[LeArc] Forecast Discussion : MLI@ 3/8/03 2:37:10 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 082045
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
240 PM CST SAT MAR 8 2003

LATEST SFC ANALYSIS AND MSAS LOOP INDICATE ARCTIC FRONT HAS
QUICKLY MADE ITS WAY THROUGH THE CWA...WITH IMPRESSIVE PRESSURE RISE
FIELD BUILDING IN BEHIND FROPA. ISALLOBARIC SURGE AND TIGHT PRESSURE
GRADIENT ON LEADING EDGE OF INCOMING CANUCK ANTICYCLONE...INDUCING
STIFF NORTH WINDS ACRS MOST OF THE WESTERN HALF OF THE CWA ATTM. THIS
PROCESS WILL BUILD TO THE EAST AS WELL...ALTHOUGH STRONGER WINDS MAY
DROP JUST TO THE SOUTHWEST OF THE CWA WITH BETTER PRESSURE RISE
SURGE. AFTER BRISK EVENING...THE WIND SHOULD DROP OFF AS NIGHT
PROGRESSES WITH RELAXING GRADIENT...THUS WIND CHILLS SHOULD STAY
ABOVE ADVISORY CRITERIA. BRISK NORTH FLOW WILL USHER IN COLD
AIR FROM THE NORTHLANDS...WITH TRAJECTORY FETCH FROM NORTHWEST WI
SUGGESTING LOWS TONIGHT WILL BE IN THE LOW SINGLE DIGITS ABOVE ZERO
ACRS MUCH OF THE NORTHERN CWA WITH SNOW COVER. SOUTH HALF OF THE CWA
TO BE GENERALLY IN THE UPPER SINGLE DIGITS OR AROUND 10. THUS COOLER
MAV LOWS IN THE BALLPARK. INCOMING SUBSIDENCE BEHIND DEPARTING VORT
SHOULD CLEAR THINGS OUT OVER MOST OF THE CWA BY MIDNIGHT...SOONER
ACRS THE NORTHWEST. ANOTHER FACTOR FOR THE MAKING OF A COLD MARCH
NIGHT.

SFC RIDGE SETTLES OVER THE AREA ON SUNDAY FOR FAIR BUT CHILLY DAY.
SOME MARCH INSOLATION SHOULD HELP HIGHS SURPASS COLD MAV TEMPS...BUT
FWC MAY BE TOUCH TOO WARM...THUS WILL TAKE A COMPROMISE BETWEEN THE
TWO.

NEXT MAIN NEARER TERM CONCERN IS IN HANDLING OF CLIPPER TYPE SYSTEM
DROPPING DOWN IN NORTHWEST FLOW LATE SUNDAY NIGHT AND INTO MONDAY.
ETA/META NOW FURTHER SOUTH WITH SYSTEM FOLLOWING CONCEPTUAL MODELING
THINKING OF FURTHER SOUTH LAYOUT OF BAROCLINICITY AFTER COLD INFLUX
OF PREVIOUS DAY. ETA/META FORCING THOUGH IS WEAKER THAN AVN-GFS...AND
SUGGESTS LITTLE TO HAPPEN PRECIP-WISE ON MONDAY...WHILE GFS DUMPS
AN INCH OR SO OF SNOW ACRS THE SOUTH...AND AROUND A HALF INCH
ALONG THE I-80 CORRIDOR. MOISTURE AVAILABILITY AND QUICK MOVING
SYSTEM MAKE GFS SEEM BULLISH ON PRECIP AMOUNTS...AND HAVE ELECTED TO
TAKE UKMET SOLUTION IN STRENGTH OF FORCING AND GENERAL PRECIP TRACK
AND AMOUNTS. UKMET PAINTS LESS OF A QPF PICTURE AND WOULD GENERALLY
DUST THE SOUTHERN THIRD BY MID MONDAY MORNING...WITH LIFT AND
SATURATION ENOUGH TO INITIATE SNOW AT SFC BY LATE SUNDAY NIGHT ACRS
SOUTHEAST IA AND NORTHEAST MO. STILL COULD SEE SOME HALF INCH...
UP TO AN INCH AMOUNTS ALONG A NARROW FORCING RIBBON SOMEWHERE
ACRS THE SOUTHERN CWA. LIGHT SNOW SHOULD CONTINUE ACRS THE SOUTH HALF
OF THE CWA THROUGH EARLY AFTERNOON BEFORE WINDING DOWN...AS FORCING
AND CVA SHIFTS EAST. THE NORTH MAY RECEIVE LITTLE MORE THAN FLURRIES.
ALL IN ALL...APPEARING MORE AND MORE LIKE A TYPICAL WEAK AND DRY
CLIPPER/MINIMAL SNOW EVENT FOR MONDAY.

.LONGER RANGE(TUE-SAT)...MEDIUM RANGE MODEL ENSEMBLE OF SOLUTIONS
GENERALLY SIMILAR IN HANDLING NEXT WEEKS SYNOPTIC SCALE TRENDS...BUT
WILL LEAN TOWARD MRF/ECMWF BLEND. ANOTHER DISTURBANCE WILL LOOK TO
SKIRT ACRS IN NORTHWEST FLOW OVER MN AND WI ON TUE...AND MAY GLANCE
NORTHERN CWA WITH SNOW. WILL UNDERCUT GUIDANCE TEMPS FOR TUE...AS
FEEL HIGHS ACRS THE NORTH WILL BE MID UPPER 30S...AND IN THE LOW TO
MID 40S ACRS THE SOUTH AS SOME WARM AIR IS DRAWN UP ACRS THAT AREA BY
SYSTEM TO THE NORTH. REINFORCING COLD SHOT IN FORM OF WESTERN
CANADIAN HIGH DROPPING ACRS THE NORTHERN PLAINS AND UPPER MIDWEST...
TO TEMPORARILY KNOCK TEMPS BACK DOWN INTO MID 30S ON WED. BROAD UPPER
RIDGE BUILDING ACRS THE WESTERN CONUS WILL HUMP ITS WAY EAST...AND
EVENTUALLY BRING MODERATING TEMPS ACRS THE AREA BY WEEKS END. STILL
LOOKS LIKE ONE LAST SYSTEM TO DROP DOWN ACRS UPPER MS RVR VALLEY IN
NORTHWEST FLOW ON LEE SIDE OF INCOMING UPPER RIDGE FOR PRECIP CHANCE
ON THU. ALTHOUGH SFC TEMPS SHOULD BE IN THE UPPER 30S TO LOWER 40S...
STILL FEEL LIKE COOLER THERMAL PROFILE ALOFT SUGGESTS RAIN/SNOW MIX
ACRS THE NORTH HALF OF THE CWA. THEN UPPER RIDGE BUILDS ACRS THE
REGION FROM THE WEST...BRINGING WITH IT MODERATING TEMPS AND
GENERALLY DRY WEATHER FOR END OF EXTENDED PERIOD. WITH EXPECTED
DECAYED SNOW COVER BY THEN...TEMPS SHOULD OBTAIN VALUES WELL INTO THE
40S FOR FRI...AND 50S POSSIBLE BY NEXT SAT.


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

$$

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