Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 232345
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
545 PM CST MON FEB 23 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 330 PM CST MON FEB 23 2015

WARM ADVECTION HAS BEGAN WITH THE RETREAT OF ARCTIC HIGH PRESSURE
AND WILL CONTINUE IN EARNEST OVERNIGHT WITH STRONG SOUTHWEST
FLOW. TEMPERATURES WILL LIKELY BE AT THE LOWEST LEVELS THIS
EVENING WITH INCREASING SOUTHWEST WINDS OVERNIGHT AS FLOW AT
2-3KFT INCREASES CLOSE TO 50KTS AFTER MIDNIGHT. THIS FLOW WILL BE
STRONG ENOUGH TO KEEP SOME NEAR SURFACE MIXING GOING OVERNIGHT
HELPING TEMPERATURES CLIMB AS THERMAL RIDGE APPROACHES THE STATE.
WILL ALSO SEE CLOUDS INCREASE OVERNIGHT...ESPECIALLY IN THE NORTH
AND EAST AS NEXT SHORTWAVE DROPS INTO THE UPPER MIDWEST. AT THIS
POINT...PRECIPITATION APPEARS TO REMAIN JUST NORTHEAST OF THE
FORECAST AREA ALTHOUGH SOME FLURRIES TOWARD DAYBREAK NEAR MASON
CITY ARE NOT OUT OF THE QUESTION.

.LONG TERM /TUESDAY THROUGH MONDAY/...
ISSUED AT 330 PM CST MON FEB 23 2015

MAIN FORECAST CONCERN WAS FOCUSED ON LIGHT SNOW EVENT ON WEDNESDAY
AND THEN WITH SNOW POTENTIAL OVER THE WEEKEND. CONTINUED COLD
THROUGH MUCH OF THE FORECAST TIME FRAME.

TUESDAY INTO WEDNESDAY...MIXING AND PLENTY OF SUNSHINE TUESDAY
SHOULD PUSH MAX TEMPS WELL INTO THE 30S AND POSSIBLY A FEW 40S
OVER THE SOUTHWEST. TWEAKED UP MAX TEMPS SLIGHTLY TUESDAY.

THE GFS REMAINS THE OUTLIER WRT TO THE WEAK SHORTWAVE ON
WEDNESDAY AS IT CONTINUES TO PLACE THE HIGHER SNOW AMOUNTS FURTHER
SOUTHWEST INTO SW IOWA...MISSOURI AND EASTERN KANSAS. THE
ECMWF/CANADIAN AND THE LATEST SREF ARE IN GOOD AGREEMENT...AND
HAVE BEEN THE MOST CONSISTENT...TRACKING THE SNOW BAND FROM WEST-
CENTRAL TO SOUTHEAST PORTIONS OF THE STATE ON WEDNESDAY. THEY ARE
SLIGHTLY SLOWER THAN THE GFS. THE NAM HAS TRENDED FURTHER
NORTHEAST TOWARDS THE ECMWF/CANADIAN/SREF SOLUTION.

A LARGE AREA OF FORCING MOVES INTO WESTERN IOWA BY 12Z WEDNESDAY
AND TRANSITIONS SOUTHEAST DURING THE DAY AND EXITS THE SOUTHEAST
SECTIONS OF THE FORECAST AREA B/T 00-06Z THURSDAY. DECENT
ISENTROPIC LIFT AND MOISTURE TRANSPORT INTO THE STATE WITH THIS
SHORTWAVE. A FAIR AMOUNT OF OMEGA WITHIN THE DENDRITIC LAYER
WEDNESDAY...PUSHING SNOW RATIOS IN THE 12:1 TO 14:1 EARLY IN THE
EVENT AND BY THE AFTERNOON/EVENING WEDNESDAY RANGING FROM 16:1 TO
17:1 WITH THE COOLER TEMPERATURES FILTERING INTO THE STATE.
FORECAST SOUNDINGS BECOME DEEPLY SATURATED FROM 12-18Z WEDNESDAY
FROM WEST TO EAST AND LOOKS TO CONTINUE SNOWING THROUGH MUCH OF
THE AFTERNOON WEDNESDAY PER THE SLOWLY ECMWF SOLUTION. INCREASED
QPF AMOUNTS/POPS SLIGHTLY WITH THE DECENT THETA-E ADVECTION AND
AFOREMENTIONED MOISTURE TRANSPORT...PLUS PRECIPITABLE WATER VALUES
RANGE FROM AROUND 0.50 IN SOUTHWEST IOWA TO A WIDESPREAD 0.25
INCHES OVER THE REMAINDER OF THE STATE. HIGHER CONFIDENCE WITH A
DECENT 2 TO 4 INCH BAND FROM WEST-CENTRAL TO SOUTHEAST SECTIONS OF
THE FORECAST AREA.

THURSDAY AND FRIDAY...LARGE SURFACE HIGH PRESSURE BUILDS INTO THE
REGION BY THURSDAY AND PERSIST THROUGH FRIDAY NIGHT. THURSDAY NIGHT
LOOKS TO BE VERY COLD WITH THE HIGH OVERHEAD ALLOWING FOR SOME
DECENT RADIATIONAL COOLING TO SET UP. MIGHT BE TOO WARM FOR LOWS
THURSDAY NIGHT WITH THE AID OF THE FRESH SNOW PACK EXPECTED
WEDNESDAY AND TRENDED A COUPLE OF DEGREES COLDER.

SATURDAY AND SUNDAY...EXTENDED MODELS CONTINUE TO BE IN FAIR
AGREEMENT WITH SNOW PRODUCER OVER THE WEEKEND. TIMING OF BEST SNOW
CHANCES ARE LOOKING SATURDAY NIGHT INTO SUNDAY...WITH THE ECMWF
SLIGHTLY SLOWER AND FURTHER SOUTH THAN THE GFS WRT TO THE SURFACE
LOW. REGARDLESS...POTENTIAL EXIST FOR AT LEAST SOME MINOR TO
MODERATE SNOW AMOUNTS BY SUNDAY OVER CENTRAL IOWA.

&&

.AVIATION...24/00Z
ISSUED AT 545 PM CST MON FEB 23 2015

VFR CONDITIONS WILL PERSIST THROUGH THE OVERNIGHT HOWEVER
SOUTHWEST WINDS WILL INCREASE AND BECOME GUSTY. A FRONTAL BOUNDARY
WILL APPROACH THE AREA TUESDAY MORNING. POTENTIAL FOR A FEW AREAS
OF MVFR CONDITIONS. IN ADDITION...GUSTY NORTHWEST WINDS WILL
ARRIVE BY LATE MORNING INTO THE EARLY AFTERNOON. A FEW GUSTS OVER
35 KTS WILL BE POSSIBLE.

&&

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

$$

SHORT TERM...COGIL
LONG TERM...PODRAZIK
AVIATION...DONAVON



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