[LeArc] Forecast Discussion : MLI@ 7/5/2003 4:00:44 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 052047
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
345 PM CDT SAT JUL 5 2003

18Z SURFACE ANALYSIS HAD WEAK FRONTAL BOUNDARY FROM JUST N OF DVN
TO SOUTH OF DSM TO NEAR OMA.  AIRMASS SOUTH OF BOUNDARY QUITE 
UNSTABLE WITH LAPS CAPES JUST OVER 3000 J/KG BY 20Z.  VISIBLE SAT 
IMAGE SHOWING SOME ENHANCED CU ALONG THE MO BORDER...BUT SO FAR NO 
CONVECTION HAS MANAGED TO TAKE OFF.  TSRA OVER NERN NE STARTING TO 
INTENSIFY LATE THIS AFTERNOON AS APROACHING S/W INTERACTS WITH 
SURFACE BOUNDARY. EXPECT THIS CONVECTION TO SPREAD EAST AND INCREASE 
IN COVERGAGE AS LLJ COMES INTO PLAY BY LATE EVENING. BASED ON 
CURRENT POSITION OF THE CONVECTION...E/W BOUNDARY AND E/W 
OREINTATION OF MID LEVEL THICKNESS PATTERN...EXPECT AREAS NORTH OF I 
80 TO HAVE THE BEST POTENTIAL FOR TSRA AND WILL CONTINUE LIKELY 
POPS.  POPS SOUTH OF I80 WERE BUMPED UP TO CHANCE CATEGORY...WITH 
MODELS HOLDING STRONGER CAP WEST CWA...PROVIDING POTENTIAL FOR SOME 
SCATTERED TSRA SOUTH OF THE MAIN CLUSTER. THERE WILL BE POTENTIAL 
FOR SOME LOCALLY HEAVY RAINS AND WILL MENTION IN ZFP. OVERNIGHT 
SHIFTS WILL HAVE TO WATCH AREA BTWN ALO AND DBQ WHERE HEAVIEST QPF 
OCCURRED LAST NIGHT.  ONE HOUR FFG VALUES IN THIS REGION ARE AROUND 
1.3 INCHES.  FURTHER SOUTH ONE HOUR FFG VALUES INCREAS TO AROUND 3 
INCHES. HOWEVER...WILL NOT ISSUE ANY FLOOD HEADLINES ATM THINKING 
THAT MCS TONIGHT WILL BE PROGRESSIVE AS LOW LLJ VEERS TO THE WEST BY 
EARLY SUNDAY MORNING.   CHANCE POPS WILL BE CONTINUED THROUGH THE 
DAY SUNDAY FOR LEFTOVER MORNING CONVECTION...AND POSSIBILITY OF 
OUTFLOW INDUCED CONVECTION DURING THE AFTERNOON/EVENING.  SURFACE 
LOW/COLD FRONT MOVING THROUGH NORTHERN PLAINS SUNDAY NIGHT WILL 
PROVIDE ANOTHER FOCUS FOR CONVECTION DURING THE OVERNIGHT HOURS.  
PER DAY2 OUTLOOK WILL BEEF UP WORDING FOR NORTHERN HALF OF CWA...BUT 
KEEP POPS IN THE CHANCE CATEGORY FOR NOW.  FRONT SETTLES IN OVER SRN 
IA/NRN MO FOR THE REMAINDER OF THE SHORT TERM PERIOD...KEEPING A 
THREAT OF SCT TSRA OVER AREA THROUGH THE PERIOD.  TEMP FORECAST WILL 
BE DEPENDENT OF LOCATION OF TSRA AND RESULTING BOUNDARIES...THE NEXT 
COUPLE OF DAYS.  GENERALLY PREFERRED THE WARMER META TEMPS.

SOME UNCETAINTY IN THE EXTENDED PERIOD WITH GFS HAVING LITTLE RUN TO 
RUN CONTINUITY TOWARD THE END OF THE PERIOD.  AS A RESULT HAVE LEFT 
THE CURRENT FORECAST PRETTY MUCH INTACT WITH THE EXCEPTION OF 
WEDNESDAY.  BOTH THE 00Z AND 06Z GFS ALONG WITH THE UKMET SUGGEST 
THAT THE BOUNDARY SETTLE OVER MO TUESDAY NIGHT.  THEREFORE HAVE 
REMOVED MENTION OF TSRA OVER THE NRN HALF OF CWA DURING THE DAY.  
00Z GFS WOUND UP A DECENT SURFACE LOW OVER THE NRN PLAINS 
FRIDAY/SATURDAY.  HOWEVER THE 06Z RUN SHOWS NO SIGN OF THIS 
FEATURE.  WILL DISCOUNT THE 00Z RUN FOR NOW AND KEEP LATE WEEK DRY.

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

$$
DLF