Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 252339
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
639 PM CDT SAT OCT 25 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 305 PM CDT SAT OCT 25 2014

A TRANQUIL NIGHT IS IN STORE WITH HIGH PRESSURE SETTLING INTO THE
STATE. WITH DEW POINTS FALLING OFF THIS AFTERNOON QUITE
NICELY...EXPECT TO SEE TEMPS FALL FAST THIS EVENING UNDER CLEAR
SKIES AND LIGHT AND VARIABLE WINDS. WENT BELOW MOS FOR LOWS
TONIGHT WITH THAT IN MIND.

.LONG TERM /SUNDAY THROUGH SATURDAY/...
ISSUED AT 305 PM CDT SAT OCT 25 2014

NO SIGNIFICANT CHANGES WERE MADE TO THE LONG-TERM PERIOD OF THE
FORECAST. RELATIVELY QUIET WX IS STILL EXPECTED. MAIN
OPPORTUNITIES FOR PRECIP WILL BE MONDAY INTO MONDAY NIGHT...AND
WEDNESDAY NIGHT INTO THURSDAY MORNING.

FCST PERIOD BEGINS WITH DEPARTING SFC PRESSURE RIDGE. RETURN FLOW
ON ITS BACK SIDE AND THETA-E ADVECTION FOLLOW IT CLOSELY WILL
AFFECT THE CWA DURING THE DAY ON SUNDAY...AS A WARM FRONT
APPROACHES THE REGION. RH VALUES WITHIN THE COLUMN ARE NOT
EXPECTED TO BE HIGH ENOUGH TO FACILITATE PCPN...SO HAVE CONTINUED
THE TREND OF PARTLY TO MOSTLY CLOUDY ONLY. GFS AND NAM BRING IN
LOW-LEVEL MOISTURE FROM SUN AFTN THROUGH MON MORNING. IF LOW
CLOUDS END UP BEING MORE PLENTIFUL THAN EXPECTED SUN AFTN THEN
FCST MAXES MAY BE TOO HIGH. SUBSEQUENT SHIFTS WILL HAVE TO MONITOR
FOR POTENTIAL TWEAKS TO SUNDAY MAX TEMPS IN THAT REGARD.

ELEVATED TSTMS ARE POSSIBLE SUNDAY NIGHT FROM NORTHEAST IA INTO
WI AS ELEVATED INSTABILITY COMBINES WITH AMPLE FORCING WITHIN THE
WAA REGIME THERE. ATTM BELIEVE THE BEST COMBINATION OF INSTABILITY
AND FORCING WILL REMAIN NORTHEAST OF THE CWA SO HAVE LEFT THE FCST
DRY DURING THE TIME.

COLD FRONT IS PROGGED TO PUSH THRU THE CWA ON MONDAY. ALTHOUGH
MOISTURE WILL BE MINIMAL...SUFFICIENT FORCING AND INSTABILITY WILL
BE SUFFICIENT FOR AT LEAST ISOLD-SCT PCPN INVOF THE BOUNDARY.
INSTABILITY WILL BE HIGH ENUF FOR AT LEAST SOME ISOLD TSRA
ESPECIALLY ACROSS THE SOUTHEAST HALF OF THE CWA...WHERE MUCAPES OF
400+ J/KG ARE PROGGED TO EXIST. ALTHOUGH FOG REMAINS A POSSIBILITY
MONDAY MORNING BEFORE THE BOUNDARY ARRIVES...CONFIDENCE WAS NOT HIGH
ENUF FOR IT TO BE IMPACTFUL ENUF TO MENTION. SUBSEQUENT SHIFTS WILL
HAVE TO MONITOR FOR POTENTIAL IMPACTS TO FORECAST MAXES AND CLOUD
COVER.

AFTER THE SYSTEM DEPARTS THE CWA MONDAY NIGHT...NEXT CHANCE OF
PCPN WILL ARRIVE WEDNESDAY NIGHT INTO THURSDAY MORNING. BRIEF
RIDGING BUILDS IN BEHIND THE DEPARTING SYSTEM WEDNESDAY...BUT THEN
HEIGHTS FALL AGAIN AS THE NEXT SYSTEM APPROACHES. ALTHOUGH
MOISTURE WILL BE LIMITED...FORCING WILL BE AMPLE ENOUGH FOR SOME
SCATTERED SHRA MAINLY ACROSS THE EASTERN CWA.

MODELS BEGIN DIVERGING NOTICEABLY IN THEIR SOLUTIONS OF THIS
PARTICULAR SYSTEM...WITH THE ECMWF BEING THE STRONGEST/COLDEST.
REGARDLESS OF PARTICULAR MODEL...THOUGH...THEY ARE IN AGREEMENT
WITH A SEASONABLY COOL CANADIAN AIR MASS FILLING IN BEHIND IT.
FCST MINS ON FRIDAY MORNING ARE IN THE 20S AND 30S.

&&

.AVIATION...26/00Z
ISSUED AT 637 PM CDT SAT OCT 25 2014

RELATIVELY TRANQUIL AVIATION WEATHER TONIGHT INTO SUNDAY. WILL SEE
WIDESPREAD VFR CONDITIONS OVERNIGHT AS SURFACE RIDGING PASSES
THROUGH THE STATE. MOISTURE WILL RETURN ON SUNDAY WITH INCREASING
SOUTHEAST WINDS. LIKELY TO SEE SOME VFR CEILINGS INCREASE THROUGH
THE DAY AS THETA-E ADVECTION PASSES THROUGH THE STATE.

&&

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

&&

$$

SHORT TERM...MS OCT 14
LONG TERM...ZOGG
AVIATION...COGIL



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