Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDMX 300820
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
320 AM CDT SUN AUG 30 2015

.SHORT TERM /TODAY/...
ISSUED AT 320 AM CDT SUN AUG 30 2015

FOG AND TEMP TRENDS WILL BE THE MAIN CONCERNS EARLY THIS MORNING.
WET SOILS FROM RECENT HEAVY RAINS AND LIGHT WINDS HAVE MADE FOR
FAVORABLE RADIATION FOG CONDITIONS WHERE SKIES HAVE CLEARED EARLY
THIS MORNING. THE ONLY THING HOLDING WIDESPREAD DENSE FOG BACK
APPEARS TO BE PATCHY LINGERING STRATUS PER RECENT VIS/FOG SATELLITE
IMAGERY. THUS HAVE OPTED FOR AN SPS IN LIEU OF A DENSE FOG HEADLINE
FOR THE TIME BEING. EVEN UNDER CLEAR SKIES IN THE DES MOINES AREA
OBSERVATIONS HERE AT THE OFFICE AND AIRPORT HAVE NOT
DETERIORATED...AND VISIBILITIES ALSO REMAIN UP FROM NEWTON TO
KNOXVILLE UNDER STRATUS. THUS WENT SPS RATHER THAN TRYING TO DRAW A
PATCHWORK HEADLINE.

HAVE ALSO LOWERED HIGH TEMPS A CATEGORY OR TWO FROM PREVIOUS
FORECAST. RECENT VERIFICATION HAS SHOWN A WARM BIAS AND CANNOT SEE
ANY APPRECIABLE WARMING TODAY WITH LINGERING STRATUS/FOG AND WINDS
NOT INCREASING UNTIL LATE. GFS AND ITS ASSOCIATED MOS ALSO CONTINUES
ITS RECENT WARM BIAS SO STAYED CLOSER TO COOLER NAM MOS.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 320 AM CDT SUN AUG 30 2015

LITTLE HAS CHANGED IN OVERALL FORECAST THINKING TONIGHT. THE 500
MB SYNOPTIC PATTERN FOR THE COMING WEEK IS CHARACTERIZED BY A
LARGE WARM AREA OF HIGH PRESSURE ACROSS THE SOUTHERN AND EASTERN
U.S. AND LONGWAVE TROUGHING ACROSS THE NORTHERN ROCKIES AND
PACIFIC COAST. THE FORECAST CHALLENGE IS IDENTIFYING TO WHAT
EXTENT SHORTWAVES EJECTING OUT OF THE NORTHWEST TROUGH WILL BE
ABLE TO DENT THE RIDGE AND NUDGE IT SOUTHWARD. IF THE RIDGE HOLDS
STRONG...THEN WE WILL REMAIN HOT AND DRY FOR THE COMING WEEK. IF
THE SHORTWAVES ARE ABLE TO FLATTEN THE RIDGE OUT...THEN IT WILL BE
A BIT LESS WARM AND WE WILL HAVE INTERMITTENT THUNDERSTORM
CHANCES. LONG RANGE MODELS HAVE GENERALLY TRENDED MORE TOWARD THE
LATTER SCENARIO SINCE LAST NIGHT...AND AS A RESULT LOW POPS ARE
NOW BEING CARRIED FROM LATE TUESDAY NIGHT THROUGH THURSDAY...AND
AGAIN NEXT WEEKEND.

OTHER THAN THE AFOREMENTIONED INTERMITTENT LOW POPS...THE WORK
WEEK WILL FEATURE MILD LATE SUMMER WEATHER WITH HIGHS IN THE 80S
AND LOWS GENERALLY IN THE MID TO UPPER 60S. LITTLE CHANGE HAS BEEN
MADE TO THE FORECAST TEMPERATURES...EXCEPT TO LOWER THEM BY A
DEGREE OR TWO AROUND MIDWEEK CONCURRENT WITH THE POPS AND
ASSOCIATED WEAKENING OF THE RIDGE. THE HOTTEST DAYS WILL LIKELY
COME AT THE END OF THE WEEK AS THE RIDGE BUILDS BACK IN
OVERHEAD...ESPECIALLY AROUND FRIDAY AND SATURDAY. THERE IS PRETTY
GOOD AGREEMENT BETWEEN THE ECMWF AND GFS THAT A MORE ROBUST 500 MB
TROUGH WILL THEN MOVE EASTWARD ALONG THE U.S./CANADA BORDER AND
PUSH A COOL FRONT ACROSS IOWA LATE IN THE WEEKEND. THIS SYSTEM IS
RESPONSIBLE FOR THE CHANCE POPS AT THE END OF THE LONG TERM
FORECAST AND WILL LIKELY RESULT IN COOLER WEATHER JUST BEYOND A
WEEK FROM NOW.

&&

.AVIATION...30/06Z
ISSUED AT 1144 PM CDT SAT AUG 29 2015

MODELS CONTINUE TO POORLY HANDLE THE LOW CLOUD COVER ACROSS TAF
LOCATIONS.  CURRENTLY SKIES ARE CLEARING ACROSS THE SOUTHEAST WHILE
STRATUS IS SPREADING NORTHWEST.  WHERE SKIES ARE CLEARING...FOG IS
DEVELOPING AND VSBYS WILL PLUMMET AND WHERE STRATUS IS MOVING IN
VSBY WILL IMPROVE SOME.  THE STRATUS SHOULD EXPAND SOME OVERNIGHT
AND VSBYS SHOULD COME UP SOME.  EITHER WAY WE WILL EITHER SEE
MVFR/IFR CIGS OR IFR VSBYS THROUGH 15Z.  WE SHOULD FINALLY BEGIN TO
CLEAR AFT 18Z.


&&

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

$$

SHORT TERM...SMALL
LONG TERM...LEE
AVIATION...FAB


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.