[LeArc] Forecast Discussion : MLI@ 4/27/2003 3:38:17 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 272034
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
334 PM CDT SUN APR 27 2003

COMMA CLOUD ON SATELLITE IMAGERY AT 19Z HIGHLIGHTED SURFACE LOW NW 
OF KINL. ASSOCIATED COLD FRONT CURVED SOUTHWEST ACROSS NORTHWEST IA 
TO SOUTHWEST KS. VISIBLE IMAGERY AND RADAR MOSAIC SHOWED ELEVATED 
CONVECTION IN LAYER OF STEEP MID LEVEL LAPSE RATES WELL BEHIND THE 
FRONT HAS PERSISTED SINCE THIS MORNING FROM NEB PANHANDLE INTO 
NORTHWEST IA. AT UPPER LEVELS...FLAT RIDGE WAS OVER CENTRAL CONUS 
WITH LONG WAVE TROUGH OFF WEST COAST SENDING SHORTWAVES TOWARD AREA 
IN SOUTHWEST FLOW...WHILE SIGNIFICANT WAVE IN NORTHERN STREAM 
ASSOCIATED WITH SURFACE CYCLONE AND COLD FRONT WAS MOVING ALONG 
CANADIAN BORDER TOWARD GREAT LAKES. MAIN FORECAST CHALLENGE IS POPS 
TONIGHT THROUGH MIDWEEK AS FRONT PUSHES THROUGH EARLY MONDAY...
STALLS TO SOUTH...AND THEN COMES BACK NORTH ON TUESDAY TO KEEP AREA 
IN ACTIVE AND WET WEATHER PATTERN. 

SHORTWAVE SEEN ON WATER VAPOR IMAGERY MOVING OUT OF NEW MEXICO ON 
TRACK TO MOVE INTO KS AND SET OFF THUNDERSTORM COMPLEX ALONG AND 
NORTH OF FRONTAL BOUNDARY THIS EVENING. ALL MODELS TRACK SIGNIFICANT 
VORT MAX LATE TONIGHT ALONG IA/MO BORDER TO NORTH CENTRAL IL BY 18Z 
MONDAY. SURFACE INSTABILITY WILL BE LIMITED AS WAVE MOVES 
THROUGH...BUT STRONG ENOUGH OMEGA AND DEVELOPING NOCTURNAL JET 
TAKING AIM AT SOUTHERN CWFA MAY BE STRONG ENOUGH TO COMPENSATE AND 
KEEP SOME TSRA GOING IF COMPLEX HOLDS TOGETHER TO TRACK ACROSS 
SOUTHERN ZONES LATE TONIGHT AND WENT WITH HIGH CHANCE POPS. AREA 
NORTH OF I-80 MORE QUESTIONABLE. BEST CHANCES LOOK TO BE LATE 
EVENING WHEN STEEP LAPSE RATES AT H7-H5 LAYER MOVE INTO NORTHEAST IA 
AS SURFACE FRONT APPROACHES...THEN ISOLATED POST FRONTAL SHOWERS AS 
FRONT DROPS SOUTHEAST. MOISTURE MORE QUESTIONABLE THERE AND THUS 
REDUCED TO SLIGHT CHANCE POPS. ON MONDAY...APPEARS MODELS HOLDING 
ONTO QPF TOO LONG AS WAVE PUSHES EAST AND LIMITED RAIN CHANCES TO 
MORNING. WENT WITH ETA/GFS BLEND...PLACING FRONT SOUTH ALONG I-70 
COORIDOR BY 18Z MONDAY. SUBSIDENCE WILL BRING CLEARING TO 
NORTH...BUT THINK NORTHEAST FLOW AND COLD AIR ADVECTION WILL LIMIT 
HIGHS TO LOW END OF GUIDANCE WITH LOWER 70S AT MOST. MODELS THEN 
DIVERGE ON HANDLING OF NEXT WAVE AND NORTHWARD PUSH OF WARM FRONT 
TUESDAY. WENT WITH BLENDED SOLUTION...KEEPING CHANCES FOR MAINLY 
AFTERNOON TSRA AS FRONT APPROACHES. BETTER CONSENSUS THAT WARM FRONT 
WILL PUSH THROUGH IN LATE TUES NIGHT/WED MORNING TIMEFRAME AND KEPT 
CHANCES GOING THROUGH DAY WEDNESDAY. 

IN EXTENDED PORTION...GFS HAS WEAKENED WAVE PASSING TO NORTHWEST ON 
THURSDAY WTIH SURFACE LOW NOW TRACKING WELL TO NORTHWEST AND CLOSER 
TO UK SOLUTION. WILL STILL KEEP TSRA CHANCES FOR THURSDAY.    
SURFACE HIGH SETTLES BEHIND FRONT FRIDAY AND SATURDAY...THEN 
INTRODUCED SUNDAY WITH TSRA CHANCES AS NEXT LOW APPROACHES FROM 
SOUTHWEST. 

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

$$
SHEETS