

000

FXUS63 KDMX 051744

AFDDMX



AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE DES MOINES IA

1145 AM CST SAT JAN 5 2013



...UPDATED FOR 18Z AVIATION DISCUSSION...



.SHORT TERM /TODAY/...

FIRST BAND OF WAA MID AND HIGH CLOUDS ARE LIFTING INTO NRN IA AHEAD 

OF APPROACHING UPPER LEVEL LOW.  LOW LOCATED OVER SOUTH CENTRAL KS 

WILL PUSH NORTHEAST TODAY AND BRUSH THE SOUTHEAST PART OF THE CWA.  

IA WILL BETWEEN SYSTEMS AS SURFACE LOW OVER ND PUSHES SOUTHEAST 

TODAY AS WELL.  THE NORTHERN LOW AND ASSOCIATED COLD FRONT WILL 

EFFECTIVELY TAKE OVER AND PUSH MOISTURE SOUTHEAST OF THE CWA BY 

EVENING.  WENT A LITTLE ABOVE MOS TEMPS FOR TODAY AND A FEW DEGREES 

ABOVE YESTERDAYS HIGHS.



...Bogus second line with a new

   line...



.LONG TERM /TONIGHT THROUGH FRIDAY/...

LARGE UPPER LEVEL RIDGE WILL BUILD INTO THE PLAINS FOR THE

BEGINNING OF THE PERIOD. THIS WILL KEEP TEMPERATURES COOLER SUNDAY

WITH NORTHWEST FLOW. TEMPERATURES WILL WARM FOR MONDAY AS RIDGE

SHIFTS EAST AND SOUTHERLY FLOW INCREASES...ALONG WITH WAA. HAVE

KEPT TEMPERATURES WARMER ACROSS THE SOUTH EAST WHERE LACK OF

SNOW COVER HAS ALLOWED TEMPERATURES TO CLIMB. A WEAK FRONTAL

BOUNDARY WILL PUSH SOUTH LATE MONDAY...CURRENT TIMING ON THIS

FRONT HAS PASSAGE OVERNIGHT MONDAY...BUT IF TIMING SPEEDS UP WILL

SEE COOLER AFTERNOON TEMPERATURES BEHIND FROPA. FRONTAL PASSAGE

WILL BE DRY WITH VERY LIMITED MOISTURE.



FOCUS THEN SHIFTS TO LOW PRESSURE SYSTEM FOR LATE IN THE PERIOD.

AREA OF LOW PRESSURE WILL PUSH NE FROM SOUTHWESTERN TEXAS. MODELS

REMAIN IN VERY POOR AGREEMENT WITH HANDLING OF THIS SYSTEM. THE

GFS LIFTS THE LOW THROUGH ARKANSAS...WITH LITTLE IMPACT ON

IOWA. THE ECMWF REMAINS CONSISTENT WITH BRINGING LOW ACROSS

MISSOURI...WITH DEF ZONE PRECIPITATION AFFECTING IOWA. GEM MODEL

HAS ALSO TRENDED THIS WAY WITH RECENT RUNS. HAVE THEREFORE TRENDED

FORECAST TOWARDS ECMWF MODELS...REMAINING CONSISTENT WITH PREVIOUS

FORECASTS. RUN TO RUN TIMING WITH ECMWF REMAINS FAIRLY CONSISTENT

AS WELL...AND HAVE KEPT ONSET OF PRECIPITATION WEDNESDAY NIGHT.

WITH WARMER TEMPERATURES...PRECIPITATION TYPE COULD BECOME A

PROBLEM...BUT GIVEN TEMPERATURE PROFILES...HAVE KEPT A RAIN/SNOW

MIX...WITH A CHANGE OVER TO RAIN THURSDAY BEFORE BACK TO A MIX.

SYSTEM WILL PUSH OUT FOR THE END OF THE PERIOD...HOWEVER MODELS

ARE INDICATING ANOTHER AREA OF LOW PRESSURE PUSHING ACROSS THE

NORTHERN PLAINS WILL BRING ADDITIONAL CHANCES FOR PRECIPITATION.

HOWEVER...AGAIN MODELS DO NOT HAVE GOOD AGREEMENT WITH TIMING AND

PLACEMENT OF THIS LOW AND MAY SEE A BREAK IN PRECIPITATION BETWEEN

SYSTEMS FRIDAY. GIVEN UNCERTAINTY...HAVE LEFT SLIGHT CHANCE FOR

PRECIPITATION THROUGH END OF PERIOD.



&&



.AVIATION...05/18Z

UPPER LOW WILL PASS JUST SOUTH OF THE STATE THIS AFTERNOON WITH 

ANOTHER WEAK SHORTWAVE ARRIVING FROM THE NORTHWEST.  WILL GENERALLY 

SEE VFR CONDITIONS ACRS THE STATE THIS AFTERNOON ALTHOUGH SOME MVFR 

CEILINGS WILL SPILL INTO THE FAR SOUTH NEAR THE TRACK OF THE UPPER 

LOW. SURFACE FRONT IS FORECAST TO PASS THROUGH THE STATE THIS 

AFTERNOON AND EVENING WITH WINDS BECOMING NORTHWEST AND QUITE 

BREEZY.  A FEW SNOW SHOWERS MAY ALSO OCCUR IN THE WAKE OF THE LOW 

ALONG WITH MVFR CEILINGS. BY SUNDAY MORNING...DRIER AIR WILL 

OVERSPREAD THE STATE AS SUBSIDENCE INCREASES WITH WIDESPREAD VFR 

CONDITIONS AND NORTHWEST SURFACE WINDS.



&&



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



&&



$$



SHORT TERM...MS JAN 13

LONG TERM...AWB

AVIATION...COGIL



