[LeArc] Forecast Discussion : MLI@ 7/13/2003 2:03:37 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 131859
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
155 PM CDT SUN JUL 13 2003

STEEP LAPSE RATES WITH AMPLE LLVL MOISTURE FUELING CU DEVELOPMENT 
ONCE AGAIN. VISIBLE SATELLITE AND OBSERVATION FROM THE 
OFFICE WINDOW SHOW DECENT VERTICAL EXTENT WITH SOME OF THE 
CU...ESPECIALLY ALONG AND EAST OF THE MISSISSIPPI. 12Z UA ANALYSIS 
PLACES 70 KT H25 JET STREAK OVER MN. WATER VAPOR SHOWS
THIS DIVING SOUTHEAST ALONG BACKSIDE OF EASTERN U.S. TROUGH. RIGHT 
ENTRANCE REGION OF SPEED MAX AND WEAK VORT LIKELY AIDING 
ISOLD WEAK SHOWERS...WHICH HAVE DEVELOPED OVER PORTIONS OF NORTHEAST 
IA AND NORTHWEST IL. 
 
WILL CONTINUE TO MONITOR LATEST SATELLITE/RADAR TRENDS...BUT FEEL
THE SHOWERS WILL REMAIN VERY ISOLD AND BEST HANDLED WITH NOWCASTS. 
ANY ACTIVITY WILL DIMINISH QUICKLY AROUND SUNSET ALONG WITH 
THE CU FIELD. VORT MAX OVER SOUTHERN MANITOBA CURRENTLY GENERATING
SOME MID/HIGH CLOUDS INTO NORTHERN MN...WILL SHEAR AND WEAKEN 
WHILE DIVING SOUTHEAST. THIS COULD GENERATE SOME MID/HIGH CLOUDS 
LATE TONIGHT...BUT OVERALL FEEL MOSTLY CLEAR WILL SUFFICE. 
ATTENTION LATER TONIGHT SHIFTS OUT WEST TO FRONTAL ZONE WHICH 
WILL BE MARCHING THROUGH THE PLAINS. CONVECTION EXPECTED TO FIRE ALONG
THE FRONT OVER PORTIONS OF THE DAKOTAS IN REGION OF BEST
H85 MOISTURE TRANSPORT AND LLVL MOISTURE CONVERGENCE IN ADVANCE
OF FRONT AND MID LEVEL SHORTWAVE. POTENTIAL EXISTS 
FOR CONVECTION TO DEVELOP INTO A FORWARD PROPAGATING MCS. CONVECTION
SHOULD MOVE EAST/SOUTHEAST TOWARD THE CWA DURING THE DAYTIME
ON MON...BUT REMAIN JUST TO OUR WEST. PRESSURE GRADIENT TIGHTENS
AHEAD OF FRONT ON MON WHILE FAIRLY STEEP LAPSE RATES SUPPORTIVE OF 
DEEP LAYER MIXING. THIS SHOULD RESULT IN SUSTAINED WINDS 10 TO 
20 MPH FROM THE SOUTH-SOUTHWEST LATE MORNING AND AFTERNOON WITH 
GUSTS TO AROUND 25 MPH ESPECIALLY IN THE NORTH/WEST.
DEEP LAYER MIXING WILL TAP INTO WARM WEDGE AT H85 AIMED AT CWA.
THUS...IT WILL FEEL VERY SUMMERLIKE THOUGH WINDS WILL TAKE
EDGE OFF HEAT/HUMIDITY. GOING TEMPS LOOK REAL GOOD AND THUS PLAN
LITTLE IF ANY CHANGE. 

MON NIGHT FRONTAL ZONE WILL BE APPROACHING...AND IS PROGGED TO MOVE
INTO THE NORTHWEST AFTER MIDNIGHT. CONVECTION EXPECTED 
TO DEVELOP LATE AFTERNOON AND EARLY EVE OUT TO OUR WEST WITHIN LLVL 
CONVERGENCE ALONG AND AHEAD OF FRONT DESPITE DECENT 
CAPPING INVERSION. ACTIVITY SHOULD AGAIN EVOLVE INTO A FORWARD
PROPAGATING MCS WHICH WILL MOVE SOUTHEAST AND THEN MORE TO THE SOUTH
FEEDING INTO THE AXIS OF MOIST...UNSTABLE AIR...BRUSHING THE
SOUTH/WEST ZONES. STILL...DEEP LLVL MOISTURE (70-75 DEWPTS)...LLVL
CONVERGENCE AND FAVORABLE UPPER LEVEL DIFFLUENCE SUPPORTS ONGOING 
LIKELY POPS. SEVERE POTENTIAL APPEARS LIMITED DUE TO TIMING.
BEST POTENTIAL WOULD APPEAR TO BE WELL NORTH ACROSS PORTIONS OF THE
UPPER MIDWEST AND GREAT LAKES ASSOCIATED WITH UPPER JET...AND
THEN TO OUR WEST AND SOUTH WITH SEVERE MCS. FRONT MOVES THROUGH 
EARLY ON TUE...SO CUT BACK ON POPS WITH SLIGHT CHC NORTH AND
CHC IN THE SOUTH FOR THE MORNING. HIGH PRESSURE QUICKLY BUILDS IN WITH
DECREASING CLOUDS AND TRANQUIL WX ON WED. THE HIGH THEN RETREATS ON 
THU WITH RETURN FLOW COMMENCING. BEST PCPN CHCS ON THU LOOK TO 
BE TO OUR NORTH ON THE NOSE OF STRONG WARM ADVECTION. MEANWHILE...HEAT
FESTERS IN THE PLAINS. 

EXTENDED (THU-SUN)...
NEXT FRONT PROGGED ON FRI...THOUGH TIMING OF CONCERN AS IT MAY END 
UP BEING QUICKER...SIMILAR TO TRENDS WITH FRONT NOW ARRIVING
MON NIGHT. AXIS OF HADLEY CELL 500 RIDGE IS SOUTH 
OF DVN THUS EXPECT THE TRAILING EDGE OF THE FRONT TO GO SOUTH 
OF CWA AND LIE IN THE VICINITY OF CENTRAL IL ON SAT. 
THEREFORE...WILL GO WITH CHC POPS FRI/FRI NIGHT AND LEAVE OUT MENTION
ON SAT AND SUN. 

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

$$

FIVE