Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 132353
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
553 PM CST SAT FEB 13 2016

.SHORT TERM /TONIGHT/...
ISSUED AT 327 PM CST SAT FEB 13 2016

SOME ECHOES STARTING TO SHOW UP ACROSS WESTERN IOWA...WITH CLOUDS
BASES DROPPING. NO REPORTS OF PRECIPITATION AT THE GROUND
YET...BUT LOWER LEVELS EXPECTED TO SATURATE CLOSER TO LATE
AFTERNOON/EARLY EVENING AS MOISTURE ADVECTION INCREASES. PUSH OF
WAA AHEAD OF THE SURFACE LOW CURRENTLY STRETCHING ACROSS THE FRONT
RANGE OF THE NORTHERN ROCKIES...WILL INCREASE ACROSS THE AREA
TONIGHT AS THE SFC LOW SLIDES INTO THE CENTRAL/EASTERN DAKOTAS BY
EARLY SUNDAY. AS LOWER LEVEL SATURATE FROM WEST TO EAST THIS
EVENING...A BAND OF LIGHTS NOW IS EXPECTED TO PUSH EASTWARD ACROSS
THE CWA. THE UPPER SHORTWAVE TROUGH TO DROP INTO WESTERN IOWA
BRINGING ANOTHER ROUND OF SNOW TO THE AREA LATE TONIGHT INTO
SUNDAY. POTENTIAL EXISTS FOR A BREAK IN THE SNOW IN THE EARLY
MORNING HOURS ACROSS THE FAR SOUTHWEST...SO HAVE TRENDED POPS MORE
TOWARD SLIGHT CHANCE TO LOW CHANCE IN THAT AREA. OTHERWISE EXPECT
AROUND A HALF INCH OF NEW SNOW IN THE SOUTH TO AROUND AN INCH
THROUGH MIDNIGHT...WITH THE SNOW PICKING UP ACROSS THE NORTH LATE
TONIGHT. SOUTHWESTERLY WINDS PICK UP AHEAD OF THE APPROACHING SFC
LOW AS WELL LATE TONIGHT. THEREFORE STILL HAVE THE MENTION OF
BLOWING SNOW. SOMEWHAT CONCERNED ABOUT HOW FAR VISIBILITIES MAY
DROP IN THE SNOW/BLOWING SNOW DUE TO THE LIGHT FLUFFY NATURE OF
THE SNOW ON THE GROUND AND EXPECTED NEW SNOW. FOR NOW SUSTAINED
WINDS AROUND 20 MPH EXPECTED WITH HIGHER GUSTS ACROSS NORTHERN
IOWA...COULD DROP VISIBILITIES TO AROUND ONE QUARTER TO ONE HALF
MILE WITH BLOWING AND DRIFTING SNOW. TIMING OF THE ADVISORY STILL
LOOKS GOOD AT THIS TIME...AND DID OPT TO ADD IN APPANOOSE COUNTY
WITH AROUND 3 INCHES OF SNOW EXPECTED IN THE NORTHEAST HALF OF THE
COUNTY.

.LONG TERM /SUNDAY THROUGH SATURDAY/...
ISSUED AT 327 PM CST SAT FEB 13 2016

MAIN FORECAST CONCERN WAS FOCUSED ON SNOW SUNDAY AND AGAIN
TUESDAY. THEN WARMER TEMPERATURES THE REMAINDER OF THE WORK WEEK
INTO NEXT WEEKEND. LEANED TOWARD A BLEND OF THE GFS/ECMWF AS THE
NAM SEEMED TOO WARM AT THE SURFACE TUESDAY. OTHERWISE...MODELS ARE
IN GOOD AGREEMENT WITH THE OVERALL SYNOPTIC SETUP THROUGH TUESDAY
AND ONLY A FEW MINOR DIFFERENCES WRT TO MESOSCALE FEATURES.

SUNDAY INTO SUNDAY NIGHT...SNOW LOOKS TO CONTINUE OVER MUCH OF THE
FORECAST AREA SUNDAY MORNING BEFORE THE DEEP FORCING QUICKLY PUSHES
EAST INTO NORTHERN ILLINOIS/SOUTHERN WISCONSIN. THE 500MB SHORTWAVE
WILL BE EXITING THE STATE BY AROUND 18Z...SO KEPT LIKELY/CATEGORICAL
POPS GOING EAST OF I-35 THROUGH THIS TIME FRAME. LINGERING FORCING
AND DEEP MOISTURE BEHIND THE SHORTWAVE IN THE NORTHEAST MAY PRODUCE
SOME ADDITIONAL LIGHT SNOW B/T MASON CITY AND WATERLOO THROUGH
21Z. HOWEVER...ANY OMEGA TOMORROW WEAKENS AND/OR SHIFTS OUT OF THE
DGZ PAST 15Z SUNDAY...SO NOT EXPECTING MUCH ACCUMULATIONS LATE
TOMORROW MORNING INTO THE AFTERNOON. THE MORNING PERIOD WILL SEE
ROUGHLY 1-2 INCHES EAST OF I-35. CONCERNED ABOUT THE GFS BRINGING
IN A WEAK SECONDARY SHORTWAVE INTO NORTHEAST IOWA...WHICH PLACES
SOME ADDITIONAL LIGHT SNOW ACROSS THE NORTHEAST CWA SUNDAY NIGHT.
THE NAM/ECMWF ARE LITTLE FURTHER NORTH WITH THIS SECOND PUSH OF
FORCING...SO LEFT SUNDAY NIGHT DRY ATTM. DECREASED POPS
CONSIDERABLY THROUGH THE AFTERNOON FROM WEST TO EAST. WINDS REMAIN
FAIRLY GUSTY DURING THE MORNING HOURS...ROUGHLY 18-21 KNOT
GUSTS...SO KEPT MENTION OF BLSN ACROSS THE NORTH. CERTAINLY ENOUGH
TO CAUSE SOME TRAVEL CONCERNS THROUGH THE DAY SUNDAY.

MONDAY INTO TUESDAY...ANOTHER QUICK MOVING SHORTWAVE RIDES THE
NORTHWEST FLOW ALOFT LATE MONDAY NIGHT INTO TUESDAY. ECMWF/GFS ARE
IN GREAT AGREEMENT WITH TIMING AND PLACEMENT OF HIGHEST QPF...SO
CONFIDENT TO INCREASE POPS 06-12Z TUESDAY AND EVEN THROUGH 18Z
TUESDAY ACROSS THE EAST. FAIRLY STRONG FRONTOGENETICAL FORCING
DEVELOPS BETWEEN 850MB TO 700MB AND SETS UP A DECENT BAND OF
MODERATE SNOW FROM THE NORTHWEST TO SOUTHEAST...SOMEWHAT
SIMILAR TO THE ORIENTATION OF TONIGHT/TOMORROWS SNOW BAND. STRONG
FORCING WITHIN THE DGZ...SUBTLE -EPV AND WEAK THETA-E DECREASING
WITH HEIGHT...BUT ENOUGH TO PRODUCE A QUICK BURST OF SNOW B/T
06-12Z TUESDAY. THIS BAND MAY EVEN LINGER ACROSS THE SOUTHEAST
THROUGH 18Z. AS A RESULT...INCREASED SNOW AMOUNTS OVERNIGHT MONDAY
NIGHT INTO TUESDAY AND LOOKS TO LOW-END WINTER WX ADVISORY LEVEL
AS A ROUGHLY 2-4 INCHES WILL BE COMMON NW TO SE.

WEDNESDAY THROUGH FRIDAY...YET ANOTHER WEAK SHORTWAVE QUICKLY CUTS
ACROSS THE STATE ON WEDNESDAY. HOWEVER...LACK OF SIGNIFICANT
MOISTURE AND LIFT...LEFT CONDITIONS DRY ATTM. ECMWF/GFS DO PUMP OUT
SOME VERY LIGHT QPF BUT SOUNDINGS DO NOT SUPPORT EVEN THAT MUCH QPF
AS THEY SUGGEST A DRY LAYER IN THE MID AND ANOTHER ABOVE 600MB.
MIGHT BE A DRIZZLE/FZDZ EVENT WITH THE LACK OF ICE INTRODUCTION.

BIG WARMUP STILL ON TAP LATE IN THE WEEK...WITH FRIDAY ANTICIPATED TO
BE THE WARMEST DAY OF THE EXTENDED AS SEVERAL LOCATIONS LIKELY TO
REACH THE MIDDLE 50S.

&&

.AVIATION...14/00Z
ISSUED AT 541 PM CST SAT FEB 13 2016

SNOW WILL BECOME WIDESPREAD TONIGHT AS LOW PRESSURE MOVES
SOUTHEAST THROUGH THE PLAINS. THE SNOW WILL LEAD TO A DROP IN
CEILINGS AND VISIBILITIES WITH WIDESPREAD MVFR TO IFR CONDITIONS
AT MOST TAF LOCATIONS. THESE RELATIVELY POOR CONDITIONS WILL
PERSIST INTO SUNDAY MORNING BEFORE THE SNOW GRADUALLY ENDS INTO
THE EARLY AFTERNOON. LOW CEILINGS WILL LINGER THROUGH THE END OF
THE FORECAST PERIOD WITH MVFR VISIBILITIES.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST
SUNDAY FOR APPANOOSE-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-
CERRO GORDO-DALLAS-DAVIS-EMMET-FRANKLIN-GREENE-GRUNDY-HAMILTON-
HANCOCK-HARDIN-HUMBOLDT-JASPER-KOSSUTH-MAHASKA-MARION-MARSHALL-
MONROE-PALO ALTO-POCAHONTAS-POLK-POWESHIEK-SAC-STORY-TAMA-
WAPELLO-WARREN-WEBSTER-WINNEBAGO-WORTH-WRIGHT.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...PODRAZIK
AVIATION...COGIL


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