Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 271752
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1252 PM CDT FRI MAR 27 2015

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
ISSUED AT 303 AM CDT FRI MAR 27 2015

CURRENTLY A SHORTWAVE IS PASSING ACROSS IA. THERE IS SOME LOW
LEVEL MOISTURE ASSOCIATED WITH THIS FEATURE BUT ANY FORCING WITH
THIS FEATURE US OFF TO THE SOUTH AND EAST. THUS ALL WE HAVE IS
SOME CLOUD COVER WITH CEILINGS RANGING FROM ABOUT 3500-6000FT AGL.
THE CLOUDS ARE SHIFTING TO THE SOUTHEAST AND SHOULD EXIT THE
SOUTHEAST AROUND 12Z. FOR THE REMAINDER OF TODAY WEAK HIGH
PRESSURE WILL PUSH ACROSS THE STATE AND THERE IS LITTLE MOISTURE
TO SPEAK OF SO IT WILL BE MOSTLY SUNNY TODAY. WE WILL STILL BE IN
A DEEP NORTHERLY FLOW ALTHOUGH THE FAR WEST SHOULD SHIFT AROUND TO
THE WEST OR SOUTHWEST VERY LATE IN THE AFTERNOON. WHILE I KEPT
TEMPS ON THE COOL SIDE TODAY I WENT MORE MIDDLE OF THE ROAD
BETWEEN ALL GUIDANCE.

.LONG TERM /TONIGHT THROUGH THURSDAY/...
ISSUED AT 303 AM CDT FRI MAR 27 2015

PATTERN WILL BEGIN TO DECREASE IN AMPLITUDE THROUGH THE WEEKEND
LEADING TO WARMER TEMPERATURES NEXT WEEK AND A FEW PRECIP WINDOWS.
THE PERIOD WILL BEGIN WITH ONE LAST SHORT WAVE DROPPING INTO
DEPARTING ERN CONUS MEAN TROUGH TONIGHT. MID LEVEL KINEMATIC
FORCING WILL CONTRIBUTE SOMEWHAT...BUT NOTED SLOPED FRONTOGENETIC
FORCING IN THE WARM ADVECTION WILL LIKELY BE THE PRIMARY
CONTRIBUTER AS WAVE DROPS DOWN MO VALLEY BAROCLINIC ZONE. STATIC
STABILITY IS NOT TOO LOW BUT SHOULD BE SUFFICIENT TO RESULT IN
BANDED STREAKS OF PRECIP WHICH IS SUPPORTED BY HI RES MODEL
PROJECTED REFLECTIVITY. HAVE KEPT POPS JUST ON THE BRINK OF
LIKELIES FOR NOW WITH BANDING LIKELY KEEPING COVERAGE FROM BEING
TOO WIDESPREAD. MUCH OF THE PRECIP WOULD BE LIGHT SNOW WITH
THERMAL PROFILES ONLY ABOVE FREEZING JUST NEAR THE SURFACE
INITIALLY BUT WITH WET BULB TEMPS BELOW 2KM EVENTUALLY FLIPPING
THINGS TO SNOW AS THE COLUMN TRIES TO SATURATE. MOISTURE ONLY
APPROACHES 4KM OR SO...BUT SUFFICIENT FOR ICE INTRODUCTION AND
SNOW.

SUBSIDENCE SHOULD FOLLOW INTO SAT...BUT TEMPS WILL REMAIN
SEASONALLY COOL UNTIL THE NEXT ROUND OF WARM ADVECTION STARTS
AGAIN SAT NIGHT. THIS WILL LEAD TO PRECIP SOMETIME AROUND
SUN...HIGH CONFIDENCE IN THAT...BUT LOW WITH REGARDS TO TIMING.
NEARLY ALL OF THE NON-ECMWF DETERMINISTIC AND ENSEMBLE FORECAST
SUITE SPED UP TIMING AROUND SIX HOURS VS 12Z MODELS...BUT THE 00Z
ECMWF REMAINS ON THE SLOW SIDE. CANNOT FIND MUCH REASON TO CHOOSE
A SIDE LOOKING AT INITIALIZATION OR BIASES AT THIS POINT SO WILL
SIDE WITH FASTER CONSENSUS FOR THE TIME BEING WITH POPS MAINLY SUN
MORNING. WHENEVER THE LOBE OF FORCING COMES THROUGH IS WILL BE AT
LEAST MODERATE AND WITH MORE THAN ADEQUATE MOISTURE SO HAVE HIGH
END CHANCE/LOW LIKELY POPS. HAVE GONE WITH SHOWER WORDING FOR NOW
TO BLEND WITH NEIGHBORS...BUT INSTABILITY PARAMETERS SUGGEST THERE
COULD BE RUMBLES OF THUNDER AS WELL.

MILD TEMPERATURES AND LITTLE IN THE WAY PRECIP ARE THEN EXPECTED
INTO NEXT WEEK. TEMPS SHOULD BE WELL INTO THE 60S AND POSSIBLY
TOUCHING 70 PLUS IN SPOTS. THE NEXT PRECIP WINDOW WILL BE AROUND
WED WITH A SYSTEM SOMEWHAT SIMILAR TO SUN. TEMPS WILL MODERATE
SOMEWHAT BEHIND THIS...BUT STILL REMAIN ABOVE NORMAL.

&&

.AVIATION...27/18Z
ISSUED AT 1252 PM CDT FRI MAR 27 2015

VFR CONDITIONS WILL PREVAIL THROUGH TAF PERIOD WITH FOD AND DSM
HAVING THE BEST POTENTIAL FOR MVFR CIGS THIS EVENING.
HOWEVER...DECENT DRY LAYER NEAR THE SURFACE AND KEPT MENTION OF
MVFR CIGS OUT ATTM. MAY SEE SOME LIGHT SNOW BUT NOT ENOUGH TO
DIMINISH VISIBILITY FOR AN EXTENDED TIME FRAME. WINDS SHIFT AND
INCREASE OUT OF THE SOUTH LATE SATURDAY MORNING.

&&

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

&&

$$

SHORT TERM...FAB
LONG TERM...SMALL
AVIATION...PODRAZIK


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