[LeArc] Forecast Discussion : MLI@ 6/20/02 2:06:30 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 200707
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
205 AM CDT THU JUN 20 2002

POTENTIAL FOR SEVERE WEATHER AND SIGNIFICANT RAINS NEXT 48 HRS. TRYING TO
PINPOINT LOCATION IS MAIN CHALLENGE...ALONG WITH 
TEMPERATURES AS POTENTIAL FOR DECENT GRADIENT DEPENDING UPON LOCATION
OF FRONT AND EXTENT OF CLOUDS. 

SURFACE FRONT EXTENDS FROM EASTERN MN THROUGH NORTHWEST IA INTO NORTHWEST KS
AT 06Z...FAIRLY CLOSE TO MODELS. UPPER SUPPORT LIFTING AWAY FROM
MIDWEST WITH SHORTWAVE TROUGH CURRENTLY OVER MANITOBA LIFTING NORTHEAST TOWARD
JAMES BAY. FRONT STILL HAS DECENT PUSH (6 MB/3 HR PRESSURE RISES)
WITH AID OF CONVECTION. FRONTAL MOVEMENT EXPECTED TO SLOW AND WEAKEN WITH
TIME...AS UPPER SUPPORT LIFTS OUT AND FLOW ALOFT BECOMES 
NEARLY PARALLEL. REGIONAL RADARS SHOW CONVECTION FROM NORTHWEST IA INTO EASTERN
MN WITH NEWLY DEVELOPED ELEVATED CONVECTION FROM NORTHEAST IA INTO 
CENTRAL WI ON NOSE OF VEERING 45-50 KT LLJ. WILL MONITOR RADAR TRENDS TO
DETERMINE FIRST PERIOD WORDING. RAIN CHANCES THIS MORNING APPEAR WILL BE 
MAINLY NORTH OF CEDAR RAPIDS...TO CLINTON LINE WITH LIMITED 
ELEVATED INSTABILITY FURTHER SOUTH. WITH FRONT THROUGH SOUTHWEST NE AT 00Z
THU...OLD RULE SAYS IT SHOULD BE INTO ATLEAST THE FAR NORTH SOME 24 HRS
LATER. THEREFORE...ANTICIPATE THE WEAKENING FRONTAL ZONE TO MAKE
NORTHEAST IA ZONES BY EVENING. SCATTERED SHRA/TSRA EXPECTED TO DEVELOP WITH
AFTN HEATING. THUS...WILL PLACE HIGHEST POPS NORTH AND ESPECIALLY WEST
OF RIVER IN CLOSER PROXIMITY TO FRONT. STRONG/HIGH CAPES OF 2500+ J/KG...IN
MODERATE SHEAR ENVIRONMENT SUGGEST SEVERE POTENTIAL AND AGREE WITH SPC/S 
SLIGHT RISK OUTLOOK ACROSS THE NORTHERN ZONES. MAX TEMPS SOMEWHAT CHALLENGING...
AS WE SAW YESTERDAY ANY DEBRIS CLOUDINESS WHICH LINGERS FOR A WHILE 
WILL IMPACT TEMPS. OVERALL...CIRRUS LOOKS TO BE THINNING ON SATELLITE...SO 
BELIEVE WE/LL SEE MORE SUNSHINE PEEKING THROUGH. THUS...WILL RAISE MAXES UP TO 
NEAR GUIDANCE.

TONIGHT...SIGNS POINT TOWARD POTENTIAL HEAVY RAIN EVENT WITH PW/S INCREASING
TO NEARLY 2 INCHES...WEAK FLOW AND DECENT THETA-E ADVECTION.
QUESTION REALLY IS WHERE...AND IT WOULD APPEAR INITIALLY THE FOCUS WILL BE
ACROSS NORTHERN IA WITH LLJ...WITH POSSIBLE MCS OR TRAINING CELLS
AFFECTING NORTHERN THIRD OF CWA. WILL CONTINUE WITH HIGHEST POPS (LIKELY)
HERE AND FOR NOW GIVEN UNCERTAINTY JUST MENTION HEAVY RAIN POSSIBLE 
IN ZONES AND HIGHLIGHT IN SIG WEATHER OUTLOOK. COULD BE SHARP CUTOFF TO PCPN
WITH SOUTH POSSIBLY STAYING DRY WITH CAP AND GIVEN 
CLOSER PROXIMITY TO UPPER LEVEL HIGH...ALTHOUGH ANY OUTFLOW COULD SERVE
AS FOCUS. 

FRONT EXPECTED TO LIFT NORTH BY SATURDAY EVENING...TAKING BULK OF PCPN THREAT
WITH IT. HOWEVER...SOME CONCERNS WITH UPPER LEVEL LOW DEPICTED BY
MODELS. COULD SEE SOME PCPN DEVELOP LATE WEEKEND AND ESPECIALLY EARLY NEXT
WEEK OVER REGION ON PERIPHERY OF UPPER SYSTEM.

TEMPERATURES EXPECTED TO REMAIN QUITE WARM INTO THE WEEKEND WITH RISING 
UPPER HEIGHTS. HUMIDITY TO ADD IN MAKING IT FEEL EVERY BIT 
SUMMER.


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