770
FXUS63 KILX 071942
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
142 PM CST SAT NOV 7 2009
DISCUSSION
ISSUED 140 PM CST SAT NOV 7 2009
18Z SURFACE MAP SHOWING WEAK COLD FRONTAL BOUNDARY BEGINNING TO
ENTER FAR NORTHWEST ILLINOIS...EXTENDING SOUTHWEST TO NEAR KANSAS
CITY. TEMPERATURES HAVE SURGED INTO THE MID 70S ACROSS THE WESTERN
CWA EARLY THIS AFTERNOON...AND WERE AROUND 70 IN THE EAST. THE
ENTIRE REGION WAS DEVOID OF CLOUDS...ASIDE FROM A FEW CIRRUS
CLOUDS MOVING NORTHEAST ACROSS MISSOURI.
MAIN FORECAST ISSUES FOR THE DAY INVOLVE FRONTAL PASSAGES IN THE
MONDAY/TUESDAY TIME FRAME...AS WELL AS LATE NEXT WEEK.
SHORT TERM...TONIGHT THROUGH TUESDAY...
CURRENT COLD FRONT EXPECTED TO BECOME STATIONARY OVERNIGHT...NORTH
OF THE CWA...THEN LIFT BACK NORTH ON SUNDAY. ANOTHER UNSEASONABLY
MILD DAY IS ANTICIPATED ACROSS THE AREA ON SUNDAY...WITH HIGHS
AGAIN REACHING THE 70S. SKIES EXPECTED TO BECOME PARTLY CLOUDY
LATE TONIGHT AS THE FRONT APPROACHES...THEN CLEAR UP AGAIN ON
SUNDAY.
LOW PRESSURE EXPECTED TO FORM IN KANSAS ON SUNDAY AND MOVE
NORTHEAST INTO THE MIDWEST. A COLD FRONT WILL SHARPEN UP AS A
RESULT AS IT MOVES EAST TOWARD THE CWA. MODELS IN REASONABLE
AGREEMENT THROUGH 48 HOURS...THEN THE NAM BECOMES SHARPLY
DIVERGENT WITH THE SPEED OF THIS FRONT...AND RATHER GLARING WITH
ITS DIFFERENCES BY TUESDAY. WILL SIDE WITH THE SLOWER SUITE OF
GUIDANCE AS A RESULT...BRINGING THE FRONT THROUGH THE AREA MONDAY
NIGHT AND EXITING TUESDAY MORNING. EXTRATROPICAL LOW IN THE
NORTHERN GULF OF MEXICO TO PRECLUDE MUCH MOISTURE RETURN AHEAD OF
THE FRONT. WILL CONTINUE WITH SLIGHT CHANCES ACROSS THE NORTHWEST
CWA ON MONDAY...WITH RAIN CHANCES SPREADING OVER THE CWA MONDAY
NIGHT. SOUTHEAST CWA MAY STAY DRY UNTIL TUESDAY MORNING. DID BUMP
UP POPS A BIT MONDAY NIGHT INTO THE 40 PERCENT RANGE...PRIMARILY
WEST OF I-55. A CLEARING TREND IS EXPECTED ON TUESDAY AND TUESDAY
NIGHT...AS HIGH PRESSURE BUILDS INTO THE MID-MISSISSIPPI VALLEY
BEHIND THE FRONT.
LONG TERM...WEDNESDAY THROUGH SATURDAY...
UPPER LEVEL RIDGING TO ADVANCE EAST ACROSS THE CONUS MIDWEEK...AS
A TROUGH BEGINS TO DIG ACROSS THE WESTERN STATES IN RESPONSE TO
LEFTOVER ENERGY FROM A POWERFUL LOW MOVING SOUTHEAST FROM THE
GULF OF ALASKA. LONGER RANGE MODELS BEGIN TO DIVERGE SIGNIFICANTLY BY
FRIDAY. THE GFS IS RATHER AGRESSIVE IN DEVELOPING A STRONG UPPER
LOW ACROSS THE NORTHERN PLAINS...WITH SHARPLY COLDER CONDITIONS
SPREADING IN BEHIND A FRONT ON SATURDAY. MEANWHILE...THE NEWLY
ARRIVED ECMWF HAS A BOUNDARY OSCILLATING ACROSS THE AREA THROUGH
THE WEEKEND...BEFORE FINALLY PUSHING THROUGH SUNDAY EVENING. AT
THIS POINT...WILL SIDE MORE WITH THE ECMWF...KEEPING THE CWA DRY
THROUGH FRIDAY NIGHT AND INCLUDING ONLY SILENT 20 POPS FOR
SATURDAY AS THE MODELS TRY TO RESOLVE THEIR DIFFERENCES.
GEELHART
AVIATION
ISSUED 1130 AM CST SAT NOV 7 2009
CLEAR SKIES TO CONTINUE. ONLY ISSUE IS WIND FLOW. PRESSURE
GRADIENT AHEAD OF APPROACHING FRONT WILL KEEP WINDS GUSTY TODAY.
WILL SEE SOME START TO DROP OFF TOWARD EVENING AS GRADIENT
WEAKENS. TOWARD MORNING TONIGHT...WITH THE APPROACH OF THE
FRONT...LIGHT WINDS JUST AHEAD OF FRONT AND NEARLY CLEAR
CONDITIONS MAY ALLOW SOME FOG DEVELOPMENT. FEEL ONLY WILL BE MVFR
THOUGH...JUST AS OCCURRED LAST NIGHT IN IA NEAR APPROACH OF FRONT.
GOETSCH
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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