FXUS63 KDMX 012316 AAA
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
516 PM CST TUE DEC 1 2009

...AVIATION DISCUSSION 02/00Z

.SHORT TERM [TONIGHT]...
FAIRLY STRONG SURFACE COLD FRONT CURRENTLY FROM MINNEAPOLIS TO 
LINCOLN NEB HAS MOVED THROUGH THE NW CORNER OF THE DMX CWA. TEMPS 
AHEAD OF THE FRONT HAVE RISEN IN THE LOWER TO MID 60S IN THE DSM 
METRO AREA AND NEARBY LOCATIONS. HOWEVER...THE MILD WEATHER WILL 
COME TO AN END TONIGHT. THE FRONT WILL PASS THROUGH THE DSM AREA 7-9 
PM AND BE THROUGH THE ENTIRE CWA BY 3 AM. AIRMASS QUITE DRY 
INITIALLY...SO NOT EXPECTING MORE THAN AN INCREASE IN MID TO UPPER 
LEVEL CLOUDS OVERNIGHT...POSSIBLY SOME LOWER LEVEL CLOUDS ACROSS THE 
NORTH BY MORNING. NW WINDS WILL INCREASE BEHIND THE FRONT...GUSTING 
TO 25 OR SO.

.LONG TERM [WEDNESDAY THROUGH TUESDAY]...
BEHIND COLD FRONT TONIGHT MUCH COOLER AIR WILL STREAM INTO THE STATE 
FOR THE REMAINDER OF THE SEVEN DAY FORECAST...WITH THE COLDEST 
TEMPERATURES SO FAR THIS SEASON ON TAP FOR LATER THIS WEEK. COLD AIR 
ADVECTION IN A STIFF NORTH NORTHWEST BREEZE...ALONG WITH SOME LOW 
STRATUS...WILL HOLD TEMPERATURES IN CHECK ON WEDNESDAY WITH HIGHS 
GENERALLY LESS THAN 10 DEGREES ABOVE MORNING LOWS. DRY AIR WILL BE 
FIRMLY IN PLACE PROHIBITING PRECIPITATION...UNLESS JUST A FEW FLAKES 
OF SNOW ARE SQUEEZED OUT IN THE NORTH. DEEP COLD AIRMASS WILL ADVECT 
IN ALOFT WITH A MID/UPPER LOBE OF LOW PRESSURE FROM WEDNESDAY NIGHT 
THROUGH FRIDAY NIGHT...BRINGING A COUPLE OF DAYS OF MUCH 
COLDER...CLOUDY...AND GENERALLY WINTER LIKE WEATHER ACROSS THE AREA. 
GIVEN THE DEPTH OF THE COLD AIR AND PERSISTENT CLOUD COVER ON 
THURSDAY AND FRIDAY...EXPECT VERY SMALL DIURNAL TEMPERATURE RANGES 
TO CONTINUE. INCREASE IN LOW/MID LEVEL RH ASSOCIATED WITH THIS LOBE 
WILL RESULT IN PERSISTENT SNOW CHANCES DURING THIS PERIOD...HOWEVER 
A LACK OF LIFT AND A NEAR SURFACE DRY LAYER WILL LIMIT THE PRECIP 
INTENSITY WITH JUST FLURRIES LIKELY MOST OF THE TIME...AND A CHANCE 
OF LIGHT SNOW ON THURSDAY/THURSDAY NIGHT WHEN LIFT IS MAXIMIZED WITH 
THE PRIMARY MID LEVEL WAVE MOVING OVERHEAD. ANY ACCUMULATIONS ARE 
EXPECTED TO BE LIGHT. THIS SYSTEM WILL FINALLY MOVE OFF TO THE 
NORTHEAST ON FRIDAY NIGHT...WITH A BRIEF SUBSEQUENT PERIOD OF 
SOUTHERLY WINDS AND MODEST WARM AIR ADVECTION BEFORE ANOTHER COLD 
FRONT MOVES THROUGH LATE SATURDAY.

EARLY NEXT WEEK THERE IS MORE SIGNIFICANT DIVERGENCE AMONG THE LONG 
RANGE MODELS...HOWEVER THERE IS GOOD AGREEMENT IN THE GENERAL 
SCENARIO OF A BROAD MID/UPPER TROUGH SETTING UP OVER THE ROCKIES 
WITH SURFACE LOW PRESSURE OVER THE SOUTHERN PLAINS AND A SURFACE 
TROUGH EXTENDING NORTHEASTWARD ACROSS THE MIDWEST AND NEAR OUR AREA. 
WITHIN THIS GENERAL SET UP PRECIPITATION IS LIKELY...HOWEVER IT IS 
TOO EARLY TO GET A GOOD READ ON TIMING AND TYPE OF SAID PRECIP. SNOW 
APPEARS MOST LIKELY...AND HAVE INCLUDED SLIGHT CHC TO LOW CHC POPS 
FROM MONDAY NIGHT THROUGH TUESDAY NIGHT TO BEGIN TO ADVERTISE THIS 
SYSTEM. THIS WILL BEAR CLOSER MONITORING DURING THE NEXT SEVERAL 
DAYS.

&&

.AVIATION...
02/00Z...COLD FRONT CONTINUES TO TRACK SOUTHEAST OVER THE AREA. 
BIGGEST CHANGES OVERNIGHT AND INTO WED WILL BE THE GRADUAL LOWERING 
OF CIGS AND INCREASE IN NW FLOW. WINDS STILL GUSTING TO 25-28KTS 
OVER NW IOWA AND SOUTH DAKOTA. SOME MIXING EXPECTED TO CONTINUE 
OVERNIGHT AND INCREASE BY 15Z WED. CLOUDS WILL REMAIN VFR...BUT SHOW 
SOME LOWERING TO MVFR BY 15Z. WILL MONITOR CLOUD TRENDS FOR 06Z TAF 
PACKAGE. SNOW SHOWERS SHOULD HOLD OFF BEYOND THIS TAF PERIOD AND 
DEVELOP WHEN DEEP UPPER LOW DROPS SOUTH INTO THE REGION./REV
&&

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

&&

$$

SHORT TERM...MOYER
AVIATION...REV
LONG TERM...LEE