63 KDVN 110535
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1135 PM CST TUE DEC 10 2013

.UPDATE...
ISSUED AT 1126 PM CST TUE DEC 10 2013

WITH SNOW TOTALS COMING IN FAR LESS THAN FORECAST THROUGH 06Z...I
HAVE HAD TO CUT BACK GREATLY ON SNOW TOTALS FOR THIS EVENT.
FORCING STILL LOOKS TO IMPACT LOCATIONS GENERALLY NORTH OF
INTERSTATE 80 OVERNIGHT...WITH WIDESPREAD 0.05 TO 0.10 OF QPF.
THUS...A 1 TO 2.5 INCH TOTAL EVENT LOOKS TO BE MOST LIKELY OVER
THIS AREA BEFORE IS SHUTS DOWN LATE TONIGHT. WINDS TOMORROW DO NOT
APPEAR AS LIKELY TO BE STRONG AS EARLIER FORECAST. I HAVE TRIMMED
LEVELS BACK TO A 20 GUST 30 FORECAST FOR NOW. I WILL PASS TO THE
NEXT SHIFT THAT THIS MAY GREATLY INHIBIT SEVERITY OF BLOWING
SNOW...OR IN THIS CASE ENHANCE A LACK OF ITS OCCURRENCE.
ERVIN

&&

.SYNOPSIS...
ISSUED AT 236 PM CST TUE DEC 10 2013

SURFACE AND UPPER AIR ANALYSIS SHOWS STRONG ALBERTA CLIPPER SYSTEM
DIVING SOUTHEAST ON A DIGGING 150+ KTS JET FROM ALASKA. INITIALIZATION
AND VERIFICATION SUPPORTS SYSTEM TO INTENSIFY AND DEVELOP A 20-50+
MILE WIDE SWATH OF SNOW AND STRONG WINDS ON THE BACK SIDE OF SFC
LOW AS IT EXIT EAST. LONG WAVE TROUGH OVER MISSISSIPPI RIVER SUPPORTS
SYSTEM TO MAX OUT IN INTENSITY NEAR TO OVER FORECAST AREA. SURFACE
TEMPERATURES IN PLAINS ARE RUNNING GENERALLY NEAR TO BELOW COLDEST
GUIDANCE WITH WIDESPREAD SNOW FIELD IN CENTRAL CANADA SUPPORTING A
NEGATIVE FEEDBACK FOR ARCTIC AIR TO INTENSIFY. LOCAL TECHNIQUES DO
SUPPORT A STRONG CLIPPER SYSTEM TO PASS WITH EXACT TRACK THE CHALLENGE.
LONG WAVE TROUGH AND DEPTH AND EXTENT OF COLD AIR IN NA SUPPORTS
BELOW TO WELL BELOW NORMAL TEMPERATURES FOR AT LEAST THE NEXT 10
DAYS WITH NEAR RECORD MINS POSSIBLE DUE LOTS OF POWDERY SNOW.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 236 PM CST TUE DEC 10 2013

TONIGHT AND WEDNESDAY...WILL HOIST A WINTER WEATHER ADVISORY FROM 04-18Z
FOR 2-5 INCHES OF SNOW WITH HIGH LWE OF 20-25:1 ALONG AND NORTH OF I-80.
LOCAL FORCING TOOLS SUGGEST A 40 MILE SWATH OF 3+ INCHES WITH CENTER
OF THE AXIS ROUGHLY NEAR A VTI-CID-CWI-VYS LINE. LOCALLY 4 INCHES OR
MORE OF SNOW ARE SUPPORTED. TEMPERATURES WILL STAY IN THE TEENS TO
ALLOW FOR THE SNOW TO QUICKLY ACCUMULATE ON ROADS. AFTER SURFACE LOW
PASSES EAST NEAR DAYBREAK...STRONG NW WINDS OF 25 TO 35+ MPH WITH
SOME GUSTS NEAR 40 MPH WILL RESULT IN THE VERY POWDERY SNOW TO LIFT
AND BLOW ACROSS SURFACES...AS EVIDENCED TO WHAT HAPPENED THIS AM BUT
MORE SO DUE TO MORE SNOW AND STRONGER WINDS. ALONG AND SOUTH OF HIGHWAY
34...AS TYPICAL WITH CLIPPERS...LITTLE OR NO SNOW TO FALL SOUTH OF SURFACE
LOW TRACK. LOCATIONS ALONG AND ESPECIALLY NORTH OF HIGHWAY 20 CORRIDOR
WITH SEE MORE LIKELY SNOW AMOUNTS AROUND 2 INCHES.

AFTER SURFACE LOW PASSES...SNOW SHOULD DIMINISH TO FLURRIES AND END
WITHIN A COUPLE OF HOURS. GUSTY NW WINDS AND PATCHY TO AREAS OF BLOWING
AND DRIFTING SNOW TO PERSIST UNTIL ISALLOBARIC AXIS MOVES EAST...AROUND
NOON OR 18Z. TEMPERATURES TO CRASH INTO SINGE DIGITS TO AROUND ZERO
BY LATE MORNING THAT WILL RESULT IN WIND CHILLS OF 15-20 BELOW ZERO
WITH POSSIBLY SOME WIND CHILLS AROUND -25F FOR LATER SHIFTS TO REASSESS.
EXPECT WIDESPREAD BELOW ZERO TO WELL BELOW ZERO READINGS WITH RAPIDLY
DIMINISHING WINDS BY 6 PM.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 236 PM CST TUE DEC 10 2013

WINDS WILL DECREASE WED NIGHT AS THE ARCTIC HIGH MOVES ACROSS THE
AREA. THE NEW DRY SNOW WILL CREATE A STRONG NEGATIVE FEEDBACK AND
ALLOW TEMPERATURES TO PLUMMET DURING THE EVENING WITH LOWS OCCURRING
8 PM TO 2 AM FOLLOWED BY RISING TEMPERATURES. THE WAPSI AND SAUK
VALLEYS AND OTHER FAVORED COLD AREAS NORTH OF I-80 MAY SEE MINS NEAR
OR COLDER THAN 15 BELOW.

GIVEN THESE LOW TEMPERATURES AND SOME WIND...PREDICTED WIND CHILLS
ARE IN THE ADVISORY CRITERIA FOR AREAS NORTH OF A OSKALOOSA IOWA TO
GALESBURG ILLINOIS LINE. HEADLINES FOR WIND CHILL WILL BE ISSUED
WITHIN THE NEXT 24 HOURS. THE END TIME WILL BE THURSDAY MORNING WITH
THE START TIME STILL IN QUESTION.

DRY AND COLD CONDITIONS WILL BE SEEN ACROSS THE AREA THURSDAY AND
THURSDAY NIGHT. WARMER RETURN FLOW WILL ALLOW TEMPERATURES TO
MODERATE THURSDAY NIGHT AS CLOUDS STREAM INTO THE AREA AHEAD OF THE
NEXT SYSTEM.

FRIDAY MORNING WILL BE DRY AS WARMER AIR FEEDS INTO THE AREA.
PRECIPITATION WILL BEGIN DEVELOPING/MOVE INTO THE SOUTHERN THIRD OF
THE AREA DURING THE AFTERNOON HOURS. THE INITIAL DRY AIR WILL NEED
TO BE OVERCOME BEFORE PRECIPITATION REACHES THE GROUND. THUS IT IS
POSSIBLE FOR SOME SLEET TO BE SEEN BEFORE THE PRECIPITATION
TRANSITIONS OVER TO ALL SNOW AROUND SUNSET.

FRIDAY NIGHT ON...
THE MODEL CONSENSUS HAS CHANCE POPS FRIDAY NIGHT/SATURDAY AS THE
BULK OF THE NEXT SYSTEM PASSES TO THE SOUTH/EAST OF THE AREA. THESE
POPS WILL INCREASE OVER THE REMAINDER OF THE WEEK TO LIKELY AND
POSSIBLY CATEGORICAL ACROSS THE SOUTHEAST HALF OF THE AREA.
ACCUMULATING SNOW WILL BE SEEN FOR MUCH OF THE AREA.

THE VARIABLES OF MOISTURE...FORCING AND STORM TRACK ARE NOT YET
FULLY KNOWN AND WILL RESULT IN FORECASTED SNOWFALL AMOUNTS TO CHANGE
WITH EACH MODEL RUN. HOWEVER...A REASONABLE ESTIMATE THIS FAR OUT IS
1 TO 3 INCHES WITH THE HIGHER AMOUNTS OVER THE SOUTHEAST HALF OF THE
AREA.

SATURDAY NIGHT THE SYSTEM EXITS THE AREA AND THE MODEL CONSENSUS HAS
MAINLY DRY CONDITIONS AND COLDER TEMPERATURES.

SUNDAY INTO SUNDAY NIGHT THE NEXT ARCTIC HIGH BUILDS INTO THE
MIDWEST. THE MODEL CONSENSUS HAS DRY CONDITIONS BUT THE STRENGTH OF
THE NEGATIVE TEMPERATURE ANOMALY IS CONSIDERABLE. TEMPERATURES FOR
BOTH SUNDAY AND SUNDAY NIGHT WILL LIKELY BE LOWERED OVER THE
REMAINDER OF THE WEEK. THE POTENTIAL DOES EXIST FOR HIGHS IN THE
SINGLE DIGITS SUNDAY WITH DOUBLE DIGIT LOWS BELOW ZERO SUNDAY NIGHT.

MONDAY INTO TUESDAY THE ACTIVE FLOW PATTERN CONTINUES ACROSS THE
AREA. THE MODEL CONSENSUS HAS SLIGHT CHANCE TO CHANCE POPS DURING
THE ENTIRE PERIOD WITH TWO SEPARATE DISTURBANCES MOVING THROUGH IN
THE FLOW ALOFT. TEMPERATURES ARE EXPECTED TO REMAIN BELOW NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1126 PM CST TUE DEC 10 2013

A FAST MOVING STORM WILL BRING A PERIOD OF LIGHT TO MODERATE SNOW
TO LOCATIONS GENERALLY ALONG AND NORTH OF INTERSTATE 80 OVERNIGHT.
VISIBILITIES WILL BE 3SM IN SNOW...DIPPING TO 3/4 MILE AT TIMES.
POSSIBLY A BRIEF 1/2SM MODERATE SNOW COULD OCCUR BETWEEN 06Z AND
10Z TODAY. THIS SNOW SHOULD OCCUR WITH LIGHT AND VARIABLE WINDS
AND CIGS BETWEEN 2500 AND 3500 FT. A STRONG COLD FRONT WILL SWEEP
THROUGH BETWEEN 12 AND 15Z...SHIFTING WINDS TO NORTHWEST 20 KTS AND
GUSTING TO 30 KTS. SHALLOW DRIFTING/MINOR BLOWING CAN BE EXPECTED
OVER RUNWAYS...BUT VISIBILITIES AT AIRPORT OBSERVATIONS ARE LIKELY
TO REMAIN ABOVE 6 MILES MOST OF THE TIME.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR BENTON-
     BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-IOWA-JACKSON-
     JOHNSON-JONES-LINN-MUSCATINE-SCOTT.

IL...WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR BUREAU-
     CARROLL-HENRY IL-JO DAVIESS-PUTNAM-ROCK ISLAND-STEPHENSON-
     WHITESIDE.

MO...NONE.
&&

$$

UPDATE...ERVIN
SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...08
AVIATION...ERVIN