[LeArc] Forecast Discussion : MLI@ 7/31/02 2:48:13 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 310749
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
249 AM CDT WED JUL 31 2002

SCATTERED TSRA ONGOING FROM NORTHWEST IA AND SOUTHEAST SD EAST ALONG
IA/MN BORDER AND APPEARS TO BE DRIVEN BY STRONG LLJ ACROSS KS/ERN NE.
THE CONVECTION WAS ALSO JUST NORTH OF A SECONDARY WARM FRONT FROM
NORTHEASTERN NE THROUGH SOUTHWEST IA. MAIN WARM FRONT WAS WELL NORTH
OF REGION ACROSS CENTRAL SD AND MN.  UA ANALYSIS AT 31/00Z SHOWED
NEARLY ZONAL FLOW OVER THE NORTHERN THIRD OF THE U.S. WITH HIGH PRESSURE
RIDGE FIRMLY IN PLACE TO THE SOUTH.

MAIN SHORT TERM CONCERN WILL BE HEAT AND HUMIDITY TODAY.  FOCUS THEN
SHIFTS TO THURSDAY WITH MODELS NOW TRENDING TOWARD SLOWER UKMET
SOLUTION...MOVING SURFACE FRONT THROUGH CWA LATE THURSDAY AFTERNOON
AND EVENING.  GOOD LOW LEVEL WAA PATTERN DEVELOPING TODAY WAS SURFACE
PRESSURE GRADIENT TIGHTENS AHEAD OF DEVELOPING NORTHERN PLAINS LOW
PRESSURE SYSTEM.  SHOULD SEE GOOD MIXING IN THE LOWER LEVELS TODAY WITH
DEEP LAYER OF SOUTHWESTERLY WINDS AND DRY ADIABATIC LAPSE RATES.  850
TEMPS SUGGEST MID TO UPPER 90S...HOWEVER ETA BUFR DATA SHOWS WARM
LAYER JUST ABOVE 900MB.  ALSO WILL HAVE DEBRIS CLOUDS FROM CONVECTION
TO WEST AND NORTH STREAMING OVER AREA THIS MORNING.  WILL GENERALLY
KEEP TEMPS IN THE 90 TO 95 RANGE TODAY WHICH IS A COMPROMISE BETWEEN
COOLER MAV AND WARM FWC NUMBERS.  THE OTHER QUESTION WILL BE DEW
POINTS.  AGAIN...I THINK THERE WILL BE ENOUGH MIXING TO KEEP DEW
POINTS IN THE UPPER 60S OR LOWER 70S...WHICH WILL KEEP HEAT INDICES
JUST BELOW ADVISORY CRITERIA.  WILL HOLD OFF ON ANY POPS THIS MORNING.
IT APPEARS TSRA TO OUR WEST IS WEAKENING AS IT MOVES AWAY FROM THE BEST
FORCING AND FORCING WILL DIMINISH AFTER SUNRISE.

WINDS SHOULD STAY UP TONIGHT...LIMITING TEMPERATURE FALL.  WILL GO A
LITTLE ABOVE GUIDANCE...WHICH IS IN LINE WITH GOING FORECAST.
THURSDAY...LOOKS LIKE ETA/AVN ARE TRENDING CLOSER TO THE UKMET WHICH
HAS BEEN SLOWER ALL ALONG WITH FRONTAL PASSAGE.  SEVERE WEATHER
POTENTIAL EXIST WITH GOOD LOW LEVEL CONVERGENCE AND CAPES OF 3000-4000
J/KG TO HELP BREAK CAP OVER CWA. WITH CONVECTION FIGHTING CAP...STORMS
SHOULD STAY CLOSE TO THE FRONT AND WILL ADJUST POPS TO FIT FROPA.  WILL
PLAY UP SEVERE WEATHER THREAT IN SWO BUT WILL HOLD OFF MENTIONING IN
ZFP.  FRONT MOVES SOUTH OF CWA FRIDAY EVENING WITH COOL CANADIAN
AIRMASS SETTLING IN FOR FRIDAY AND WILL STICK WITH MAV TEMPS.  SOME
DISAGREEMENT EXISTS WITH RETURN FLOW FRIDAY NIGHT AND SATURDAY.  AVN
SLOWER THAN UKMET.  WILL NOT MAKE ANY CHANGES AT THE MOMENT AND
CONTINUE LOW POPS FOR FRIDAY NIGHT.  LOOKS LIKE NEXT FRONT IS STILL ON
TRACK TO MOVE THROUGH LATE IN WEEKEND.


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

DLF