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000
FXUS63 KDMX 102336
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
536 PM CST TUE DEC 10 2013

.SHORT TERM /TONIGHT/...
ISSUED AT 315 PM CST TUE DEC 10 2013

MAIN CONCERN WILL BE CLIPPER SYSTEM TONIGHT. TRACK OF SYSTEM STILL
PLACES MOST OF THE EXPECTED 1 TO 3 INCHES OF SNOW ACROSS THE
NORTHERN AREAS. MODELS TODAY VARY A BIT WITH THE EURO THE MOST
CONSISTENT FROM LAST NIGHT. SOME MINOR DIFFERENCES ON FORCING AND
QPF BUT OVERALL WITH SNOWFALL RATIOS OF 20:25:1 CONTINUE TO GET 1.5
TO 2.5 INCH TOTALS. BUFR SOUNDINGS SUGGEST WINDS BEHIND THE SYSTEM
WILL INCREASE TO 15 TO 25 MPH FROM 04Z NORTHWEST TO ABOUT 16Z OR SO
EAST AS THE SYSTEM DEPARTS AND RIDGE BUILDS INTO THE AREA. BY MID TO
LATE MORNING MOST AREAS WILL SEE WINDS LESSENING IN STRENGTH ONCE
AGAIN. WITH THE COMBINATION OF LIGHT POWDERY SNOW...WIND...AND COLD
AIR SPILLING INTO THE REGION OVERNIGHT...WILL BE GOING WITH A WINTER
WX ADVISORY ACROSS THE NORTH WHERE CONDITIONS WILL BE IMPACTED THE
MOST BY ALL THREE ELEMENTS. FARTHER SOUTH...LESS SNOW...LESS IMPACT
FROM WIND CHILLS SO WILL HAVE NO HEADLINE THERE. CURRENT EXPECTED
TRACK STILL FAVORS NORTH... BUT MINOR ADJUSTMENTS MAY NEED TO BE
MADE IF THE LOW DIGS A BIT MORE TO THE SOUTH. LOWS WILL BOTTOM NEAR
12Z WITH NEGATIVE READINGS AGAIN NORTHWEST/NORTH AND SINGLE DIGITS
IN THE CENTRAL AND SOUTHEAST THROUGH 12Z WITH COLD ADVECTION
CONTINUING THROUGH WEDNESDAY.

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 315 PM CST TUE DEC 10 2013

FORECAST CONCERN FOR MUCH OF EXTENDED REVOLVES AROUND
TEMPERATURES...WITH FEW PERIODS OF PRECIPITATION. ANTICIPATE
DIGGING SHORTWAVE TO BE PAST MOST OF CWA FOR BEGINNING OF
PERIOD...WITH ONLY LIGHT LINGERING SNOW IN THE EAST. WINDS WILL
REMAIN STOUT FROM THE NORTHWEST BEHIND THIS SYSTEM AS AN AREA OF
HIGH PRESSURE BEGINS TO PUSH INTO THE EAST. PRESSURE GRADIENT WILL
RELAX SOMEWHAT INTO THE AFTERNOON WITH WINDS BECOMING LIGHTER FROM
WEST TO EAST INTO THE LATE AFTERNOON WEDNESDAY...AS HIGH PUSHES
INTO WESTERN IOWA. TEMPERATURES WILL STRUGGLE TO WARM MUCH
WEDNESDAY...ESPECIALLY IN NORTH GIVEN FRESH SNOWFALL. WITH WINDS
AND TEMPERATURES WIND CHILL VALUES WILL REMAIN NEAR OR BELOW
ADVISORY CRITERIA ACROSS MUCH OF NORTHERN CWA THROUGH NOON. HAVE
OPTED NOT TO ADD WIND CHILL ADVISORY ON TOP OF WINTER WEATHER
ADVISORY FOR THIS PERIOD. HOWEVER...MAY NEED TO TRANSITION
HEADLINES AT EXPIRATION OF WINTER WEATHER ADVISORY TO ALLOW FOR A
WIND CHILL ADVISORY FOR A TIME IN THE LATE MORNING/EARLY
AFTERNOON ACROSS THE NORTH.

WAA WILL BEGIN TO INCREASE IN THE WEST AS HIGH SHIFTS
EASTWARD...WITH WARMER TEMPERATURES WEST. HOWEVER...AS HIGH SHIFT
TO THE EAST FOR THE EVENING EXPECT TEMPERATURES TO DROP OFF
SHARPLY WITH LIGHT WINDS AND SNOW ON GROUND. WILL REACH OVERNIGHT
LOWS SHORTLY AFTER SUNSET ON WEDNESDAY NIGHT BEFORE WAA INCREASES
AND CLOUDS BEGIN TO ALSO INCREASE...ESPECIALLY ACROSS THE NORTH
FOR WEDNESDAY NIGHT AND WILL SEE TEMPERATURES RISE BEGINNING
GENERALLY NEAR 06Z. TEMPS WILL CONTINUE TO WARM UNDER HIGH FOR
THURSDAY AND FRIDAY...WITH TEMPERATURES STILL REMAINING SLIGHTLY
BELOW NORMAL...THOUGH LIKELY WILL BE WARMEST TEMPERATURES FOR THE
PERIOD.

MODELS PUSH ANOTHER WEAK WAVE ACROSS CENTRAL IOWA OVERNIGHT
WEDNESDAY. CURRENTLY HAVE LEFT FORECAST DRY WITH EXPECTED LOW LEVEL
DRY AIR IN PLACE. HOWEVER...MODEL SOUNDINGS INDICATE SATURATION WRT
ICE THROUGH MOST OF THE MID AND UPPER LEVELS...AND MAY SEE SOME
LIGHT -SN REACH THE GROUND. THIS WILL BE A BRIEF PERIOD OVERNIGHT
BEFORE SYSTEM PUSHES EAST.

BEST CHANCE FOR PRECIPITATION IN THE EXTENDED WILL COME BEGINNING
LATE FRIDAY AS A LOW PRESSURE SYSTEM LIFTS NORTH FROM KS.
HOWEVER...AS STUBBORN NORTHWESTERLY FLOW REMAINS ACROSS IOWA...DO
NOT HAVE HIGH CONFIDENCE IN NORTHERN EXTENT OF THIS SYSTEM.
ANOTHER WAVE WILL DROP SOUTH THROUGH NW FLOW INTO IOWA FOR
SATURDAY...THOUGH THIS WILL AGAIN BE QUICK MOVING. MODELS ARE IN
DECENT AGREEMENT WITH TIMING OF THESE SYSTEMS. HAVE OPTED TO KEEP
MOSTLY SLIGHT CHANCE POPS THROUGH SATURDAY GIVEN UNCERTAINTIES IN
AMOUNT OF AVAILABLE MOISTURE. BEHIND SYSTEM YET ANOTHER COLD HIGH
PRESSURE SYSTEM WILL SETTLE INTO IOWA FOR REMAINDER OF EXTENDED
WITH TEMPERATURES REMAINING BELOW NORMAL.

&&

.AVIATION...11/00Z
ISSUED AT 536 PM CST TUE DEC 10 2013

AN AREA OF LIGHT SNOW AND LOW CIGS WILL MOVE ACROSS THE AREA IN
THE NEXT SIX TO EIGHT HOURS...WITH MVFR VSBYS/CIGS PREVAILING AND
PERIODS OF IFR CONDITIONS POSSIBLE ESPECIALLY AT THE NORTHERN
TERMINALS. THE SNOW WILL END AND LOW CIGS WILL CLEAR OUT RAPIDLY
AS A SHARP COLD FRONT MOVES THROUGH AFTER 06Z...FOLLOWED BY STRONG
AND GUSTY NNW WINDS. THE WINDS MAY BE ENOUGH TO REDUCE VSBYS IN
BLSN EVEN AFTER THE SNOWFALL HAS ENDED...BUT WILL WAIT TO REASSESS
THAT POTENTIAL FOR THE 06Z TAFS. ON WEDNESDAY CONDITIONS WILL BE
VFR AND NEARLY CLEAR BUT WITH STIFF NNW BREEZES CONTINUING IN THE
MORNING.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST
WEDNESDAY FOR BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CERRO GORDO-
EMMET-FRANKLIN-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-JASPER-
KOSSUTH-MARSHALL-PALO ALTO-POCAHONTAS-POWESHIEK-SAC-STORY-TAMA-
WEBSTER-WINNEBAGO-WORTH-WRIGHT.

&&

$$

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