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000
FXUS63 KDMX 121736
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1236 PM CDT SUN MAY 12 2013

.UPDATE...
ISSUED AT 750 AM CDT SUN MAY 12 2013

WITH FULL SUNSHINE AND TEMPS QUICKLY RISING FURTHER ABOVE
FREEZING...CANCELLED FROST ADVISORY AND UPDATED CODING BELOW.

&&

.SHORT TERM.../TODAY/
ISSUED AT 255 AM CDT SUN MAY 12 2013

LITTLE OF CONCERN IN SENSIBLE WEATHER TODAY.  IOWA WILL BE BETWEEN
DEPARTING GREAT LAKES SYSTEM AND THETA-E ADVECTION SOUTH OF MO
RIVER.  SURFACE HIGH PRESSURE WILL REMAIN IN PLACE WITH TEMPS ONLY
REAL QUESTION.  EXPECT NEARLY FULL SUNSHINE BUT WITH LIGHTER WINDS
THAN YESTERDAY.  HAVE TRIMMED HIGHS BACK A TAD BASED ON FORECAST
SOUNDINGS AND PROJECTED MIXING.  HAVE CONTINUED TREND OF GOING AT OR
BELOW THE COOLEST MOS WITH MOS LIKELY BEING DRAWN TOO WARM DUE TO
CLIMO.

NO CHANGE TO FROST ADVISORY.  LOOKS LIKE MORNING LOWS WILL MAINLY
BE IN THE LOW/MID 30S...POSSIBLY SUB 30F IN A FEW SPOTS.  DEWPOINTS
ARE MARGINAL IN SOME AREAS...TOO LOW...BUT CONFIDENCE IS NOT GREAT
ENOUGH TO ALTER ADVISORY AT THIS POINT AS SOME SPOTS MAY FREEZE
REGARDLESS OF FROST POTENTIAL.

.LONG TERM.../TONIGHT THROUGH FRIDAY/
ISSUED AT 255 AM CDT SUN MAY 12 2013

UPPER RIDGE OVER THE WESTERN CONUS THIS MORNING IS FORECAST TO
MOVE EAST INTO THE NORTHERN PLAINS/UPPER MIDWEST BY TUESDAY
MORNING. THE UPPER RIDGE OVER THE REGION WILL BE SHORT LIVED. THE
MODELS ARE CONSISTENT IN MOVING A SHORTWAVE EAST NEAR THE
US/CANADIAN BORDER TUESDAY INTO WEDNESDAY. THE WAVE SHOULD DRIVE A
COLD FRONT INTO CENTRAL IOWA TUESDAY NIGHT. BEFORE THEN...STRONG
WARM ADVECTION SHOULD START TONIGHT AND CONTINUE INTO TUESDAY. BY
TUESDAY...VERY WARM 850 MB TEMPERATURES ARE LOCATED OVER CENTRAL
IOWA IN THERMAL RIDGE AHEAD OF THE APPROACHING FRONT. FAVORABLE
SOUTHWEST FLOW BELOW 850 MB AND GOOD MIXING POTENTIAL SUPPORTS
RECORD OR NEAR RECORD HIGHS ON TUESDAY. ALL MODELS HAVE BEEN
CONSISTENT CONCERNING TEMPERATURES IN THE THERMAL RIDGE. GIVEN
EVERYTHING...BUMPED TEMPERATURES UP A DEGREE OR TWO.

THE 00Z GFS/ECMWF BOTH MOVE THE COLD FRONT THROUGH MOST OF CENTRAL
IOWA TUESDAY NIGHT. ALTHOUGH LARGE SCALE FORCING IS MINIMAL
TUESDAY NIGHT AND DEEP MOISTURE SHOULD NOT BE AVAILABLE...THE
BOUNDARY IS WORTH A MODEST CHANCE OF THUNDERSTORMS AS IT SAGS
ACROSS THE STATE.

BOTH THE ECMWF AND GFS SUGGEST AN UNSETTLED WEATHER PATTERN FOR
CENTRAL IOWA IN THE EXTENDED. INITIALLY ZONAL FLOW MIDWEEK WILL BE FOLLOWED
BY THE APPROACH OF A DECENT LOOKING SHORTWAVE TOWARDS THE END OF
THE FORECAST PERIOD. THE SURFACE BOUNDARY WILL LIKELY STALL IN OR
NEAR IOWA GIVEN THE ZONAL FLOW ALOFT WEDNESDAY AND THURSDAY. ONCE
GULF MOISTURE RETURNS...THUNDERSTORM CHANCES SHOULD INCREASE. AT
THIS POINT...THE FORECAST WILL SLOWLY INCREASE POPS AS WE MOVE
TOWARDS NEXT WEEKEND WITH SEASONABLE TEMPERATURES.

&&

.AVIATION...12/18Z
 ISSUED AT 1236 PM CDT SUN MAY 12 2013

FEW CONCERNS THIS PERIOD. RIDGE BUILDING OVER THE AREA TODAY AND
TONIGHT WITH GENERALLY CLEAR SKIES THROUGH 00Z. UPSTREAM WARM AIR
ADVECTION WILL PUSH SOME MID TO HIGH CLOUDS INTO THE REGION AFT
05Z AND THICKEN BETWEEN 12-18Z MONDAY TO ABOUT BKN130-BKN180.
WINDS TO REMAIN LIGHT AFT DAYTIME MIXING ENDS AT 23Z TODAY...THEN
INCREASE WITH SOUTHWEST MIXING MONDAY AFT 15Z MOST AREAS. DEEPER
BOUNDARY LAYER WILL PROMOTE STRONGER MIXING AFT 18Z MONDAY.

&&

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

$$

UPDATE...SMALL
SHORT TERM...SMALL
LONG TERM...JOHNSON
AVIATION...REV