Flooding in Iowa, April 1 to 30, 2019

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1045 PM CDT Sun Mar 31 2019

.SHORT TERM...(This Evening through Monday)
Issued at 358 PM CDT Sun Mar 31 2019

Scattered flurries/sprinkles associated with a mid-level shortwave
will continue to move east as it slowly dissipates through the
evening hours. Behind this system, stratus will begin to surge
south into the region during the night. In addition, patchy fog
could develop on the edge of the cloud deck through the morning
hours. Increasing clouds will inhibit lows from dropping much;
therefore lows will range from the mid 20s north of I-90 to the
lower 30s south.

An upper trough/PV advection begins to move into the area by Monday
afternoon, bringing the chance for rain and snow. The main question
will be precipitation type and amounts as some models still
diverge in surface temperatures and low-level dry air. However,
soundings suggest a better environment in the evening with a
saturated layer along with a decent 850 hPa frontogenetic forcing into
the overnight. Given that and dewpoints in the upper 20s and low
30s; scattered flurries and light snow will be possible. Snow
amounts from a couple of tenths to 0.5 are possible. The best
chance for precipitation looks to be along the I-90 corridor into
our farthest east counties in Iowa.

.LONG TERM...(Monday Night through Sunday)
Issued at 358 PM CDT Sun Mar 31 2019

Surface high pressure brings a quiet and breezy day on Tuesday. Have
bumped winds a bit on Tuesday to produce gusty winds from 25 to 30
mph in the afternoon hours.

The next significant chance of precipitation arrives late Tuesday
night into Wednesday as a surface moves over the High Plains from the
Rockies. Models are in good agreement in bringing the bulk of
precipitation mainly along and south of I-90. However, there are
some differences in timing and intensity. The GFS is the fastest
model, with precipitation arriving early Wednesday morning while
the NAM arrives 3-hrs later. On the other hand, the ECMWF looks
mainly dry for our forecast area. Given this, have lowered
precipitation chances for areas along and north of I-90. At this
time, better chances will be along the Missouri River into
northwest Iowa. In terms of precipitation type, rain will be the
dominant type throughout the day, but a mix of rain and snow will
be possible at the onset of precipitation early Wednesday
morning.

A warming trend is expected after Thursday into the weekend as an
upper ridge builds in from the west and warmer southerly winds
surge northward into the region. Highs in the upper 50s and 60s
looks possible during the weekend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1041 PM CDT Sun Mar 31 2019

Areas of low stratus will drift southward tonight, affecting KHON,
and possibly KFSD toward 12Z. Ceilings are expected to lift by
mid morning on Monday. Light rain will then move in by later on
Monday afternoon and continue into Monday evening. Rain may mix
with or change to snow briefly before ending later in the evening.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

SHORT TERM...05
LONG TERM...05
AVIATION...JM