[LeArc] Forecast Discussion : MLI@ 7/15/02 1:40:10 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 150639
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
140 AM CDT MON JUL 15 2002

UPPER LEVEL LOW OVER LOWER MISSISSIPPI VALLEY WITH PROFILERS AND WATER VAPOR
IMAGERY INDICATING POSITION NEAR LITTLE ROCK ARKANSAS. SURFACE RIDGE
AXIS EXTENDS FROM WISCONSIN THROUGH CENTRAL IOWA AND INTO EASTERN KANSAS. 
00Z KDVN SOUNDING SHOWS STRONG INVERSION IN H8-H7 LAYER. SURFACE MOISTURE HAS
INCREASED SOME WITH DEWPOINTS GENERALLY IN THE L60S. NO FOG BEING
REPORTED YET AT ANY AWOS/ASOS SITES. TEMP/DEWPT SPREADS CURRENTLY 3-6 DEGS SO
WON/T BE MUCH LONGER BEFORE SHOULD SEE PATCHY FOG ESPECIALLY IN 
RIVER VALLEYS WITH EXCELLENT RADIATIONAL COOLING. 

CONCERNS ARE WITH FOG...EVENTUAL PCPN CHCS...AND EXTENT OF COOL DOWN LATE 
WEEK WITH BACKDOOR COLD FRONT. 

VARYING MODEL SOLUTIONS EXIST WITH HANDLING OF MID/UPPER LEVEL LOW OVER THE
LOWER MISSISSIPPI VALLEY. AVN AND UKMET REMAIN CONSISTENT IN
BRINGING UPPER LOW/SHEAR AXIS NORTH INTO MID MISSISSIPPI VALLEY BY MIDWEEK. 
GIVEN UPPER RIDGE BUILDING INTO MID-ATLANTIC AND SOUTHEAST STATES...AND
PROGGED DEAMPLIFICATION ACROSS NORTHERN CONUS...FURTHER NORTH SOLUTION SEEMS
REASONABLE. MODELS ALSO HAVE BEEN TRENDING SLOWER WITH SYSTEM...SO
ANY IMPACTS WOULD BE FELT ON WED. UNTIL THEN...FAIRLY BENIGN WEATHER PERSISTS
WITH SFC HIGH DOMINANT FEATURE. OVERALL...NEXT COUPLE OF DAYS/NIGHTS 
WILL SEE TEMPS A LITTLE WARMER WITH DEWPTS GRADUALLY CLIMBING. PERSISTENCE PLUS
A COUPLE DEGS HAS WORKED VERY WELL WITH REGARD TO TEMPS AND WILL STICK WITH 
THIS INTO TUE WHICH IS CLOSE TO BLEND OF MAV/MET GUIDANCE.

PCPN CHCS...ALBEIT SLIGHT...IN QUESTION LATE TUE AND TUE EVENING. 
SFC ANTICYCLONE CONTROLLING OUR WEATHER WILL SHIFT EAST INTO OHIO VALLEY LATE
TUE ALLOWING SOME LLVL MOISTURE AND INSTABILITY TO RETURN...ESPECIALLY ACROSS
SOUTHERN ZONES. MOISTURE RETURN INITIALLY ELEVATED...AS DEEP MOISTURE
(SFC-H8) LIFTS NORTH BUT ONLY TO I-70 CORRIDOR IN CENTRAL MISSOURI BY TUE EVE.
AVN AND UKMET PROG VORT MAX INTO CENTRAL MISSOURI AS WELL WITH
AND POSITIVE VORTICITY ADVECTION FROM EAST CENTRAL MISSOURI INTO SOUTH
CENTRAL ILLINOIS ROUGHLY ALONG AND SOUTH OF QUINCY TO SPRINGFIELD LINE.
ETA SHOWS ELEVATED LI/S (H85) OF -1 TO -2 WITH CAP-FREE ENVIRONMENT. WITH
LACK OF FORCING AND DEEP MOISTURE PLAN TO REMOVE POPS LATE TUE AND TUE EVE IN
THE SOUTH. WILL LEAVE CHC PCPN WED WITH AVN AND UKMET SHOWING 
UPPER LEVEL SHEAR AXIS IN CLOSE PROXIMITY. 

AVN HAS BEEN CONSISTENT IN LAST FEW RUNS INDICATING BACKDOOR FRONT TO SLIDE
THROUGH CWA THU. AVN IS FURTHER SOUTH WITH FRONT AT 00Z THU THAN
UKMET. BOTH MODELS HAVE MUCH BETTER TRACK RECORD WITH SUCH FRONTS THIS SUMMER.
AVN TAKES BACKDOOR FRONT THROUGH CWA ON THU...WITH DRY AND 
COOLER WEATHER ON FRI. CURRENT FORECAST IS QUITE WARM FRI WITH CHC OF PCPN.
HATE TO MAKE SUCH FULL SCALE CHANGES TO EXTENDED. WILL LOOK AT MORE
DATA BEFORE MAKING DECISION. 
  
FOG POTENTIAL MAY BE BETTER MON NIGHT WITH GOOD RADIATIONAL COOLING SETUP
AND FURTHER INCREASE IN BOUNDARY LAYER MOISTURE. WILL INTRODUCE
PATCHY FOG WORDING IN ZONES.  


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

05