[LeArc] Forecast Discussion : MLI@ 12/2/02 2:50:23 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 022103
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
256 PM CST MON DEC 2 2002

MAIN TRICK TONIGHT IS EXTENT OF CLOUD COVER AND POTENTIAL LOWS.
RIDGE NOSE EXTENDING SOUTH ACRS THE NORTHEAST PLAINS AND SUBSIDENCE
HAS SCOURED OUT POST FRONTAL STRATUS ACRS MUCH OF IA. THIS PROCESS
WILL CONTINUE TONIGHT...HOLDING LOW DECK ACRS THE DAKOTAS AND NEB AT
BAY TO THE WEST. NORTHEAST FLOW UP TO H85 MB WILL FEED LAKE
ENHANCED STRATOCU REMNANTS ACRS THE EAST CWA THIS EVENING...BUT MUCH
OF THIS MAY ERODE BY MIDNIGHT. PORTIONS OF MID TO HIGH DECK OVER
THE NORTHERN PLAINS MAY STREAM IN ALONG NORTHWEST FLOW/H7-H3 MB
THICKNESS AND MAKE OVER THE WEST CWA LATER TONIGHT...IF THEY
SURVIVE EROSIVE SUBSIDENCE AND DRY COLD CONVEYOR BELT INFLUX FROM
NORTH. THUS PARTLY CLOUDY WOULD BE A GOOD CATCH ALL...ALTHOUGH CWA
TO EXPERIENCE PERIODS OF MOSTLY CLEAR...TO MOSTLY CLOUDY OVERNIGHT.
ELONGATED VORT SHEARING ACRS JUST TO NORTH OF CWA TONIGHT TO BRING
CVA IN CHANNELED FASHION...BUT MAY BE ENOUGH TO PRODUCE SOME
FLURRIES OUT OF ANY LOW/MID DECK THAT MAKES IT ACRS OR PERSISTS OVER
THE CWA. CHANCE MAY NOT BE WORTH MENTIONING THOUGH...ESPECIALLY
ACRS THE SOUTH. ENOUGH CLEAR TO PARTLY CLOUDY PERIODS TO ALLOW TEMPS
TO PLUMMET INTO SINGLE DIGITS TO LOWER TEENS...LOOKING AT COLD
UPSTREAM SOURCE REGION AIR THAT INFLUX TRAJECTORIES WILL SHUTTLE IN
FROM NORTHERN WI/THE U.P. BEST CHANCE FOR LOWS NEAR 5 ABOVE IN THE
MANCHESTER...TO DBQ AREA(LIGHT BUT FRESH SNOW COVER) IF SKIES REMAIN
CLEAR AND NORTHEAST WIND DECREASES TOWARD 12Z TUE.

TUESDAY LOOKS PARTLY CLOUDY AND COLD AND WITH HIGHS IN THE LOW TO
MID 20S...BUT FEEL FLURRY CHANCE TOO LIMITED TO MENTION.

NEXT FEATURE OF CONSEQUENCE WILL BE IN THE FORM OF RATHER VIGOROUS
VORT COMPLEX DROPPING OUT OF THE NORTHWEST TERRITORIES AND SWEEPING
ACRS THE UPPER MIDWEST IN CYCLONIC FLOW ON WED. AVN-GFS/ETA/META
ALL IN GOOD AGREEMENT WITH STRENGTH AND TIMING OF SYNOPTIC SCALE
FEATURES...AND AS OF NOW LOOKS LIKE ANOTHER LIGHT SNOW/FLURRY
PRODUCER FOR WED. SYSTEM TO BE MOISTURE STARVED THOUGH AS GULF STORM
SYSTEM IN MID CONUS TROUGH BASE...GATHERING STEAM ACRS THE MOUTH OF
THE MS RVR...MAKES FOR AN EFFICIENT MOISTURE HOG. INCOMING CVA AND
MID LVL CONVERGENT QG FORCING SUGGESTS LIGHT SNOW CHANCE INTO
NORTHWEST CWA BY LATE TUE NIGHT...BUT FULL SATURATION FOR FLAKE
ARRIVAL AT SFC COULD BE A PROBLEM EARLY WED MORNING. IF MID DECK
AHEAD OF THIS FEATURE STREAM IN QUICK ENOUGH...WILL PREVENT
COMPLETE TEMP BOTTOM OUT IN LOW SINGLE DIGITS ABOVE ZERO F.

.LONGER RANGE(THU-MON)...LINGERING CYCLONIC FLOW ALOFT WITH AN UPPER
DISTURBANCE TO MAKE FOR ONE MORE COLD DAY WITH FLURRIES ON THU...
BEFORE TEMPORARY FLATTENING OUT OF PATTERN AHEAD OF NEXT MAIN DIGGING
WAVE...BRINGS MODERATING TEMPS ON FRI. STILL FEEL POTENTIAL FOR MID
TO UPPER 30S(ABOVE GUIDANCE) BY LATE FRI AFTERNOON WITH WARMING
POTENTIAL ON BACKSIDE OF SFC HIGH...BUT COLD START TO DAY WILL
PROBABLY TEMPER BACK TO MID 30S. MEDIUM RANGE MODEL ENSEMBLE
GENERALLY SUGGESTS WAVE TO SURGE ACRS NORTHERN GRT LKS AND SWEEP
ASSOCIATED SFC FRONT THROUGH CWA BY LATE SAT/SAT NIGHT WITH RAIN/SNOW
CHANCE AHEAD AND ALONG IT. FRONTAL TIMING TO MAKE SAT HIGH TEMPS
TRICKY...BUT CURRENT THINKING AND EXPECTED LATE AFTERNOON ARRIVAL
ALLOWS FOR MID 30S. HUDSON BAY POLAR VORTEX AGAIN TO BUILD DOWN SOUTH
ACRS THE WESTERN GRT LKS WITH YET ANOTHER COLD DUMP FOR THE END OF
NEXT WEEKEND AND EARLY NEXT WEEK. STEEPENING CYCLONIC FLOW AND IN-
FUNNELING VORTS SUPPORT ONGOING SUNDAY FLURRIES.


.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

12