[LeArc] Forecast Discussion : MLI@ 6/8/02 2:37:21 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 081936
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CDT SAT JUN 8 2002

.OVERVIEW...LATE SPRING AND EARLY SUMMER PATTERN IN PLACE WITH DECENT
JET ALONG CANADIAN BORDER AND LATE SEASON STORM SYSTEM IN PACIFIC
NORTHWEST.  EVIDENCE OF SOME MONSOON MOISTURE BEING PULLED UP FROM SW
US.  MODERATE STRENGTH SURFACE LOW IN WESTERN NEBRASKA PUSHING LOTS OF
MOIST AND WARM AIR INTO MIDWEST PER SURFACE ANALYSIS AND SATELLITE.
UPPER AIR ANALYSIS SHOWS SLOW MOVEMENT OF CLOSED LOW IN NW WITH A NEARLY
VERTICALLY STAKED STRUCTURE.

...WARMING NEAR TERM AND THEN INCREASING POPS AHEAD OF NEXT FRONT WITH
SUBSEQUENT COOL-DOWN THE MAIN ISSUES THIS FORECAST...

.DIAGNOSIS AND DAYS 1-3...MODELS HANDLE LARGE SCALE FEATURES AT 18Z
EXCEPT FOR ETA QPF FEEDBACK PROBLEMS ALONG FRONT IN SD.  THIS NOT A
CONCERN SINCE NEXT 36 HOURS TO BE DRY WITH JUST GRADUALLY INCREASING
MOISTURE AHEAD OF SLOW MOVING BOUNDARY.  TEMPERATURES...WILL TEND ONE
MORE NIGHT WITH LIGHT WINDS AND DVV LOWS SLIGHTLY BELOW GUIDANCE...THEN
NEAR SUNDAY AND SLIGHTLY ABOVE BY MONDAY.  KEEP CHANCE TO SLIGHT CHANCE
POPS WITH WEAK DISTURBANCE FROM WESTERN TEXAS IN MONSOON FLOW AHEAD
FRONT. THEN RAISE POPS TO LIKELY TUESDAY AND TUESDAY NIGHT WITH ONLY
QUESTION ON TIMING.  APPEARS NOW FROPA TO OCCUR LATE TUESDAY INTO EARLY
WEDNESDAY BUT SOME MODEL VARIANCE WITH BIG QUESTION THE PHASING OF
SHORT WAVES AROUND LOW/TROUGH TO IMPACT TIMING.  SIGNIFICANT QPF A
HIGHER CONFIDENCE ISSUE WITH DECENT MOISTURE...TRIGGER WITH FRONT AND
TROUGH AND ALSO GOOD DIFFLUENCE ALOFT TO SUPPORT ONGOING MODERATE
INSTABILITY CONVECTION.  AT LEAST MODERATE AMOUNTS OF QPF REASONABLE
MIDWEEK WITH SOME POTENTIAL FOR HEAVIER AMOUNTS.  PASS FOR LATER SHIFTS
TO MONITOR CLOSELY WITH OUR VERY WET GROUNDS...PROBABLY A COUPLE MORE
DAYS THO BEFORE WE CAN PROPERLY ASSESS FORCING/PHASING QUESTION.

.EXTENDED (WED-SAT)...ALL MODELS SUGGEST NW LOW CURRENTLY IN WASHINGTON
STATE TO ROTATE OVER LONG WAVE RIDGE NEAR 100 DEGREES WEST AND DIVE SE
INTO EASTERN US FRI/SAT.  THIS PROGRESSION IS A TYPICAL SUMMER PATTERN
AND THUS REASONABLE.  RESULT WILL ALLOW FOR GOOD COOL OF AREA THU/FRI
INTO SATURDAY WITH NEAR IDEAL TEMPS...WEATHER AND LOW HUMIDITIES.  BL
TEMPS FROM ALL MODELS SUPPORT GOING ONE TO TWO CATEGORIES BELOW MEX/FMR
GUIDANCE.  SOME CHANCE OF AN EMBEDDED SHORT WAVE LATE FRI/SAT FOR CHANCE
POPS THEN BUT WILL LEAVE DRY FOR NOW.

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

NICHOLS