Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 230826

Area Forecast Discussion
National Weather Service Quad Cities IA IL
326 AM CDT Mon Oct 23 2017

Issued at 301 AM CDT Mon Oct 23 2017

Surface high pressure and clearing skies are allowing patchy fog,
locally dense, to develop this morning. Meanwhile a potent storm
system aided by 160 kt jet in southwest Canada is taking shape in
the Northern Plains and southern Canada.


.SHORT TERM...(Today and Tonight)
ISSUED AT 301 AM CDT Mon Oct 23 2017

Main concern in the short term is the cold frontal passage and
associated rainfall later today and tonight.

A strong surface cold front associated with a surface low along
the U.S. Canadian border is just beginning to push into northwest
Iowa at this time. Synoptic and CAM model guidance generally
agree on the front reaching the western CWA ~18Z, the Mississippi
River ~21Z, and exiting the CWA after 00Z.

Strong low-level convergence should be sufficient to help generate
a narrow postfrontal rainband followed by strong gusty winds.
Rain amounts will not be significant with this feature since it
will be fast moving and moisture is somewhat limited. Rain chances
are relatively higher further north in line with the stronger

Models also agree in developing wrap-around precip this evening in
the strong cyclonic flow associated with the surface flow. Again
rainfall should not be significant with limited moisture. Snow
threat is minimal with 850mb temps just touching below 0C and
warmer air below. Winds will remain strong through the night
helping push temperatures down into the upper 30s and lower 40s.

.LONG TERM...(Tuesday through Sunday)
ISSUED AT 301 AM CDT Mon Oct 23 2017

Trend toward colder weather is still on track for the upcoming week.
Precipitation chances though have decreased late this week with
models keeping bulk of the precipitation north of the DVN forecast

A large 500mb trof will be well established over the central U.S. by
Tuesday morning.  northwest flow on the back side of the trof will
usher in much colder air to the region. a surface low located over
the northern Great Lakes will send wrap around clouds and pcpn over
the area during the day Tuesday. Have kept the precipitation all
rain with marginal low level temperatures and shallow warm mixed
surface based mixed layer.  given cold low level temps/clouds/light
pcpn over the area temperatures will likely stay in the 40s.  Winds
will also be strong with 40kt winds plus near the top of the mixed
layer.  Tuesday night will see temperatures dipping into the mid 30s
most areas.  At this point it looks like winds will stay up around
10 mph which should limit any extensive frost development.

Wednesday and Thursday will see near normal temperatures as the
upper flow flattens ahead of the next system headed for the region.
There is better agreement among the operational models that this
system will track across the north central U.S. keeping
precipitation north of our area. Therefore most of the precip
chances have been removed from the end of the week forecast.  The
exception is some low pops in the northeast for Saturday, which is a
nod to the ECMWF`s more southern solution.  This system is still
progged to bring much colder air to the region with lows Friday
through Sunday expected to be in the low to mid 30s. We could see
some upper 20s Saturday morning.  Highs through this period
are expected to be in the 40s.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) ISSUED
AT 301 AM CDT Mon Oct 23 2017

Areas of fog, locally dense with IFR or LIFR conditions, are
expected this morning, but the fog should lift fairly quickly
after sunrise at any affected terminals. A sharp cold front will
move through the area later this afternoon and early evening with
a notable shift and increase in winds from the northwest. VFR
conditions should hold through the afternoon, but developing
rain this evening will likely be accompanied by at least MVFR




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