[LeArc] Forecast Discussion : MLI@ 11/15/02 2:52:15 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 152103
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
303 PM CST FRI NOV 15 2002

PLENTY OF CLOUDS LINGERING OVER FORECAST AREA THIS AFTERNOON WITH 
SOME THIN SPOTS IN OVERCAST OVER CENTRAL AND WEST. MAIN FORECAST 
CHALLENGE IS CLOUD COVERAGE AND RESULTING AFFECT ON TEMPERATURES 
TONIGHT AND SATURDAY.

SURFACE ANALYSIS AT 18Z HAS LOW OVER NORTHERN ALABAMA WITH CYCLONIC 
CURVATURE IN WIND FIELD NORTHWEST TO EASTERN IA. AT UPPER 
LEVELS...12Z ANALYSIS HAD LONG WAVE TROUGH DOMINATING CENTRAL CONUS. 
RECENT WATER VAPOR IMAGERY SHOWED MAIN TROUGH AXIS MOVING THROUGH 
CENTRAL IA. A SIGNIFICANT SHORTWAVE WAS DIGGING BASE OF TROUGH IN 
WEST TEXAS...WITH SHORT TERM MODELS IN AGREEMENT WITH THIS FEATURE 
SHARPENING THE LONGWAVE TROUGH JUST TO OUR EAST SATURDAY.
PLENTY OF PACIFIC MOISTURE IN NW FLOW DOWNBACK SIDE OF TROUGH 
PROVIDING LOW TO MID CLOUDS STREAMING INTO IA...WHILE SURFACE 
CYCLONIC FLOW AND ENHANCEMENT FROM TROUGH AXIS KEEPING AREAS EAST OF 
RIVER OVERCAST. ALL MODELS FAIRLY SIMILAR WITH LARGE SCALE 
FEATURES...BUT EDGE GOES TO ETA WITH SLIGHTLY SLOWER SPEED OF TROUGH 
AXIS VERIFYING THIS AFTERNOON AND WENT WITH BLEND OF ETA AND GFS 
THIS RUN.

MODEL TIME AND CROSS SECTIONS SHOW SHALLOW MOIST LAYER LINGERING 
OVER EASTERN ZONES WHERE WEAK CYCLONIC SURFACE FLOW CONTINUES AND 
WILL STAY CLOUDY THERE. FURTHER WEST...WESTERN EDGE OF IA ZONES WILL 
HAVE BEST POTENTIAL FOR BREAKS IN CLOUD COVER...WITH LESS FAVORABLE 
SURFACE FLOW AND BULK OF MID LEVEL MOISTURE REMAINING TO WEST. 
WITH PLENTY OF UPSTREAM AT LEAST HIGH LEVEL CLOUDINESS...WILL GO 
WITH MOSTLY CLOUDY FOR IA ZONES. RESULT WILL BE LESS OF A DROP IN 
TEMPERATURES AND SIGNIFICANT CHANGE FROM GOING FORECAST CLOSER TO 
PERSISTENCE AND META 2M TEMPERATURES WITH LOWS FROM MID 20S NORTH TO 
AROUND 30 SE. 

CLOUDS WILL LINGER THROUGH THE DAY IN EAST ON SATURDAY WITH LATE 
AFTERNOON CLEARING IN WEST. GUIDANCE HIGHS IN MID TO UPPER 30S 
REASONABLE. SATURDAY NIGHT WILL BE COLDEST OF SEASON SO FAR WITH 
NORTHERLY FLOW ALOFT AND SHARP SURFACE RIDGE AXIS MOVING OVERHEAD TO 
CLEAR SKIES OUT. STAYED CLOSE TO MAV WITH TEENS. NEXT SHORTWAVE 
PASSES TO NORTH SUNDAY NIGHT WITH ENOUGH FORCING AND MOISTURE 
BRUSHING NORTHERN ZONES TO WARRANT INTRODUCTION OF FLURRIES. 
POTENTIAL FOR FLURRIES OR SPRINKLES CONTINUES MONDAY AND MONDAY 
NIGHT...BUT WITH CONSIDERABLE MODEL DISAGREEMENT WITH TIMING AND 
STRENGTH OF THIS WAVE...WILL KEEP MONDAY AND MONDAY NIGHT DRY. 

IN EXTENDED...LATEST UKMET HAS GONE AWAY FROM CUTOFF LOW AROUND 
MIDWEEK IN PREVIOUS RUN WITH CLOSER AGREEMENT TO SIMILAR MRF/GFS AND 
CANADIAN. PROGRESSIVE PATTERN CONTINUES WITH BUILDING WESTERN CONUS 
RIDGE THROUGH MIDWEEK...SHIFTING EAST AND FLATTENING TOWARD END OF 
WEEK. RESULT WILL BE TEMPERATURES MODERATING CLOSE TO NORMAL. LITTLE 
CHANGE TO ON-GOING EXTENDED GRIDS.

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

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