[LeArc] Forecast Discussion : MLI@ 7/16/2003 3:24:52 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 160818
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
317 AM CDT WED JUL 16 2003

SURFACE HIGH CENTERED OVER NORTH CENTRAL IA EARLY THIS MORNING TO 
KEEP CLEAR SKIES OVER CENTRAL AND EASTERN ZONES...WHILE CI FROM MCS 
IN HIGH PLAINS WILL DRIFT INTO WEST LATER THIS MORNING. DISSIPATING 
TSRA COMPLEXES SEEN ON SATELLITE OVER WESTERN NEB INTO SD OCCURRING 
ON BAROCLINIC ZONE AT EDGE OF UPPER RIDGE CENTERED OVER ROCKIES. 
MAIN SHORT TERM FORECAST CHALLENGE IS THUNDERSTORM CHANCES THROUGH 
END OF WEEK AS DEPARTING HIGH ALLOWS RETURN FLOW AND PERIODIC 
SHORTWAVES IN NW FLOW AFFECT AREA.

GFS 06Z POSITION OF VORT ASSOCIATED WITH SD CONVECTION LOOKS BETTER 
THAN STRONGER/FURTHER WEST ETA SOLUTION. THIS TAKES THE MCV IN A 
PATH INTO SE IA BY 00Z...BUT WITH DRY LOW LEVELS AND CAP IN 
PLACE...WILL KEEP TODAY DRY WITH HIGHS ON WARM END OF GUIDANCE. 
TONIGHT...HIGH PLAINS THETA E RIDGE AXIS SHIFTS EAST WITH SOME 
ELEVATED CONVECTION POSSIBLE IN WESTERN ZONES AS SURFACE WARM FRONT 
EDGES INTO S CENTRAL IA AND THUS KEPT IN SLIGHT CHANCE POPS IN 
WEST.  THURSDAY...THIS FRONT WILL BE SOMEWHERE IN CENTRAL OR 
SOUTHERN CWFA...DEPENDING ON MODEL SOLUTION AND CANNOT RULE OUT TSRA 
WITH H85 DEWPOINT RIDGE AXIS OVERHEAD SO KEPT LOW SCATTERED POPS. 
STAYED WITH TREND OF UNDERCUTTING HIGH TEMP GUIDANCE...ESPECIALLY 
NORTH OF FRONT WHERE LOW LEVEL EASTERLY FLOW AND INCREASED CLOUD 
COVER TO HOLD TEMPS DOWN. BETTER TSRA CHANCES FRIDAY AS MORE 
SIGNIFICANT SHORTWAVE IN NORTHWEST FLOW PUSHES THROUGH...ALTHOUGH 
GFS WAY OVERDONE SUFFERING FROM FEEDBACK ISSUES. HOWEVER...UKMET HAS 
SIMILAR TIMING TIMING BUT WEAKER SHORTWAVE THAT COULD PRODUCE MAINLY 
MORNING THUNDERSTORM COMPLEX THAT WILL PUSH THE FRONT BACK TO SOUTH. 
WENT WITH SCATTERED POPS EXTENDED INTO EVENING WITH SOME UNCERTAINTY 
THAT FAR OUT IN TIMING AND MESOSCALE BOUNDARIES. SURFACE HIGH 
SETTLES OVER AREA SATURDAY FOR DRY AND COOLER DAY.
...SHEETS

EXTENDED...SUN-TUE
MODELS ALL POINTING TO ANOTHER COOL DOWN BY EARLY NEXT WEEK. THE GFS 
AND THE EUROPEAN MODELS SHOW A STRONG MID LEVEL TROF SWINGING 
THROUGH THE GREAT LAKES SUNDAY.  SIGNIFICANTLY COOLER AIR 
INFILTRATES THE MID MISSISSIPPI VALLEY MONDAY AND TUESDAY WITH THE 
GFS SHOWING H8 TEMPS DIPPING BELOW 10C BY MONDAY. UKMET...WHICH IS 
SHOWING A SLIGHTLY STRONGER SURFACE HIGH...SUPPORTS THE COOL TEMPS.  
THERE ARE SOME TIMING DIFFERENCES BETWEEN THE MODELS WITH THE 
FRONTAL PASSAGE SUNDAY.  THE BY 00Z MONDAY THE GFS SHOWS THE FRONT 
OVER THE NW CWA WHILE THE UKMET HAS IT WELL INTO MISSOURI.  WILL GO 
WITH A COMPROMISE AND INTRODUCE CHANCE POPS SUNDAY.  BY MONDAY 
MODELS SHOW A SHARP H5 TROF OVER THE GREAT LAKES WITH A SURFACE 
AROUND 1020MB MOVING INTO NRN MN.  THE GFS PLACES THE CENTER OF THE 
H5 TROF OVER LM WITH THE UKMET KEEPING IT JUST NORTH OF SUPERIOR.  
THE STRENGTH OF THE TROF SUGGEST A GOOD MID LEVEL COOL POOL SUPPORT 
INSTABILITY SHRA/TSRA. AGAIN HAVE COMPROMISED BETWEEN THE 
GFS/UKMET...PLACING CHANCE POPS OVER THE NERN HALF OF THE CWA 
MONDAY.  HIGH PRESSURE BUILDS INTO WESTERN IOWA BY TUESDAY 
AFTERNOON.  BASED ON H8 TEMPS OFF THE GFS...HAVE LOWERED MINS/MAXES 
ABOUT A CATEGORY FOR MONDAY AND TUESDAY...AND WILL LIKELY HAVE TO GO 
COOLER IF MODELS FOLLOW THROUGH WITH THIS SOLUTION.  DLF

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

$$