[LeArc] Forecast Discussion : MLI@ 7/22/2003 4:43:11 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 220931
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
415 AM CDT TUE JUL 22 2003

CURRENT W/V LOOP SHOWING STREAM MOTIONS IN PLAY NICELY AND EVOLVING
TROUGH DEVELOPMENT OVER THE GRT LKS. TWO MAJOR VORTS INDICATED ON
SAME IMAGERY...ONE CURRENTLY OVER THE CWA AND STARTING TO EXIT TO THE
SOUTHEAST...AND THE OTHER ELONGATED FEATURE SHEARING SOUTH DOWN ACRS
THE EASTERN PLAINS. SHORT RANGE MODELS SUGGEST BOUT OF NEG
OMEGAS/SUBSIDENCE ACRS THE FCST AREA THIS MORNING BEHIND DEPARTING
WAVE...BUT VARY ON EXTENT OF SECONDARY WAVE COMING ACRS THE AREA THIS
AFTERNOON.  FEEL BEST CVA OFF ABOVE MENTIONED PLAINS WAVE TO REMAIN
JUST TO THE WEST OF LOCAL AREA OF CONCERN ACRS WEST IA TODAY...AS
WELL AS ON EDGE OF SOUTHWARD DIGGING 90-100 KT JET MAX. THUS PROBABLY
BETTER CHANCE OF AFTERNOON SHOWERS TO THE WEST...BUT EXTENT OF
UNSTABLE AIRMASS SETTING UP OVER THE CWA TODAY PREVENTS REMOVAL OF 30
POPS ONGOING IN CURRENT PACKAGE. SUBSIDENCE INVERSION NOTED ON FCST
SOUNDINGS BETWEEN H7 AND H6 MB MAY PREVENT MUCH OF ANY SHOWER
ACTIVITY THIS AFTERNOON THOUGH...IF IT MATERIALIZES.

PLENTY OF CU AND AC TO DEVELOP TODAY...WITH LINGERING AND ADVECTED IN
FROM THE NORTH H85 MOISTURE....FOR AT LEAST PARTLY CLOUDY CONDITIONS.
PORTIONS OF THE DAY MAY BE FLAVORED MOSTLY CLOUDY AT TIMES...BUT
STILL ENOUGH JULY INSOLATION AND MIXING IN UNSTABLE LOW TO MID LEVELS
FOR TEMPS TO CLIMB INTO THE MID TO UPPER 70S OVER MUCH OF THE CWA
THIS AFTERNOON. SFC FETCH MORE OF A WARM-ABLE NORTHERLY DIRECTION...
AS OPPOSED TO A BRISK NORTHEAST FLOW/LK MI EFFECT WHICH WOULD KEEP
TEMPS MORE SUPPRESSED IN THE LOW TO MID 70S. THUS HAVE BUMPED UP
TEMPS A CATEGORY.

UPPER RIDGING TO LEAN OVER THE UPPER MIDWEST FOR FAIR WX WED. RIDGE
CENTER BUILDS SOUTHEAST TO HAVE DIRECT IMPACT WITH CLEAR SKIES AND
LIGHT WINDS WED NIGHT...POSSIBLY ALLOWING TEMPS TO AGAIN DIP TOWARD
RECORD LOW LEVELS OVER PORTIONS OF THE CWA.   ..12..

DAYS 3-7 (THU-MON)
SURFACE RIDGE WILL RETREAT INTO THE OHIO VALLEY ON THU WITH LLVL
SOUTHERLY FLOW DEVELOPING. RESULT WILL BE AN INCREASE IN
HEAT/HUMIDITY...ESPECIALLY FRI-SAT. NEXT FRONT SAGS SOUTH ACROSS THE
REGION ON SAT. POTENTIAL FOR NOCTURNAL CONVECTIVE COMPLEX
DEVELOPING OVER THE UPPER MIDWEST FRI NIGHT PROPAGATING TOWARD
CWA LATE. 00Z GFS SHOWS CAP BUILDING TO OUR WEST...SO THREAT ATTIM
WOULD APPEAR TO BE ACROSS THE EASTERN HALF OF CWA WHICH WOULD BE ON
THE COOL SIDE OF THE H85-H7 THERMAL GRADIENT...TYPICALLY A FAVORABLE
TRACK FOR MCS/S. HELD OFF ON INTRODUCING POPS BUT DAY CREW WILL WANT
TO RE-EVALUATE. FRONTAL ZONE TO HANG AROUND THROUGH THE WEEKEND SO
WILL CONTINUE WITH CHC POPS. UKMET INDICATES UPPER RIDGE AMPLIFYING
OUT WEST ON MON RESULTING IN NORTHWEST FLOW ALOFT...WHICH WOULD GIVE
FRONT A NUDGE TO THE SOUTH. ECMWF OFFERS DIFFERENT SOLUTION AND SHOWS
THE UPPER RIDGE FLATTENING OVERHEAD BY 12Z MON WITH SHORTWAVE AND
ASSOCIATED FRONT DIVING SOUTH/EAST THROUGH THE PLAINS...WHICH WOULD
BRING PCPN THREAT BACK LATE MON. GIVEN DISCREPANCIES WILL CONTINUE
WITH DRY FORECAST AND LET LATER MODEL RUNS CLARIFY.   ..05..


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

$$

12/05