000
FXUS63 KDMX 082139
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
339 PM CST SUN DEC 8 2013

.SHORT TERM /TONIGHT/...
ISSUED AT 339 PM CST SUN DEC 8 2013

STORM CONTINUES TO BRING LIGHT TO MODERATE SNOW AT TIMES TO THE
AREA WITH THE FORCING BEST ALONG THE BOUNDARY NOW MOVING ACROSS
CENTRAL IOWA. WAVE UPSTREAM IN CENTRAL NEBRASKA WILL MOVE EAST AND
BRING ANOTHER SHOT OF LIGHT SNOW TO THE AREA THROUGH THE EVENING
HOURS...THOUGH MODELS CONTINUE TO SHOW THE FORCING WEAKENING WITH
TIME AS IT MOVES THROUGH. TOTAL AMOUNTS STILL ON TRACK FOR ABOUT 2
TO 4 INCHES...WITH MOST AREAS RECEIVING AROUND 3 INCHES MAX. WINDS
TO REMAIN LIGHT THIS EVENING THOUGH WILL PICK UP LATER TONIGHT AS
THE SYSTEM SHIFTS TO THE EAST. COLD AIR WILL AGAIN DRIVE SOUTHEAST
OVERNIGHT AND AS CLOUDS CLEAR OUT AFTER MIDNIGHT WILL SEE LOWS
DROPPING BELOW ZERO NORTHWEST AND IN THE LOWER SINGLE DIGITS
ACROSS THE SOUTHEAST. WIND CHILLS VALUES WILL DROP DOWN TO 20 TO
25 BELOW ZERO OVER THE FAR WEST AND NORTHWEST AFT 09Z THIS
EVENING. WILL MENTION IN THE WINTER WEATHER ADVISORY AND ADVISE
THE EVENING CREW ON THE SITUATION FOR POSSIBLE UPDATES LATER THIS
EVENING.

.LONG TERM /MONDAY THROUGH SUNDAY/...
ISSUED AT 339 PM CST SUN DEC 8 2013

A LARGE 500 MB GYRE OVER CENTRAL CANADA WILL KEEP IOWA BENEATH
CYCLONIC FLOW FOR THE NEXT SEVERAL DAYS...WITH MULTIPLE SHORTWAVES
ROTATING AROUND THE BASE OF THE FLOW AND BRINGING REINFORCING COLD
FRONTS NEAR OR ACROSS OUR AREA. THE FIRST OF THESE WILL SWEEP
THROUGH ON MONDAY NIGHT BUT WITH LIMITED MOISTURE AND NO
PRECIPITATION EXPECTED OTHER THAN PERHAPS SOME FLURRIES. AS THE
NEXT WAVE APPROACHES LATE TUESDAY IT WILL BE PRECEDED BY A BROAD
SWATH OF MODEST FORCING AND MOISTURE...WITH FORECAST SOUNDINGS
INDICATING A FAVORABLE ENVIRONMENT FOR LIGHT SNOW ACROSS MUCH OF
THE AREA ON TUESDAY NIGHT. HAVE INCREASED POPS FOR THAT PERIOD BUT
ANY SNOWFALL AMOUNTS SHOULD BE LIGHT...AROUND IN INCH OR LESS. FOR
THE MONDAY THROUGH WEDNESDAY TIMEFRAME HAVE CONTINUED TO FORECAST
TEMPERATURES BELOW GUIDANCE...ESPECIALLY WITH THE SNOW PACK FROM
TODAYS EVENT IN PLACE. THIS MAY RESULT IN DANGEROUS WIND CHILLS
DURING THE MORNING HOURS ON MONDAY AND TUESDAY.

BEHIND THE TUESDAY NIGHT/WEDNESDAY 500 MB WAVE THE CYCLONIC FLOW
WILL FINALLY BEGIN TO SHIFT OFF TO THE EAST AS THE CANADIAN GYRE
MOVES OVER HUDSON BAY. THIS WILL ALLOW WEAK THERMAL RIDGING TO
BUILD IN FOR THURSDAY AND FRIDAY RESULTING IN A WARMING TREND WITH
HIGHS IN THE MID 20S TO LOWER 30S BY THE END OF THE WORK WEEK. ON
FRIDAY NIGHT AND SATURDAY A SOUTHERN STREAM 500 MB TROUGH/LOW WILL
SLIDE BY ACROSS TX/OK AND MAY SPREAD SOME LIGHT SNOW UP ACROSS
IOWA WARRANTING SLIGHT CHANCE POPS...BUT IT APPEARS TO BE A LOW
IMPACT SYSTEM WITH LITTLE CHANCE FOR APPRECIABLE ACCUMULATION.

&&

.AVIATION...08/18Z
ISSUED AT 1141 AM CST SUN DEC 8 2013

LIGHT TO MOD SNOW CONTINUES WITH IFR/MVFR CONDITIONS THROUGH
06-08Z PRIOR TO SOME IMPROVEMENT AS THE SYSTEM LIFTS OUT.
EXPECTING THAT ONCE THE LIFT DIMINISHES...SCT CONDITIONS WILL GIVE
WAY TO CLEARING BY 12Z MOST AREAS. WINDS ON THE BACK SIDE PICK UP
WITH GUSTS 22 TO 25KTS WITH HIGHER GUSTS NORTH THROUGH END OF
PERIOD.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLACK
HAWK-BOONE-BREMER-BUTLER-CLARKE-DALLAS-FRANKLIN-GRUNDY-HAMILTON-
HARDIN-JASPER-MADISON-MARION-MARSHALL-POLK-POWESHIEK-STORY-TAMA-
UNION-WARREN-WRIGHT.

WINTER WEATHER ADVISORY UNTIL 9 PM CST THIS EVENING FOR ADAIR-
ADAMS-AUDUBON-CALHOUN-CARROLL-CASS-CERRO GORDO-CRAWFORD-EMMET-
GREENE-GUTHRIE-HANCOCK-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-SAC-
TAYLOR-WEBSTER-WINNEBAGO-WORTH.

&&

$$

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