671
FXUS63 KLOT 161105
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
605 AM CDT FRI MAY 16 2008
DISCUSSION
313 AM CDT
HIGH PRESSURE WORKING IN BEHIND DEPARTING LOW PRESSURE SYSTEM
CUTTING ACROSS THE CENTRAL APPALACHIANS AT THIS TIME. WINDS HAVE
WEAKENED AND GOOD SUBSIDENCE INVERSION SHUD BE IN PLACE BY NOW.
CONCERN FOR FAR SOUTH WHERE RAIN DROPPED NEAR 1/2 INCH THIS AFTN AND
EVENING IS SOME FOG DEVELOPING IN SATURATED SFC LAYER. NOT EXPECTING
FOG ADVISORY CRITERIA BLO QRTR MILE BUT CERTAINLY NOTICEABLE.
SKIES OTHERWISE EXPECTED TO BE SUNNY AT START OF DAY WITH INCRSG
AFTN CLOUDS AS RIDGE PASSES AND CYCLONIC FLOW RETURNS IN THE AFTN
WITH WEAK TROF WORKS ACRS MS RVR. THIS PRODUCED A FEW SHOWERS WITH
AFTN HTG YDA OUT WEST. WUD EXPECT TODAY TO DO SAME WITH CU
DEVELOPING AFTER NOON AND BECOMING NEARLY OVC BY LATE AFTN. LEFT
PCPN MENTION AS ISOLATED SHOWERS THIS AFTN IN GRIDS WITH POPS UNDER
25% SO THESE NOT LIKELY TO SHOW UP IN WORDING IN ZONES PACKAGE. A
SECONDARY WAVE DROPS DOWN TONIGHT AND IS WORTH A MENTION SINCE LOWER
LAYERS LIKELY TO BE VIRGA PRIMED FROM PREVIOUS TROF PASSAGE.
MAIN VORTEX IN ONTARIO CONTINUES TO SPIN DOWN CYCLONIC LOBES OF
INSTABILITY THRU SATURDAY AND MAY SEE SOME ISOLATED SHOWERS AGAIN AS
MODELS PROG WEAK PERTURBATIONS IN UPR FLOW TO SWING THRU THE AREA
THRU THE WEEKEND. BETTER CHANCES FOR RAIN THIS WEEKEND PROBABLY
SUITED FOR WI AND MI THEN IL AND IN.
ONTARIO VORTEX KICKS OUT THRU QUEBEC SUNDAY...ALLOWING ANOTHER HIGH
PRESSURE RIDGE TO BUILD OVER THE MS VLY SUN NGT AND EARLY MONDAY.
THIS BREAKS DOWN BY AFTN AS A SOMEWHAT IMPRESSIVE TROF WORKS ACROSS
THE PALINS INTO THE MID AND UPR MS VLY MON AFTN AND CROSSING IL
MONDAY EVENING WITH WRAP AROUND SHOWERS MORE LIKELY NORTH OF IL AND
INDIANA ON TUESDAY. AM HOLDING OFF ON TWEAKING EXTENDED BEYOND
TUESDAY.
RLB
AVIATION
12Z TAFS...A QUIET DAY ON TAP FOR AVIATION WEATHER CONCERNS. WITH
WEAK SFC RIDGING MOVING OVER THE REGION...WINDS WILL START OUT
NEAR CALM...BUT AS A SFC TROUGH DROPS OUT OF THE UPPER MISSISSIPPI
VALLEY TODAY...WINDS WILL INCREASE AND BECOME MORE WLY LATER THIS
MORNING AND THEN SWLY LATER THIS AFTERNOON. SKIES WILL BE VFR WITH
ONLY SCT CI THROUGH THIS AFTERNOON WHEN SCT STRATOCU WILL DEVELOP.
THE ONE COMPICATING FACTOR WILL BE A SECOND...STRONGER
TROUGH...AND ASSOCIATED COLD FRONT...DROPPING SEWD OUT OF THE UPPER
MIDWEST LATE THIS EVENING. THIS SYSTEM AS A BIT MORE UPPER FORCING
ASSOCIATED WITH IT...AS WELL AS...STRONGER COLD ADVECTION. THIS
SYSTEM WILL BRING A CHANCE OF SHRA TO THE TERMINALS...BUT WITH
VERY LIMITED LOW LEVEL MOISTURE...AND SHRA WILL LIKELY BE WIDLY
SCT. SO...AT THIS TIME...WILL ONLY INDICATE THE PCPN POTENTIAL
WITH A VCSH GROUP AND A LOWERING OVC VFR CLOUD DECK OF AC/AS.
KREIN
MARINE
315 AM CDT
A WEAK RIDGE OF HIGH PRESSURE EXTENDS FROM LOWER MICHIGAN SOUTHWEST
THROUGH MISSOURI. THIS RIDGE WILL SLOWLY SLIDE SOUTHEAST FRIDAY.
MEANWHILE...LOW PRESSURE OVER THE UPPER OHIO VALLEY WILL MOVE
EAST OFF THE MID ATLANTIC COAST LATER THIS EVENING. FRIDAY
AFTERNOON...LOW PRESSURE WILL DROP OUT OF NORTHERN WINNIPEG AND
TRACK ACROSS THE NORTHERN GREAT LAKES FRIDAY NIGHT AND SATURDAY.
THIS WILL INCREASE THE GRADIENT OVER THE LAKE AND WINDS WILL
INCREASE INTO THE 15-25KT RANGE. WINDS MAY APPROACH SMALL CRAFT
ADVISORY LEVELS FOR THE ILLINOIS NEARSHORE WATERS LATE FRIDAY AS
THE LOW APPROACHES...BUT WILL HOLD OFF ON ISSUING ANY HEADLINES
JUST YET. THIS LOW WILL THEN PROCEED INTO SOUTHERN ONTARIO BY
SATURDAY NIGHT WHILE DRAGGING AN ASSOCIATED COLD FRONT ACROSS LAKE
MICHIGAN. INCREASED COLD ADVECTION OVER THE NORTHERN PORTIONS OF
THE LAKE WILL ALLOW STRONGER WINDS TO MIX DOWN TO THE SURFACE AND
LOWER END GALES ARE EXPECTED FOR THE NORTHERN PORTIONS OF THE LAKE
FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING. HIGH PRESSURE WILL
BUILD OVER THE NORTHERN PLAINS SUNDAY AND SPREAD INTO THE WESTERN
GREAT LAKES REGION BY MONDAY.
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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