Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 191140
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
640 AM CDT Thu Apr 19 2018

.SHORT TERM.../Today through Tonight/
Issued at 351 AM CDT Thu Apr 19 2018

There will be a welcome break in the weather through this period
with temperatures and fog the only concern. Although no
precipitation is expected, it will remain cold with near record
temperatures possible early Friday morning. Patchy clouds remain
in place but they should dissipate with the loss of lift and
moisture as our recent system moves away through the upper Ohio
Valley.

High pressure across the Dakotas at 08z will slide into Iowa
tonight with skies remaining mostly clear through the period and
winds becoming light. The SREF and several high resolution models
suggest fog and low visibilities into the early morning hours
north so patchy/areas fog wording has been introduced.

Highs today will be impacted by snow cover north ranging from +/-
40 north to the lower 50s south. With favorable radiational
cooling, lows tonight should approach record lows with readings
dropping from near 20s north to the lower 30s south.

.LONG TERM.../Friday through Wednesday/
Issued at 351 AM CDT Thu Apr 19 2018

Strong surface high pressure remains in control of the weather
pattern Friday into Sunday before moving into the eastern CONUS by
Monday. A cool start to the day Friday with the high centered over
the eastern part of the state, but with plenty of sunshine for
much of the day, should be a pleasant day. An upper level trough
moves out of the southern Rockies and passes to the south of the
state beginning Friday night and finally moves well southeast of
the region by early Monday. Little to no precipitation expected
with this system, just mainly cloud cover. Mid to high clouds
look to stream into the state by Friday evening across the west
and spread east over the rest of the state by Saturday morning.
The cloud cover remains across the region into Sunday before it
begins to dissipate or shift south during the afternoon as the
upper low pushes into the southeast CONUS. With the cloud cover
on Saturday, this will keep the deep mixing in check but still may
see a few gusts to around 15-20 knots during the afternoon.
Temperatures also look to remain below normal on Saturday. Lesser
cloud cover anticipated on Sunday and should allow for a little
better mixing resulting in slightly higher temperatures and a
breezier afternoon. Plenty of sunshine is expected on Monday and
with winds trending to be more south by the afternoon, expecting a
warm day across the state.

Next precipitation chances look to be Tuesday with the passing of
a cold front and 500mb shortwave trough. GFS is quicker with the
FROPA and the latest ECMWF has come around to mention QPF by
Tuesday night. Not a significant amount of instability with this
front and shear looks to be mainly unidirectional. GFS has
stronger UVM with the front and certainly need to keep an eye on
this front for potential severe weather. Albeit, low confidence
with anything widespread, but just based on climatology, there
should be at least a low end threat Tuesday.

&&

.AVIATION.../For the 12Z TAFS through 12Z Friday morning/
Issued at 640 AM CDT Thu Apr 19 2018

There is high confidence in VFR conditions today with nothing
beyond departing patchy high cloudiness. The potential for
radiation fog does increase overnight tonight however, mainly
north and east, so confidence does decrease. Fog with visibilities
anywhere from MVFR to LIFR may occur.

&&

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

&&

$$

SHORT TERM...Small
LONG TERM...Podrazik
AVIATION...Small



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