[LeArc] Forecast Discussion : MLI@ 7/15/02 1:41:28 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 151841
AFDMLI

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

.OVERVIEW...QUIET...STAGNANT PATTERN CONTINUES WITH STALLED WEAK RIDGE
OVERHEAD AND SMALL UPPER LOW IN MISSOURI FOR SEASONABLY SLIGHTLY COOLER
TO COOLER TEMPS WITH FAIR SKIES AND LOW DEWPOINTS AS IN PAST THREE DAYS.
UPPER AIR ANALYSIS SUPPORTS GRADUAL CHANGE THO WITH SHORT WAVE MOVING
INTO WESTERN CANADA MOVING EAST HELPING TO DRAG UPPER LOW NE AND INDUCE
LIGHT SOUTH WINDS AT SURFACE FOR SLOWLY RISING DEWPOINTS NEXT 24-36
HOURS.  PERSISTENCE BEEN WAY TO GO PAST SEVERAL DAYS AND REASONABLE AT
LEAST INTO WEDNESDAY MORNING.  PATCHY FOG ACROSS AREA LAST NIGHT
SOMEWHAT MORE WIDESPREAD AND HEAVIER WITH A FEW LOCATIONS APPROACHING OR
REACHING 1/2 MILE IN FAVORED LOW LYING AREAS...PERSISTENCE AND GOOD
RADIATIONAL COOLING WITH INCREASING DEWPOINTS SUPPORTS MAINTAINING
PATCHY WORDING TONIGHT...ALSO WED AM. SFC WINDS CALM OR NEARLY CALM AT
18Z WITH LITTLE CHANGE IN OUR WIND FIELD UNTIL TUESDAY PM AND THEN ONLY
SOUTH 5 TO 10 MPH.  SOME CONVECTION UNDER UPPER LOW IN SOUTHERN MISSOURI
AND NORTHERN ARKANSAS CLOSEST PRECIP TO REGION IN OUR DRY REGIME.

...PATCHY FOG CHANCES TONIGHT AND GRADUAL WARMUP NEAR TERM CONCERNS AND
THEN POPS AS UPPER LOW APPROACHES WED/THU ALONG WITH NEXT FRONT...

.DIAGNOSIS AND DAYS 1 THRU 3...USE MAINLY PERSISTENCE THROUGH TUESDAY
NIGHT AS LITTLE DYNAMIC CHANGES...OR LOW END OF MAV/FWC/MET BLEND WITH
COUPLE MORE NIGHTS OF GOOD RADIATIONAL COOLING FOR LOWS. UPPER LOW TO
APPROACH SOUTHEAST AREAS WED PM AND NIGHT SO WILL MAINTAIN CHANCE POPS
THERE WITH WARMING TREND ALREADY IN CURRENT FORECAST.  FOR THURSDAY...
MODELS VARY SOMEWHAT ON SURFACE FEATURES WITH NEXT FRONT BUT ALL SUGGEST
SW LOW LEVEL WINDS AND COMPRESSIONAL HEATING FOR TEMPS WELL INTO 90S
MOST AREAS.  ALSO FAVORABLE UPPER DYNAMICS AND MOISTURE FOR PM AND
EVENING CONVECTION TO DEVELOP NORTH AND NORTHWEST OF OUR AREA AND
PROPAGATE SE WITH GOOD UPPER DIFFLUENCE TO BOOT.  WILL NOT GET TOO CUTE
AS TOO MANY UNCERTAINTIES YET ON PHASING OF SMALL SCALE FEATURES BUT
WILL GO WITH 40 TO 50 POPS MOST AREAS THURSDAY NIGHT.  ADD WARM AMD
HUMID WORDING TUE/WED AND ADD HOT AND HUMID TO VERY HUMID THURSDAY AS
DEWPOINTS SHOULD PUSH WELL INTO 70S AND COMBINE WITH LOWER 90S FOR HEAT
INDICES NEAR OR OVER 100...THIS IS BIGGEST CHANGE TO FORECAST.  PASS TO
LATER PACKAGES TO CONSIDER FOR DECISION ON WHEN TO INSERT INDICES.

.EXTENDED (FRI-MON)...AVNXT CONTINUES DRAGGING BACKDOOR FRONT ACROSS
REGION FRIDAY INTO SATURDAY WITH ECMWF LESS OPTIMISTIC AND 12Z UKMET
SLIGHTLY LESS AGGRESSIVE AS AVNXT.  84 HOUR ETA ALSO SUGGESTS FRONT TO
REACH NORTH SECTIONS FRIDAY.  LARGE SCALE PATTERN CONTINUES SUPPORT
CHANCE OF POPS WITH SIGNIFICANT WIDESPREAD RAIN POTENTIAL IF AVNXT/MRF
AND EVEN UKMET CORRECT.  PLAN ONLY MINOR CHANGES DUE TO MODEL VARIANCE
AND WEAK FORCING LIMITS CONFIDENCE.


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

NICHOLS