Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 152203
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
403 PM CST Wed Nov 15 2017

.SYNOPSIS...
Issued at 330 PM CST Wed Nov 15 2017

Latest sfc analysis was indicating that while the main cold front
was moving eastward acrs the western GRT LKS, the real cold push was
noted acrs western WI into northeastern and central IA ATTM. The
area hi-lighted by lower level stratocu deck, and flowing acrs the
northwestern CWA. Late afternoon temp-contrast from the lower 30s in
the far northwest, to the mid 50s in the south. This incoming cloud
deck has been temporarily impeded by in-wrapping dry subsiding slot,
but now seems to be making headway again to the southeast. A cooler
dry day in store for Thursday, before another frontal system arrives
for the next round of precip Friday into early Saturday.

&&

.SHORT TERM...(This Evening through Thursday)
ISSUED AT 330 PM CST Wed Nov 15 2017

Tonight...Cloud cover the main challenge for tonight and handling in-
building stratocu deck out of southern MN. This deck will have to
continue to battle ongoing post-frontal drying and subsidence, but
also be aided in maintaining under a trapping inversion aloft as
well. Just watching upstream trends on the latest satellite Vis
loop, feel the cloud deck will continue to slide southeastward and
engulf much of the northeastern 2/3`s of the DVN CWA through mid
evening, before some holes or at least partial erosion occurs from
the west/northwest through the rest of the night. Thus while the
southern third of the CWA stays mainly clear, the rest of the CWA
will have mostly cloudy to variable cloudiness to deal with. But
with brisk northwest llvl flow and cold air advection, despite the
clouds and mixing wind, the advection process itself should
translate into widespread lows in the mid to upper 20s over most of
the local area. The gusty winds will eventually drop to 10 MPH or
less after midnight into early Thu morning.

Thursday...High pressure slides acrs the region for a fair wx day,
with early to midday sunshine getting filtered in the afternoon by
increasing/elevated warm air advection processes. After cold start
to the day and weaker mixing profiles in the fcst soundings/BUFKIT,
high temps to be limited to the upper 30s to mid 40s in most of the
local fcst area. Rather light and variable sfc winds Thu around
passing ridge center, then some late day east-southeasterly return
flow.   ..12..

.LONG TERM...(Thursday Night through next Wednesday)
ISSUED AT 330 PM CST Wed Nov 15 2017

Thursday Night through Friday

Moisture advection head of the next strong trough will lead to a
lowering overcast and development of widespread drizzle and light
rain sometime Friday morning. The precip will become much more
widespread through the afternoon. Models keep the heavier precip
with this first round to the SE of the E Iowa/NW Illinois, across
central Illinois into northern Indiana, slightly to the SE of the
sfc low track. The sfc low is not expected to be tightly wound up
over our area, but pass through as an elongated trough. Therefore,
the exact track will not significantly affect the forecast in our
CWA.

Thunder Chances:

GFS/ECMWF have a fair amount of MUCAPE for mid November, around 600
J/kg, over the southern third of the CWA. So, continued the slight
chances for thunder in the forecast. The NAM is further SE with the
better elevated instability, which means adjustments to the
north/south placement of thunder chances remain possible.

Saturday

Precipitation and Model Trends:

Widespread light rain expected to begin the day with a changeover to
a rain/snow mix or all snow possible later in the morning into the
afternoon when CAA ramps up.

Models have trended deeper with the mid-level trough, and with an
elevated frontogenetic band of precip, from mid morning Saturday
into part of the afternoon. Sfc wet-bulb temps above 32 F and
antecedent wet conditions will make it very difficult for any snow,
if it occurs, to accumulate. Unless, there is a heavier band of
forcing/precip which would dynamically cool the environment.
However, it`s too far away to forecast with that level of detail or
to have even moderate confidence on that scenario.

Winds:

In addition to the precip, expect breezy NW winds, 20-25 mph
sustained with gusts up to 30-35 mph.

Sunday through Wednesday.

Quiet, mainly dry weather heading into early next week. Model blend
starts out with below normal temps on Sunday in the 30s, moderates
into the 40s for early next week, then drops to below normal again
for next Wednesday behind the next cold front. Uttech

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1143 AM CST Wed Nov 15 2017

As a frontal system and associated IFR to MVFR clouds/fog/drizzle
exit off to the east for temporary clear skies, attention turns to
a MVFR cloud deck acrs MN/far northern IA streaming quickly down
toward the area. This deck on track to engulf most of the TAF
sites from NW-to-SE as the afternoon progresses. Just BRl may be
spared but a BKN deck may get close to this site as well by late
afternoon. Some subsidence may erode holes in this deck at times
this evening and overnight, but also signs of it getting trapped
under an inversion and maintaining in locations into early Thu
morning. Otherwise, gusty northwest winds this afternoon should
subside later this evening and overnight to 7-11 KTS.  ..12..

&&

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

$$

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


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