000
FXUS63 KDMX 091736
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1236 PM CDT SUN MAR 9 2014

.SHORT TERM /TODAY/...
ISSUED AT 410 AM CDT SUN MAR 9 2014

NORTHWEST FLOW PATTERN ALOFT...WITH THE UPPER RIDGE OVER THE WESTERN
THIRD TO HALF OF THE US NUDGING EASTWARD SLIGHTLY TODAY. SFC HIGH
PRESSURE TO SLIDE SOUTHEAST EXITING THE AREA TODAY...WITH RETURN
FLOW SETTING UP AND STRONG WAA ALOFT. SFC WINDS ALREADY OUT OF THE
SOUTH TO SOUTHWEST ACROSS MUCH OF THE CWA WITH TEMPS HOLDING STEADY
OR BEGINNING TO RISE. H85 TEMP CLIMB TO AROUND +10C ACROSS THE CWA
TODAY...WITH A WARMING SFC FLOW OUT OF THE SOUTH TO SOUTHWEST.
THEREFORE TEMPS SHOULD WARM NICELY TODAY...BUT WILL BE LIMITED
SOMEWHAT BY INCREASING MID/HIGH CLOUDS THROUGHOUT THE DAY WITH A
VERY WEAK SHORTWAVE DROPPING THROUGH MN/NRN IA. LITTLE LOW LEVEL
MOISTURE SO NO PRECIPITATION EXPECTED. TRENDED HIGHEST TEMPS ACROSS
THE USUAL WARM SPOTS AND ALSO IN AREAS WHERE LESS SNOW COVER/NO SNOW
PRESENT...WITH HIGHS TOPPING OUT IN THE MID 40S NORTH/NORTHEAST TO
THE MID/UPPER 50S SOUTH/WEST CENTRAL.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 410 AM CDT SUN MAR 9 2014

PRIMARY CONCERNS REMAIN TEMPS EARLY AND PRECIP AROUND TUE WITH A
FAIRLY INACTIVE EXTENDED FORECAST. WARM UP WILL BE WELL UNDERWAY BY
TONIGHT WITH MON MORNING MINS LIKELY THE WARMEST SINCE
NOV...WIDESPREAD 30S. MADE LITTLE CHANGE TO MON HIGHS BASED ON
SOUNDINGS AND PROJECTED MIXING...TAKING THE MORE AGGRESSIVE END AS
MODELS TYPICALLY OVER-EMPHASIZE SNOW EFFECTS IN THESE INSTANCES.
HISTORICALLY WELL PERFORMING ECMWF MOS HAS ALSO CHANGED
LITTLE INCLUDING FRESH 09/00Z RUN...WHICH WHILE TOO LATE TO
INCORPORATE INTO THE FORECAST...NOW SUGGESTS HIGHS INTO THE UPPER
60S FROM DSM SOUTH AND WEST. THESE WARMER TEMPS WILL CERTAINLY
INCREASE THE POTENTIAL FOR ICE JAMS THROUGH THE WEEK...WORKING
SOUTH TO NORTH AS STREAMS AND RIVERS FREE...AND WILL CONTINUE TO
BE HIGHLIGHTED IN PRODUCTS AND HWO.

ATTENTION WILL THEN TURN TO THE SYSTEM CURRENTLY OFF THE WRN
U.S./CANADIAN COASTS...WHICH WILL EVENTUALLY CROSS THE ROCKIES INTO
THE MO VALLEY SPREADING PRECIP INTO NE/SD BY LATE MON...AND INTO NRN
IA TUE MORNING. MUCH OF OUR SENSIBLE WEATHER WILL BE DRIVEN BY
KINEMATIC AND FRONTOGENETIC FORCING AS SATURATED COLUMN DRIFTS NORTH
TO SOUTH THROUGH THE STATE. STRONG H85/H7 THETA-E ADVECTION IS
NOTED TO OUR SOUTH INTO MO...BUT IS MOISTURE STARVED AND MAY NOT
PRODUCE MUCH PRECIP. ONE FEATURE OF NOTE IS THE STRONG AND DEEP
FRONTOGENETICAL FORCING WHICH WILL BE PAIRED WITH FAIRLY LOW
STATIC STABILITIES INCREASING PRECIP RATES SOMEWHAT. ALL THIS
LEADS TO INCREASED CONFIDENCE IN PRECIP SUPPORTING CATEGORICAL
POPS.

THE BIG QUESTION WILL BE RESULTANT PRECIP TYPE HOWEVER.  MODEL
SOUNDINGS CERTAINLY SHOW WARM LAYER TEMPS EVENTUALLY CRASHING TO
SUPPORT SNOW.  HOWEVER WITH NEAR SURFACE TEMPS HOVERING AROUND
CRITICAL MID 30S AND WARM GROUND TEMPS FROM MON WILL MAKE SNOW
ACCUMS QUITE PROBLEMATIC DUE TO THE RAIN/SNOW MIX AND DEGREE OF
MELTING...WHICH MAY BE ENHANCED BY EVENT OCCURRING DURING THE DAY.
BEST SCENARIO FOR NOW IS AN INCH OR TWO OF SNOW OVER NRN HALF OF
THE FORECAST AREA...AND MAINLY ON ORGANIC SURFACES. THE POTENTIAL
IS THERE FOR GREATER AMOUNTS WITH DECENT UPWARD MOTION NOTED IN
H6/H5 OR 305K DENDRITIC GROWTH ZONE ENHANCED BY NOTED
FRONTOGENETICAL FORCING IN SAME LOCATIONS. WILL CERTAINLY NEED TO
MONITOR THERMAL TRENDS WHICH COULD RESULT IN LESSER OR GREATER
SNOW AMOUNTS. HIGHER SNOW RATES MAY OVERCOME MELTING RESULTING IN
HIGHER ACCUMS AS WELL...SO THERE ARE MANY VARIABLES HERE TO
CONSIDER.

WINDS WILL FLIP TO THE NORTH BEHIND THIS SYSTEM DROPPING TEMPS BACK
TO SEASONAL NORMS INTO MID WEEK.  THIS WILL ALSO INCLUDE A DRY
PERIOD WITH RELATIVELY INACTIVE NW FLOW.  DECENT SHORT WAVE WILL
PASS TO OUR NORTH THROUGH THE NRN PLAINS AND GREAT LAKES THU INTO
FRI...BUT WITH INSUFFICIENT FORCING AND MOISTURE FOR ANYTHING HERE.
WITH IA STAYING ON WARM SIDE OF THE SYSTEM...THIS WILL LIKELY
INTRODUCE ANOTHER ROUND OF ABOVE NORMAL TEMPS...ALBEIT NOT AS WARM
AS MON. A STRONGER SHORT WAVE EVENTUALLY DROPS INTO THE MO VALLEY
BY THE END OF THE WEEKEND...BUT WOULD LIKELY BE JUST BEYOND THE
VALID PERIOD INTO SAT NIGHT OR SUN.

&&

.AVIATION...09/18Z
ISSUED AT 1233 PM CDT SUN MAR 9 2014

WIDESPREAD VFR CONDITIONS WILL PERSIST ACROSS IOWA THROUGH THE
FORECAST PERIOD WITH ONLY MID TO HIGH LEVEL CEILINGS. WINDS WILL
BE STRONG AND GUSTY FROM THE SOUTHWEST TODAY WITH SOME WEAKENING
TONIGHT AS THE GRADIENT RELAXES. WINDS WILL BEGIN TO SHIFT TO THE
NORTHWEST ON MONDAY AS A BOUNDARY SLIDES GRADUALLY THROUGH THE
STATE.

&&

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

&&

$$

SHORT TERM...BEERENDS
LONG TERM...SMALL
AVIATION...COGIL