Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 261141
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
641 AM CDT Sun Mar 26 2017

.SHORT TERM.../Today through Tonight/
Issued at 400 AM CDT Sun Mar 26 2017

Surface low pressure is centered over far southeast Iowa early
this morning with the upper level low trailing just to the
southwest. This is keeping cool northeast flow in place over Iowa.
Areas of drizzle and fog have developed across central Iowa
overnight and a few showers have rotated into far south central
Iowa. A few sites have visibilities near one quarter to one half
mile but attm widespread dense fog conditions have yet to develop.
Will hold on to the dense fog advisory over the southeast for a
little longer as visibilities have been dropping just to the east
of this region but may very well need to cancel at some point.

The area of low pressure will lift northeast into the Lake
Michigan region and as it does, the areal extent of the drizzle
and showers will diminish. High temperatures today likely will
remain below guidance as a wide region of cloud ceiling heights at
500 ft or less is in place well to the west into Nebraska now.
Temperatures will have a difficult time making much progress while
these low clouds persist though they should raise a bit this
afternoon as the low continues to depart to the east.

The next upper low system now over southeast Colorado will reach
eastern Kansas tonight. This system will lift another round of
moisture and theta-e advection into far southern Iowa and will
bring another chance of rain to that portion of the state after
midnight.

.LONG TERM.../Monday through Saturday/
Issued at 400 AM CDT Sun Mar 26 2017

The main focus this week was on temperatures and precipitation
chances Wednesday into Friday. The GFS and ECMWF still have large
discrepancies and both are holding true to their respective
solutions. The Canadian is closer to the ECMWF with the upper low
tracking further north Wednesday through Friday. Leaned slightly
more toward the ECMWF and thus the biggest change to ongoing
forecast was cooled down maximum temperatures Thursday and Friday.

Monday and Tuesday...A weak 500mb vort max and associated surface
low track across Kansas into southern Missouri tonight into Monday
providing some lingering light rain across the southern portions of
the forecast area 12-18z Monday. Sky cover and light CAA will hold
temperatures down Monday and went slightly cooler across the south
for maximum temperatures.  Dry air finally makes its way into the
western part of the state as surface high pressure builds into the
region. The eastern sections of the forecast area looks to remain
under stratus shield as the low level moisture is slow to move east
as it remains trapped underneath inversion until Tuesday morning. By
then, the inversion weakens but high clouds look to roll into the
state ahead of next shortwave to impact the state by mid-week.

Wednesday through Friday...slowed the progression of pops slightly
until past 06z Wednesday and likely could delay the onset until past
12z Wednesday as soundings take time to saturate with the surface
high over the Great Lakes providing some dry air into the state.
Weak shortwave rides the upper ridge Wednesday morning looks to
provide a brief period of rain before the main low pressure system
transitions north-northeast across the central CONUS Wednesday night
into Thursday.  The ECMWF is further north with the precipitation
shield and much colder than the GFS.  With leaning toward the
ECMWF, trended cooler for maximum temperatures Thursday and Friday.
The 26.00z GFS is slightly cooler as well, thus higher confidence in
the ECMWF solution for late this week.

&&

.AVIATION.../For the 12Z TAFS through 12Z Monday morning/
Issued at 641 AM CDT Sun Mar 26 2017

Widespread IFR to LIFR cigs will continue to persist though much
of period. Area of fog with vsbys less than 2sm this morning
should improve some during the day though may linger over the
northeast. Best potential for cigs to improve to MVFR is over
southern Iowa this afternoon. Potential for fog and lowering cigs
to return again tonight. Expect north to northwest winds through
the period.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT this morning for IAZ061-062-
074-075-084>086-095>097.

&&

$$

SHORT TERM...Donavon
LONG TERM...Podrazik
AVIATION...Donavon


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