[LeArc] Forecast Discussion : MLI@ 3/13/03 5:05:14 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 131113
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
513 AM CST THU MAR 13 2003

SYNOPTIC PICTURE THIS MORNING SHOWS COLD FRONT DEPARTING AREA TO THE
EAST...AS THE SURFACE WAVE MOVES EAST OF STL.  A LARGE AREA OF HIGH
PRESSURE SITS OVER THE NORTHER GREAT LAKES.  AT 500H A WEAK SHORT
WAVE OVER THE AREA IS HEADING EAST.  TO THE WEST...A LARGE RIDGE
SITS OVER THE WESTERN HALF OF THE COUNTRY.  AT 300MB...A 140KT JET
EXTENDS ACROSS SOUTHERN CANADA...DIPPING SOUTH INTO THE WESTERN
GREAT LAKES.

THE PRIMARY FORECAST CHALLENGES THIS MORNING ARE INCREASING
TEMPERATURES OVER THE NEXT SEVERAL DAYS...BRINGING US OUR FIRST
SPRING WEATHER...AND CHANCES OF PRECIP STARTING SUNDAY NIGHT AND
EXTENDING INTO WEDNESDAY....AS A SLOW MOVING LOW APPROACHES THE
AREA.

THE SHORT-TERM MODELS AGREE ON SURFACE RIDGING INTO FRIDAY...WITH A
SOUTHERLY FLOW DEVELOPING IN THE AFTERNOON AND CONTINUING THROUGH
THE WEEKEND.  A SHORT WAVE WILL CLIP THE NORTH SUNDAY NIGHT...AND
COULD HELP LAY DOWN A STATIONARY FRONT ACROSS NORTHERN MISSOURI
MONDAY INTO TUESDAY.  THIS IS THE ETA SOLUTION.  THE 06Z
AVN CONTINUES ITS PREVIOUS TREND OF FORMING A LOW AND ASSOCIATED
FRONT NORTH OF THE AREA...WHICH WOULD PRODUCE A WARMER...LESS
CLOUDY...NON-PRECIP SCENARIO.  EITHER WAY A LOW MOVES EAST ALONG THE
FRONT TUESDAY...WITH HIGH PRESSURE BUILDING IN WEDNESDAY.

AT THE JET LEVEL...THE SOUTHERN STREAM BECOMES ACTIVE...WITH A 120KT
JET MOVING ONSHORE SATURDAY...AND INTO THE LOWER MISSISSIPPI VALLEY
TUESDAYS.  AT 500MB RIDGING CONTINUES OVER THE AREA THROUGH
SATURDAY...WITH A SHORT WAVE SATURDAY NIGHT...AND CONTINUED RIDGING
SUNDAY AND MONDAY.  ON OR ABOUT TUESDAY...DEPENDING ON WHICH MEDIUM-
RANGE MODEL...A CLOSED LOW MOVES OUT OF THE ROCKIES INTO KANSAS...AND
WEDNESDAY LIFTS INTO NEBRASKA AS THE SOUTHERN JET FORKS NORTH TO JUST
EAST OF OUR AREA.

THIS PROVIDES A COMPLICATED FORECAST SCENARIO WITH NO CLEAR-CUT
ANSWERS BUT STILL WITH STRONG SIGNALS FOR A WARM-UP STARTING
FRIDAY...AND FOR INCREASED PRECIP CHANCES.  WHETHER OR NOT PRECIP
CHANCES WILL BE OF THE STRATIFORM OR CONVECTIVE VARIETY REMAINS A
QUESTION...BUT THE CHANCE OF SIGNIFICANT RAIN EXIST EITHER WAY IN
THE MONDAY NIGHT THRU TUESDAY NIGHT PERIOD...AND LOWER CHANCES
SUNDAY AND SUNDAY NIGHT.

WILL STAY CLOSE TO ONGOING FORECAST OTHER THAN MINOR TEMPERATURE
ADJUSTMENTS.  BELIEVE THAT THE MENTION OF RAIN SUNDAY MAY NEED TO
BE REMOVED AT SOME POINT DUE TO SLOWING PATTERN.

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

$$

REA