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afddvn

Area forecast discussion...corrected
National Weather Service Quad Cities Iowa Illinois
546 am CST Thu Nov 14 2019

..12z aviation update...

Synopsis...
issued at 257 am CST Thu Nov 14 2019

A weak, slow moving cold front stretched roughly from Freeport
through Sterling to Quincy, Illinois at 2 am. Very light snow or
flurries that occurred out ahead of this feature over the area last
evening had shifted well east of the region by midnight. Low
clouds and weak wind fields were found across the forecast area
with temperatures ranging from the lower 20s over the deepest snow
in northwest Illinois, to the lower 30s in southeast Iowa and
northeast Missouri. A stronger push of cooler, drier air and
patchy clear skies, were found well behind the front across north
central Iowa into southwest Minnesota.

&&

Short term...(today and tonight)
issued at 257 am CST Thu Nov 14 2019

The main challenges for today and tonight are centered on cloud
cover and continued well below normal temperatures. Satellite
imagery early this morning showed low clouds extending upstream in
the northwest flow to a well defined vort Max over west central Minnesota.
While there will be a few breaks, the timing of these features would
favor mostly cloudy skies this morning, then early afternoon
clearing. The passing of the surface ridge to our southwest will
keep winds rather light, from the west to northwest, limiting mixing
and much warming. With a similar airmass as yesterday, but likely
more afternoon sunshine, will go with highs in the upper 20s to near
30 over the deeper snow cover across the north and northeast, to
lower 30s in the south,

Tonight will start out mostly clear under subsidence and a very deep
dry layer aloft as depicted on forecast soundings. Incoming high
level moisture may lead to some thin, high cloud cover toward
sunrise. This will lead to another cold night and for now have gone
with lows in the lower teens north to near 20 in the south, trended
close to the colder GFS MOS guidance and National blend model. These
values could still end up being too conservative with single digits
possible based on current values upstream across the Dakotas.

Long term...(friday through wednesday)
issued at 257 am CST Thu Nov 14 2019

Overview:

*temperatures will moderate into next week but remain slightly below
normal.

*There are no big systems on the horizon through next Wednesday. A
few weaker systems may bring light precipitation to the area Sunday
and again Monday night and Tuesday.

Friday and Saturday

High pressure will move through the Midwest into the Great Lakes and
Ohio Valley into the first part of the weekend. Temperatures for
eastern Iowa and northwest Illinois will remain about 5-10 degrees
below normal into the 30s and 40s for highs.

Sunday

A shortwave trough, over the Pacific northwest on Friday, is
expected to reach the Midwest on Sunday bringing chances for light
precipitation. There are model discrepancies on the timing and
overall strength of this system. The European model (ecmwf) is the driest with under
0.10" of quantitative precipitation forecast. The CMC, NAM, and GFS are a little bit wetter. Have
low chances for precip in the forecast until models come into better
agreement.

850mb temps between -1 c to +2 c and Max wetbulb aloft and surface
wetbulb temps near 0 c could lead to light snow or a rain/snow mix
at times, especially along/north of I-80. Temps for the afternoon
are forecast to reach the mid to upper 30s north and low to mid 40s
central and south.

Next week

Slightly below normal temperatures are expected through midweek with
highs in the 30s and 40s.

Another clipper low tracking in from the northwest could impact
eastern Iowa and northwest Illinois Monday night and Tuesday. The
European model (ecmwf) has a mild boundary layer over the area with rain as the
dominant precip type. The GFS and CMC are colder and could support
snow or a mix at times over the north half of the forecast area.
Uttech

&&

Aviation...(for the 12z tafs through 12z Friday morning)
issued at 520 am CST Thu Nov 14 2019

An MVFR deck of low clouds behind a cold front will affect
all terminals this morning. The back edge of these clouds over
northwest Minnesota and central Iowa would not reach the eastern
Iowa terminals until late this afternoon at the current rate.
However, will anticipate this cloud erosion process to
accelerate and have thus forecast all sites to become VFR by
early afternoon. Mostly clear and cold VFR conditions are then
expected for overnight into Friday morning.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

..corrected aviation discussion wording...

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