Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 190511
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1111 PM CST Thu Jan 18 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 330 PM CST Thu Jan 18 2018

Near zonal sfc pressure gradient, draped acrs the mid CONUS between
GRT LKS clipper and southern ridge, still driving temp moderating
southwest LLVL flow acrs the area. This moderation to continue into
the weekend, before a large storm system ejects out of the southwest
plains and into the upper Midwest Sunday into Monday.

&&

.SHORT TERM...(This Evening through Friday)
ISSUED AT 330 PM CST Thu Jan 18 2018

Tonight...Sfc pressure gradient to maintain southwest winds of 8 to
15 MPH overnight, while robust H9-H7 MB inversion get`s even more
enhanced into Fri morning. These factors combined with cirrus shield
trying to spill down around northern plains upper ridge should make
for lows in much of the area staying up in the 20s, with a few areas
in the upper teens.

Friday...Most models in good agreement of suggesting upstream upper
ridge to shift acrs the region and flatten through Friday night.
Southwesterly H85 MB flow of 30-40+ KTs to continue to warm air
advect during the day, with low to mid teens C building in this
layer`s inversion. How deep we mix and thus how warm we get the main
challenge, while the lingering snow cover continues to take a
beating. Just a marginal mix depth up to 950 MB makes for widespread
low to mid 40s, and up to 925 MB supports mid to upper 40s. With
more rounds of high clouds/cirrus possible, will play it more toward
the conservative side for now.   ..12..

.LONG TERM...(Friday Night through next Thursday)
ISSUED AT 330 PM CST Thu Jan 18 2018

Friday Night through Saturday

Quiet and mild January weather for the end of the week and start of
the weekend. Highs in the 30s and 40s will melt the shallow
snow cover we had, except for maybe trace to 1 inch snow depths
remaining along and north of highway 20. 850mb temps are forecast to
peak near 13 C on Friday ahead of a weak cold front before falling
into the single digits (C) on Saturday.

Saturday Night and Sunday

All models have a lee-side low forming in the Southern Plains, then
tracking to the NE along a zone of low-level baroclinicity. Model
consensus is for mild air to entrain into the east side of the low,
which means rain will be the dominant precip type for the DVN CWA.

ENE sfc winds may keep temps cold enough for a period of freezing
drizzle or light freezing rain approximately along and north of
highway 30 beginning late Saturday night. The NAM is the coldest
model, holding temps at or just below freezing in the NW forecast
area through the day on Sunday. The synoptic models are warmer with
little to no threat for freezing drizzle Saturday night or Sunday.
Therefore, confidence is low due to the model discrepancies and
because this is several days away. Fog is also possible Saturday
night and Sunday, and could become dense at times.

Sunday Night and Monday

Periods of rain are likely Sunday night as temps stay above freezing
overnight. We could even have a few rumbles of thunder if MUCAPE
values get high enough. One change from a day or two ago is the
models have the impressive low-level water vapor transport and heavy
rain missing us to the east, into E Missouri, Illinois, and Indiana.

The sfc low begins to occlude as it moves into southwest Iowa. There
is still some question on how far north the warm sector makes it
into E Iowa/NW Illinois as the occlusion process slows its northward
progression and decreases its areal extent. Right now we have a
chance for lower 50s across the south. The latest ECMWF has our NW
corner only reaching the upper 30s.

Wrap around light snow is possible on the backside of the low in a
weakening deformation zone later Monday. Coupled with gusty winds,
there could be some impacts to travel but doesn`t look like anything
significant.

Tuesday On

Dry conditions with a return to more seasonable temps in the 20s and
30s. Uttech

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
ISSUED AT 1110 PM CST Thu Jan 18 2018

Another VFR TAF cycle through Friday evening, with high
pressure south of the area maintaining southwest sfc winds of
10-15 KTs through the period. Otherwise, passing rounds of high
clouds from the west through the period.

ERVIN

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...Uttech
AVIATION...Ervin



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