FXUS63 KDMX 252329 AAA
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
528 PM CST WED NOV 25 2009

...UPDATED 00Z AVIATION DISCUSSION...

.SHORT TERM /TONIGHT/...
COLD AIR IS BEING BROUGHT INTO THE CWA THANKS TO AN UPPER LEVEL LOW 
DROPPING INTO THE UPPER MIDWEST. THE LOW SHOULD MOVE OVER SOUTHERN 
LAKE MICHIGAN BY 12Z TOMORROW. IN THE MEANTIME...BANDS OF RAIN AND 
SNOW WILL MOVE THROUGH AS A VORT LOBE WORKS ITS WAY AROUND THE LOW 
AND ISENTROPIC LIFT AT 285K ENHANCES LIFT IN THE LOWER LEVELS. AS 
THE AIR COOLS TONIGHT...PRECIP SHOULD TURN MAINLY TO SNOW. THERE 
SHOULD BE LITTLE ACCUMULATION AS MOST OF THE SNOWFALL SHOULD MELT ON 
CONTACT WITH A WARMER SURFACE. PRESSURE GRADIENT REMAINS FAIRLY 
TIGHT SO WINDS OVER 20 MPH SHOULD PERSIST THROUGH THE NIGHT. MOST OF 
THE MVFR/IFR CIGS SHOULD BEGIN CLEARING OUT AROUND 12Z AS THE LOW 
LOSES ITS INFLUENCE ON CENTRAL IOWA WEATHER AND HIGH PRESSURE BEGINS 
BUILDING IN. 

.LONG TERM /THURSDAY THRU WEDNESDAY/...
DEEPENING EASTERN TROF WILL BE PULLING AWAY ON THURSDAY AS SFC 
RIDGING BUILDS INTO THE MISSOURI RIVER VALLEY.  LOW LEVEL MOISTURE 
WILL BE SCOURED DURING THE DAY AS SUBSIDENCE AND DRIER AIR PUSH INTO 
THE STATE.  WL SEE CLOUDS DECREASE WITH THERMAL TROF OVER STATE 
EARLY GIVING WAY TO WAA BY LATE IN THE DAY.  THE WAA WILL INCREASE 
INTO THURSDAY NIGHT AS SFC RIDGE SLIDES EAST OF THE AREA BY 
SUNRISE.  TEMPS SHOULD COOL NICELY TOMORROW NIGHT WITH LIGHT WINDS 
AND CLEAR SKIES AND HAVE GONE WITH COOL END OF GUIDANCE.  FRIDAY AND 
SATURDAY WILL SEE THERMAL RIDGE PUSH INTO THE STATE WITH SOUTHERLY 
FLOW AND SUNNY SKIES.  HAVE GONE ON HIGH END OF GUIDANCE GIVEN THE 
AMPLE SUNSHINE AND FAVORABLE WINDS.  

PROGRESSIVE TROF WILL ENTER THE WESTERN US EARLY THIS WEEKEND WITH 
SYSTEM SPLITTING.  NORTHERN END WILL REMAIN PROGRESSIVE AND PASS 
THROUGH THE MIDWEST BY LATE SUNDAY INTO EARLY MONDAY.  MEANWHILE... 
THE SOUTHERN PORTIONS WILL LINGER ACROSS THE SOUTHWEST US AND 
NORTHERN MEXICO INTO EARLY NEXT WEEK.  IA WILL GENERALLY BE IN 
BETWEEN THE MAJOR FORCING OF THESE TWO SYSTEM WITH LITTLE THREAT OF 
PRECIPITATION.  ONLY CONCERN IS NEW 12Z EURO WHICH DOES GRAZE FAR 
SOUTHERN IA WITH PCPN INTO MONDAY WITH SOUTHERN STREAM SYSTEM.  
OTHERWISE...WILL SEE TEMPERATURES COOL INTO NEXT WEEK FROM SATURDAYS 
WARMTH TO MORE NORMAL LEVELS.  

&&

.AVIATION...
26/00Z...AREA OF LOW MVFR CIGS MOVING THROUGH CNTRL IOWA TONIGHT AND 
WILL BE ACCOMPANIED BY RAIN AND SNOW THIS EVENING. MAY HAVE BRIEF 
PERIODS OF IFR VISIBILITIES MAINLY NEAR KALO AND KMCW. PRECIPITATION 
WILL END LATE THIS EVENING. STRATUS WILL LINGER BEFORE CLEARING 
THURSDAY MORNING. COOLING AT 900 MB SHOULD STEEPEN LOW LEVEL LAPSE 
RATES AFTER 06Z TONIGHT AND COULD RESULT IN GUSTS OVER 30 KTS. HAVE 
COVERED THIS IN THE TERMINALS. BREEZY NORTHWEST WINDS CONTINUE ON 
THURSDAY THOUGH GUSTS SHOULD BE 25 KTS OR LESS.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...HINSBERGER
LONG TERM...COGIL
AVIATION...DONAVON