[LeArc] Forecast Discussion : MLI@ 4/19/2003 3:18:35 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 192013
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
308 PM CDT SAT APR 19 2003

FIRST ROUND OF ELEVATED CONVECTION STRATIFYING OUT OVER THE NORTHERN
HALF OF THE CWA ATTM. NICHOLS BLEP TECHNIQUE OFF KDVN 18Z SPECIAL
SOUNDING INDICATES STRONG WINDS OF 40 TO 60 KTS JUST OFF SFC...CAME
CLOSE TO MIXING DOWN FOR SEVERAL SEVERE REPORTS. JUST NEEDED A LITTLE
MORE AMBIENT WARMTH AND MORE WIDESPREAD SFC DPTS IN THE LOWER 60S...
CAPES PUSHING 900 TO 1000 J/KG AS OPPOSED TO THE 600 J/KG WE HAVE OFF
THE 18Z PROFILE. AS IT WAS...SEVERAL REPORTS/ASOS INDICATED 35 TO
AT LEAST 45 MPH WIND GUSTS RECEIVED AS INITIAL LINE PUSHED NORTH
THROUGH THE CWA.

AVN-GFS AND ETA/META ARE CLOSE WITH SYNOPTIC SCALE FEATURES AND WILL
GENERALLY FOLLOW BLEND THROUGH SUNDAY...ALTHOUGH NOT THAT TRUSTING OF
PRECIP PLOTS...AMOUNTS AND EVOLVEMENT OVERNIGHT. W/V INDICATED VORT
NOW LIFTING UP THROUGH THE NORTHERN CWA...WILL CONTINUE TO EXIT
TO THE NORTH THIS EVENING...BUT NEXT MAIN VORT ROUNDING BASE OF
SOUTHERN PLAINS/GRT BSN TROUGH THIS MORNING TO STREAK UP OVER THE
AREA BY 05Z-06Z. THUS ANOTHER ROUND OF DEEP CVA LOOKS ON TAP FROM
AROUND 03Z-07Z FOR ANOTHER ROUND OF MIDNIGHT CONVECTION. INTERESTING
THOUGH THAT SHORT RANGE MODELS SUGGEST BEST MID LEVEL POS OMEGAS GET
SHUNTED JUST SOUTH AND THEN EAST OF THE CWA FROM 06Z-12Z SUNDAY. NEW
MORE SOUTHERN SFC LOW WILL BECOME MAIN FEATURE AS IT DEEPENS IN
RESPONSE TO THE ABOVE MENTIONED WAVE AS IT ARRIVES...AND WILL PULL
UP THROUGH IA/MN/WI TRI-STATE REGION THROUGH 06Z. THUS MAIN SFC
BOUNDARY TO REMAIN WEST OF THE CWA UNTIL LATE TONIGHT WHEN IT GATHERS
SOME HEADWAY EAST...KEEPING LOCAL AREA OF CONCERN IN PRE-FRONTAL
STORM TRACK...ESPECIALLY WITH NEW ROUND OF UPPER SUPPORT. CONVECTIVE
ACTIVITY MAY PROPAGATE OUT OF EASTERN KS/WESTERN MO HOT BOX AND UP
OVER THE CWA...AS WELL AS NEW DEVELOPMENT AHEAD OF SFC FRONT IN
NORTHEAST MO AND EASTERN IA ITSELF. STORMS TO STILL BE RACERS WITH
CONTINUING 45-50 KT SOUTHWESTERLY LOW TO MID LEVEL FLOW OVER THE
EASTERN 2/3'S OF THE CWA. SEVERE THREAT...AS WELL AS HEAVY RAINFALL
CHANCES SEEM TO BE MORE LIMITED NOW IN MORE STABLE REGIME ALOFT(AND
AT SFC) THAN EARLIER EXPECTED. BUT ISOLATED HAIL AND EVEN LOCALIZED
HIGH WIND GUSTS STILL NOT OUT OF THE QUESTION THOUGH EARLY SUN
MORNING. WILL LEAN TOWARD HIGHER MET LOWS TONIGHT WITH CWA BATHED IN
PREFRONTAL DPTS AND SOUTHERLY FLOW...EXCEPT FAR WESTERN AND
NORTHWESTERN CWA WHICH WILL EXPERIENCE FROPA FROM THE WEST TOWARD SUN
MORNING.

MAIN CONVECTION PRODUCING PARAMETERS SET UP TO THE EAST OF THE CWA ON
EASTER SUNDAY...WITH CWA TO BE DRY SLOTTED. WRAP AROUND RAIN WILL
STILL BE POSSIBLE ACRS THE NORTH HALF BY LATE SUN AFTERNOON AND NIGHT
AS VORT SPOKE ROTATES AROUND UPPER SYSTEM. LIKE GFS TREND OF
MAINTAINING CLOSED UPPER LOW THE LONGEST OVER THE GRT LKS INTO MON
NIGHT...WITH ANOTHER WRAP AROUND VORT AND MID LEVEL COOL POOL
POSSIBLY INDUCING SOME SCATTERED INSTABILITY SHOWER ACTIVITY ON MON.

.LONGER RANGE(TUE-SAT)...MEDIUM RANGE MODELS HAVE THEIR DIFFERENCES
...BUT GENERAL ENSEMBLE STILL SUGGESTS BLOCKING PATTERN ALOFT AND
GRT LKS SFC HIGH TO BRING FAIR BUT SEASONABLY COOL WX FOR TUE AND
WED. DIFFERENCES ARRIVE MAINLY IN STRENGTH AND PLACEMENT OF NEXT
LARGE PIECE OF WESTERN CONUS L/W ENERGY THAT ROLLS OUT AND TRIES TO
BUCK UPPER RIDGE BY LATE WED AND THU. STILL WILL LEAN TOWARD OVER-
RUNNING RAIN EVENT FOR THU AS LLVL THERMAL RIBBON SHIFTS BACK
NORTH OF THE AREA. FEEL RAIN THREAT WILL LINGER INTO FRI WITH SLOW
MOVING CLOSED UPPER SYSTEM. AS OF NOW...APPEARS PRECIP TO EXIT FOR
START OF WEEKEND...BUT YET ANOTHER BACKDOOR HIGH/GRT LKS COOL FETCH
TO SET UP FOR SAT AND WILL UNDERCUT MEX HIGHS A CATEGORY.

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

$$

12