Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 251753
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1153 AM CST SUN JAN 25 2015

.UPDATE...
ISSUED AT 1155 AM CST SUN JAN 25 2015

SPED UP THE DEPARTURE OF THE SNOW OVER THE SOUTHEAST CWA FOR THE
EARLY AFTERNOON HOURS AND ALSO INCREASED CLOUD COVER FOR THIS
AFTERNOON AND TONIGHT. MOSTLY CLOUDY TO OVERCAST SKIES ARE
FORECAST GIVEN THE UPSTREAM CLOUDS ON VISIBLE SATELLITE AND THE
LACK OF ANY DECENT PUSH TO ADVECT THE CLOUDS OUT OF THE REGION
UNTIL WAA COMMENCES TOMORROW MORNING. SOME BREAKS IN THE CLOUDS
OVER MINNESOTA AND WISCONSIN MAY PUSH INTO THE NORTH...BUT OVERALL
THERE WILL BE MUCH MORE CLOUDS THAN SUN.

&&

.SHORT TERM /TODAY/...
ISSUED AT 339 AM CST SUN JAN 25 2015

LOW PRESSURE CENTERED DIRECTLY OVER KNOXVILLE WILL CONTINUE
TO PUSH SOUTHEAST THIS MORNING BEFORE CENTERING ITSELF OVER SOUTHERN
ILLINOIS BY AROUND MIDDAY TODAY. THE ONGOING PRECIP IS TAKING ITS
TIME SWITCHING OVER THE SNOW ACROSS NORTHERN AND WESTERN IOWA AS THE
CAA HAS NOT QUITE DEVELOPED AND COOLED THE BOUNDARY LAYER ENOUGH TO
KEEP PRECIP ALL SNOW. CERTAINLY SNOWING ALOFT AND KEPT A RAIN/SNOW
MIX FOR A LONGER DURATION THIS MORNING. THE SOUTHERN PORTIONS OF THE
FORECAST AREA LOOK TO REMAIN RAIN MUCH OF THE DAY AND LIKELY NOT
RECEIVE ANY SNOW BEFORE THE PRECIP MOVES OUT BY 20Z.

FORCING WITHIN THE SNOW GROWTH LAYER IS WEAK AND WITH THE SLOWER CAA
TO DEVELOP THIS MORNING...LOWERED SNOW TOTALS SLIGHTLY. LIKELY TO
SEE A WET SNOW/RAIN MIX THROUGH 14-16Z OVER THE CENTRAL PORTION OF
THE FORECAST AREA...FROM HIGHWAY 30 TO HIGHWAY 34 CORRIDOR. METRO
ROADCAST SUGGEST THE ROADS IN THIS AFOREMENTIONED AREA WILL REMAIN
JUST WET AND SO ANY ACCUMULATIONS SHOULD REMAIN ON GRASSY/ELEVATED
SURFACES.

LEANED TOWARD THE RUC/HRRR WRT TO RAIN TO SNOW TRANSITION AND
RADAR/POP TRENDS THROUGH 18Z TODAY. THE HIGHER SNOW AMOUNTS LOOK TO
BE TOWARDS THE ALO TO MIW AREA WHERE THE RAIN LOOKS TO SHIFT TO SNOW
QUICKEST AND REMAIN IN THE BETTER FORCING AND DEEP MOISTURE FOR MUCH
OF THE MORNING. THIS LOCATION HAS THE BEST POTENTIAL FOR ANY TRAVEL
IMPACTS.

OTHERWISE...STRONG WINDS PICK UP LATE THIS MORNING AND CONTINUE INTO
THE AFTERNOON HOURS. WITH THE CAA DEVELOPING DURING THIS TIME
FRAME...HAVE A NON-DIURNAL TEMPERATURE TREND GOING FOR THE FORECAST
AREA TODAY.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 339 AM CST SUN JAN 25 2015

MAIN CHALLENGES THROUGH THE PERIOD WILL BE THE EXTENT OF WARMING
WITH EACH CLIPPER RACING TOWARD US FROM THE WESTERN/NORTHERN
PLAINS. PERSISTENT RIDGE ALOFT AT H500 BUILDING SLIGHTLY EAST
THROUGH MONDAY MORNING WITH NEXT UPSTREAM WAVE EXPECTED TO PASS
EAST OF THE AREA ON MONDAY. THE REGION WILL SEE A SUN CLOUD
MIXTURE WITH H850 TEMPS WARMING TO NEAR 0C NORTHEAST TO ABOUT 4C
WEST. AS A TROUGH PASSES EAST ON MONDAY MIXING WILL HELP BUMP
TEMPS INTO THE 40S AND LOWER 50S OVER THE AREA. AMPLE WARMING OVER
THE WESTERN PLAINS DUE TO ONGOING DOWNSLOPE WINDS WILL KEEP
TEMPERATURES MILD. OVERNIGHT LOWS MONDAY NIGHT WILL ONLY DIP INTO
THE 20S TO LOWER 30S WITH SOME CLOUDS CONTINUING OVER THE REGION.
TUESDAY SEES EVEN MILDER H850 TEMPS BUT MIXING IS LACKING. ALONG
WITH SOME MID LEVEL CLOUDS TEMPS WILL REMAIN ABOVE NORMAL BUT A
FEW DEGREES COOLER THAN MONDAY. THE NEXT UPSTREAM WAVE PUSHES EAST
ON WEDNESDAY. A LARGE POOL OF WARM AIR WILL MOVE RAPIDLY INTO THE
STATE WEDNESDAY WITH H850 TEMPERATURES WARMING TO 6C NORTHEAST TO
10C SOUTHWEST BY 18Z. BY 00Z CLOUDS WILL COOL TEMPS ALOFT...BUT
STRONG MIXING THROUGHOUT THE DAY SHOULD ALLOW FOR HIGHS TO REACH
THE MID 40S NORTHEAST TO THE MID TO UPPER 50S FROM CENTRAL TO
SOUTHWEST IOWA. AS THE WAVE TRACKS EAST WEDNESDAY NIGHT INTO
THURSDAY THERE IS SOME UNCERTAINTY HOW FAR WEST LIGHT RAIN AND
LIGHT SNOW WILL EXTEND WEST INTO OUR AREA. FOR NOW CHANCE POPS
WILL BE MAINTAINED IN THE FORECAST. THE EURO MODEL SUGGESTS A
RATHER STRONG H500 SHORT WAVE WILL ACCOMPANY THE SFC FEATURE
THURSDAY RESULTING IN SOME LIGHT RAIN OR LIGHT ACCUMULATING
SNOWFALL. STRONG NORTHWEST WINDS WILL ACCOMPANY THE SYSTEM...
POSSIBLY WITH GUSTS REACHING WIND ADVISORY CRITERIA THURSDAY
AFTERNOON. WILL MONITOR OVER THE NEXT SEVERAL DAYS. SLIGHTLY
COOLER TEMPERATURES FOLLOW FOR FRIDAY WITH HIGHS BACK IN THE 30S.
PER PREVIOUS MODEL RUNS COLDER AIR IS PROGGED TO ARRIVE LATE
FRIDAY INTO SATURDAY. PIECES OF ENERGY ROTATING SOUTH ON THE BACK
SIDE OF THE H500 HUDSON BAY POLAR ANCHOR LOW WILL BRING AN ARCTIC
COLD FRONT INTO THE AREA SATURDAY MORNING. THERE IS MORE
UNCERTAINTY TODAY ON HOW THE WEEKEND SYSTEMS WILL
EVOLVE...HOWEVER...WITH THE EURO FASTER WITH THE ARRIVAL AND
DEPARTURE OF THE COLD AIR WHILE THE GFS IS NEARLY 30 HOURS SLOWER
WITH THE ARCTIC BOUNDARY. OVERALL...THE TIMING IS SIMILAR WITH THE
COLD AIR ARRIVING ON THE WEEKEND. WILL NEED TO SORT OUT DETAILS IN
THE COMING DAYS. OTHERWISE...OUR WEATHER FEATURING ABOVE NORMAL
TEMPERATURES ALONG WITH FAST MOVING BUT SOMEWHAT MOISTURE
CHALLENGED SYSTEMS WILL CONTINUE.

&&

.AVIATION...25/18Z
ISSUED AT 1155 AM CST SUN JAN 25 2015

IFR CIGS AND VSBYS TIED TO THE DEPARTING SNOW SYSTEM WILL COME TO
AN END OVER THE SOUTHEAST BY EARLY AFTERNOON. CIGS ACROSS THE REST
OF CENTRAL IOWA WILL GENERALLY BE LOW TO MID MVFR WITH SOME
POCKETS OF IFR AND VFR CIGS. THERE IS MEDIUM CONFIDENCE IN THIS
STRATUS DECK LINGERING ON INTO THE OVERNIGHT...BUT WITH SOME
POCKETS OF CLEARING UPSTREAM SOME SITES MAY RISE TO VFR CONDITIONS
AT TIMES DURING THE TAF PERIOD. GUSTY NORTH TO NORTHEAST WINDS
WILL LESSEN THIS AFTERNOON AND SWITCH TO THE SOUTH AROUND
MIDNIGHT.

&&

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

$$

UPDATE...SKOW
SHORT TERM...PODRAZIK
LONG TERM...REV
AVIATION...SKOW


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