[LeArc] Forecast Discussion : MLI@ 5/27/2003 4:31:20 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 272128
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
428 PM CDT TUE MAY 27 2003

SYNOPTIC PICTURE THIS AFTERNOON SHOWS HIGH PRESSURE OVER THE
SOUTHERN PLAINS...WITH A COLD FRONT ACROSS THE DAKOTAS INTO WESTERN
NEBRASKA.  AT 500MB A SHORT WAVE ASSOCIATED WITH THE COLD FRONT
EXTENDS ACROSS THE DAKOTAS.  AT THE JET LEVEL A 100KT JET EXTENDS
FROM SASKATCHEWAN INTO THE DAKOTAS.

THE PRIMARY FORECAST CONCERNS ARE A WEAK COLD FRONT MOVING THROUGH
THE FORECAST AREA WEDNESDAY MORNING...AND A SECOND STRONGER COLD
FRONT IN THE FRIDAY TIME FRAME.

THE MODELS BRING THE FIRST FRONT THRU DVN AROUND 15Z WEDNESDAY.
ALTHOUGH TECHNICALLY A COLD FRONT...WARMER AIR WILL FOLLOW
INITIALLY...WITH A BRIEF COOLER PUNCH WEDNESDAY NIGHT. CAPES AND LI'S
WEDNESDAY WILL BE MARGINAL THRU MIDDAY...AFTER WHICH A NORTHWEST
BREEZE TAKES OVER. SPEED AND DIRECTIONAL SHEAR WILL BE MARGINAL IN
THE MORNING INTO MIDDAY...AS WILL MOISTURE.  700MB VV'S AND 300MB
DIVERGENCE WILL BE FAVORABLE FOR CONVECTION FROM 12Z THRU 18Z...
PERHAPS 2 TO 3 HOURS EARLIER EXTREME NORTHWEST...AND A FEW HOURS
LATER EXTREME EAST AND SOUTHEAST.  THE 500MB SHORT WAVE GOES
OVERHEAD MIDDAY.  THUNDERSTORMS COULD BECOME STRONG INTO THE
AFTERNOON AT THE EASTERN EDGE OF THE FORECAST AREA...AND EAST INTO
NORTH CENTRAL ILLINOIS...PER BETTER DIURNAL TIMING...AS SEEN IN SPC'S
SLIGHT RISK OF SEVERE ACROSS MOST OF ILLINOIS.

AFTER THIS FRONT...THICKNESSES WILL RECOVER THURSDAY AS A RIDGE
BUILDS IN.  THE NEXT COLD FRONT...FRIDAY...ARRIVING ON A
CONTINUED NORTHWEST FLOW COULD PRODUCE STRONGER CONVECTION...BUT
THAT DEPENDS ON TIMING.  AS WITH THE FIRST FRONT...PASSAGE COULD
BE EARLY IN THE DAY...WHICH WOULD SHOVE THE STRONGEST CONVECTION
EAST.  EITHER WAY...THE COOL AIR ADVECTION BEHIND THIS SYSTEM WILL BE
CONSIDERABLY STRONGER...CONTINUING INTO SATURDAY NIGHT.  ANOTHER
RIDGE MOVES OVERHEAD SUNDAY...AND THE NEXT SYSTEM SEEMS TO BE IN
THE TUESDAY/WEDNESDAY TIME FRAME.

WILL MAKE ONLY MINOR ADJUSTMENTS TO CURRENT FORECAST...MAINLY IN THE
SHORT TERM.  WILL INTRODUCE PRECIP NORTHWEST LATE TONIGHT...AND
WILL CLEAR PRECIP FROM WESTERN AREAS IN THE MORNING.

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

$$

REA