FXUS63 KDMX 291721 AAA
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1120 AM CST SUN NOV 29 2009

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...
LONG WAVE TROUGH IS ADVANCING THROUGH CENTRAL CONUS WITH RIGHT 
ENTRANCE REGION OF MN/LAKE SUPERIOR SPEED MAX AIDING UVM.  PRIMARY 
SHORT WAVE ASSOCIATED WITH NRN PORTION OF TROUGH LOCATED OVER SD PER 
1.5 PV ANLYS.  KINEMATIC AND THERMODYNAMIC FORCING AHEAD OF THIS 
FEATURE IS RATHER WEAK WITH NO VERTICAL CONTINUITY AND IS SOMEWHAT 
MOISTURE STARVED.  ALTHOUGH TOKEN MUCAPES ARE APPARENT IN TROUGH 
AXIS...FAIRLY HIGH STATIC STABILITY EXISTS AHEAD IN FORCING.  THIS 
HAS ALL RESULTED IN NOTHING MORE THAN A NARROW BAND OF LIGHT 
PRECIP...WHICH IS REMOVED FROM DMX FORECAST AREA FOR THE TIME BEING.

&&

.SHORT TERM /TODAY/...
MAIN QUESTION TODAY BECOMES WHETHER MN PRECIP WILL BRUSH MCW AREA.  
GFS 280-290K ISENT LAYER MORE BULLISH THAN SIMILAR NAM FIELDS IN 
TERMS OF MOISTURE BRINGING LOW PRESSURE DEFICITS JUST TO FAR NE 
CORNER AND WILL BE FAVORED...BUT EVEN SO UVM SPOTTY AT BEST.  A FEW 
SRN MN SITES ARE REPORTING PRECIP REACHING THE GROUND SO WILL ADD 
ISOLATED SPRINKLE/FLURRY WORDING...BUT DO NOT FEEL AREAL COVERAGE OR 
DURATION ENOUGH TO WARRANT ANY MEASURABLE POPS.  AN ENSEMBLE OF 
VARIOUS DETERMINISTIC SOUNDINGS SUGGESTS TEMPS AT OR JUST BELOW 
COOLER END OF GUIDANCE FOR HIGHS TODAY.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
TEMPERATURES WILL BE THE MAIN FORECAST ISSUE THIS WEEK.  THE BEFORE 
MENTIONED UPPER TROUGH WILL BE MOVING EAST INTO THE GREAT LAKES 
REGION BY THIS EVENING.  LARGE SCALE SUBSIDENCE BEHIND THE WAVE AND 
WEAK SURFACE RIDGING SHOULD ALLOW FOR MOSTLY CLEAR SKIES TONIGHT. 
THE SURFACE RIDGE AND RESULTING LIGHT WINDS AND GENERALLY CLEAR 
SKIES SHOULD ALLOW FOR DECENT RADIATION COOLING. FORECASTED A LITTLE 
BELOW A MAV/MET BLEND FOR LOW TEMPERATURES TONIGHT. UPPER LEVEL 
RIDGING MONDAY AND TUESDAY AHEAD OF NEXT NORTHERN STREAM TROUGH WILL 
RESULT IN A DECENT WARMING TREND. AT THE SURFACE...GREAT BASIN 
SURFACE RIDGE WITH BROAD WESTERLY FLOW OVER THE NORTHERN AND CENTRAL 
PLAINS SHOULD ADVECT MODIFIED PACIFIC AIR INTO IA.  FORECASTED MILD 
TEMPERATURES TUESDAY WITH THERMAL RIDGE INTO THE STATE JUST AHEAD OF 
NEXT COLD FRONT WHICH IS DUE TO ARRIVE TUESDAY NIGHT.

PREFERRED THE 00Z GFS CONCERNING TIMING AND STRENGTH OF THE MIDWEEK 
NORTHERN STREAM UPPER TROUGH AND ASSOCIATED SURFACE FEATURES.  THE 
NEW 00Z ECMWF WAS IN THE BALLPARK. THE COLD FRONT TUESDAY NIGHT 
SHOULD BE STRONGER WITH DECENT CAA CONTINUING THROUGH THURSDAY.  NOT 
MUCH IN THE WAY OF FORCING AND MOISTURE TO SUPPORT MEASURABLE 
PRECIPITATION WITH THIS SYSTEM. HOWEVER...SC DECK IN THE CAA MAY BE 
CAPABLE OF PRODUCING FLURRIES GIVEN THE THERMAL CONDITIONS.  WILL 
LEAVE OUT OF THE FORECAST SINCE IT IS SEVERAL DAYS OUT AND NOT 
SIGNIFICANT.  THE LARGER STORY WILL BE THE COOL DOWN FROM MUCH ABOVE 
NORMAL TEMPERATURES TO SEASONABLE OR EVEN BELOW NORMAL TEMPERATURES 
BY LATE IN THE WEEK. 

&&

.AVIATION...
29/18Z...IFR-MVFR CEILINGS OVER CENTRAL IA AT THIS TIME WITH A 
RIBBON OF VFR TO THE NW BEFORE MORE MVFR. SHOULD BE SEEING GRADUALLY 
RISING CEILINGS THIS AFTN...SO THAT BY THE TIME SECONDARY BATCH OF 
MVFR CEILINGS REACH NRN TAF SITES...THE DECK SHOULD BE OVER 030. 
THE SKY WILL BE GENERALLY CLEAR TONIGHT WITH LIGHT NW WIND BACKING 
TO THE SOUTHWEST BY MORNING. MID LEVEL CLOUDS WILL BE ON THE 
INCREASE AFT 12Z. 

&&

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

&&

$$

SHORT TERM...SMALL
LONG TERM...JOHNSON
AVIATION...MOYER