Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 151013 AAA
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
413 AM CST MON DEC 15 2014


.SHORT TERM /TODAY/...
ISSUED AT 347 AM CST MON DEC 15 2014

FIRST PUSH OF RAIN MOVING THROUGH THE CWA ATTM...STRETCHING FROM
AROUND DENISON ESE TO DES MOINES AND OTTUMWA. THIS BAND OF RAIN
SHOULD CONTINUE TO ROTATE NORTHWARD THROUGH THE CWA THROUGH SUNRISE.
UPPER CIRCULATION CENTERED OVER CENTRAL KS...AND WILL LIFT
NORTHEASTWARD INTO SOUTH CENTRAL TO SOUTHEASTERN IOWA BY LATE THIS
AFTERNOON. CURRENTLY HAVE THE DRY SLOT PUSHING INTO THE EXTREME
SOUTHERN CWA...WITH THE NEXT BATCH OF PRECIP EXPECTED WITH THE MAIN
UPPER LOW AS IT MOVES THROUGH LATER TODAY. EXCEPTION WILL BE ACROSS
THE FAR WEST/NORTHWEST WHICH MAY ALSO SEE SOME DEF ZONE PRECIP
TOWARD LATER TODAY. DENSE FOG STILL IN SPOTS ACROSS THE
NORTH/NORTHEAST AND SHOULD REMAIN UNTIL PRECIP MOVES IN...WHEN
VISIBILITIES SHOULD START TO IMPROVE. HAVE THEREFORE SHORTENED THE
TIME OF THE ADVISORY TO 8 AM...AND EXPECT VISIBILITIES MAY
IMPROVE EVEN FASTER SO WILL CONTINUE TO MONITOR. MODELS CONTINUE
TO SHOW SOME ELEVATED CAPE ACROSS THE SOUTHERN HALF OF THE CWA
THROUGH THE DAY...SO HAVE CONTINUED THE MENTION OF ISOLATED
THUNDER ROUGHLY ALONG AND SOUTH OF I-80. TEMPERATURES SHOULD BE
NEAR THE EXPECTED HIGHS WITH TEMPS REMAINING STEADY OR FALLING
THROUGH THE REMAINDER OF THE DAY AS COLDER AIR BEGINS TO FILTER
INTO THE CWA ALOFT.

.LONG TERM /TONIGHT THROUGH SUNDAY/...
ISSUED AT 347 AM CST MON DEC 15 2014

PRIMARY CONCERN REMAINS APPROACHING SYSTEM WHOSE CORE WILL BE
CENTERED OVER SERN IA AT THE BEGINNING OF THE PERIOD.  CURRENT LOBE
OF ASSOCIATED THERMODYNAMIC AND KINEMATIC FORCING GENERATING
ELONGATED ARC OF SHOWERS AND ISOLATED STORMS SHOULD BE WELL EAST OF
THE FORECAST AREA BY THAT TIME.  HOWEVER SCATTERED PRECIPITATION
WILL CONTINUE DUE TO LOWER STATIC STABILITY IN THE SYSTEM CORE...AND
PHASING OF UPSTREAM FORCING ASSOCIATED WITH TROUGH DROPPING THROUGH
THE CANADIAN PROVINCES. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH
THIS PROGRESSION. MUCH OF THIS LIFT WILL BE IN THE FORM OF A
DEFORMATION ZONE FROM SD INTO MN...HOWEVER LOWER BASED H85/H7
FORCING WITH SOME FRONTOGENETIC COMPONENT SHOULD BRUSH MAINLY NWRN
HALF OF FORECAST AREA THROUGH THE EVENING.  MODERATE FORCING IS
NOTED IN THIS LAYER...BUT WITH IT OCCURRING IN RELATIVELY WARMER
TEMPS BELOW THE DENDRITIC GROWTH ZONE ANY SNOW ACCUMS SHOULD BE
MINOR AND ALSO REDUCED BY A PERIOD OF SLEET IN THE TRANSITION. ANY
ACCUMS SHOULD BE QUITE MINOR UNDER AN INCH IF THAT ALONG AND NORTH
OF A DENISON TO ALGONA TO MASON CITY LINE...POSSIBLY JUST PUSHING
AN INCH TOWARD ESTHERVILLE. TIME SHIFTED HOPWRF IS QUITE SIMILAR
TO THIS SCENARIO PAINTED BY THE OPERATIONAL MODELS AS WELL.

PRECIPITATION SHOULD END OVERNIGHT WITH THE PRIMARY WEATHER STORY
TRANSITIONING TO WIND AND COLDER TEMPERATURES. PASSAGE OF
ISALLOBARIC MAX AND NOTED MSLP GRADIENT WILL BOOST SUSTAINED WINDS
TO 30 MPH OR MORE WHICH WILL LIKELY NEED A HEADLINE IN SUBSEQUENT
FORECAST PACKAGES. BUFKIT SOUNDINGS SHOW ONLY A SHALLOW MIXED
LAYER TO 700M OR SO...BUT ADEQUATE ENOUGH TO MIX GUSTS TO 40 MPH
OR MORE. THESE WINDS SHOULD REACH THE NWRN FORECAST AREA
COINCIDENT WITH THE BRIEF PERIOD OF LIGHT WINTRY PRECIP SO THERE
MAY BE A SHORT TIME WHERE TRAVEL BECOMES DIFFICULT DUE TO REDUCED
VISIBILITIES IN THOSE LOCATIONS. THE WORSE WINDS WILL END FAIRLY
QUICKLY TUE MORNING WITH THE WINDOW SEEMING TO BE 03Z-15Z. TEMPS
WILL TAKE AROUND A 25 DEGREE DROP TONIGHT WITH LITTLE REBOUND TUE.

REMAINDER OF FORECAST INCLUDES MAINTAINING THIS ABRUPT FLIP TO
SEASONAL TEMPERATURES AND LITTLE IN THE WAY OF PRECIPITATION.  WEAK
BLOCKING FLOW THROUGH THE CENTRAL CONUS DOES NOT PRESENT MUCH
OPPORTUNITY BUT SRN STREAM TROUGH MOVING FROM TX INTO THE MID/LOWER
MS WILL NEED TO BE MONITORED. RIGHT NOW ONLY A GLANCING BLOW OF WEAK
FORCING MAY OCCUR SOUTH FROM LATE WED NIGHT INTO FRI WITH ONLY
SLIGHT CHANCES FOR LIGHT SNOW WARRANTED.

&&

.AVIATION...15/06Z
ISSUED AT 1142 PM CST SUN DEC 14 2014

RAIN NOW MOVING INTO SW IA AND WILL SLOWLY SHIFT INTO TAF
LOCATIONS OVERNIGHT REACHING THE NE CLOSER TO 12Z. I EXPECT LIFR
CIGS AND VSBYS BOUNCING FROM 2 TO 5SM WITH OCCASIONALLY LOWER
VSBYS. FOR KMCW AND KALO CIGS WILL BE LOW FOR MUCH OF THE PERIOD
WITH VSBYS BETWEEN A HALF MILE AND A QUARTER MILE. ONCE THE RAIN
MOVES IN VSBYS SHOULD IMPROVE SOME. SFC WIND WILL BE SE AT
10-15KTS WITH A FEW GUSTS. AFT 00Z WINDS WILL BECOME NRLY AND
DRAMATICALLY INCREASE TO 18G30KTS.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...

DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR BLACK HAWK-
BREMER-BUTLER-CERRO GORDO-EMMET-FRANKLIN-GRUNDY-HANCOCK-HARDIN-
HUMBOLDT-KOSSUTH-PALO ALTO-WINNEBAGO-WORTH-WRIGHT.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...SMALL
AVIATION...FAB



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