000
FXUS63 KDMX 112009
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
309 PM CDT SAT MAY 11 2013

.SHORT TERM.../TONIGHT /...
ISSUED AT 309 PM CDT SAT MAY 11 2013

MAIN CONCERN TONIGHT WILL REMAIN COLD TEMPERATURES AND CHANCES
FOR FROST. FULLY MIXED CUMULUS FIELD OVER THE NORTHEAST WILL MOVE
OUT OF THE AREA BY EARLY EVENING AND DISSIPATE AS SUNSETS OVER
THE REGION. WINDS WILL GRADUALLY DECOUPLE THIS EVENING. DEW
POINTS HAVE REALLY DROPPED WITH MIXING AND ARE GENERALLY LOWER
THAN EARLIER PROGGED...LEADING TO LOWER OVERNIGHT LOWS OVER THE
AREA BY EARLY SUNDAY MORNING WHICH WILL LEAD MOST AREAS TO SEE
INCREASED CHANCES FOR FROST OVERNIGHT AND HAVE EXPANDED ADVISORY
TO INCLUDE THE ENTIRE FORECAST AREA GIVEN THE LIKELIHOOD OF LOWER
OVERNIGHT MINS. STILL SOME QUESTIONS ABOUT CLOUD COVER NORTHEAST
AREAS...WITH MODELS SHOWING SOME MOISTURE ROTATING AROUND BY
MORNING THERE. TEMPERATURES BY EARLY MORNING WILL BE NEAR RECORD
MINS FOR THE DAY AND HAVE ADDED WORDING TO ZONES AS WELL. RECORD
LOW TEMPS FOR SUNDAY ARE 32 AT KDSM...30 AT KALO...26 AT KMCW AND
35 AT KOTM.

RIDGE WILL SETTLE INTO THE AREA FROM NORTHWEST TO SOUTH CENTRAL
SO AREAS WEST OF THE RIDGE AND NORTH OF HIGHWAY 30 WILL HAVE A
BETTER CHANCE OF WIDESPREAD FROST...WHILE THE SOUTHEAST WILL GOOD
CHANCES FOR PATCHY FROST AND FROST IN LOW LYING AREAS. LARGE
URBAN AREAS WILL MORE THAN LIKELY ESCAPE THE COOLEST TEMPERATURES
SO THOSE AREAS NOT AS LIKELY TO EXPERIENCE FROST WHILE MORE RURAL
AREAS WILL BE MORE SUSCEPTIBLE FOR FROST OVERNIGHT.

.LONG TERM.../SUNDAY THROUGH SATURDAY/...
ISSUED AT 309 PM CDT SAT MAY 11 2013

AFTER NEAR RECORD LOW TEMPERATURES TONIGHT...TEMPERATURES DURING
THE FORECAST PERIOD WILL WARM RAPIDLY TO NEAR RECORD HIGH
TEMPERATURES ON TUESDAY...FOLLOWED BY COOLER BUT STILL ABOVE
NORMAL TEMPERATURES AND UNSETTLED WEATHER BY THE END OF THE
PERIOD.

ON SUNDAY MORNING...THE HIGH PRESSURE RIDGE AXIS WILL BE ACROSS
THE WESTERN CWA. IT WILL SLIDE EASTWARD QUITE SLOWLY DURING THE
DAY ON SUNDAY. THE PRESSURE RIDGE ALONG WITH STRONG CYCLONIC FLOW
ALOFT WILL HELP KEEP TEMPERATURES BELOW THEIR SEASONAL AVERAGES
FOR ONE MORE DAY. AMPLIFIED UPPER LEVEL RIDGE THEN HELPS TO BRING
IN SHARPLY WARMER TEMPERATURES AS THE UPPER LEVEL TROF DEPARTS.
APPROACHING SHORTWAVE FROM THE PACIFIC NW WILL HELP FLATTEN IT
THOUGH. TEMPS WILL WARM ON MONDAY AND EVEN MORE SO ON TUESDAY.
850 MB TEMPS ACROSS THE WESTERN CWA WARM FROM 5 TO 10C ON MONDAY
MORNING...TO AROUND 20C ON TUESDAY MORNING. GFS AND ECMWF 850 MB
TEMPS DURING THE DAY ON TUESDAY ARE IN THE +2.5 TO +3.0 SIGMA
RANGE. NOT SURPRISING THAT MOS IS HAVING DIFFICULTY WITH MAXES ON
TUESDAY GIVEN THESE STANDARDIZED ANOMALY VALUES. HAVE NOT CHANGED
GOING MAX TEMPS ON TUESDAY MUCH...SO UPPER 80S TO LOWER 90S STILL
LOOKS REASONABLE. THOSE HIGHS WOULD BE NEAR THE RECORDS FOR
TUESDAY. RECORD HIGH TEMPS FOR TUESDAY ARE 93 AT KDSM...94 AT
KALO...92 AT KMCW AND 92 AT KOTM.

H5 SHORTWAVE HELPS TO FLATTEN THE RIDGE BY LATE TUESDAY. IT ALSO
HELPS PUSH A PACIFIC FRONT INTO OUR CWA AT THE SAME TIME. AM
CARRYING SLIGHT CHANCE POPS DURING THIS TIME. DESPITE THE WARM
SURFACE TEMPS AND ELEVATED DEW POINTS...EXPECT THAT IT WILL BE
DIFFICULT TO SEE SIGNIFICANT...ORGANIZED CONVECTION DUE TO
ELEVATED WARM LAYER AROUND 850 MB.

FRONTAL BOUNDARY HANGS UP IN THE VICINITY OF THE CWA FROM
WEDNESDAY INTO FRIDAY AS UPPER LEVEL FLOW BECOMES NEARLY PARALLEL
TO IT. GFS DOES PUSH THE BOUNDARY JUST SOUTH OF THE CWA ON
WEDNESDAY WHILE THE ECMWF KEEPS IT AROUND. HAVE LEANED TOWARD THE
ECMWF SOLUTION WHICH FAVORS MAINLY SLIGHT CHANCE POPS ACROSS MUCH
OF THE CWA THROUGH FRIDAY. PATTERN THEN BECOMES MORE UNSETTLED
FROM FRIDAY INTO SATURDAY AS UPPER LEVEL FLOW TRANSITIONS TO A
SOUTHWEST FLOW REGIME. THIS CONFIGURATION WILL HELP BRING IN
ADDITIONAL MOISTURE. THIS MOISTURE COMBINED WITH THE FRONTAL
BOUNDARY IN THE VICINITY OF THE CWA WILL BRING INCREASED CHANCES
FOR TSRA BY THE WEEKEND.

&&

.AVIATION...11/18Z
 ISSUED AT 1236 PM CDT SAT MAY 11 2013

WINDS CONTINUE TO BE THE MAIN CONCERN THIS AFTERNOON WITH GUSTS
EXCEEDING 35 KTS ACROSS THE AREA FOR THE NEXT SEVERAL HOURS. CIGS
WILL REMAIN VFR BUT EXPECT HIGHER GUSTS AT TIMES NEAR CU FIELD.
AS HIGH BUILDS INTO THE REGION TONIGHT WINDS WILL RELAX AND DROP
OFF SIGNIFICANTLY AFT 01Z MOST AREAS. SOME INCREASE AGAIN IN
WINDS AFT 15-16Z SUNDAY WITH MIXING AND A FEW CUMULUS OVER THE
NORTHEAST AT THAT TIME.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 9 AM CDT SUNDAY FOR ENTIRE AREA.

&&

$$

SHORT TERM...REV
LONG TERM...ZOGG
AVIATION...REV