FXUS63 KDVN 010923
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
320 AM CST TUE DEC 1 2009

.SYNOPSIS...
QUIET WEATHER ACROSS THE AREA THIS MORNING AS LIGHT SOUTHWEST FLOW
CONTINUES.  TEMPERATURES HAVE FALLEN LESS THAN 5 DEGREES NEARLY
EVERYWHERE SINCE 00Z...A SYMPTOM OF THE WARM AIR ADVECTION THAT HAS
BEEN ONGOING ALL NIGHT.  ALOFT AT 850MB THE WARM AIR ADVECTION IS
ALSO ONGOING THERE...WITH WEST FLOW AND A TEMPERATURE GRADIENT FROM
HERE TO OMAHA OF 3 DEGREES C...WITH EVEN MORE WARM AIR TO THE WEST.
OF NOTE...THERE IS A SURFACE LOW OVER NORTHWEST NORTH DAKOTA...WITH
PRESSURE FALLS ALL ACROSS THE DAKOTAS...AND SNOW FALLING FROM
NORTHERN MINNESOTA BACK UP INTO SASKATCHEWAN AND MANITOBA. THIS IS
A RATHER POTENT LOOKING ALBERTA CLIPPER ON SATELLITE.

&&

.SHORT TERM...TODAY AND TONIGHT...
PLENTY OF SUNSHINE TODAY...SOUTHWEST WINDS...AND WARM AIR ADVECTION
ALOFT WILL SERVE TO PRODUCE DEEP MIXING AND WARM TEMPERATURES
TODAY.  STRICT MIXING TECHNIQUES TO 925-950MB WOULD PRODUCE ONLY MID
50S SOUTH BASED ON THE NAM12 TEMPERATURE DATA.  THESE RESULTS ARE
BACKED BY MAV AND MET GUIDANCE AVAILABLE FOR TODAY.  HOWEVER...WE
HAD A SIMILAR SETUP ON SATURDAY...AND THE GUIDANCE WAS SEVERAL
DEGREES TOO COOL...AND STRICT MIXING TECHNIQUES UNDERDID THE MAX
TEMPERATURES THEN TOO.  THUS...HAVE GONE A FEW DEGREES ABOVE
GUIDANCE...ESPECIALLY IN THE SOUTHWEST WHERE THERE WILL BE THE LEAST
CLOUDS AND TEMPERATURES WILL BE WARMEST ALOFT.  THIS MIXING IS ALSO
EXPECTED TO TAP INTO STRONGER WINDS...WITH 925MB WINDS AS HIGH AS 35
KTS.  THEY ARE OVERDONE A LITTLE RIGHT NOW WHEN COMPARED TO PROFILER
AND 88-D VWP DATA...BUT WE SHOULD STILL BE MIXING DOWN WINDS AROUND
25 KTS FAIRLY EASILY.  HAVE GONE WITH GUSTS THIS AFTERNOON IN THE
20-25KT/25-30MPH RANGE.  TONIGHT WINDS DROP OFF PRETTY QUICKLY...AND
SHOULD BE DOWN TO LESS THAN 10 KTS BY 01Z.  WHILE WINDS SHOULD
NEARLY DECOUPLE TONIGHT...WE WILL STILL BE AHEAD OF OR NEAR THE
FRONT MOST OF THE NIGHT...AND MID AND HIGH LEVEL CLOUDS WILL STREAM
OVER THE AREA FROM THE SOUTHWEST BEGINNING AROUND MID EVENING.
THUS...TEMPERATURES SHOULD NOT DROP OFF TOO BADLY...AND HAVE STUCK
FAIRLY CLOSE TO GUIDANCE VALUES.     ..LE..

.LONG TERM...WEDNESDAY THROUGH NEXT MONDAY...
WITH REGARDS IN HANDLING OF LARGE DIGGING L/W TROF ACTING UPON
SOUTHERN STREAM CUT-OFF UPPER LOW...LATEST SUITE OF 00Z RUN MODELS
COMING INTO MORE OF A GENERAL AGREEMENT BUT STILL SOME PERTURBATIONS.
IN THE PHASING OR TRYING TO PHASE PROCESS...THE LOW ACRS THE DEEP
LOWER MS RVR VALLEY WILL MOST LIKELY GET DRAWN UP ACRS THE TN AND
MID/EASTERN OH RVR VALLEYS ALONG A PATH WHERE THE BULK OF IT/S DEF
ZONE PRECIP REMAINS OFF TO THE SOUTHEAST AND EAST OF THE DVN CWA WED
AND WED NIGHT. DPROG-DT ANALYSIS SUGGESTS THE LAST THREE ECMWF RUNS
HAVE REALLY STABILIZED WITH RESPECT TO THE PATH OF THE NORTHEASTWARD
EJECTING LOW AND WILL GENERALLY FOLLOW IT/S SOLUTION INTO DAY 5/SAT.
THIS SOLUTION WOULD SUGGEST THAT THE FAR NORTHWESTWARD FLANK OF DEF
ZONE PRECIP WOULD CLIP THE FAR SOUTHEAST AND EASTERN CWA WED
AFTERNOON AND INTO THE EVENING GENERALLY FROM MACOMB UP TOWARD
PRINCETON IL. WILL KEEP RAIN-SNOW MIX WORDING GOING THROUGH 00Z THU
BUT EVAPO-COOLING AND DYNAMICAL COOLING PROCESSES MAY TREND ANY
PRECIP IN THESE AREAS TO ALL SNOW AS THE DAY PROGRESSES. A HALF
INCH OR LESS OF SNOW ACCUMULATION CURRENTLY EXPECTED ALONG AND EAST
OF A MACOMB-PRINCETON LINE BY MID WED EVENING. MILD SOIL TEMPS WILL
AGAIN MAKE TRUE ACCUMULATIONS HARD TO MEASURE. TEMPS ON WED SHOULD
RANGE FROM THE MID TO UPPER 30S IN THE NORTHWEST...TO THE LOW TO MID
40S IN THE SOUTHEAST.

AS THE CYCLONE MIGRATES ACRS THE FAR EASTERN GT LKS...THE COLD CORE
L/W UPPER TROF WILL CONTINUE TO PIVOT RIGHT ACRS THE UPPER AND MS
RVR VALLEYS LATE WED NIGHT THROUGH THU NIGHT. AS IT DOES...THIS
FEATURE AND IT/S EMBEDDED BOUTS OF CVA WILL PRODUCE OCCASIONAL
ROUNDS OF SNOW SHOWERS AND FLURRIES THROUGH THE END OF THE WEEK.
LITTLE ACCUMULATION EXPECTED IS EXPECTED WITH THIS ACTIVITY...
ALTHOUGH A FEW AREAS OF REPEATED SNOW SHOWERS THU AFTERNOON MAY
RECEIVE UP TO A HALF INCH. WITH COLD AIRMASS RIGHT OVERHEAD EXPECT
WIDESPREAD LOW TO MID 30S ON THU AND LOW THU NIGHT IN THE UPPER
TEENS TO LOWER 20S EVEN WITH MIXING WINDS AND CLOUD COVER. MANY
AREAS ON FRI MAY NOT BE ABLE TO CLIMB OUT OF THE UPPER 20S FOR HIGHS.

THE 00Z GFS...ECMWF AND THE CANADIAN GEM HAVE TRENDED TOWARD
FLATTENING OUT THE FLOW PATTERN ACRS THE SOUTH HALF OF THE PLAINS
AND ACRS THE OH RVR VALLEY FOR THE START OF THE WEEKEND. THIS MAY
LEAD TO THERMAL MODIFICATION INTO THE LOCAL AREA BY LATER SAT AND
ESPECIALLY SUNDAY WITH SIGNS A RETURN TO A SPLIT FLOW REGIME AGAIN AS
TROFFINESS LINGERS ACRS THE NORTHEASTERN GRT LKS. WILL BUMP UP SAT
HIGHS SOME BUT NOT QUITE TO THE POTENTIAL THE NEW RUNS ARE INDICATING
AS THEY SUGGEST A RETURN TO THE UPPER 30S TO LOWER 40S. NO CHANGES
PAST SAT FOR NOW.     ..12..

&&

.AVIATION...
VFR CONDITIONS TO CONTINUE THROUGH THE 12Z TAF PERIOD. WINDS TO BE
THE MAIN CONCERN WITH LIGHT SOUTHWEST WINDS THIS MORNING TO INCREASE
TO AROUND 15KTS LATE THIS MORNING...WITH GUSTS OF 20-25KTS POSSIBLE
IN THE MID AFTERNOON.  THE STRONGEST SPEEDS CAN BE EXPECTED AT KMLI
...KCID AND KBRL...WITH LESSER SPEEDS AT KDBQ. WINDS TO RAPIDLY
DIMINISH AROUND SUNSET.  FRONT COMING THROUGH TONIGHT TO TURN WINDS
TO NORTHWEST AT LESS THAN 10 KTS OVERNIGHT. AFTER 03Z TONIGHT SOME
MID AND HIGH CLOUDS WILL BEGIN STREAMING INTO THE AREA FROM THE
SOUTHWEST...BUT WILL REMAIN ABOVE 6KFT THROUGH 12Z.     ..LE..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

LE/12