000
FXUS63 KLSX 071136
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
635 AM CDT SUN SEP 7 2008
.DISCUSSION...
/436 AM CDT SUN SEP 7 2008/
LONGWAVE MID TO UPPER LEVEL TROF WHICH HAS DOMINATED THE N CNTRL
CONUS AND MUCH OF NOAM FOR THAT MATTER OVER THE PAST FEW DAYS IS
EXPECTED TO PERSIST THRU THE NEXT FEW DAYS...ALTHOUGH ITS GRIP
WILL LOOSEN A BIT. A SERIES OF DISTURBANCES ARE STILL EXPECTED TO
MOVE AROUND THE BASE OF THIS TROF DURING THIS TIME. THE FIRST IS
IN THE PROCESS OF EXITING THE FA NOW AND SHOULD COMPLETE ITS
DEPARTURE BY MID MORNING. THE NEXT WILL BE A UNION OF NRN AND SRN
STREAM WAVES...AND BE COINCIDENT WITH A MODERATELY STRONG SFC
CDFNT...AND WILL PASS THRU MONDAY AFTERNOON AND EVENING. A THIRD
DISTURBANCE WILL APPROACH THE FA DURING MID WEEK...ALTHOUGH ITS
TIMING AND LOCATION ARE MUCH MORE QUESTIONABLE THAN THE FIRST TWO.
AT THE SFC...WEAK HI PRES OVER THE AREA TODAY WILL GIVE WAY TO A
CDFNT MONDAY AND MONDAY NIGHT WITH A DECENTLY STRONG 1025MB HI
PRES DOMINATING THE FA ON TUESDAY AND TUESDAY NIGHT.
FIRST DISTURBANCE IS EXITING THE FA NOW AND THE REMNANTS OF THE
SHRA THAT IT LEAVES BEHIND SHOULD COMPLETELY EXIT OR DISSIPATE BY
15Z. WHILE THE BULK OF THE CLOUD COVER SLOWLY EDGES SWD AND WILL
SETTLE INTO THE CNTRL/SRN FA THIS MORNING...THIS LEAVES THE FAR
NRN FA APPROACHING AN AREA OF CLEARING. THE CLEARING AREA IS
LARGELY BEING CONVERTED INTO FOG AND WILL NEED TO BE MONITORED
CLOSELY FOR THE NEED FOR AN ADVISORY SHOULD IT PUSH FURTHER S INTO
THE NRN FA.
AS THE CLOUDS SINK SLOWLY SWD...THEY WILL EVENTUALLY REGROUP AND
THIN OUT OR BREAK UP OVER MOST AREAS BY AFTN...BUT WILL BE MOST
PERSISTENT IN CNTRL MO. FAVOR THE COOLER MET MOS TEMPS MOST AREAS.
THE APPROACH OF A SET OF DISTURBANCES ON MONDAY WHICH WILL
EVENTUALLY ACT IN CONCERT WILL LEAD TO DECENT WAA AHEAD OF THE
SYSTEM BY SUNDAY NIGHT...AND HAVE CONTINUED THE CHANCE CATEGORY
POPS CENTERED OVER AREAS N AND W OF KSTL. THE DEEPER AND MORE
ORGANIZED LIFT WILL ARRIVE BY MIDDAY MONDAY AND PERSIST THRU
MONDAY EVENING...ESPECIALLY OVER THE NRN HALF OF THE FA...AND WILL
SEE LIKELY PROBABILITIES FOR PCPN. IT IS APPEARING MORE LIKELY
THAT THERE WILL BE CONSIDERABLE POST-FRONTAL PCPN WITH THIS EVENT
ALTHOUGH SHOULD ALSO SEE SFC FRONT ITSELF IGNITE NEW TSRA LATE
MONDAY AFTERNOON AND MONDAY EVENING FOR AREAS FURTHER S AND E FROM
THE BETTER AND DEEPER LIFT TO THE N. ALL OF THE ACTIVITY MONDAY
NIGHT IS EXPECTED TO DISSIPATE LATE AS MUCH DRIER AIR WORKS IN.
WITH +17C H850 AIR PUSHING IN OVER THE SERN HALF OF THE FA ON
MONDAY AFTERNOON...WAS TEMPTED TO GO MID 80S OVER A LARGE
SWATH...BUT CLOUD COVER MORE UNCERTAIN OVER THE STL METRO AREA DUE
TO PROXIMITY OF FRONT AND PCPN AND SO ONLY WENT LOW 80S FOR NOW
WITH MID 80S FURTHER S. TEMP BUST POTENTIAL ALSO EXISTS TO A
LARGER DEGREE FOR AREAS FURTHER N OF KSTL...WITH CLOUDS...PCPN AND
FRONTAL POSN ALL KEY.
HAVE PLAYED DOWN IMPACTS FROM MID WEEK DISTURBANCE FOR NOW DUE TO
ENOUGH UNCERTAINTY FROM MODELS ON TRACK AND TIMING.
TES
&&
.AVIATION...
/615 AM CDT SUN SEP 7 2008/
FOR THE 12Z TAFS...
PRIMARY CONCERN FOR AVIATORS THIS MORNING WILL BE MVFR/IFR CIGS
OVER PARTS OF THE BI-STATE REGION. THE REGION OF LOWEST CLOUDS
APPEARS TO EXTEND FROM THE JEFFERSON CITY/COLUMBIA AREA NORTH AND
NORTHEAST INTO THE KIRKSVILLE/HANNIBAL/QUINCY AREAS. VFR CIGS AND
VSBYS ARE BEING REPORTED IN THE ST. LOUIS METRO AREA AND POINTS
EAST AND SOUTH ALL THE WAY TO FARMINGTON AND SPARTA ILLINOIS. I
MUST ADMIT...I DON`T HAVE A GOOD FEEL FOR HOW THE CIGS ARE GOING
TO EVOLVE THIS MORNING. SOME SHREDS OF IFR CLOUD ARE BEING
REPORTED AT THE METRO AREA TERMINALS...AND THOSE SHREDS COULD
CONCEIVABLY BUILD INTO AN IFR/LOW MVFR CIG EARLY IN THE TAF
PERIOD. ESTABLISHING TRENDS OVER THE LAST FEW HOURS HAS BEEN NEXT
TO IMPOSSIBLE AS OBSERVATIONS HAVE BEEN BOUNCING BETWEEN IFR AND
VFR AND ALL POINTS IN BETWEEN IN MANY LOCATIONS. NEEDLESS TO
SAY...THIS IS A LOW CONFIDENCE FORECAST THIS MORNING.
REGARDLESS...MVFR/IFR CIGS SHOULD GENERALLY IMPROVE TO VFR TOWARD
MID-DAY.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
