[LeArc] Forecast Discussion : MLI@ 5/17/2003 3:37:18 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 172035
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
335 PM CDT SAT MAY 17 2003

H5 LOW LUMBERING THROUGH THE LOW MS VALLEY THIS MORNING WAS 
SPREADING MID/HIGH CLOUDS AS FAR N AS CENTRAL IL AND NE MO LATE THIS 
AFTERNOON.  MORNING FOG/STRATUS OVER NRN IL/SRN WI CU'D OUT FAIRLY 
QUICK THE MORNING WITH CU FIELD SPREADING AS FAR WEST NORTH CENTRAL 
IA WITH CU OVER W CENTRAL IL HAVING A HARD TIME CROSSING THE MS.  

MAIN CONCERNS THIS ROUND WILL BE THE CLOUD/FOG POTENTIAL TONIGHT 
THEN STRONG COLD FRONT MOVING THROUGH MONDAY NIGHT.  

MODELS SHIFT UPPER LOW FURTHER SOUTH OVERNIGHT AND LESSENS POTENTIAL 
FOR ANY SIGNIFICANT CLOUD COVER OVER CWA ONCE THE CU DISSIPATES 
EARLY THIS EVENING.  SURFACE RIDGE ACROSS NORTHERN IA THIS AFTERNOON 
SHOULD SETTLE OVER NRN HALF CWA OVERNIGHT.  WITH CLEAR SKIES AND 
LIGHT WIND NEAR THE RIDGE...EXPECT TO SEE SOME FOG DEVELOPMENT 
ESPECIALLY NORTH AND WILL EXPAND MENTION IN NORTHEAST IN CURRENT 
PACKAGE TO NRN HALF OF CWA. MET/MAV ARE IN AGREEMENT FOR MINS TONIGHT
AND LOOK REASONABLE.  SURFACE RIDGE MOVES SOUTHEAST OF CWA SUNDAY 
KEEPING REGION IN LIGHT SELY FLOW.  LITTLE MIXING WILL LIMIT MAX 
TEMPS AND WILL STAY CLOSER TO THE FWC.  MAV A LITTLE TOO COOL SINCE 
THERE SHOULD BE SOME SUN THROUGH THE DAY WITH ONLY SCT-BKN CU 
EXPECTED.  MODELS ARE IN DECENT AGREEMENT WITH STRONG COLD FRONT 
MOVING THROUGH LATE MONDAY.  AS FOR TIMING...GFS IS A LITTLE 
FASTER...MOVING THE FRONT ALMOST TO THE MS BY 00Z TUE WHILE THE ETA 
HOLDS IT BACK OVER WESTERN CWA. BASED ON THE STRENGTH OF THE HIGH 
OVER THE NORTHERN PLAINS WILL LEAN TOWARD THE QUICKER MOVEMENT. 
SURFACE FLOW AHEAD OF FRONT IS WEAK AND DON'T EXPECT TEMPS TO GET 
OUT OF HAND.  WILL LEAN TOWARD THE MIDDLE OF THE ROAD FWC.  ETA 
SOUNDINGS SHOW AIMASS AHEAD OF FRONT IS STRONGLY CAPPED UNTIL LATE 
AFTERNOON...WHICH WILL KEEP CONVECTION CLOSE TO THE BOUNDARY.  
CURRENT FORECAST REFLECTS THIS THINKING...WITH BEST POPS AFTER 00Z 
AND ONLY CHC POPS IN THE LATE AFTERNOON IN THE WEST.  THIS EVENT IS 
SHAPING UP TO BE A LOW SHEAR...HIGH BOUANCY SCENARIO...THUS EXPECT 
MORE LINEAR CONVECTION WITH PREDOMINANT SEVERE THREAT BEING STRAIGHT 
LINE WINDS. HAIL THREAT SHOULD BE MINIMAL WITH WBZ'S CLOSE TO 11KFT 
LATE MONDAY AFTERNOON. THERE MAY ALSO BE A FLASH FLOOD THREAT WITH 
THE ETA SUGGESTING PW'S AROUND 1.5 MONDAY AFTERNOON AND GROUND IN 
MOST AREAS VERY MOIST.   HOWEVER...SPEED OF SYSTEM SHOULD LIMIT 
RAINFALL...AND KEEPING FF THREAT LOCALIZED. POST FRONTAL PCPN SHOULD 
BE LIMITED WITH ANTICYCLONIC FLOW DEVELOPIING QUICKLY AFTER FROPA 
AND HAVE LIMITED RN CHANCES TO JUST THE OVER NIGHT HOURS.  SHOULD BE 
WINDY FROM LATE MONDAY NIGHT TO MIDDAY TUESDAY AS STRONG SFC 
PRESSURE GRADIENT MOVES THROUGH. 

EXTENDED....
MODELS IN GENERAL AGREEMENT THROUGH THE PERIOD KEEPING REGION UNDER 
THE INFLUENCE OF H5 TROUGH.  SHOULD SEE BELOW NORMAL TEMPS AND WILL KEEP
TEMPS A LITTLE UNDER MEX NUMBERS.  ONLY PRECIPITATION THREAT APPEARS 
TO BE OVERNIGHT THURSDAY WITH BACKDOOR FRONT MOVING THROUGH.  GFS 
THE MOST AGRESSIVE WITH PCPN...MOVING SURFACE LOW SOUTH ALONG THE MO 
RIVER.  FOR NOW WILL GO WILL LOW CHANCE POPS FOR -SHRA THINKING THAT 
CONVECTION WILL BE MOST LIKELY NEAR ERN NE/WRN IA IN REGION OF BEST 
LOW LEVEL FORCING.  CONVECTION SHOULD STRATIFY OUT AS MOVES E INTO 
COOLER AIR MASS.


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

$$

DLF