FXUS63 KLSX 300538
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1138 PM CST SUN NOV 29 2009
.DISCUSSION...
/344 PM CST SUN NOV 29 2009/
PCPN DEVELOPMENT TODAY HAS BEEN VERY DISAPPOINTING...WITH LIMITING
STREAMLINE INDICATED NOT FAR BEHIND THE CDFNT. THE CDFNT HAS NOW
PUSHED ALMOST TO A KMTO-KFAM LINE WITH DECENTLY STRONG CAA JUST
BEHIND IT...BUT ONLY FOR A RELATIVELY NARROW RIBBON...WHICH WILL
HELP SHOVE TEMPS DOWN INTO THE 40S SHORTLY AFTER FROPA. EXPECT ANY
NEW PCPN AFTER 00Z TO BE E OF THE FA AND AFFECT THE FAR SRN FA FROM
SLUG OF PCPN IN NERN OK AND NWRN AR. KEPT TOKEN SLIGHTS IN FOR THE
KSLO AREA.
MONDAY AND TUESDAY WILL BE MILD DAYS...ESPECIALLY TUESDAY...WITH
DEEPENING MIXED LAYER MONDAY AFTERNOON AND REMAINING ON THE DEEP
SIDE FOR EARLY DECEMBER THANKS TO ABUNDANT SUNSHINE AND
UNIDIRECTIONAL FLOW. STRONGLY FAVORED THE WARMER MAV MOS TEMPS
DURING THESE DAYS FOR MAXES AND EVEN IN SOME CASES WENT A COUPLE
DEGS HIR.
REGARDING THE SYSTEM TO AFFECT OUR AREA WEDNESDAY/WEDNESDAY NIGHT...
MODELS CONTINUE TO FAVOR A BIT MORE SLY SOLN THAN WHAT WE SAW 24HRS
AGO. AGAIN ALL OF THIS HINGES ON MODELS ABILITY TO RESOLVE THE NRN
KICKER WHICH WILL NOT COME ONSHORE UNTIL THE 12Z RUNS ON MONDAY AT
THE EARLIEST...AND PERHAPS NOT UNTIL THE 00Z RUNS MONDAY EVENING.
BUT THE LATEST TRENDS ARE INDICATING THAT THE NRN KICKER WILL HAVE
MUCH OF ITS ENERGY STAY TO THE N THUS DELAYING A FUSING OF THE NRN
AND SRN STREAMS AND THIS WILL TEND TO DELAY AND KEEP TO THE S THE
MAIN SRN STORM. WITH ALL OF THIS IN MIND...HAVE MAINTAINED THE
PREVIOUS FORECAST WITH RESPECT TO PCPN PROBS AND KEEPING THE MAIN
NRN EXTENT JUST S AND E OF THE STL METRO AREA ALTHOUGH THE NAM IS
HINTING AT A FINGER OF PCPN EXTENDING FURTHER NW THRU THE STL METRO
AREA...THIS IS A RESULT OF THE VERY TRICKY PHASING OF THE TWO
STREAMS AND SO CONFIDENCE ON THIS FEATURE NOT VERY HIGH ATTM. PCPN
FORECAST IS BASED SANS THIS PCPN FINGER SINCE THIS IS MORE OF A
MESOSCALE FEATURE AND SKILL IS LOW AT THIS POINT IN TIME. ONE OTHER
TREND OF NOTE BETWEEN THE 12Z RUNS TODAY AND WHAT WE SAW FROM THE
00Z LAST NIGHT AND 12Z YESTERDAY IS THAT THE DELAY OF THE SRN STORM
BY JUST A TAD WILL ALLOW THE LO LEVEL COLD AIR TO SEEP A BIT MORE
SEWD AND WILL RESULT IN HIR PROBS FOR FROZEN PCPN OUT OF WHAT PCPN
WE WILL SEE. SO IN SUMMARY...MAINTAINED THE MORE SLY NRN EDGE OF THE
DEF ZONE PCPN FOR LATE WEDNESDAY AFTN/WED NIGHT BUT THE END RESULT
APPEARS TO BE A QUICKER CHANGEOVER TO SNOW IN WHAT WE DO GET.
FOR THE EXTENDED PERIOD (THURSDAY - SUNDAY)...IN THE WAKE OF THE
STORM SYSTEM THE MODELS ARE IN REASONABLY GOOD AGREEMENT THAT A DEEP
MID LEVEL TROF WILL BUILD INTO THE UPR MIDWEST AND GRTLKS REGIONS
AND REMAIN THRU THE END OF THE WORKWEEK. THIS WILL KEEP THINGS COLD
WITH PERSISTENT CLOUDS AND A FEW FLURRIES INTO THURSDAY WITH THE
CLOUDS/PCPN CHCS LOOKING MORE DOUBTFUL HEADING INTO FRIDAY. NEXT
WEEKEND STILL LOOKS COMPLETELY UP IN THE AIR AS THE MODEL SPREAD
REMAINS VERY LARGE...PRIMARILY OVER THEIR HANDLING OF A STRONG NRN
STREAM WAVE INTO WRN CANADA. WILL FALL BACK TO THE GFS ENSEMBLE MEAN
SOLUTION WHICH TEMPERS THIS FEATURE BETWEEN THE SPECTRUM OF
POSSIBILITIES AND YIELDS INSTEAD A MORE NEUTRAL ZONAL FLOW PATTERN
OVER THE CNTRL CONUS WITH TEMPS SLOWLY MOVING BACK TOWARDS CLIMO
VALUES. SATURDAY/S PCPN EVENT STILL LOOKS IFFY EVEN WITH THE MORE
AGGRESSIVE OPERATIONAL GFS OUTPUT AND HAVE MAINTAINED A DRY FCST FOR
NOW.
TES
&&
.AVIATION...
/1118 PM CST SUN NOV 29 2009/
FOR THE 06Z TAFS...PRIMARY CONCERN THIS TAF PD IS TIMING OF MVFR
CIGS MOVING ACROSS E CENTRAL MO AND CENTRAL IL. SFC OBS OVER THE
PAST 6 HRS SHOW THE CLD DECK IS NEARLY STATIONARY WITH A SLOW SEWD
MOVEMENT OF THE BACK EDGE. HIGHER CLOUDS STREAMING NEWD ACROSS
MO/IL ARE OBSCURING THE LOWER MVFR DECK ON SATELLITE
IMAGERY...THUS TIMING OF CIGS AT STL/SUS IS BASED LARGELY ON OBSVD
TIMING FROM UIN METARS. HIGH PRES WILL CONTINUE BUILDING IN TO THE
REGION ON MON...LEADING TO CLRG SKIES AND BACKING WINDS.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
