Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 292009

Area Forecast Discussion
National Weather Service Des Moines IA
309 PM CDT Wed Mar 29 2017

.SHORT TERM.../Tonight through Thursday/
Issued at 309 PM CDT Wed Mar 29 2017

Midafternoon water vapor imagery shows an elongated trough of low
pressure stretching from west Texas into the central Plains with
a cyclonic circulation over central Kansas. A widespread area of
rain extends from western Kansas into northern Iowa with a few
thunderstorms developing over eastern Kansas ahead of the surface
low pressure. Temperatures were in the low and middle 40s across
central Iowa with a brisk wind from the northeast accentuating the
chill. A steady, stratiform rain will continue through evening
over the northern half of Iowa where deformation zone will be
located. Rain won`t be as widespread across the south, but showers
will be scattered. In addition across the far south tonight,
rumbles of thunder may be heard as a bit of elevated instability
works toward the state this evening as the surface low moves
through eastern Kansas. For overnight lows, stayed on the warmer
side of guidance given plenty of clouds.

As the low trudges eastward through Missouri on Thursday, rain will
begin to taper off as lifting and moisture wane. Rain totals will
range from around a half inch near the Minnesota border to around
1.5 to 1.75 near the Missouri border. At this point, river rises are
expected to be within bank given forecasted totals, but several
rivers are near action stage so will have to monitor rainfall
trends. Plenty of clouds will persist and this will impact the
potential for highs tomorrow and have kept them on the cooler side.
Winds won`t be as strong tomorrow, but will still be brisk averaging
10 to 15 mph.

.LONG TERM.../Thursday night through Wednesday/
Issued at 309 PM CDT Wed Mar 29 2017

Thursday Night through Sunday Night.  Confidence Medium to High.

Generally active and wet weather pattern to remain through much of
the period. Biggest questions remain timing of breaks in
precipitation and any periods of possible sunshine. Through Sunday
both the GFS/Euro are in generally good agreement. By Thursday night
departing low will still have influence over the area with cyclonic
curvature/clouds and potentially very light precipitation remaining
either in the form of sprinkles or drizzle. By 12z Friday the
forcing is mainly east of the region...but aloft only a weak ridge
of high pressure will enter the region with remain light cyclonic
flow aloft.  Bufr soundings show moisture lingering around 2500 to
3000 feet so even with some clearing/breaks in the clouds forecast
its more likely that clouds in some fashion will be favored over
significant clearing.  With that in mind will maintain cooler highs
than warmer guidance on Friday. If the forecast ridge axis fails to
bring any clearing to the region Friday...the next upstream wave
will already be influencing the region on Saturday.  We remain close
to a weak trough aloft at H850/H700 Friday clouds will
most likely be present into the night and remain on Saturday.  Both
the Euro/GFS suggest a return of warm air advection and a return of
weak isentropic lift over the west by the afternoon hours.  This
will increase chances for light precipitation over the west between
18-00z either in the form of light rain or sprinkles. Temperatures
Friday night will likely fall to the 30s to around 40 with cloud
cover expected. On Saturday temperatures should begin responding to
warmer air aloft and continued warm air advection. Even with ample
cloud cover expected highs should recover to the 50s. There remain
some minor differences with regard to the track of the Sat/Sun
system when comparing the GFS/Euro...mainly on the extent of
rainfall amounts and timing of heavier rainfall. In either
case...clouds and a chance for light rainfall will be around most of
the day on Sunday.

Monday through Wednesday.  Confidence Low to Medium.

Though there may be a break in the precipitation Sunday night yet
another southern stream low may graze the south Monday with
potential light rain and cloud cover. With the overall pattern
continuing to favor a quick transition from one storm to another...
weak high pressure forecast to move over the area Monday afternoon
and night may be enough to provide the area with some clearing and
possibly some sunshine.  The 12z Euro is departing from its previous
solution which suggested a quicker arrival of the Tuesday storm. If
this becomes favored over the faster GFS...milder and more pleasant
conditions may be in the offing for Monday and part of Tuesday. High
temperatures will be highly dependent on any breaks in the cloud
cover. Generally with climate norms suggesting low to mid 50s...any
hint of sunshine with H850 temps both days Monday and Tuesday will
drift into the lower to mid 60s. Another in a series of
strengthening upper level systems is forecast by both the GFS/Euro
to impact the mid-Mississippi River Valley Tuesday night/Wednesday.
There remains a fair amount of uncertainty with the track and
precipitation due to a forecast of a rapidly deepening low. The
current Euro forecast is slightly farther north though both models
suggest ample moisture again with this system. Initially thunder may
move into the south with the initial push of warm air advection. If
Iowa remains on the north side of the system...highs will be quite
chilly and mainly in the 40s to lower 50s along with breezy
northeast winds. Plenty of time to monitor the details.


.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1156 AM CDT Wed Mar 29 2017

Clouds were widespread over the state along with a swath of rain
showers extending from southwest to northeast Iowa at midday.
While a bit of drier air has temporarily ended the rain over
parts of the southeast, low clouds and/or the combination with
rain have IFR conditions over the southern half of the state with
MVFR conditions at KFOD and KALO. While conditions are presently
VFR at KMCW, they will soon deteriorate as clouds lower and rain
arrives. Expect MVFR or IFR at all sites this afternoon falling
into IFR and even LIFR ceilings at a few sites overnight. Gusty
winds from the east-northeast will continue through late tonight.
Conditions may remain in IFR through the end of the TAF period due
to low clouds persisting as the rain tapers off from west to




SHORT TERM...Ansorge
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