[LeArc] Forecast Discussion : MLI@ 8/30/02 2:04:36 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 301908
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
205 PM CDT FRI AUG 30 2002

STAGNATE UPPER AND LOWER RIDGING OVER THE AREA WILL WARRANT THE IDEA
TO KEEP RIDING THE PERSISTENCE WAVE OVER THE NEXT FEW DAYS...BUT WILL
TAKE INTO ACCOUNT SLIGHT DAY-BY-DAY TEMPERATURE MODERATION.

WILL KEEP TONIGHT FOG FREE IN ZONES...AS AGREE WITH PREVIOUS SHIFT
THAT BIT MORE WIND OVERNIGHT AND CONTINUED DAILY DRYING OVER THE PAST
FEW DAYS...SHOULD AMOUNT TO NOTHING MORE THAN FOG OF CONCERN ONLY TO
THE AVIATION COMMUNITY. STILL...SFC DPTS HIGHER TODAY AND WITH
DIURNAL CU DIE OFF TONIGHT LEADING TO CLEAR SKIES...ANY LULL IN THE
LIGHT SOUTHEAST BREEZE WILL LEAD TO PATCHY FOG. ANY DENSE FOG THAT
MAY DEVELOP SHOULD STILL BE TOO SPOTTY OR CONFINED TO A FEW RIVER
VALLEYS FOR ZONE MENTION. MAV LOWS DID WELL LAST NIGHT...AND LOOKING
AT CURRENT AND UPSTREAM DPTS...LOWS GENERALLY AROUND 60 OR THE LOWER
60S SHOULD HANDLE MOST OF THE CWA.

STEEP LLVL LAPSE RATES AND ENOUGH H9-H85 JUICE FOR CU PRODUCTION WILL
PUSH SAT AFTERNOON INTO PARTLY SUNNY REALM...WHICH MID SHIFT ALREADY
HAS ADJUSTED. SLIGHT MODERATION OF H9-H85 TEMPS WILL ALLOW HIGHS BACK
INTO THE LOW TO MID 80S..THUS BLEND OF FWC/MAV TEMPS FOR SAT WILL
HANDLE THE HIGHS.

INCREASED SFC BUOYANCY AND MORE BULLISH APPROACH TO VORT PASSING OVER
AREA ON SUNDAY HAS LED TO THE AVN BREAKING OUT SPOTTY PRECIP...WHILE
OTHER SHORT RANGE MODELS DRY. FORECAST SOUNDINGS BECOME INCREASINGLY
UNSTABLE BY SUNDAY AFTERNOON...ANY ANY UPPER DISTURBANCE MAY BE
ENOUGH FOR ISOLATED TO WIDELY SCATTERED CONVECTION TO BREAK OUT. WILL
KEEP DRY PERSISTENCE FOR NOW...BUT SEE WHAT LATER RUNS DO WITH THIS
SET-UP. SOUTH WINDS...PROJECTED H9-H85 TEMP RECOVERY AND MIXING
SHOULD PUMP HIGHS INTO MID TO UPPER 80S SUNDAY AFTERNOON. INTERESTING
ETA FORECAST TRIGGER TEMP FOR SUNDAY IS 86. EXPECTED BLOW-OFF DEBRIS
FROM CONVECTION TO THE NORTHWEST...AS WELL AS SFC MOISTURE INCREASE
SHOULD LEAD TO A MILDER OVERNIGHT FOR THE SUNDAY NIGHT/MONDAY MORNING
PERIOD WITH LOWS IN THE MID TO UPPER 60S.

.LONGER RANGE(MON-FRI)...LATEST MEDIUM RANGE MODEL RUN NOW LESS
AGGRESSIVE WITH COOL AIR DUMP OVER THE GRT LKS BY MID NEXT WEEK...AS
ALL ARE AMPLIFYING L/W TROUGH JUST OFF THE WEST COAST. THIS
AFFECTIVELY BUILDS UPPER HIGH DOME OVER THE CENTRAL AND EASTERN CONUS
BY NEXT WED. INCREASING SOUTHWEST FLOW AND WARMING LLVL THERMAL POOLS
JUST TO THE WEST WILL NEGATE ANY REAL COOL INFLUX. STILL WILL SIDE
WITH LATEST UKMET RUN WHICH HAS KEPT THE MOST SIMILARITIES TO ITS
PREVIOUS RUNS. THIS SOLUTION WOULD SUGGEST LABOR DAY STILL A WARMING
PRE-FRONTAL DAY...WITH MAINLY A NOCTURNAL CHANCE OF THUNDERSTORMS
WITH FROPA TOWARD TUE MORNING. EXTENDED AVN AND ETA BREAK OUT PRECIP
SOONER BY MON AFTERNOON...ESPECIALLY AVN WHICH IS MORE PROGRESSIVE
WITH FRONTAL ENCROACHMENT ON CWA BY 00Z TUE. THUS WILL KEEP ALREADY
ADJUSTED CHANCE FOR FULL DAY. UKMET STILL SUGGESTS BACK-DOOR COOL
FRONT SCENARIO FOR LATER TUE AND WED AS CANADIAN HIGH GLANCES ACRS
THE NORTHERN GRT LKS. THUS STILL OPPORTUNITY FOR LK MI EFFECT FROM
NORTHEAST AND COOLER HIGHS ON WED...JUST NOT THE LOW TO MID 70S THAT
APPEARED POSSIBLE YESTERDAY. AGAIN BUILDING SOUTHWEST FLOW AND
INCREASING LLVL THERMAL POOLS ACRS THE PLAINS AND TOWARD IA TO BRING
QUICK MODERATION INTO THE LATE WEEK PERIOD. LOW TO MID 80S LOOK LIKE
A START FOR THU HIGHS. WOULD FEEL LIKE THESE PARAMETERS WOULD PERSIST
INTO FRI AND PUZZLED WHY GUIDANCE SO COOL FOR THAT DAY...BESIDES THE
CLIMO BIAS FACTOR. SOUTHWEST FLOW ENERGY "EJECTI" MAY ALSO BE DUE TO
THE LOCAL AREA ON FRI...BRINGING PRECIP THREAT. WILL PONDER
WHETHER(WEATHER) TO ADD THIS CHANCE SO FAR OUT WHILE MASHING THROUGH
THE GRIDS.


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

JDH