000
FXUS63 KDMX 020933
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
333 AM CST MON DEC 2 2013

.SHORT TERM /TODAY/...
ISSUED AT 330 AM CST MON DEC 2 2013

WEAK BOUNDARY LOCATED IN WESTERN NEBRASKA WILL SLOWLY PUSH EASTWARD
INTO IOWA THROUGH THE DAY TODAY...ALLOWING TEMPERATURES TO WARM
THROUGHOUT THE DAY. HAVE KEPT TEMPERATURES WELL ABOVE NORMAL FOR
EARLY DECEMBER IN ACROSS MUCH OF THE CWA GIVEN RECENT WARM
TEMPERATURES AND RELATIVELY WARM OVERNIGHT LOWS...THOUGH HAVE KEPT
TEMPERATURES A BIT LOWER IN THE NORTHEAST WHERE CLOUDS WILL REMAIN
THROUGH THE DAY.

BAND OF THETA-E ADVECTION AHEAD OF BOUNDARY WILL BRING INCREASED
CHANCES FOR PRECIPITATION TO CENTRAL IOWA...THOUGH MOISTURE IS A
LIMITING FACTOR AS LOW LEVEL DRY AIR REMAINS IN PLACE. GIVEN LACK
OF PRECIPITATION REACHING THE GROUND IN NORTHERN IOWA ATTM...HAVE
LEFT PRECIPITATION OUT OF MUCH OF CENTRAL IOWA...WITH POPS FOCUSED
IN THE NORTHEAST AND EAST WITH BEST MOISTURE AND INCREASING
FORCING...IN LINE WITH HIGH RESOLUTION MODELS. HOWEVER...MAY SEE
BRIEF PERIODS OF ISOLATED LIGHT RAIN ACROSS CENTRAL IOWA IN THE
MORNING HOURS AS FORCING INCREASES. PRECIPITATION WILL BE
LIGHT...WITH SNOW POSSIBLE IN THE MORNING BEFORE CHANGING TO RAIN.
GOOD SET UP FOR HIGH POP/LOW QPF...BUT HAVE KEPT POPS IN CHANCE
RANGE ATTM WITH UNCERTAINTY AND EXPECTED SCATTERED NATURE OF
PRECIP. HOWEVER...MAY NEED TO INCREASE POPS IN THE AFTERNOON IN
THE EAST AS SYSTEM EVOLVES.

.LONG TERM /TONIGHT THROUGH SUNDAY/...
ISSUED AT 330 AM CST MON DEC 2 2013

GENERAL THEME FOR THE NEXT 5 TO 7 DAYS REMAINS THE SAME WITH SOME
MINOR DETAILS STILL TO CONSIDER.  OVERNIGHT TONIGHT MODEST LIFT WILL
CONTINUE OVER NORTHERN IOWA IN VICINITY OF WARM FRONT AND THETAE
ADVECTION. THIS SHOULD ONCE AGAIN RESULT IN AN AREA OF POSSIBLE
LIGHT RAIN OR LIGHT RAIN/SNOW MIXED ACROSS THE FAR NORTHEAST DURING
THE OVERNIGHT HOURS. MINS WILL REMAIN QUITE MILD...COMPARED TO WHATS
ARRIVING BY WEDNESDAY AND THURSDAY MORNINGS. WARM CONDITIONS WILL
REMAIN FOR TUESDAY AS SOUTH SFC FLOW AND ALOFT PUSHES H850 TEMPS TO
8 TO 10C ALOFT...BUT DECENT INVERSION COUPLED WITH SHALLOW MIXED
LAYER AND MID LEVEL CLOUD DECK FOR MUCH OF THE DAY WILL DETRACT FROM
WHAT WOULD BE AN EVEN MILDER AFTERNOON. THERE IS SOME POTENTIAL THAT
MORNING CLOUDS WILL GIVE WAY TO SOME PARTIAL CLEARING BY AFTERNOON.
WITH THAT SAID...LOWER 40S NORTH TO MID TO UPPER 50S SOUTHEAST STILL
LOOKS POSSIBLE FOR THE DAY. QUESTIONS STILL REMAIN REGARDING THE
TIMING OF THE COLD FRONT EARLY WED MORNING. THE GFS/NAM CONTINUE TO
LEAD THE PACK WITH THE GEM LAGGING A FEW HOURS AND THE EURO HAVING
AGAIN SLOWED DOWN TO HAVING THE FRONT JUST EAST OF I35 MORE OF LESS
BISECTING THE FORECAST AREA BY 12Z WED. THOUGH THE BIG PICTURE
REMAINS THE SAME...MORNING LOWS AND EVENTUAL HIGHS FOR WED WILL BE
IMPACTED BY THE TIMING OF THE ARRIVAL OF THE COLD AIR...MORE
ACADEMIC AN EXERCISE THAN A MAJOR CHANGE IN THE REALITY OF WHATS TO
COME FOR THE NEXT SEVERAL DAYS. WILL TAKE A COMPROMISE BETWEEN THE
GFS/GEM AND THE EURO...WHICH DELAYS THE BOUNDARY A BIT AND ONLY
MODIFY TEMPS SLIGHTLY. STILL HAS THE POTENTIAL FOR A 15 DEGREE SWING
IN EARLY MORNING HIGHS/LOWS DEPENDING ON THE MODEL SOLUTION. TEMPS
ACROSS THE BOUNDARY WILL BE QUITE DRAMATIC. LOOKING UPSTREAM AT SFC
TEMPS OVER SOUTHERN CANADA EXPLAINS WHY. TEMPS NOW IN THE LOWER 20S
WITH CENTRAL PROVINCE TEMPS ABOUT 5 TO 10 ABOVE ZERO.  THUS... VERY
SHALLOW ARCTIC AIR SHOULD THOROUGHLY UNDERCUT THE LINGERING WARMER
AIR ALOFT. BUFR SOUNDINGS RIGHT NOW INDICATE LITTLE SATURATION AS
THIS OCCURS OVER THE SOUTH AND OVER THE NORTH IT APPEARS THAT THE
COLD AIR ADVECTION ARRIVES AT ALL LEVELS ABOUT THE SAME TIME. SO ANY
TRANSITION FROM R/S TO S- SHOULD BE FAIRLY QUICK.  MODELS ALSO
BEGINNING TO INDICATE SOME STRONG UPPER LEVEL FORCING AT H700 BUT
THERE ARE SOME UNCERTAINTIES AS TO THE LOCATION OF THE FORCING BY
WEDNESDAY MORNING. THE GFS/GEM ARE FARTHER SOUTH INTO NORTHWEST AND
NORTH CENTRAL IA WITH THIS FEATURE WHILE THE EURO LAGS BOTH MODELS
IN TIMING AND ALSO KEEPS MOST OF THE FORCING IN SOUTHERN MN. WITH
THE UNCERTAINTY WILL NOT INCREASE SNOWFALL AMOUNTS OVER NORTHERN
SECTIONS TOO MUCH YET...BUT MAY INCREASE POPS NORTH AND NORTHWEST
THIRD TO REFLECT THE POSSIBILITY OF SOME SNOW WEDNESDAY MORNING AND
AFTERNOON. THE GFS ON THE OTHER HAND NEARLY DRYS THE AREA OUT WITH
SUBSIDENCE AND COLD AIR ADVECTION. SOME OF THESE DETAILS WILL HAVE
TO BE SOLIDIFIED IN THE NEXT 2 MODEL RUNS AS CONFIDENCE STILL
LACKING ON STORM EVOLUTION. THE SYSTEM IS JUST ENTERING THE PACIFIC
NORTHWEST AND WITH SUCH A LARGE PATTERN CHANGE...THIS IS USUALLY THE
CASE.

THE REST OF THE FORECAST REMAINS THE SAME. THEME IS COLD. SCATTERED
FLURRIES AND A MIXTURE OF SUN/CLOUDS LIKELY TO STICK AROUND FOR 24
TO 36 HOURS BEYOND THE INITIAL FRONTAL PASSAGE PRIOR TO ARCTIC HIGH
FINALLY SETTLING INTO THE REGION BY FRIDAY AFTERNOON OR NIGHT. WINDS
WILL QUICKLY RACHET UP BEHIND THE BOUNDARY ON WEDNESDAY...RESULTING
IN MIXED LAYER OF 25 TO 35 MPH GUSTS WITH LOWERING WIND CHILLS.
THOUGH ADVISORIES ARE NOT NEEDED WED...AFTERNOON WIND CHILLS WILL
DROP TO NEAR ZERO NORTHWEST TO AROUND 20 SOUTHEAST BY LATE
AFTERNOON.

&&

.AVIATION...02/06Z
ISSUED AT 1130 PM CST SUN DEC 1 2013

MID LEVEL DECK CONTINUES TO STREAM ACROSS THE STATE AND WILL
REMAIN IN PLACE THROUGH MUCH OF THE FORECAST PERIOD. A FEW BREAKS
IN THE CLOUDS ALLOWING FOR SOME BRIEF PERIODS OF CLEARING AT KALO
AND KMCW. THIS HAS LED TO SOME LIGHT FOG AND MVFR VSBYS. CLOUD
DECK EXPECTED TO FILL IN IN A FEW HOURS...SO ONLY HAVE A BRIEF
MENTION. SOME CHANCES FOR SOME LIGHT SNOW/FLURRIES MAINLY AT KMCW
AND KALO THROUGH THE PERIOD...BUT UNCERTAIN ON ANY TIMING/IF EVEN
HAVE A VSBY REDUCTION SO HAVE LEFT MENTION OUT ATTM. OTHERWISE
ONLY OTHER ISSUE IS WITH LOW LEVEL MOISTURE EXPECTED TO RESULT IN
SOME MVFR CIGS ACROSS KALO AND KMCW BY MONDAY AFTERNOON INTO THE
EVENING. EAST TO SOUTHEAST WINDS THROUGHOUT THE PERIOD.


&&

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

$$

SHORT TERM...AWB
LONG TERM...REV
AVIATION...BEERENDS