[LeArc] Forecast Discussion : MLI@ 3/25/03 5:05:02 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 251101
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
455 AM CST TUE MAR 25 2003

REGIONAL AND LOCAL 88D LOOPS INDICATING ELEVATED CONVECTION HAS
EXITED THE CWA...WITH NEW AREAS DEVELOPING FROM SOUTHEAST KS...INTO
NORTH CENTRAL MO ATTM. SOUTHERN STREAM VORT PULLING OUT SOUTHERN
PLAINS HELPING SPAWN THIS ACTIVITY...BUT WILL BE OF NO CONSEQUENCE
TO THE LOCAL AREA TODAY. SECONDARY AREA OF ELEVATED RAIN STREAKING
QUICKLY OUT OF KS AND TOWARD EXTREME NORTHWEST MO...MAY GLANCE THE
FAR SOUTHERN CWA THIS MORNING AND HAVE KEPT SLIGHT CHANCE FOR THIS
POSSIBITLTY...BUT WILL PROBABLY STAY SOUTH OF THE AREA OR
DISSOLVE(NORTHERN FRINGE OF PRECIP SHIELD THAT IS).

CENTRAL ROCKIES VORT WILL LOOK TO SHEAR EAST ACRS IA TODAY...AS L/W
TROUGH PUSHES ACRS THE UPPER MS RVR VALLEY. MODELS ACTUALLY SUGGEST
DECENT UPPER LEVEL FORCING AND UPWARD VERTICAL MOTIONS AHEAD OF THIS
FEATURE BY MIDDAY ACRS THE CWA...BUT DEEPENING NORTH-NORTHWEST FLOW
AT THE SFC TO BRING ABOUT DRYING/SCOURING EFFECT. SO JUST EXPECT
SOME MID TO HIGH LEVEL CLOUDS AND POSSIBLY SOME VIRGA AS FEATURE
PUSHES OVER THE AREA TODAY. ALTHOUGH CWA UNDER CAA TODAY...WITH
INCREASING NORTHWEST MIXING WIND AND SOME PATCHY SUNSHINE BREAKING
OUT...EXPECT MID TO UPPER 50S OVER MOST OF THE CWA TODAY....MAYBE
EVEN A 60. FAR SOUTHERN CWA MAY HAVE TROUBLE GETTING OUT OF THE LOW
TO MID 50S...IF CLOUDS HOLD TOUGH AND WITH WET GROUND EFFECT FROM
OVERNIGHT RAINFALL. BRIEF BOUT OF WEAK SFC RIDGING TO BRING CLEARING
AND COOL CONDITIONS TONIGHT.

INCOMING LOW AMPLIFIED BROAD UPPER RIDGE...CLOSE TO ZONAL FLOW...TO
USHER IN PACIFIC WAVE COMPLEX ACRS THE NORTHERN/CENTRAL PLAINS
AND UPPER MIDWEST LATER ON WED...INDUCING LARGE SCALE CYCLOGENESIS
AT THE SFC OVER WESTERN HIGH PLAINS. SHORT RANGE MODEL ENSEMBLE
GENERALLY HAS WEST-TO-EAST ORIENTED WARM FRONT/LLVL BAROCLINIC
RIBBON SETTING UP AND STRENGTHENING OVER NORTHERN IA TO WI/IL
BORDER BY WED AFTERNOON. AVN-GFS AND ETA VARY ON EXTENT OF STRENGTH
AND DIRECTION OF BACKING H85 FLOW INTO THIS DEVELOPING BOUNDARY BY
WED AFTERNOON...WITH ETA MUCH MORE VIGOROUS EARLY ON WITH SOUTHWEST
25 KT FLOW CONVERGING UP AND OVER SLIGHTLY ELEVATED BOUNDARY BY MID
AFTERNOON...WHILE GFS HAS 15 KT WEST-SOUTHWEST FLOW RUNNING MORE
PARALLEL TO BOUNDARY. INTERESTING THOUGH GFS MUCH MORE BULLISH ON
BREAKING OUT PRECIP ALONG AND OVER WARM FRONT WED AFTERNOON AND
EVENING OVER THE NORTHERN CWA. IN ANY CASE...GENERAL SOLUTION IS
INCREASING 1000-H85 MB THETA-E ADVECTION AND CONVERGENCE OVER THE
NORTHERN CWA WED AFTERNOON AND ESPECIALLY THE EVENING WITH INCREASING
LLVL JET. COMBINE ELONGATED VORT STRUCTURE SWEEPING OVER THE AREA
AND 100 KT JET NOSE OFF APPROACHING MAX PUNCHING DOWN INTO THE
AREA...SUGGEST A CHANCE OF ELEVATED CONVECTION LATER WED AFTERNOON
AND EVENING OVER AT LEAST THE NORTH HALF...POSSIBLY AN MCS. HAVE
ADDED THIS THREAT TO ZONE PACKAGE WITH MAIN PERIOD OF CONCERN BEING
WED NIGHT.

MODELS THEN VARY ON NORTH-SOUTH TREND OF DEVELOPING SFC CYCLONE AND
EXTENT OF NORTHWARD WARM FRONTAL PUSH ON THU. BY 18Z THU...ETA
SUGGESTS MAIN SFC LOW TO BE ACRS CENTRAL KS...WHILE FURTHER NORTH
GFS HAS DEEPER LOW ACRS EXTREME SOUTHEAST SD. LIKE SOMEWHAT WEAKER
WAVE ENERGY PATTERN ALOFT OF ETA...AND SUGGESTS BIT FURTHER SOUTH
LAYOUT THE ONE TO GO WITH FOR NOW. WARM FRONT STILL TO BE ALONG
NORTHERN CWA THU MORNING FOR LINGERING PRECIP THREAT...BUT EVEN
FURTHER SOUTH SOLUTION SUGGESTS MOST OF CWA TO BE IN WARM SECTOR BY
THU AFTERNOON WITH INCREASING SOUTH BREEZE AT SFC BOOSTING TEMPS INTO
THE MID TO UPPER 60S AT LEAST...LOOKING AT PROJECTED THERMAL PROFILES
AND ROBUST LLVL WAA. THUS HAVE MADE BIG UPWARD ADJUSTMENT TO THU
HIGHS. CYCLONE STORM SYSTEM TO PULL OUT TOWARD THE CWA LATE THU NIGHT
FOR SHOWER AND THUNDERSTORM CHANCE...ESPECIALLY ACRS THE WEST.
EASTERN HALF(OR EVEN MOST) OF THE CWA MAY STAY DRY UNTIL FRI WITH ANY
SLOW DOWN OF SYSTEM.

NO CHANGE TO LONGER RANGE(FRIDAY ON) FOR NOW...

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

$$

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