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000
FXUS63 KDMX 112039
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
339 PM CDT TUE MAR 11 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 330 PM CDT TUE MAR 11 2014

TONIGHT...FORECAST CONCERN FOCUSED ON DEEPENING SURFACE LOW IN
KANSAS THAT WILL TRACK EAST ACROSS MISSOURI TONIGHT INTO
WEDNESDAY MORNING. 12Z MODEL RUNS ARE IN MUCH BETTER AGREEMENT
THAN 06Z RUNS...BUT THE GFS/SREF ARE SLIGHTLY FURTHER NORTH WITH
THE HEAVIEST SNOW BAND THAN NAM/ECMWF. LEANED MORE TOWARD THE
SOUTHERN NAM/ECMWF SOLUTION...WITH UTILIZING THE 11.15Z HOPWRF FOR
FINER DETAILS IN THE POP/WX TRENDS AND SNOW AMOUNTS.

SIGNIFICANT PRESSURE FALLS CONTINUE ACROSS MISSOURI INTO FAR
SOUTHEAST IOWA THIS AFTERNOON...WHILE THE TIGHT PRESSURE GRADIENT IN
SOUTHWEST IOWA THROUGH KANSAS LOOKS TO CONTINUE TO CAUSE GUSTY
NORTHEAST WINDS THROUGH THIS EVENING. WITH CURRENT WINDS ACROSS
SOUTHWEST IOWA AND HIGHER CONFIDENCE WITH WINDS REMAINING STRONG
THROUGH TONIGHT AS THE CAA DEVELOPS BEHIND THE SURFACE LOW...LEANED
TOWARD A WIND ADVISORY IN THE SOUTHWEST THROUGH 03Z.

NEXT ISSUE IS WITH SHARP DEFORMATION ZONE TO DEVELOP ON THE BACKSIDE
OF THE SURFACE LOW LATE THIS EVENING INTO THE EARLY MORNING HOURS
WEDNESDAY. STRONG ISENTROPIC UPGLIDE ALONG THE 295 TO 305K SURFACES
AND MOISTURE TRANSPORT PUMPS IN PWAT VALUES OF 0.5 TO 0.75 INCHES
OVER SOUTHEAST IOWA...WHICH CREEPS INTO A FEW COUNTIES OF THE
FORECAST AREA. A CROSS SECTION FROM NORTHEAST MISSOURI TO CENTRAL
IOWA SHOWS IMPRESSIVE FRONTOGENETICAL FORCING AND DECENT NEGATIVE
EPV IN THE FAR SOUTHEAST CORNER OF THE CWA. PLUS...WITH THE STRONG
OMEGA IN THE DENDRITIC LAYER...POTENTIAL FOR SIGNIFICANT SNOWFALL
RATES ALONG THE MISSOURI BORDER. HOWEVER...THE ISSUE IS TIMING OF
RAIN CHANGING TO SNOW AS THE WINDOW OF SNOW ACCUMULATIONS LOOKS TO
BE SHORT. CONFIDENT THAT WITH THE SNOWFALL RATES WILL COOL THE
COLUMN TO THE WET BULB TEMP AND SWITCH PRECIP TO ALL SNOW BETWEEN
03Z TO 05Z. AS A RESULT...INCREASED QPF AMOUNTS ALONG THE MO/IA
BORDER AND THUS INCREASED SNOW AMOUNTS IN THIS AREA. WITH THE HIGHER
SNOWFALL RATES AND WINDS ATOP THE MIXED LAYER RANGING FROM 3O TO 35
KNOTS...LEANED TOWARD A WINTER WEATHER ADVISORY FROM 03-09Z
WEDNESDAY. GENERALLY LOOKING AT A SHARP 2-4 INCH BAND IN THIS AREA
AND VISIBILITY RESTRICTIONS.

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 330 PM CDT TUE MAR 11 2014

IN THE NEAR TERM...NORTHWEST FLOW IS FORECAST INTO THE WEEKEND.
THE 12Z GFS/ECMWF ARE IN DECENT AGREEMENT WITH THE MASS FIELDS
WITH A NORTHWEST FLOW SHORTWAVE MOVING THROUGH THE UPPER MIDWEST
ON FRIDAY. COLD ADVECTION ON WEDNESDAY BEHIND TONIGHT/S SYSTEM
WITH THE SURFACE HIGH MOVE THROUGH CENTRAL IOWA BY AFTERNOON. WARM
ADVECTION GETS GOING ALREADY WEDNESDAY AND INCREASES ON THURSDAY
AHEAD OF THE APPROACHING SHORTWAVE. 850 MB TEMPS ARE EXPECTED TO
REACH AROUND 4-6 C BY 00Z FRI WHICH SUPPORTS RAPID WARMUP COMPARED
TO WEDNESDAY. THE 12Z GFS/ECWMF ARE CLOSE WITH RESPECT TO THE
TIMING OF A FAST MOVING COLD FRONT WHICH WILL CROSS CENTRAL IOWA
THURSDAY. GIVEN THE SPEED AND POSITION OF THE WAVE AND THE DRY
AIRMASS...DO NOT EXPECT PRECIPITATION FROM THE SYSTEM THURSDAY
NIGHT AND FRIDAY...JUST A DRY FRONTAL PASSAGE.

FOR THE EXTENDED...COLDER TEMPERATURES LOOK IN STORE WITH
NORTHWEST FLOW CONTINUING WITH LOW MODEL AGREEMENT CONCERNING THE
DETAILS. THE ECMWF IS COLDER KEEPING IA IN THE COLD AIR THROUGH
THE EXTENDED WHILE THE GFS HAS ANOTHER SIGNIFICANT WARMUP AHEAD OF
ANOTHER FRONT MONDAY INTO TUESDAY. CURRENT FORECAST DOES NOT HAVE
A MUCH TEMPERATURE VARIABILITY AS SUGGESTED BY THE GFS. KEPT SMALL
POPS SATURDAY NIGHT AND AGAIN ON DAY SEVEN...BUT SIGNIFICANT
PRECIPITATION IS NOT EXPECTED.

WILL NEED TO WATCH THE RIVERS IN NORTHERN IOWA AGAIN LATE THIS
WEEK FOR ICE JAM POTENTIAL...ESPECIALLY ON THURSDAY AND FRIDAY.


&&

.AVIATION...11/18Z
ISSUED AT 1245 PM CDT TUE MAR 11 2014

MVFR TO IFR CIGS WILL CONTINUE TO DEVELOP THIS AFTERNOON AND INTO
THE EVENING FROM NORTH TO SOUTH. FIRST BAND OF PRECIP ACROSS
NORTHERN IOWA MAY CAUSE SOME IFR TO MVFR VIS THROUGH 00Z WED BUT
MVFR CIGS LOOK TO PERSIST INTO TOMORROW MORNING. GUSTY NORTHEAST
WINDS WILL CONTINUE AS WELL THIS AFTERNOON AND SHIFT NORTHWEST
THIS EVENING AND REMAIN STRONG WITH GUSTS TO 25 KNOTS THROUGH
TOMORROW MORNING. OTM IS THE MAIN CONCERN WHERE MODERATE SNOW AND
WINDS LOOK TO AFFECT THE AIRPORT THIS EVENING. HAVE INTRODUCED
LIFR CIGS/VIS FOR WINDS AND SNOWFALL TONIGHT. STRATUS AND CAA WILL
PERSIST THROUGH WEDNESDAY AND MVFR CIGS MAY CONTINUE THROUGH MUCH
OF THE DAY TOMORROW.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR ADAIR-ADAMS-
AUDUBON-BOONE-CARROLL-CASS-CLARKE-CRAWFORD-DALLAS-DECATUR-GREENE-
GUTHRIE-MADISON-POLK-RINGGOLD-TAYLOR-UNION-WARREN.

WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 4 AM CDT
WEDNESDAY FOR APPANOOSE-DAVIS-WAYNE.

&&

$$

SHORT TERM...PODRAZIK
LONG TERM...JOHNSON
AVIATION...PODRAZIK