FXUS63 KDMX 261756
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1156 AM CST SAT DEC 26 2009

.UPDATE...
MORNING UPDATE HIT SNOW A LITTLE HARDER DUE TO MINOR SHALLOW 
CONVECTIVE SNOW BURSTS WHICH APPEAR TO BE WANING SOMEWHAT.  ALSO 
LOWERED HIGHS PER RECENT OBS VS FORECAST SOUNDINGS.  18Z TAF 
DISCUSSION APPENDED AS WELL.

&&

.SHORT TERM.../TODAY/
LOW PRESSURE OVER SOUTHWEST IOWA...CENTERED NEAR CRESTON...IS 
CONTINUING TO FILL AND WEAKEN. SOME LIGHT SNOW IS STILL 
ONGOING...MAINLY TO THE EAST AND NORTHEAST OF THE SFC FEATURE WHILE 
DRIER AIR IS MOVING WEST SOUTHWEST OUT OF WISCONSIN AND INTO THE 
NORTHEAST PART OF THE STATE. SOME OF THE SNOW WILL LIKELY LINGER 
OVER THE SOUTHEAST AFTER 12Z WITH MINOR ADDITIONAL ACCUMULATIONS 
POSSIBLE BEFORE ENDING. FARTHER TO THE WEST...LIGHT SNOW REMAINS 
HOWEVER VISIBILITIES HAVE BEEN REMAINING 5SM OR GREATER INCLUDING 
WITHIN THE CURRENT WINTER STORM WARNING AREA. WILL BE DROPPING THIS 
HEADLINE WITH THIS MORNINGS PACKAGE ISSUANCE. WILL BE DROPPING THE 
WINTER WEATHER ADVISORY AS WELL. AS MENTIONED SOME MINOR ADDITIONAL 
ACCUMULATIONS ARE POSSIBLE THOUGH LITTLE IMPACT IS EXPECTED FROM THE 
LIGHT FLUFFY SNOW CURRENTLY ONGOING. 

HIGH TEMPERATURES TODAY WILL BE COLD WITH HIGHS GENERALLY IN THE 20 
TO 25 DEGREE RANGE. DUE TO THE LOW PRESSURE CIRCULATION...OUR 
PRIMARY WEATHER TODAY WILL BE ORIGINATING FROM CENTRAL AND SRN 
WISCONSIN RESULTING IN WEAK LOW LEVEL COLD ADVECTION ALL DAY AND A 
REDUCTION IN PRECIPITATION CHANCES. THERE ARE CURRENTLY A FEW BREAKS 
IN THE CLOUDS OVER THIS REGION AS WELL...WHICH SHOULD REACH PORTIONS 
OF NORTH CENTRAL AND CENTRAL IA BY THIS AFTERNOON. 

.LONG TERM.../TONIGHT THROUGH FRIDAY/
SURFACE LOW FINALLY MOVES OFF INTO THE GREAT LAKES TONIGHT AND 
SUNDAY...BUT ONE MORE SPOKE WILL ROTATE SOUTHWARD AROUND THE UPPER 
LOW TONIGHT BEFORE THE PRECIPITATION EVENT IS OVER. ALL MODELS SHOW 
BEST FORCING TO BE WEST OF I-35 BEFORE MIDNIGHT TONIGHT AND THEN 
OVER SE HALF OF FORECAST AREA UNTIL MORNING. SATURATION IS NOT DEEP 
BUT IT IS WITHIN THE DENDRITIC THERMAL ZONE FOR A FEW HOURS...ENOUGH 
FOR HIGH CHANCE TO LIKELY POPS AND POSSIBLY AN INCH OR SO OF SNOW. 
COULD BE SOME FLURRIES SUNDAY BELOW THE INVERSION BUT NO 
ACCUMULATION EXPECTED. MODERATE WNW WINDS STAY UP INTO MONDAY... 
ALONG WITH WARM AIR NOSING IN ABOVE 850 MB. THIS WILL KEEP TEMPS 
FROM GETTING TOO COLD THROUGH MONDAY...BUT HIGH PRESSURE MOVES 
ACROSS THE AREA MONDAY NIGHT. LIGHT WINDS NEAR THE HIGH SHOULD ALLOW 
LOWS TO DROP BELOW ZERO OVER THE WEST AND NORTH. 

BY TUESDAY NIGHT AND WEDNESDAY...A WEAK SHORT WAVE IN THE NORTHERN 
STREAM BEGINS TO PHASE WITH A MUCH STRONGER SOUTHERN STREAM SHORT 
WAVE...BUT MOST OF THE ACTION WILL TAKE PLACE EAST OF IOWA. NET 
RESULT WILL BE A LOW PRESSURE SYSTEM ALONG THE CANADIAN BORDER AND A 
PACIFIC COLD FRONT CROSSING IOWA WEDNESDAY...WHILE A BIGGER SYSTEM 
CRANKS UP ALONG THE GULF COAST. SLIGHT CHANCE TO CHANCE POPS IN 
PLACE FOR TUESDAY NIGHT AND WEDNESDAY WITH THIS FEATURE BUT ANY 
ACCUMULATIONS WOULD APPEAR TO BE LIGHT. NO CHANGES TO THU/FRI 
FORECAST BUT IT APPEARS THAT DEEPENING EASTERN U.S. SYSTEM WILL WRAP 
DOWN SOME COLDER AIR BEGINNING THURSDAY INTO THE NEW YEAR.

&&

.AVIATION...
26/18Z...LARGE LOW PRESSURE SYSTEM CONTINUES TO ROTATE AROUND IA 
WITH LOBES OF CLOUDS AND CLEARING RESULTING IN LOW CONFIDENCE 
FORECAST.  CURRENT NOTCH OF CLEARING HAS PUSHED INTO CENTRAL IA FROM 
SERN MN WITH VARIOUS CIG LEVELS EITHER SIDE OVER WRN AND SERN IA.   
AS SYSTEM PULLS AWAY TONIGHT...PLAYED A MIDDLE OF THE ROAD TREND 
WITH MVFR CIGS/VSBYS BECOMING MORE PREVALENT WITH PERIODS OF SNOW 
OVERNIGHT.  COULD DIP TO IFR BUT LIKELIHOOD NOT GREAT ENOUGH TO 
INCLUDE.  SNOW MAY DIMINISH OR END ALTOGETHER TOWARD DAYBREAK...BUT 
WITH AT LEAST MVFR CIGS CONTINUING.

&&

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

&&

$$

SHORT TERM...DONAVON/SMALL
LONG TERM...JUNGBLUTH
AVIATION...SMALL