Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 140442

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1142 PM CDT Thu Jul 13 2017


Issued at 300 PM CDT Thu Jul 13 2017

This afternoon sunny to partly sunny skies were found across the
area with drier air in place. High pressure in place over Fargo,
ND is forecast to move south through the period. This high
pressure will drive the weather in the short term forecast period.


.SHORT TERM...(This Evening through Friday)
ISSUED AT 300 PM CDT Thu Jul 13 2017

Temperatures and chances for patchy fog are the main forecast
concerns for this iteration. Post frontal lows with lower Td
values are usually too high in the guidance. Looking at the data,
the American gridded models seem to be the lowest as far as temps
go. Wouldn`t be surprised to see lows in the 50s areawide and
possibly low 50s across the north. This will be dependent on the
advection of drier air as the high builds south into the CWA.
There is also a chance for patchy fog tonight as temps drop to
near the dewpoint overnight. The main limiting factor to more
widespread fog will be the winds, winds could stay up overnight.

.LONG TERM...(Friday Night through Thursday)
ISSUED AT 300 PM CDT Thu Jul 13 2017

Friday Night through Saturday

NW flow aloft progged to strengthen as shortwave trough reaches the
Northern Great Lakes/Lake Superior area. For us locally in E Iowa/NW
Illinois, SW winds will develop north of a sfc high located over the
Southern U.S. Moisture advection will increase humidity, with
dewpoints rising into the mid/upper 60s through Saturday afternoon.
Blended guidance of sfc temps in the lower to middle 80s looks on
track. Although, there could be some upper 80s across the western
CWA. Models in agreement keeping the CWA dry through the day.

Saturday Night and Sunday

Mid-level trough and core of associated height falls forecast to
stay well NE of Iowa/Illinois, tracking across Lake Superior,
Wisconsin, and into Northern Lower Michigan. Consequently, the best
chances for thunderstorms with this feature and the attendant cold
front are north and east of the CWA. Due to lack of organized upper
forcing for ascent, confidence for anything beyond isolated coverage
of storms is quite low at this lead time. If storms form, a few
could become strong to severe given MUCAPE of +2500 J/kg and
marginally sufficient shear (+25 kts).

With the cold front moving through on Sunday, forecast max temps
have a greater spatial range than the previous few days - from upper
70s far northeast to lower 90s far southwest. Otherwise, expect
humid conditions (dewpoints in the upper 60s to lower 70s) until a
significant push of drier air comes in Sunday evening and night.

Monday through Thursday

Short break in the high humidity on Monday before the Western U.S.
and Plains upper ridge expands and shifts eastward. After Monday,
forecast consensus has the hot and muggy air making a return --
possibly requiring heat headlines at times.

Another active "ring of fire pattern" is possible Tuesday through
Thursday with periodic rounds of thunderstorms and heavy rain as
disturbances aloft ride to the ESE over a sfc boundary. The
CMC/GFS are much wetter on Tuesday and Wednesday compared to the
ECMWF. The latter advects the capped elevated mixed layer through
and north of Iowa and Illinois. Since the location of the sfc
boundary will depend heavily on where convection occurred on
previous days, confidence is low with respect to placement and
timing of storms this far out. Uttech


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
ISSUED AT 1141 PM CDT Thu Jul 13 2017

VFR conditions and fair skies will continue as high pressure from
the northern plains moves into Iowa by Friday evening. Winds will
be out of the northwest to north at 5 to 10 MPH.





LONG TERM...Uttech
AVIATION...Nichols is the U.S. government's official web portal to all federal, state and local government web resources and services.