Area Forecast Discussion
Issued by NWS Des Moines, IA
FXUS63 KDMX 282026
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
326 PM CDT Fri Oct 28 2016
.SHORT TERM.../This evening through Saturday/
Issued at 325 PM CDT Fri Oct 28 2016
WAA looks to continue this evening and into the overnight
hours before a weak surface trough moves into northern Iowa past 06z
Saturday. Winds will decouple between 00-03z tonight allowing for
the gustiness to subside. Surface gradient across the southeast
will remain strong enough to keep sustained winds up through much of
the night. Temperatures are expected remain fairly mild, especially
southeast of the boundary. Should be a decent temperature gradient
(roughly 15F from north to south) set up overnight.
.LONG TERM.../Saturday night through Friday/
Issued at 325 PM CDT Fri Oct 28 2016
Summary...Overall picture, especially through Monday, remains
largely unchanged. Cool/cold front to move through Sat, with rain
increasingly likely across northern and into central/eastern
portions of the state through the evening. Monday continues on track
for rapid warm up well into 70s and windy, much like today.
Precipitation chances return across southern Iowa Tue night into
early Thur ahead of another frontal boundary.
Tomorrow through Monday...Two main stories through this time frame,
cold front moving through with rain increasingly likely across
northern Iowa and another warm and windy day Monday. First, front
will sag through state Sat turning winds northerly and cooling
temps. Precipitation opportunities will be purely behind the front
with chances more closely associated with elevated 850mb boundary
and mid-level shortwave/vort max moving through. Upped POPs into
chance across north with growing confidence and kept slights down
into central and eastern areas. Being post frontal, nothing more
than light rain/showers expected primarily in the evening and
overnight hours. Temps ahead of front will remain warm, with mid-
upper 70s likely from roughly I-80 southward, while upper 50s to 60s
for those that see passage during morning/early afternoon. Sunday
quiet and cooler with high pressure skirting through, temps in the
mid 50s to low 60s. Upper level ridging will quickly build in Sun
night, bringing back solid southerly flow. With good mixing expected
and tightening surface press gradient, winds likely to reach 20kt
sustained with gusts pushing 30kts. Upped winds and gusts over
guidance as a result of good model sounding consensus.
Tuesday through Friday...Models have come into much better agreement
within this time frame over previous runs where POPs ran rampant.
Upper level pattern transitions to SW flow with returning
opportunity for showers and thunder Wed as wave moves through.
Temps will come down slightly over low-mid 70s Mon, but remain
solidly above normal for this time of the year. While Euro/GFS in
fairly good agreement, Euro is roughly 12hrs slower than GFS.
Regardless, both similar in depiction of building in 500+ J/kg CAPE
through the Wed to Thur AM time frame ahead of another frontal
boundary and trough passage. With growing confidence in thunder,
have primarily gone with prevailing thunder. High pressure then to
build in behind on Thur and cooler temps in the low to mid 60s.
.AVIATION.../For the 18Z TAFS through 18Z Saturday afternoon/
Issued at 1248 PM CDT Fri Oct 28 2016
VFR conditions are expected throughout the TAF period. Main
concern was focused on winds and wind gusts this afternoon. May
see some brief gusts over 30 knots but the fairly thick cirrus
shield looks to mitigate mixing somewhat and left out mention of
anything higher than 28 knots.