[LeArc] Forecast Discussion : MLI@ 5/21/02 3:05:22 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 210803
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 AM CDT TUE MAY 21 2002

HIGH AMPLITUDE FLOW REMAINS IN PLACE OVER THE U.S.  UPPER RIDGE
CENTERED OVER THE HIGH PLAINS BOUNDED BY H5 LOWS OVER ERN CANADA
AND OFF THE PAC COAST.  AT 06Z SURFACE HIGH PRESSURE WAS CENTERED
OVER NORTHERN IL WHERE TEMPS WERE IN THE LOW TO MID 30S. MODELS IN
OVERALL AGREEMENT AS PATTERN BECOMES MORE PROGRESSIVE.  H5 RIDGE
DRIFTS EAST TODAY AS STRONG SYSTEM OVER SRN CA COAST MOVES ON SHORE.
SYSTEM THEN LIFTS NORTHEAST INTO THE NORTHERN PLAINS WITH THE ETA/NGM  A
LITTLE STRONGER AND FURTHER EAST THAN AVN.  AT THE SURFACE MODELS MOVE
HIGH PRESSURE INTO THE CAROLINAS BY EARLY WEDNESDAY...WHERE IT TAKES UP
RESIDENCE UNTIL LATE IN THE WEEK.  COLD FRONT ASSOCIATED WITH
NORTHERN PLAINS SYSTEMS MOVES INTO NW IA BY LATE THURSDAY AND MOVES
THROUGH CWA BY FRIDAY MORNING.

CONCERNS THIS FORECAST ISSUANCE WILL CENTER ON TEMP TRENDS NEXT COUPLE
OF DAYS.  CWA WILL BE ON THE WESTERN EDGE OF THE RETREATING HIGH
PRESSURE TODAY.  LOW LEVEL RH IS FINALLY DRYING OUT...SO CU DEVELOPMENT
SHOULD BE FAR LESS THAN PREVIOUS FEW DAYS.  LIGHT SOUTHEASTERLY FLOW
OFF SURFACE HIGH WILL LIMIT TEMP RISE EVEN WITH SUNSHINE.   RETURN
FLOW SETS UP BY LATE TONIGHT...SO MIN TEMPS SHOULD BE ATTAINED AROUND
06Z.  CURRENT FCST PACKAGE LOOKS IN GOOD SHAPE THROUGH TONIGHT AND SEE
NO REASON TO MAKE SIGNIFICANT CHANGES.  GOING TEMPS ARE IN LINE WITH
MAV/FWC BLEND.  PRESSURE GRADIENT TIGHTENS BY WEDNESDAY MORNING WITH
H850 WINDS INCREASING TO 40 TO 50 KTS DURING THE DAY.  WILL GO WITH
WINDY WORDING AND PUSH TEMPS ABOVE GUIDANCE WITH GOOD MIXING AND ONLY
HIGH CLOUDS MOVING IN LATE IN THE DAY.  WILL ADD IN SOME POPS LATE WED
NIGHT.  BOTH AVN/ETA PRINTING OUT PCPN...ESPECIALLY WEST OF THE
MISSISSIPPI RIVER BY 12Z THURSDAY.  THIS IS SUPPORTED BY SOME THEA-E
ADVECTION AND MID LEVEL LAPSE RATES AROUND 6.5C OVER CWA.  IF
CONVECTION GETS GOING NEAR THE FRONT IN WESTERN IOWA IT SHOULD BE
ABLE TO MAINTAIN ITSELF AS IT MOVES INTO EASTERN IOWA.

LOOKS LIKE THE BEST SHOT FOR RAIN WILL OCCUR THURSDAY NIGHT AS COLD
FRONT MOVES ACROSS CWA.   AVN IS GENERATING SOME SIGNIFICANT PCPN OVER
THE CWA AND WILL HAVE TO BE WATCHED...ESPECIALLY IN THE SOUTH WHERE ITS
STILL DRYING OUT FROM LAST WEEKS WET WEATHER. MODELS STALL FRONT TO OUR
SOUTH FOR THE END OF THE WEEK...KEEPING THE THREAT OF RAIN IN THE
FORECAST THROUGH EARLY SATURDAY.


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

DLF