000
FXUS63 KDMX 151556
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1056 AM CDT SAT MAR 15 2014

.UPDATE...
ISSUED AT 1055 AM CDT SAT MAR 15 2014

A FEW CHANGES WITH MORNING UPDATE. DELAYED POPS FURTHER INTO THE
AFTERNOON WITH CIGS NOW 10KFT OR HIGHER OVER NRN IA. ALSO LOWERED
MAXES A BIT...WHICH STILL MAY NOT BE ENOUGH. ELY OR NELY WINDS
ACROSS THE FORECAST AREA AT 15Z WITH LITTLE REBOUND NOTED OVER THE
PAST FEW HOURS. OBJECTIVE SURFACE ANALYSIS SHOWS PRESSURE FALLS
EVIDENT OVER WRN IA AT 12Z HAVE NOW BE REPLACED WITH WEAK PRESSURE
RISES. WILL CONTINUE TO MONITOR TEMP TRENDS...WHICH WOULD
OBVIOUSLY ALSO IMPACT PRECIP TYPE AS EVENT MATURES LATER THIS
AFTERNOON.

&&

.SHORT TERM /TODAY/...
ISSUED AT 325 AM CDT SAT MAR 15 2014

A SQUEEZE PLAY WILL BE PUT ON IOWA TODAY AS GULF MOISTURE LIFTS UP
FROM THE SOUTH AND DRY AIR MOVES IN FROM THE NORTH AS A LARGE HIGH
PRESSURE SYSTEM DROPS INTO THE NORTHERN PLAINS. THE INITIAL AIR MASS
ACROSS THE STATE WILL BE RELATIVELY DRY THEREFORE PRECIPITATION
CHANCES THROUGH THE DAY WILL BE RELIANT ON SATURATION THROUGH THE
PERIOD. THE PRIMARY MOISTURE ADVECTION THROUGH MUCH OF THE DAY WILL
BE FOCUSED IN THE MID LEVELS AND WILL LEAD TO INCREASED CLOUDINESS
THROUGH THE DAY. PROFILES WILL REMAIN QUITE DRY BELOW 700 MB THIS
MORNING EXCEPT FOR THE FAR NORTH THEN GRADUALLY BETWEEN HIGHWAY 20
AND HIGHWAY 30 BY MID TO LATE AFTERNOON. THEREFORE THE SOUTHERN HALF
IS EXPECTED TO REMAIN DRY THROUGH AT LEAST LATE AFTERNOON BEFORE A
BETTER CONNECTION WITH THE LOW LEVEL MOISTURE THAT IS STREAMING
NORTH ARRIVES. PRECIPITATION TYPE WILL BE PREDOMINATELY LIGHT SNOW
OVER THE FAR NORTH...GENERALLY NORTH OF HIGHWAY 18 THROUGH MID
AFTERNOON THEN GETTING NEAR HIGHWAY 20 LATE. SNOWFALL AMOUNTS OF AN
INCH OR LESS ARE POSSIBLE.

A WIDE RANGE IN TEMPERATURES. A MIX OF CLOUDS AND COLD ADVECTION
WILL RESULT IN HIGHS IN THE MID 30S WHILE LOWER 60S ARE POSSIBLE
OVER SOUTHERN IOWA. COOLED HIGH TEMPERATURES FOR CENTRAL IOWA
INCLUDING THE AMES AND DES MOINES AREAS TO THE MID 40S TO LOWER 50S
AS THE COLD AIR SINKS SOUTH AND CLOUDS IMPACT THE REGION.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 325 AM CDT SAT MAR 15 2014

FAST MOVING SYSTEM WILL IMPACT CENTRAL IOWA FOR BEGINNING OF
PERIOD...WITH PRECIPITATION ANTICIPATE TO BE ONGOING...QUICKLY
PUSHING SOUTH AS LOW PRESSURE SYSTEM PULLS EAST AND HIGH PRESSURE
SYSTEM BUILDS IN BEHIND. MODELS HAVE BEGUN TO BRING SYSTEM THROUGH
A BIT FASTER...AND HAVE ADJUSTED TIMING OF PRECIPITATION
ACCORDINGLY...MORE IN LINE WITH PASSAGE OF MID LEVEL FN FORCING.
MODELS HAVE ALSO BEGUN TO BACK OFF OF PRECIPITATION TOTALS
SLIGHTLY TOO...AND HAVE ALSO CUT BACK A SMALL AMOUNT...ESPECIALLY
AS LATEST MODEL RUNS DECREASE FORCING...AND ANTICIPATE MOST
MOISTURE TO BE CUT OFF BY PRECIPITATION ACROSS SOUTHERN MO.
HOWEVER...FORCING IS STILL SUFFICIENT AND MODELS INDICATE
POTENTIAL FOR A SLIGHTLY HEAVIER BAND OF SNOWFALL...GENERALLY
ALONG A CRESTON TO PELLA LINE...WITH FASTER STORM TRACK THIS MAY
GET PUSHED FURTHER SOUTH TOWARDS OTTUMWA. THOUGH TOTALS ARE STILL
EXPECTED TO BE OVERALL WEAK WITH RAIN CHANGING OVER TO SNOW NEAR
06Z AS COLD AIR PUSHES SOUTH.

HIGH PRESSURE WILL KEEP TEMPERATURES COOLER FOR SUNDAY AS WEAK
CAA PUSHES ACROSS CENTRAL IOWA. WAA WILL QUICKLY RETURN WITH
SOUTHERLY WINDS ON BACK SIDE OF HIGH...WHICH WILL HELP
TEMPERATURES WARM QUICKLY AGAIN FOR MONDAY. HAVE BUMPED
TEMPERATURES UP FOR MONDAY AND TUESDAY...THOUGH MAY STILL BE A
BIT COOL. ANOTHER AREA OF LOW PRESSURE WILL DROP SE FROM MONTANA
FOR TUESDAY...HOWEVER MODELS ARE NOT IN GOOD AGREEMENT WITH THIS
SYSTEM. THOUGH HAVE BEGUN TO COME IN LINE WITH A MORE NORTHERLY
SOLUTION...TRACKING LOW ACROSS SOUTHERN SD/MN. THIS WOULD DELAY
ONSET OF PRECIPITATION ACROSS NORTHERN IOWA...AND HAVE CUT BACK
ON POPS MONDAY NIGHT. HOWEVER...WITH THIS SOLUTION THERE IS NOT
MUCH MOISTURE...AND ESPECIALLY NOT DEEP MOISTURE WHICH KEEPS A
THREAT OF FREEZING RAIN ACROSS NORTHERN AND EASTERN CWA AT ONSET
OF PRECIPITATION WITHOUT ICE INTRODUCTION. HAVE KEPT THIS MENTION
IN FORECAST...THOUGH CUT BACK SOMEWHAT. SYSTEM WILL NEED TO BE
WATCHED FOR MIXED PRECIPITATION POTENTIAL. IN ADDITION...WITH LOW
TRACKING FURTHER NORTH MAY SEE STRONG WINDS TUESDAY AND
WEDNESDAY.

BEYOND MID WEEK...WEAK RIDGE BUILDS INTO MIDWEST WITH RELATIVELY
QUIET WEATHER ON TAP AND TEMPERATURES GENERALLY NEAR NORMAL. A
CHANCE FOR PRECIPITATION AT END OF EXTENDED AS ANOTHER LOW TRACK
ACROSS MIDWEST. THOUGH GIVEN UNCERTAINTIES AT SUCH A TEMPORAL
LENGTH HAVE LEFT FORECAST MOSTLY DRY.

&&

.AVIATION...15/12Z
ISSUED AT 641 AM CDT SAT MAR 15 2014

CIGS WILL GRADUALLY DECREASE DURING THE PERIOD AS WINDS INCREASE.
CIGS WILL BECOME MVFR FROM NORTH TO SOUTH WITH THE POTENTIAL TO
FALL TO IFR. AS THIS OCCURS...PRECIPITATION CHANCES WILL INCREASE
WITH THE POTENTIAL FOR RAIN CHANGING TO SNOW. THE SNOW WILL BE
MOST PREVALENT OVER CENTRAL AND SOUTHERN IOWA THIS EVENING WHILE
CIGS BEGIN TO SCATTER ACROSS THE NORTH LATE. EXPECT WINDS TO
INCREASE FROM THE NORTHEAST TODAY. GUSTS IN EXCESS OF 35 KTS
POSSIBLE OVER SRN IA TONIGHT.

&&

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

&&

$$

UPDATE...SMALL
SHORT TERM...DONAVON
LONG TERM...AWB
AVIATION...DONAVON