Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 262339
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
539 PM CST MON JAN 26 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 341 PM CST MON JAN 26 2015

HIGH PRESSURE RIDGE WILL SHIFT SLOWLY EAST OVERNIGHT AND BE OVER
CENTRAL MINNESOTA AND INTO NW IOWA BY MORNING. OVERNIGHT WINDS WILL
BE OUT OF THE NORTHWEST TO NORTH MUCH OF THE NIGHT. THIS FLOW WILL
EXTEND UP TO NEAR 3-4 KFT AND WILL BE THE STEERING FLOW FOR A BAND
OF STRATUS CLOUDS TO THE NORTH OVER MINNESOTA. THE STRATUS WILL DROP
SOUTH INTO NORTHERN AND CENTRAL IOWA OVERNIGHT AND COMBINED WITH
WINDS 5 TO 8 MPH WILL KEEP TEMPERATURES IN UP OVERNIGHT. CURRENT
DEWPOINTS ARE HIGH AND WELL INTO THE 30S. AS TEMPERATURES
COOL...SOME QUESTION TO THE POTENTIAL FOR FOG FORMATION. STILL WITH
CLOUDS MOVING IN FROM THE NORTH AND PERSISTENT NORTHERLY WINDS...FOG
FORMATION SHOULD BE LIMITED. BEST POTENTIAL WILL BE OVER THE FAR
WEST AS WINDS DIMINISH AS THE RIDGE NEARS FROM THE WEST. DEWPOINTS
ARE EXPECTED TO LOWER OVERNIGHT AS SFC WINDS BECOME MORE NORTHERLY
WITH DEW POINT DEPRESSIONS INCREASING WHICH WILL LIMIT FOG POTENTIAL
AS WELL. LIKELY THE BIGGER HAZARD OVERNIGHT WILL BE FROST FORMATION
ON ROADS WHERE DEWPOINTS REMAIN HIGHER THAN GROUND TEMPERATURES.

.LONG TERM /TUESDAY THROUGH MONDAY/...
ISSUED AT 341 PM CST MON JAN 26 2015

MODEL RESOLUTION IN THE FURTHER OUT PERIODS (SATURDAY THROUGH
MONDAY) OF THE LONG TERM FORECAST ARE COMING INTO A LITTLE BETTER
AGREEMENT TODAY...ALTHOUGH TIMING ISSUES REMAIN.  THE GFS IS
STARTING TO LOOK MORE LIKE THE EURO AND CANADIAN MODELS NOW WITH
DEVELOP A TROUGH OVER THE REGION INSTEAD OF A HUGE RIDGE.  THAT
MEANS TEMPS WILL BE TRENDING COLDER OVER THE WEEKEND.  BY SUNDAY
MODELS ARE SUGGESTING HIGHS ABOUT 8 TO 10 DEGREES BELOW SEASONAL
NORMALS.  THERE IS A CHANCE FOR SNOW SATURDAY/SATURDAY NIGHT WITH
THE PASSAGE OF A COLD FRONT BUT AGAIN TIMING ISSUES REMAIN WITH THE
CANADIAN MUCH FASTER AND THE GFS MUCH WETTER. ALONG WITH THE COLD
AND SNOW POTENTIAL...SATURDAY NIGHT AND SUNDAY LOOK BREEZY AS WELL.
WINTER RETURNS NEXT WEEKEND.

GOING BACK TO TOMORROW (TUESDAY) SOUNDINGS SHOW A WARM NOSE OFF THE
SURFACE WHICH IS MORE PRONOUNCED ACROSS THE SOUTH BUT WINDS WILL BE
NORTHERLY AND WIND SPEEDS IN THE LOWEST GATES ARE QUITE LIGHT.  AS A
SURFACE LOW MOVES FROM THE PLAINS INTO THE UPPER MIDWEST...SURFACE
WINDS WILL SHIFT AROUND TO THE SOUTHEAST BUT STILL REMAIN LIGHT SO
IT DOES NOT APPEAR THAT THERE WILL BE MUCH MIXING. COUNTERING THAT
WILL BE A LOT OF SUN SO WHILE WE WILL NOT BE AS WARM AS
TODAY...TEMPS SHOULD STILL REACH THE MID 30S NORTHEAST TO LOWER 50S
SOUTHWEST.

DEEPER MIXING AND A LITTLE STRONGER FLOW WILL OCCUR TUESDAY NIGHT
AND WEDNESDAY AND THIS WILL BE OUR WARMEST PERIOD.  EXPECTED CLOUD
COVER AHEAD OF AN APPROACHING STILL MAKES ME A LITTLE CAUTIOUS TO
BOOST TEMPS TOO MUCH ON WEDNESDAY...ESPECIALLY SINCE THE SURFACE LOW
SHIFTS INTO THE AREA DURING THE AFTERNOON AND WINDS DIMINISH/SHIFT
BY LATE IN THE DAY BUT I AM COMFORTABLE WITH CURRENT FORECASTS SINCE
THE WARM ADVECTION WILL BE STRONG.  EXCEPT FOR THE CANADIAN...ALL
MODELS ARE SIMILAR IN THE TIMING OF THE SHORTWAVE BUT IF THE
SHORTWAVE IS SLOWER OR CLOUD COVER IS NOT EXTENSIVE THEN WE WILL BE
TOO COOL FOR WEDNESDAY. STILL GOING DRY WEDNESDAY WITH JUST SOME
INCREASING CLOUDS THROUGH THE DAY WHICH COULD HAMPER HIGHS.

WHILE MOISTURE WITH THE WEDNESDAY SYSTEM IS WOEFULLY LACKING...IT
SHOULD IMPROVE WEDNESDAY NIGHT...AT LEAST IN THE LOW LEVELS.  PRECIP
WILL BE POSSIBLE ALONG AND WITH THE PASSAGE OF A COLD FRONT AND A
SECOND SHORT WAVE WEDNESDAY NIGHT BUT THERE IS NO ICE INTRODUCTION
AND FRANKLY ABOVE 850MB THERE ISN`T MUCH MOISTURE AT ALL AND
NEGLIGIBLE FORCING.  ALL THAT I SEE WEDNESDAY NIGHT INTO THURSDAY
MORNING IS A TRANSITION FROM MAY SOME RAIN OR MORE LIKELY DRIZZLE TO
FREEZING DRIZZLE OVERNIGHT INTO EARLY THURSDAY MORNING.  THE
REMAINDER OF THURSDAY INTO FRIDAY WILL BE COLD BUT DRY WITH COLD
AIR CONTINUING TO FUNNEL INTO THE REGION THROUGH THE WEEKEND.

&&

.AVIATION...27/00Z
ISSUED AT 537 PM CST MON JAN 26 2015

PRIMARY CONCERN THROUGH THE PERIOD WILL BE PROGRESSION OF MVFR/VFR
STRATUS THAT EXTENDS ALONG AND NE OF KEST-KAMW-KOOA LINE AT
23Z...ALL THE WAY BACK INTO MN...WI AND IL IN BROAD CYCLONIC FLOW.
ALL MODELS SEEM TO SLIDE THE STRATUS SLOWLY SOUTH AND WEST INTO
THE EVENING. RAP AND ARW CORE HIGH RES MODELS SEEM TO BE DOING
BETTER THAN NAM AND NMM CORES WHICH MAY STILL BE INFLUENCED BY
OVERZEALOUS MODEL SNOW COVER INITIALIZATION. THERE IS HIGH
CONFIDENCE THAT AT LEAST PATCHY MVFR CIGS WILL OOZE SW THROUGH IA
OVERNIGHT...BUT DURATION CONFIDENCE IS LOW. HAVE TRIED TO
EXTRAPOLATE ONSET BASED ON CURRENT TRENDS...BUT JUST LEFT ENDING
TIME AT 15Z UNTIL EXIT TRENDS BECOME MORE CLEAR.

&&

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

&&

$$

SHORT TERM...DONAVON
LONG TERM...FAB
AVIATION...SMALL


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