Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 130848
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
348 AM CDT SUN APR 13 2014

.SHORT TERM /TODAY/...
ISSUED AT 328 AM CDT SUN APR 13 2014

PLENTY OF ACTION TODAY AS SYSTEM PASSES THROUGH THE REGION.  ONGOING
CONVECTION IN AREA OF MOISTURE TRANSPORT AHEAD OF NEXT SURFACE WAVE
ACROSS SOUTHWEST KANSAS.  ANTICIPATE CONVECTION TO PERSIST INTO THE
MORNING AND BECOME MORE WIDESPREAD WITH TIME.  WILL CONTINUE TO SEE
A HAIL THREAT FOR A FEW HOURS AFTER SUNRISE...MAINLY IN SOUTHERN
IOWA AS ELEVATED INSTABILITY REMAINS IN PLACE.  HOWEVER...THE
INSTABILITY WILL GRADUALLY GET PUSHED SOUTH AS COOLER AIR DEEPENS
ACROSS THE STATE WITH THE SURFACE FRONT SETTLING TO THE SOUTH.
MEANWHILE...GOOD ISENTROPIC LIFT AND STRONG KINEMATICS WILL PRODUCE
WIDESPREAD PRECIPITATION BY LATE MORNING INTO THE AFTERNOON ACROSS
MUCH OF THE CENTRAL IOWA.  AS THE INSTABILITY GETS SQUASHED
SOUTHWARD...SO WILL THE THUNDER THREAT AND ONLY FAR SOUTHEAST WILL
SEE ANY THUNDER CHANCES BY LATER AFTERNOON.  FARTHER NORTHWEST...
COLDER AIR WILL DEEPEN WITH STRONG NORTH WINDS ACROSS MUCH OF THE
FORECAST AREA BY AFTERNOON. THE STRONG LIFT AND SUBSEQUENT COOLING
OF THE SOUNDING BEGIN TO GET CLOSE ENOUGH WHERE SNOW MAY BECOME AN
ISSUE TOWARD THE END OF THE DAYTIME PERIOD IN THE NORTHWEST.  MAY
BEGIN TO SEE SOME TRANSITION BY LATE IN THE DAY AND MUCH WILL DEPEND
ON SURFACE TEMPERATURES.  CONDITIONS BY AFTERNOON WILL BE GENERALLY
DANK IN MOST LOCATIONS WITH PRECIPITATION AND STRONG NORTH WIND WITH
TEMPERATURES DROPPING INTO THE 30S AND 40S.  SOME CONCERN WITH
ADDITIONAL HEAVY PRECIPITATION TODAY ON TOP OF LOCALIZED HEAVY RAIN
FROM SATURDAY NIGHT.  LOOKS LIKE CORRIDOR OF HEAVIEST RAIN TODAY
SHOULD BE TO THE SOUTHEAST OF YESTERDAYS EVENT AND HAVE FOREGONE
WATER HEADLINES AT THIS POINT.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 328 AM CDT SUN APR 13 2014

THE FORECAST ISSUE FOR TONIGHT RESTS MORE WITH PTYPE AND WHETHER
WE WILL SEE MUCH IN THE WAY OF ACCUMULATION OF SNOW. COLD FRONT
SHOULD BE SOUTHEAST OF THE STATE TONIGHT AND DEEP COLD AIR
ADVECTION WILL BE ONGOING. SOME FORCING IS NOTED PUSHING ACROSS
THE STATE PRIMARILY FROM A SHORT WAVE MOVING ACROSS IOWA THIS
EVENING. HOWEVER...MOISTURE IS LESS THAN IMPRESSIVE ALTHOUGH IT IS
PRESENT...ESPECIALLY ACROSS THE NORTH AND NORTHEAST. ANOTHER
CAVEAT IS THAT TEMPS REALLY DON`T TANK BEFORE THE FORCING AND
MOISTURE PUSH OFF TO THE EAST. SO I DID INCREASE THE SNOWFALL
TOTALS A BIT USING OUR WINTER TOOLS BUT WE ARE STILL AT A HALF
INCH OR LESS AND THAT WILL LIKELY FALL MORE OVER GRASSY AREAS.

EVERYTHING PULLS EAST ON MONDAY AS THE UPPER TROUGH SHIFT TO THE
EAST IN RESPONSE TO AN UPPER RIDGE ACROSS THE ROCKIES. THE RIDGE
WILL KEEP A NORTHWEST FLOW OVER IOWA SO WHILE WE WILL GRADUALLY
WARM FROM VERY CHILLY EARLY WEEK HIGHS IT WILL STILL BE COOL.
ANOTHER WEAKER WAVE PASSES ACROSS THE NORTHERN PLAINS BRUSHING
IOWA AROUND THURSDAY. THE SYSTEM WILL BRING A MIX OF LIGHT PRECIP
TO MAINLY THE NORTH AND WEST WEDNESDAY NIGHT AND RAIN ON THURSDAY.
THE MODELS STILL HAVE VERY DIFFERENT SOLUTIONS FOR NEXT WEEKEND
WITH A CLOSED LOW AFFECTING THE AREA ACCORDING TO THE GFS WHILE
THE EURO KEEPS AN OPEN WAVE AND IS A BIT MORE PROGRESSIVE AND HAS
LESS QPF. FOR NOW I HAVE KEPT THE LOW END CHANCE OR SLIGHT CHANCE
POPS GOING. TEMPS WILL CLIMB BACK INTO THE MID 50S TO AROUND 60.

&&

.AVIATION...13/06Z
ISSUED AT 1232 AM CDT SUN APR 13 2014

COLD FRONT ALONG THE I-80 CORRIDOR AT THIS TIME WILL CONTINUE TO
SINK SOUTH AND EAST.  SOME STORM ALONG AND JUST BEHIND THE BOUNDARY
COULD STILL PRODUCE LARGE HAIL BUT STORM SEVERITY WILL CONTINUE TO
WANE THROUGH THE NIGHT.  SOME CONCERN THAT A LOW LEVEL JET WILL
DEVELOP LATE TONIGHT INTO SUNDAY MORNING AND INTERACT WITH THE
BOUNDARY AND REDEVELOP SOME STORMS BUT INSTABILITY WILL BE SHIFTING
OUT OF THE AREA.  BIGGER CONCERN IS THE POCKETS OF STRATUS
DEVELOPING.  I DO EXPECT THAT TO EXPAND OVERNIGHT WITH MVFR
CONDITIONS BECOMING WIDESPREAD AND POSSIBLY IFR CONDITIONS.  IT WILL
BE WINDY TOWARDS THE END OF THE TAF PERIOD AS COLD AIR SURGES IN.
ANY LINGERING PRECIP WOULD THEN CHANGE TO SNOW BUT ACCUMULATIONS
WOULD BE LIGHT.


&&

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

$$

SHORT TERM...COGIL
LONG TERM...FAB
AVIATION...FAB



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