000
FXUS63 KDMX 101132
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
632 AM CDT MON MAR 10 2014

.SHORT TERM /TODAY/...
ISSUED AT 405 AM CDT MON MAR 10 2014

A WEAK SFC TROUGH AXIS PUSHES THROUGH THE CWA THROUGH MID
MORNING...WITH WINDS SHIFTING AROUND TO THE NORTHWEST TO NORTH
TODAY. ALOFT HAVE NEAR NEUTRAL ADVECTION TO WEAK CAA WITH H85 TEMPS
STILL AROUND THE LOW TEENS CELSIUS. HIGH CLOUDS CURRENTLY IN PLACE
ACROSS THE CWA SHOULD PUSH SOUTH OF THE STATE THROUGHOUT THE EARLY
MORNING/MID MORNING HOURS...WITH HIGH CLOUDS THEN INCREASING AGAIN
LATE TODAY. GIVEN AIR MASS IN PLACE AND SOME MIXING EXPECTED SHOULD
STILL SEE VERY MILD TEMPS ACROSS THE CWA TODAY. EXPECT TEMPS IN
RELATIVE SNOW-FREE AREAS TO BE MUCH WARMER...CLIMBING INTO THE UPPER
50S TO MID/UPPER 60S. AREAS WHERE THE DEEPER SNOWPACK
REMAINS...WARMING WILL BE LESS BUT STILL RELATIVELY MILD IN THE MID
TO UPPER 40S. SOME CONCERN GIVEN THE HIGH CLOUDS TODAY...AND WINDS
SHIFTING AROUND TO THE NORTHWEST TO NORTH COMING OFF THE DEEPER
SNOWPACK...HOWEVER FEEL THIS WILL BE MINIMIZED SOME BY THE MILD
START WITH EARLY MORNING TEMPS A GOOD 20 TO 25 DEGREES WARMER THIS
MORNING THAN THOSE YESTERDAY SO 10 TO 20 DEGREE RISE IN TEMPS DOES
NOT SEEM UNLIKELY.

.LONG TERM /TONIGHT THROUGH SUNDAY/...
ISSUED AT 405 AM CDT MON MAR 10 2014

WITH MON TEMPS NOW PAST ON TO THE SHORT TERM...ONLY REAL SENSIBLE
WEATHER CONCERN FOR SEVERAL DAYS WILL BE THE TUE/TUE NIGHT PRECIP
EVENT. SYSTEM IN QUESTION IS JUST COMING ONSHORE INTO THE PACIFIC NW
AND SHOULD SPREAD PRECIP INTO IA BY TUE MORNING.  MODEL CONSENSUS IS
A BIT SLOWER THAN THIS TIME YESTERDAY WITH PRECIP MATURATION NOT
OCCURRING UNTIL LATE MORNING OR MIDDAY.  MUCH LIKE PREVIOUS RUNS
MUCH OF OUR LIFT WILL BE MID LEVEL AND KINEMATIC WITH THETA-E/WARM
ADVECTION FARTHER SOUTH IN SOMEWHAT LIMITED MOISTURE. THIS SHOWS UP
WELL IN ISENTROPIC ANALYSIS AS WELL WITH ISOBARS PARALLEL TO FLOW
WHERE SUFFICIENTLY LOW PRESSURE DEFICITS ARE PRESENT.  RAW MODEL
OMEGA IS STILL NOTED IN THE MID LEVELS HOWEVER...INCLUDING IN THE
DENDRITIC GROWTH ZONE /DGZ/. THIS ALSO APPEARS TO BE DRIVEN BY
DEEP AND AT TIMES MODERATE FRONTOGENETICAL FORCING.

BIG QUESTION FOR THIS EVENT WILL NOT BE IF...BUT RATHER PRECIP
TYPE...AND WILL BE QUITE PROBLEMATIC WITH LOW CONFIDENCE. RAIN TO
SNOW CHANGEOVER AND DEGREE OF MELTING ALL MAKE ACCUM FORECASTS
DIFFICULT. QUESTION HAS BEEN RELEGATED TO RAIN VS SNOW WITH
SOUNDINGS NOT SUPPORTING SLEET OR FREEZING RAIN. COLD LAYER IS NOT
PRESENT TO REFREEZE ANYTHING AND SURFACE TEMPS DO NOT FALL BELOW
FREEZING UNTIL WARM LAYER HAS BEEN WELL ERODED. THE BIG FLY IN THE
OINTMENT WILL BE NEAR SURFACE TEMPS. SOUNDINGS AND DGZ LIFT
SUPPORT MODERATE SNOWFALL AT TIMES WITH ONLY THING HOLDING BACK
SNOW RELATIVELY WARM BUT QUITE SHALLOW NEAR SURFACE TEMPS IN THE
30S TO NEAR 40F. THIS COULD RESULT IN A COLD RAIN OR QUICKLY
ACCUMULATING WET SNOW...EVEN WITH TEMPS IN THE 30S. HAVE GENERALLY
NOT CHANGED SNOW AMOUNTS MUCH WITH WIDESPREAD ONE TO TWO INCHES
POSSIBLE OVER THE NRN HALF OF IA...AND LOCALLY THREE INCHES OR SO.
HOWEVER HAVE SPREAD INCH OR SO ACCUMS FARTHER SOUTH INTO CENTRAL
AND SOUTHERN IA INTO THE EVENING AS COLD ADVECTION KICKS IN.
AMOUNTS MENTIONED IN THE FORECAST WILL MAINLY BE ON ORGANIC
SURFACES...BUT STILL EXPECT WET...SLUSHY ROAD ACCUMS. ROAD TEMPS
WERE INTO THE 60S SUN AND REMAIN IN THE 30S OR 40S EARLY THIS
MORNING...WITH SIMILAR TRENDS EXPECTED TODAY INTO TONIGHT. HOWEVER
PAST EVENTS HAVE SHOWN THAT INTENSE SNOWFALL RATES AND MELTING
WILL QUICKLY COOL ROAD SURFACES WHERE ACCUMS WILL BEGIN.

PRECIP SHOULD BE MAINLY SNOW INTO THE EVENING SOUTH AND EAST BEFORE
ENDING OVERNIGHT.  PASSAGE OF THIS TROUGH WILL INTRODUCE A PERIOD OF
DRY NW FLOW.  SURFACE HIGH WILL SETTLE INTO THE REGION WED WITH
TEMPERATURES BACK BELOW NORMAL.  THERE WILL BE SOME MODERATION BY
THE END OF THE WEEK...BUT THE SHORT WAVE CROSSING TO OUR NORTH FRI
SHOULD BRING GRADUAL COOLING INTO THE WEEKEND WITH OVERALL TREND
TOWARD LOWER HEIGHTS.  NEXT WINDOW FOR PRECIP LOOKS TO BE TOWARD THE
END OF THE PERIOD...SAT NIGHT OR SUN...WITH BETTER CHANCES APPEARING
TO BE DOWN THE IMMEDIATE MO VALLEY. THIS EVENT COULD BE RAIN OR
SNOW DEPENDING ON TIMING AND ITS RELATION TO DIURNAL TEMP CYCLE.
CERTAINLY NOTHING TO SUGGEST A RETURN TO TEMPS OF THE PAST FEW
DAYS IN THE FORESEEABLE FUTURE.

&&

.AVIATION...10/12Z
ISSUED AT 632 AM CDT MON MAR 10 2014

VFR CONDITIONS THROUGHOUT THE TAF FORECAST PERIOD. SOUTHWEST TO
WESTERLY WINDS SHIFTING AROUND TO THE NORTHWEST TO NORTH THROUGH
THE PERIOD. SOME THINNING IN THE HIGH CLOUDS/CLEARING LIKELY
TOWARD MIDDAY...WITH INCREASING HIGH CLOUDS AGAIN LATE THIS
AFTERNOON INTO THE EVENING.

&&

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

&&

$$

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