Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 281721
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1221 PM CDT Fri Jul 28 2017

.SHORT TERM.../Today through Tonight/
Issued at 316 AM CDT Fri Jul 28 2017

Very little going on in the short term today with high pressure
dominating the area through the period. Slightly cooler temperatures
in place aloft today, so expect highs to top out a few degrees
cooler. Also expect some mid/high clouds in place at times with
cyclonic flow aloft and return flow setting up to the west of the
area in advance of a shortwave trough pushing into the Dakotas
Saturday. Otherwise dry conditions expected, with lighter
northeasterly winds becoming more easterly to southeasterly by late
tonight.

.LONG TERM.../Saturday through Thursday/
Issued at 316 AM CDT Fri Jul 28 2017

Bottom Line up Front...
Overall forecast remains generally unchanged. Near-normal
temperatures and no appreciable weather hazards to speak of beyond
the lightning produced via a slight possibility of a few very
isolated/"hit-or-miss" non-severe thunderstorms each
afternoon/evening after Sunday.

To start this long-term fcst period, The extensive ridge that will
effectively encompass the western two-thirds of the CONUS will
remain settled in near the Oklahoma panhandle. Across the eastern
CONUS, a deep cut-off low/trough will hold influence into the
middle of next week. Meanwhile, during the next several days, a
1020 mb sfc high currently centered near Lake Superior, will
slowly drift southward through Wisconsin. The proximity of the
high to Iowa will keep winds very light...less than 10 kts... into
next week. More importantly, this synoptic setup will serve to
keep Iowa into NW to NE flow above 850 mb through the weekend.
Further, another high looks to build in mid-week across northern
Wisconsin, which should reinforce the strong northerly component
to the flow as the first high gradually drops SE of Iowa.
Resultingly, 850mb temps look to dip down to the +12C to +15C
range...which is around 0 to -1 std dev for this time of year...
suggesting near to slightly below normal temps through next week.

Best chance for precip may come sometime in the Wed-Thu timeframe as
the 00z Fri GFS and 00z ECMWF try to push a boundary through Iowa
from north to south, in between the two areas of high pressure.
Though there is some frontogenetical forcing, instability is not
great as Gulf of Mexico long closed by next week. Left guidance POPs
in there as 0.01 inches of rain may be attainable in some places...
but at this time, not realistic to expect much more than a few
hundredths at best.

&&

.AVIATION.../For the 18Z TAFS through 18Z Saturday afternoon/
Issued at 1221 PM CDT Fri Jul 28 2017

VFR conditions are expected through the forecast period. Scattered
cumulus around 4 kft through this afternoon and may reform on
Saturday. Very localized fog possible tonight. Light winds will
persist and will generally be less than 10 kts.

&&

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

$$

SHORT TERM...Beerends
LONG TERM...Kotenberg
AVIATION...Donavon


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