809
FXUS63 KDMX 202340
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
540 PM CST FRI NOV 20 2009
UPDATE
00Z AVIATION DISCUSSION
SHORT TERM /TONIGHT/
LOW LEVEL MOISTURE HAS REMAINED IN A NARROW AXIS ACROSS THE EASTERN
TWO-THIRDS OF THE CWA TODAY. THIS HAS PRODUCED SCATTERED TO BROKEN
CU AND AREAS OF HAZE AS WELL. AS WE HEAD INTO TONIGHT...WL SEE WEAK
RIDGING PERSIST ACRS THE AREAS...ALTHOUGH THE HIGH WL BE PUSHING TO
THE EAST OF THE STATE BY MORNING. WITH LOW LEVEL MOISTURE REMAINING
AND RELATIVELY CLEAR SKIES...IT APPEARS FOG IS LIKELY TO DEVELOP
ACRS THE CWA ONCE AGAIN...ESPECIALLY IN THOSE LOCATIONS WHERE HAZE
IS CURRENTLY ONGOING. HAVE INCLUDED FOG AFTER MIDNIGHT FOR THE
SOUTHEAST TWO-THIRDS OR SO OF THE CWA WHERE MOST FAVORABLE
CONDITIONS WILL EXIST. IT IS LIKELY THAT SOME AREAS OF DENSE FOG
WILL FORM AND WOULD NOT BE SURPRISED TO SEE SOME SORT OF ADVISORY
ISSUED OVERNIGHT AS LOCATIONS DROP.
LONG TERM /SATURDAY THROUGH FRIDAY/
EXTENDED MODELS STARTING TO
SHOW SIGNS OF COMING TOGETHER FOR NEXT WEEK FROM MONDAY INTO
THURSDAY. GFS IS STILL A BIT FASTER THAN THE ECMWF...BUT BOTH HAVE
A VERY ACTIVE AND COLDER PATTERN THROUGH THE MIDDLE OF THE WEEK
NEXT WEEK. THE MAIN TROUGH OF LOW PRESSURE IS PROGGED TO MOVE INTO
THE REGION BY MONDAY NIGHT...WITH A WEAK SHORTWAVE QUICKLY MOVING
ACROSS THE CWA OUT AHEAD THIS SYSTEM DURING THE DAY SUNDAY. 12Z
ECMWF HAS SLOWED THE TROUGH DOWN EVEN FURTHER FROM PREVIOUS
RUNS...PUTTING THE BEST CHANCES TUESDAY NIGHT INTO
WEDNESDAY...WITH 12Z GFS HINTING ON TWO SEPARATE SYSTEMS MONDAY
INTO WEDNESDAY. THE LATEST ECMWF SEEMS MORE REALISTIC AND LEANED
MORE TOWARDS THAT SOLUTION DURING THE EXTENDED.
SATURDAY AND SUNDAY...WEAK RIDGE MOVES IN OVER THE AREA ON SATURDAY
AND SHOULD PROVIDE A SLIGHT WARM UP WITH SOME WEAK WAA AT THE
SURFACE. TWEAK TEMPS UP A BIT ACROSS THE SOUTH FOR HIGHS
TOMORROW. INCREASING CLOUDS BY 00Z SUNDAY WITH BUFR SOUNDINGS
BECOMING SATURATED AHEAD OF WEAK SHORTWAVE EXPECTED BY SUNDAY.
KEPT WITH MENTION OF DRIZZLE OVERNIGHT SATURDAY INTO SUNDAY AND
WITH CHANCE POPS DURING THE DAY SUNDAY. WENT DRY SUNDAY NIGHT FOR
THE MAJORITY OF THE CWA.
MONDAY THROUGH WEDNESDAY....TIMING AND PRECIP TYPE WILL BE MAIN
FORECAST ISSUES WITH THE TROUGH OF LOW PRESSURE ENTERING THE REGION
MONDAY INTO TUESDAY. GFS BUFR AND ECMWF SOUNDINGS HAVE TEMPS ABOVE
FREEZING BELOW 850MB DURING THE TIME FRAME...AND WENT WITH RAIN
THROUGH TUESDAY. HAVE MENTIONED OF SNOW/RAIN TUESDAY NIGHT WITH
COLDER TEMPERATURES BEGINNING TO FILTER INTO THE CWA.
THURSDAY AND FRIDAY...GFS/ECMWF DEPICTING A DECENT RIDGE BUILDING
INTO THE REGION BY THANKSGIVING AND DOMINATING INTO NEXT WEEKEND.
SO...AS OF RIGHT NOW...LOOKING A DRY AND COOL HOLIDAY PERIOD.
AVIATION
MOISTURE IN THE NEAR SURFACE LAYER REMAINING HIGH ACROSS THE CWA
MAINLY EAST OF INTERSTATE 35...WITH MANY OF THE TAF SITES ALREADY
REPORTING MVFR VSBYS IN HAZE. WITH THE SFC RIDGE AXIS SITUATED
ACROSS THE SOUTHEAST...AND SLOWLY PUSHING SOUTH AND EAST ACROSS THE
AREA WILL CONTINUE TO SEE LIGHT WINDS OVERNIGHT. THEREFORE FOG
DEVELOPMENT AGAIN A CONCERN TONIGHT...WITH MANY SITES EXPECTED TO
FALL TO AT LEAST IFR VBSYS BY LATE TONIGHT INTO EARLY
SATURDAY...WITH SOME AREAS NEAREST THE RIDGE AXIS SUCH AS KOTM
POSSIBLY DIPPING INTO VLIFR CONDITIONS. SOUTHERLY FLOW AHEAD OF THE
NEXT SYSTEM EXPECTED FOR SATURDAY...WITH MORE MOISTURE PUSHING
NORTHWARD. THIS WILL ALLOW FOR SOME LOW CLOUDS/DRIZZLE EXPECTED TO
BEGIN ACROSS THE SOUTHEASTERN CWA LATE IN THE FORECAST PERIOD...AND
SPREAD INTO THE REMAINDER OF THE CWA JUST BEYOND THE CURRENT TAF
PERIOD.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...COGIL
LONG TERM...PODRAZIK
AVIATION...BEERENDS
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