Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 011739
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1139 AM CST SUN MAR 1 2015

.SHORT TERM /TODAY/...
ISSUED AT 317 AM CST SUN MAR 1 2015

HIGH PRESSURE IS NOW CENTERED WELL TO THE EAST ALONG THE EAST COAST
THOUGH SOME RIDGING DOES EXTEND WEST THROUGH THE LOWER GREAT LAKES
AND TOWARD FAR NORTHEAST IOWA. SOME RETURN FLOW HAS DEVELOPED INTO
IOWA WITH LOW LEVEL STRATUS AND SOME FOG DEVELOPING ALONG WITH VERY
LIGHT SNOW. A COUPLE SHORT WAVES WILL PASS THROUGH THE AREA TODAY.
THE FIRST IS MOVING ALONG THE KANSAS/NEBRASKA BORDER EARLY THIS
MORNING AND WILL HELP GENERATE SOME LIGHT SNOW INTO SOUTHERN IOWA. A
FEW FLURRIES ARE POSSIBLE FARTHER NORTH INTO CENTRAL IOWA. THE
SECOND WILL MOVE INTO NORTHWEST IOWA THIS AFTERNOON. NOT EXPECTING
ANY PRECIPITATION WITH THE SECOND SYSTEM WITH LITTLE MOISTURE TO
WORK WITH AND MUCH DRIER AIR RACING IN FROM THE WEST IMMEDIATELY
BEHIND THE SYSTEM AS ANOTHER HIGH PRESSURE SYSTEM ARRIVES.
TEMPERATURES WILL BE A BIT WARMER TODAY HOWEVER THE CLOUD COVER WILL
KEEP HIGHS IN THE MID 20S TO LOWER 30S.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 317 AM CST SUN MAR 1 2015

MAIN FORECAST CONCERN FOR EXTENDED IS LARGE SYSTEM SET TO IMPACT
IOWA BEGINNING MONDAY NIGHT THROUGH WEDNESDAY. TONIGHT AND MONDAY
WILL SEE HIGH PRESSURE PUSH EAST ACROSS IOWA...HAVE KEPT LOWS
TONIGHT UNDER GUIDANCE...THOUGH MAY STILL BE TOO WARM IN
SPOTS...ESPECIALLY THE NORTHWEST AS HIGH ALLOWS FOR LIGHT WINDS
WHICH MAY HELP TEMPERATURES DROP FURTHER. ATTENTION THEN SHIFTS TO
NEXT SYSTEM. LOW ACROSS CANADA WILL PUSH EAST...AS SURFACE LOW
LIFTS NORTHEAST FROM COLORADO. FORECAST WILL DEPEND ON TIMING AND
TRACK OF SYSTEMS...WITH SOMEWHAT LIMITED RUN TO RUN CONSTANCY IN
MODELS...HAVE TRENDED TOWARDS BLEND OF SOLUTIONS. MODELS HAVE
GENERALLY BACKED OFF STRENGTH OF SOUTHERN LOW...WHICH KEEPS SYSTEM
PROGRESSIVE AS NORTHERN LOW SWEEPS THROUGH LATE TUESDAY...AND
HAVE BEGUN TO CUT BACK ON POPS FOR TUESDAY AFTERNOON. IN
ADDITION...MODELS HAVE BEGUN TO SCALE BACK ON QPF ACROSS
IOWA...THOUGH GFS REMAINS HIGHEST AND LATEST RUNS OF OTHER MODELS
HAVE COME BACK IN LINE WITH GFS. GIVEN GOOD SOUTHERLY FLOW INTO
CENTRAL IOWA AHEAD OF SYSTEM...HAVE ONLY TRENDED AMOUNTS DOWN
SLIGHTLY.

MAIN CONCERN WITH SYSTEM WILL BE PRECIPITATION TYPE AS MOISTURE
AND FORCING ARE WELL IN LINE. WAA BEGINS SPREADING INTO IOWA
MONDAY NIGHT AHEAD OF SYSTEM WHICH WILL LEAD TO PRECIPITATION TYPE
CHALLENGES ACROSS MUCH OF CENTRAL AND SOUTHERN IOWA THROUGH EVENT.
PRECIP WILL BE PRIMARILY RAIN IN THE SOUTH THOUGH MAY SEE BRIEF
PERIOD OF FREEZING RAIN OR SLEET EARLY TUESDAY BEFORE TEMPERATURES
WARM ENOUGH. AS WAA PUSHES NORTH CHANCES FOR MIXING PRECIPITATION
WILL ALSO LIFT NORTH THROUGH THE DAY TUESDAY. SOUNDINGS INDICATING
A PROLONGED PERIOD OF MIX THROUGH THE MORNING WITH RAIN FREEZING
RAIN AND SLEET ALL POSSIBLE...BEFORE TEMPERATURES WARM ENOUGH TO
ALLOW FOR RAIN. HOWEVER...THIS WILL BE SHORT LIVED AS COLD FRONT
PUSHES SOUTHEAST TUESDAY...BRINGING VERY COLD AIR INTO IOWA.
TIMING OF THIS BOUNDARY WILL ALSO DETERMINE WHEN PRECIPITATION
SWITCHES TO SNOW WHICH WILL IMPACT SNOWFALL TOTALS IN CENTRAL AND
SOUTHERN IOWA. IN ADDITION...SOME MODELS INDICATING THAT
SATURATION MAY NOT BE DEEP ENOUGH AT FIRST FOR ICE INTRODUCTION
WHICH MAY ALLOW FOR ANOTHER SHOT OF FREEZING RAIN OR RAIN IN
CENTRAL AND SOUTHERN CWA. WINDS WILL INCREASE SHARPLY BEHIND
BOUNDARY...WITH BLOWING SNOW LIKELY TUESDAY WITH FALLING SNOW AND
FRESH FALLEN SNOW...SPECIALLY IN THE NORTH. HOWEVER...MODELS ARE
NOT AS STRONG WITH WINDS...THOUGH STILL NEARING 40KTS AT TOP OF
MIXED LAYER TUESDAY AFTERNOON. EVEN THOUGH SNOWFALL TOTALS ARE
GENERALLY NEAR ADVISORY CRITERIA...MAY BE ENOUGH SNOW TO LEAD TO
LIMITED VISIBILITIES AND HAZARDOUS TRAVEL WITH STRONG WINDS
TUESDAY. SYSTEM IS GOING TO NEED TO BE MONITORED CLOSELY FOR
HEADLINE POTENTIAL. ACROSS THE NORTH MAY NEAR BLIZZARD CONDITIONS
AT TIMES IF SNOW AND WINDS PHASE...AND FURTHER SOUTH CHANCES FOR
MIXED PRECIPITATION AND FREEZING RAIN MAY NEED HEADLINE AS WELL.
HOWEVER...AS MENTIONED...STILL MUCH UNCERTAINTY IN TRACK AND
TIMING OF SYSTEM AND WILL HOLD OFF ON ANY WATCH PRODUCTS FOR NOW.

BEHIND SYSTEM...HIGH PRESSURE PUSHES IN WHICH WILL KEEP CONDITIONS
DRY THROUGH THE REMAINDER OF THE PERIOD. HOWEVER HIGH WILL BE
VERY COLD AGAIN FOR WEDNESDAY INTO THURSDAY WITH TEMPERATURES WELL
BELOW NORMAL FOR EARLY MARCH. TEMPERATURES BEGIN TO MODERATE
SOMEWHAT FOR END OF PERIOD AS SOUTHERLY SURFACE WINDS RETURN
BRINGING WARMER CONDITIONS.

&&

.AVIATION...01/18Z
ISSUED AT 1139 AM CST SUN MAR 1 2015

MVFR CIGS LINGER OVER SE IA NEAR KOTM BUT THOSE SHOULD EXIT TO THE
EAST DURING THE EARLY AFTERNOON HOURS. THIS SHOULD LEAD TO VFR
CONDITIONS AND RELATIVELY LIGHT WINDS AT ALL TAF SITES THROUGH THE
REMAINDER OF THE PERIOD. MOSTLY CLEAR SKIES INTO THE
EVENING...THEN INCREASING MID/HIGH LEVEL CLOUDINESS AHEAD OF THE
NEXT SYSTEM LATE.

&&

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

&&

$$

SHORT TERM...DONAVON
LONG TERM...AWB
AVIATION...SMALL



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