000
FXUS63 KLOT 070552
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1252 AM CDT SUN SEP 7 2008
.DISCUSSION...
937 PM CDT
MINOR UPDATE TO RAISE POPS A BIT TO LIKELY OVERNIGHT FOR AREAS
GENERALLY ALONG/EAST OF A LASALLE TO CHICAGO LINE.
SHOWERS CONTINUE TO DEVELOP AND SPREAD FROM MISSOURI AND SOUTHEAST
IOWA INTO ILLINOIS THIS EVENING...IN ASSOCIATION WITH MID LEVEL
SPEED MAX ROTATING THROUGH BASE OF BROAD LARGE SCALE UPPER TROUGH
OVER CENTRAL NOAM. OTHER THAN BUMPING POPS...MINOR TWEAKS TO
EVENING SKY COVER...AND ADJUSTING QPF GRIDS NO CHANGES MADE AS
GOING FORECAST APPEARS ON TRACK.
RATZER
&&
.AVIATION...
1245 AM CDT
06Z TAFS...AGAIN...NOT MUCH CHANGE NECESSARY TO THE GOING TAFSS.
THE MAIN CONCERN FOR THE REMAINDER OF THE OVERNIGHT HOURS WILL
FOCUS ON THE PCPN CHANCES. A WEAK MID LEVEL IMPULSE IS MOVING
ACROSS NRN IL AND SCT SHRA HAVE MOVED OVER NERN IL/NWRN IN. LATEST
RADAR IMAGERY INDICATES THAT THE PCPN IS STILL BROKEN IN
COVERAGE...SO WILL MAINTAIN THE VCSH/TEMPO GROUPS AS PCPN IS NOT
LIKELY TO BE PREVAILING...BUT COULD WET RUNWAYS AT TIMES. UPSTREAM
OBS INDICATE CIGS IN VFR RANGES...AND GO NOT EXPECT BASES TO DROP
MUCH BLW 050KFT...EVEN IN ACTIVE PCPN AREAS. COULD SEE OCNL
PERIODS OF 5SM IN HEAVIER SHOWERS. THE IMPULSES ROTATING THROUGH
THE BROAD UPPER TROUGH OVER THE CNTRL CONUS ARE QUITE
PROGRESSIVE...SO STILL EXPECT GENERAL IMPROVEMENT BY ARND SUNRISE
WITH VFR SKIES AND VSBY FOR THE REMAINDER OF THE DAY. WITH BROAD
TROUGHING TO THE NORTH AND A WEAK RIDGE TO THE SOUTH...A GENERALLY
WLY GRADIENT WILL PREVAIL THROUGH THE DAY. SPEEDS SHOULD INCREASE
TO 10+KT BY LATE MORNING...WHICH SHOULD BE STRONG ENOUGH TO ANY
LAKE BREEZE DEVELOPMENT FROM PENETRATING INLAND FAR ENOUGH TO
AFFECT THE TERMINALS.
KREIN
&&
.MARINE...
210 PM...HAVE MADE SOME SIGNIFICANT CHANGES TO THE GOING FORECAST
AND GRIDS FROM MONDAY AFTERNOON THRU TUESDAY AFTERNOON.
IN THE SHORT TERM...WEAK HIGH PRESSURE OVER THE CENTRAL PLAINS
SLOWLY MOVES EAST ACROSS THE OH VALLEY TONIGHT WHILE A WEAK LOW
MOVES ACROSS ONTARIO. BY SUNDAY AFTERNOON/EVENING...A TROUGH/COLD
FRONT FROM THIS LOW WILL FORM/EXTEND ACROSS THE WESTERN LAKES. AS
A RESULT...THE GRADIENT WILL TIGHTEN AND EXPECT WEST/SOUTHWEST
WINDS TO INCREASE TO 15-25KTS...ESPECIALLY OVER NORTHERN LAKE
MICHIGAN. THIS TROUGH SHIFTS EAST MONDAY LEAVING A WEAK RIDGE OF
HIGH PRESSURE IN ITS WAKE.
BY MONDAY AFTERNOON...WEAK LOW PRESSURE OVER THE CENTRAL PLAINS
WILL LIFT NORTHEAST REACHING LAKE MICHIGAN EARLY TUESDAY MORNING.
AN UPPER TROF WILL BEGIN TO DEEPEN OVER THIS SYSTEM WHILE A TIGHT
AND RATHER IMPRESSIVE THERMAL GRADIENT FOR THIS TIME OF YEAR
DEVELOPS OVER THE WESTERN LAKES. MOST OF THE MODELS SHOW THIS
AREA OF LOW PRESSURE DEEPENING MONDAY NIGHT AND TUESDAY MORNING
OVER MICHIGAN AND IT CONTINUES TO DEEPEN AS IT LIFTS NORTHEAST
ACROSS THE EASTERN LAKES TUESDAY AFTERNOON/EVENING. WHILE THE
MODELS DIFFER ON THE EXACT TRACK OF THIS LOW...THE LATEST TRENDS
OF THE MODELS WARRANT INCREASING WIND SPEEDS ACROSS LAKE MICHIGAN
FROM MONDAY EVENING INTO TUESDAY. WHILE GALES ARE POSSIBLE...
CONFIDENCE IS NOT HIGH ENOUGH FOR MENTION ESPECIALLY SINCE THE
TRACK OF THE LOW IS NOT CERTAIN. HOWEVER...PLAN TO BUMP SPEEDS TO
30KTS ACROSS SOUTHERN LAKE MICHIGAN BY TUESDAY MORNING. WINDS
QUICKLY DIMINISH TUESDAY EVENING AS HIGH PRESSURE MOVES ACROSS
THE LAKES TUESDAY NIGHT. THIS HIGH QUICKLY SHIFTS EAST WITH A
SOUTHERLY GRADIENT INCREASING ACROSS THE WESTERN LAKES BY
WEDNESDAY NIGHT AND HAVE INCREASED SPEEDS DURING THIS TIME AS
WELL. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
