[LeArc] Forecast Discussion : MLI@ 7/27/02 3:03:07 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 270802
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 AM CDT SAT JUL 27 2002

IDEAL MCS SET-UP OVERNIGHT HAS TURNED IA AND NORTHWEST IL INTO
CONVECTIVE PLAYGROUND. BRISK 45 TO 50 KT SOUTHWESTERLY LLJ SEEN ON
PROFILER PLAINVIEW OVERLAYS...CONTINUING TO SLAM INTO AND OVER LLVL
THTA-E GRADIENT AND THERMAL BOUNDARY ALIGNED FROM NORTHWEST INTO
SOUTHEAST IA. LINGERING OUT-FLOW SFC COOL POOLS BEHIND COMPLEXES ALSO
AIDING UPWARD DEFLECTION. SFC BOUNDARY SHOWING SIGNS OF FOLLOWING
STRONG PRESSURE FALLS ACRS THE NORTHERN HALF OF IA AND STARTING TO
LIFT NORTH. NORTHEASTWARD SHIFTING APEX OF H85 JET THRUST HAVING ITS
AFFECT OF SHUNTING MAIN MCS DEVELOPMENT AND PROPAGATION AXIS ALONG
H85 FRONT FURTHER NORTH. ACTIVITY TO CONTINUE TO PROPAGATE EAST-
SOUTHEAST ALONG DIFFLUENT H85-H3 THICKNESS PATTERN AND OVER THE
NORTHERN CWA THIS MORNING. PRECIP THREAT CONTINUES TO BE MAINLY
CONFINED THROUGH MIDDAY
...AS NORTHWARD SHIFTING SFC AND H85 BOUNDARY TO MAKE IT NORTH OF THE
CWA BY LATE AFTERNOON...AS WELL AS WANING LLJ INFLUENCE. SHORT RANGE
MODELS GENERALLY AGREE ON THIS PROCESS WITH MINOR TIMING AND
POSITIONAL DIFFERENCES. HEFTY H7 THERMAL RIDGE/CAP ALSO TO BUILD ACRS
CWA THIS AFTERNOON...HINDERING ANY ADDITIONAL DEVELOPMENT. AFTERNOON
HIGH TEMPS AGAIN TO DEPEND ON CONVECTIVE DEBRIS...AND FEEL IT SHOULD
THIN ENOUGH THIS AFTERNOON FOR TEMPS TO REACH AROUND THE 90 DEGREE
MARK OVER MUCH OF THE CWA. CRITICAL THICKNESSES AND TRAJECTORIES
BRING IN AIRMASS WHICH HIT MID 90S YESTERDAY OVER CENTRAL MISSOURI...
BUT AGAIN LINGERING CLOUD COVER TO LIMIT FULL TEMPERATURE POTENTIAL.

SD WAVE AND NORTHWARD SHIFTING THTA-E/THERMAL GRADIENT SHIFT SHOULD
COMBINE TO MAKE FOR STORMY SAT NIGHT ACRS MN AND WI...AND DON'T THINK
MUCH WILL OCCUR THIS FAR SOUTH WITH LINGERING CAP AND FORCING WELL TO
WEST AND NORTH. STILL...MAY KEEP SLIGHT TO LOW POPS FOR POTENTIAL OF
NORTHERN ACTIVITY TO BLEED SOUTH AND AFFECT NORTHERN CWA. MORE LIKELY
THOUGH IS PROCESSES CREATING SPOTTY CONVECTION OVER EASTERN KS
ATTM...TO AFFECT THE DVN CWA TONIGHT.

WILL REMOVE POPS ON SUNDAY...WITH LINGERING WARM DOME ENTRENCHED OVER
THE CWA AND NEXT BOUT OF FRONTAL FORCING STILL OFF TO THE WEST. TEMPS
MAY STRIDE INTO MID 90S...LOOKING AT MIXING POTENTIAL AND LLVL
THERMAL PARAMETERS. THIS AMBIENT TEMPERATURE POTENTIAL...COMBINED
WITH SFC DPTS IN THE LOW TO MID 70S...WILL ALLOW HEAT INDICES TO TOP
100. NEXT AND MORE SIGNIFICANT WAVE PROGGED TO SWEEP OVER UPPER
MIDWEST SUN NIGHT...AND INCOMING LLVL FORCING WITH ASSOCIATED SFC
FRONT INTO JUICED AIRMASS TO BRING ABOUT NEXT MAJOR CONVECTIVE SHOW
TO THE AREA.

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

JDH