[LeArc] Forecast Discussion : MLI@ 3/19/03 4:49:11 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 191056
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
445 AM CST WED MAR 19 2003
 
VERTICALLY STACKED LOW CHURNING OVER SOUTHERN PLAINS WITH STRONG
130+ KT JET ROUNDING BASE SUPPORTING MODEL SOLUTIONS LIFTING SYSTEM E/NE 
TOWARD MID MISSISSIPPI VALLEY WITH UPSTREAM KICKER LURKING 
OFF PAC COAST. SYSTEM MOVING THROUGH BC TO DEEPEN AND DIVE E/SE INTO 
UPPER MIDWEST BY LATE WEEK WHICH WILL ALSO AID IN PULLING 
UPPER LOW NORTHWARD. CLOSER TO HOME...RADAR SHOWS BANDS OF LIGHT SHOWERS 
MOVING TRHOUGH REGION. MAIN SURGE OF RAIN AND EMBEDDED THUNDER LIFTING 
INTO CENTRAL MO ATTIM IN ASSOCIATION WITH LEFT EXIT REGION OF JET AND 
UPPER LEVEL DIVERGENCE. 

MAIN CONCERNS WITH PCPN CHCS AND TEMPS NEXT COUPLE OF DAYS AS LARGE
UPPER LOW TRACKS SLOWLY THROUGH REGION. 

BRISK LLVL NE WINDS...WHICH HAVE HAMPERED RAIN AND BEEN PROBLEMATIC WITH
POP FORECASTS LAST FEW DAYS...WILL CONTINUE AGAIN TODAY.
HOWEVER...FACTORS IN PLACE FOR RAIN EVENT NEXT 12-18 HRS WITH UPPER LOW
NEARING...UPPER DIVERGENCE INCREASING...BACKED H85 FLOW ADVECTING
MOISTURE FROM OHIO VALLEY...AND SEVERAL VORT MAXES STRUNG OUT FROM EASTERN
IA THROUGH OH.  EXPECT MAINLY LIGHT RAIN OR SPRINKLES THIS MORNING 
AS VORT MAX LIFTS THROUGH. KEPT POPS IN LIKELY CAT FOR LOW MEASURABLE.
THIS AFTERNOON...MAIN BAND OF RAIN WILL LIFT INTO THE FAR SOUTH 
EARLY TO MID AFTERNOON AND CONTINUE LIFTING NORTH THROUGH THE EVENING 
AS MAIN DYNAMICS AND WARM ADVECTION APPROACH. WENT CATEGORICAL POPS IN SOUTH 
1/2 THIS AFTERNOON...AND MOST EVERYWHERE FOR A WHILE THIS EVENING BEFORE
TAPERING POPS FROM SOUTH TO NORTH MID TO LATE EVENING AS BAND LIFTS THROUGH 
AND BIT OF DRY PUNCH MOVES IN. KEPT CHC POPS OVERNIGHT GIVEN 
PROXIMITY OF UPPER LOW. 

TEMPS TODAY CHALLENGING TO SAY THE LEAST AND DEPENDENT ON HOW FAR NORTH
FRONTAL ZONE MOVES. MAJORITY OF 00Z MODELS BRING FRONT TO 
NEAR A STERLING-ROCK FALLS LINE TO MOLINE TO KIRKSVILLE LINE BY 00Z.
HOWEVER...HAVE SOME CONCERNS AS RAIN LOOKS TO OUTRUN FRONTAL ZONE WITH RAIN 
COOLED AIR LIKELY TO IMPEDE NORTHWARD PROGRESS WHICH WE TYPICALLY SEE
AND IS SUGGESTED BY 06Z RUC WHICH HAS FRONT FURTHER SOUTH THROUGH 
21Z...FROM QUINCY TO BLOOMINGTON-NORMAL. THUS...HAVE OPTED TO STAY TOWARD 
LOW END OF GUIDANCE...AND COULD END UP BEING TOO WARM.

THURSDAY POSES A CHALLENGE AS WELL...WITH POTENTIAL FOR ISOLATED TO FEW
SEVERE THUNDERSTORMS DEPENDING UPON THE MODEL. 
SURFACE WAVE PROGGED GENERALLY TO LIFT THROUGH EASTERN CWA WITH
REMNANTS OF UPPER LOW NOT FAR BEHIND. WILL CONTINUE WITH LIKELY POPS.
BEST INSTABILITY IN THE EASTERN ZONES WITH LI/S -2 TO -4 AND
STEEP LAPSE RATES OF 7-7.5 C/KM. MID LEVEL COLD POOL ROTATES THROUGH THUS
CONCERNED MAINLY WITH ELEVATED HAILERS AND WILL ADDRESS POTENTIAL IN
MORNING HWO.   

TEMPS REMAIN CHALLENGING ON THURSDAY WITH BIG RANGES AMONG MODEL GUIDANCE 
(13-19 DEGS). MODELS DEPICT MUCH OF CWA IN WARM SECTOR AND WILL SIDE
TOWARD BLEND OF FWC/MET GUIDANCE. A LOT DEPENDS ON HOW MUCH 
SUNSHINE...IF ANY...WHICH IF OCCURS COULD SEND TEMPS CLOSER TO WARMEST MET 
GUIDANCE. 

SYSTEM STARTS TO SHIFT EAST THURSDAY EVE WITH COLD FRONT MOVING THROUGH.
CONTINUED WITH CHC SHOWERS THROUGH FRI WITH STRONG NORTHERN STREAM
SHORTWAVE PASSING JUST NORTH OF CWA...WITH PVA BRUSHING PORTIONS OF THE
AREA THOUGH MOISTURE SOMEWHAT LIMITED. BIG DISCREPANCIES ON AMOUNT
OF POST FRONTAL COOLING FOR FRI WITH AVN/GFS INDICATING H85 TEMPS LOWERING
TO -7C WHILE UKMET -2 TO -3C ACROSS THE NORTH. FOR NOW...WENT WITH
BLEND OF THE TWO AND ADJUSTED MAV GUIDANCE UP BY CAT OR SO MOST LOCATIONS.


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

$$

05