589
FXUS63 KIND 210435
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1130 PM EST FRI NOV 20 2009
AVIATION DISCUSSION
FOR THE 06Z TAFS
HIGH PRESSURE WILL REMAINED CENTERED OVER INDIANA THROUGH THE TAF
PERIOD. CLEAR SKIES...CALM WINDS AND SOME LOW LEVEL MOISTURE WILL
CAUSE VISIBILITIES TO DECREASE TO IFR LEVELS IN FOG BY 11Z. DUE TO
DRYING THAT OCCURED ON FRIDAY THE FOG SHOULD NOT BE AS WIDESPREAD
AND DENSE AS FRIDAY MORNING. VISIBILITIES WILL QUICKLY INCREASE TO
VFR BY 15Z.
UPDATE
MINOR ADJUSTMENTS MADE TO TONIGHT/S LOWS. DROPPED LAF/IND/MIE A
DEGREE OR TWO. SKIES ARE CLEAR...AND MANY STATIONS ALREADY
REPORTING UPPER 30S. OTHERWISE...FORECAST ON TRACK.
PREV DISCUSSION
/ISSUED 800 PM EST FRI NOV 20 2009/
AVIATION...DISCUSSION FOR 210000Z TAF ISSUANCE.
HIGH PRESSURE WILL CONTROL INDIANAS WEATHER THROUGH THE TAF PERIOD.
WITH THIS STABLE SYSTEM TAFS WILL START OUT VFR. THE CLEAR
SKIES...LIGHT TO CALM WINDS AND SOME LOW LEVEL MOISTURE REMAINING
WILL CAUSE FOG TO DEVELOP AFTER 05Z-08Z DECREASING VISIBILITIES TO
MVFR. THEY WILL CONTINUE TO DECREASE TO IFR AFTER 10Z. AREAS OF LIFR
IN FOG IS POSSIBLE. THE SUNNY SKIES ON FRIDAY HAVE ALLOWED SURFACE
LEVELS TO DRY OUT SOME SO THE FOG WILL NOT BE AS WIDESPREAD AS
FRIDAY MORNING. THE CLEAR SKIES WILL CAUSE THE FOG TO QUICKLY BURN
OFF AFTER SUNRISE. BY 15Z VFR CONDITIONS CAN BE EXPECTED.
DISCUSSION...
UPPER LOW HAS MOVED WELL TO OUR EAST AND WEAK HIGH PRESSURE OVER THE
MID MISSISSIPPI VALLEY WILL DOMINATE OUR WEATHER THROUGH EARLY
SUNDAY AND POSSIBLY LONGER DEPENDING ON FAR NORTH A DEVELOPING LOW
PRESSURE SYSTEM OVER TEXAS MOVES LATE SUNDAY OR MONDAY.
THE MAIN WEATHER CHALLENGES INCLUDE CHANCE OF FOG LATE
TONIGHT...RAIN CHANCES SUNDAY NIGHT THROUGH MIDWEEK AND
PRECIPITATION TYPE IF IT OCCURS FOR THANKSGIVING DAY.
THE GROUND HAS HAD A HALF A DAY TO DRY OUT AND FOG SHOULD NOT BE
NEARLY AS EXTENSIVE AS LAST NIGHT. BUT CURRENT CROSS OVER
TEMPERATURES ARE NEAR FORETASTED LOW AND WITH LIGHT WINDS AND MOSTLY
CLEAR SKIES WILL ADD MENTION OF PATCHY FOG. NAM SOUNDING INDICATES
SC IS POSSIBLE LATER TONIGHT AND THERE IS A SC DECK CURRENTLY OVER
NORTH CENTRAL ILLINOIS.
QUIET AND UNEVENTFUL WEATHER WILL BE THE RULE SATURDAY AND SATURDAY
NIGHT AS WEAK HIGH PRESSURE MOVES EASTWARD ACROSS OUR REGION.
THE MODELS ARE VERY WISHY WASHY ON WHETHER MOISTURE FROM THE LOW IN
OUR SOUTH WILL TRACK THIS FAR NORTH. THEY ARE ALL A LITTLE SLOWER
SO WILL NOT MENTION ANY PRECIP FOR SUNDAY AFTERNOON. THE GFS IS
DRY...THE NAM AND GEM REGIONAL BRING IT INTO OUR AREA AND THEY ALSO
LINGER SOME PRECIP INTO MONDAY. THE EUROPEAN MODEL HINTS SOME
PRECIP MAY MOVE THIS FAR NORTH...BUT LITTLE MORE THAN A TRACE. FOR
NOW WILL CONTINUE A 20 PERCENT POPS ALONG AND SOUTHEAST OF A
WASHINGTON TO INDY LINE SUNDAY NIGHT.
IN THE EXTENDED MODELS HAVE TRENDED A LITTLE SLOWER WITH NEXT COLD
FRONT WITH IT NOW MOVING IN LATE TUESDAY OR EARLY WEDNESDAY. WILL
DELAY ONSET OF PRECIP A LITTLE WITH THIS FORECAST.
MODELS BRING A STRONG UPPER TROUGH ACROSS OUR REGION THANKSGIVING
DAY. BUT THERE IS SOME DISAGREEMENT ON HOW MUCH COLD AIR GETS
TRAPPED INTO THIS SYSTEM. THE GFS HAS 1000-850 MB THICKNESS OF 1285
METERS WHICH WOULD BE MOSTLY SNOW. THE EUROPEAN HAD 1000-850 MB
THICKNESS IN THE LIQUID CATEGORY. THE GEM NW MODEL HINTED LOW LEVEL
THICKNESS MAY DROP BELOW CRITICAL THICKNESS BY THANKSGIVING. FOR NOW
WILL MENTION LOW CHANCES OF MIXED PRECIP FROM INDY N AND EAST
THANKSGIVING AND SLIGHT CHANCES OF RAIN SHOWERS ELSEWHERE. ALSO
WENT A LITTLE COLDER THAN HPC TEMPERATURES THIS PERIOD.
AN AREA OF HIGH PRESSURE WILL MOVE EAST ACROSS THE TENNESSEE AND
OHIO VALLEYS FRIDAY AND DRY AND FAIR WEATHER WILL BE THE RULE THEN.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...JH
AVIATION...SH
UPDATE...TDUD
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