618
FXUS63 KDVN 262027
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
327 PM CDT Fri May 26 2017

...HYDROLOGY UPDATE...

.SYNOPSIS...
Issued at 325 PM CDT Fri May 26 2017

18Z surface data has a weak low in southeast Iowa northwest of of
KBRL. A warm front ran east from the low across central Illinois
while a cold front went south into Missouri. Dew points were in the
40s and 50s from the Great Lakes into the northern Plains. Dew
points in the 60s ran from central Illinois to the Gulf Coast.

&&

.SHORT TERM...(This Evening through Saturday)
ISSUED AT 325 PM CDT Fri May 26 2017

Through sunset, the remnants of the thunderstorm complex will exit
the far east and southeast areas. The remainder of the area will see
dry conditions with slowly clearing skies.

Tonight, mainly clear skies and dry conditions will be seen across
the area. The combination of light winds and wet ground may allow
some patchy fog to develop prior to sunrise.

Saturday, quiet and dry conditions will be seen across the area
during the morning hours. The next upper level disturbance arrives
during the afternoon. The main surface low looks to pass to the
south and east of the area. Convection will move into and/or develop
across the area Saturday afternoon.

With the effective front well south of the area, there are questions
regarding the overall risk of any severe storms Saturday. The models
do show a layer of very unstable air aloft so that may be what is
being keyed on for storm development. The most unstable air aloft is
across the extreme south.

.LONG TERM...(Saturday Night through Friday)
ISSUED AT 325 PM CDT Fri May 26 2017

Northwest flow will continue the stretch of near to below normal
temperatures with a very low potential for showers and thunderstorms
throughout. The highest rain chances will Saturday night into early
Sunday.

Saturday night: Models suggest a mid level shortwave will be passing
through the area in the evening, sending a wave of low pressure
along the main synoptic boundary to the south. This will likely
trigger an MCS moving through the at least the southern half of area
with severe storms possible across the south, depending on how far
north the warm front reaches. SPC has the entire forecast area in a
day 2 marginal risk with a slight risk across our southern tier of
counties. Besides the severe threat, Gulf Moisture and resulting
high forecast PW values will lead to a threat of heavy rainfall.

Sunday and Beyond: The trailing edge of what will likely be
stratiform rain will exit early Sunday, followed by gradual
clearing. There will be a low potential for showers over the
northeast under the increasing cyclonic northwest flow aloft as an
upper low deepens over central Canada. Deep mixing in the breezy nw
flow, and at least afternoon sunshine will be needed to reach
afternoon highs in the lower to mid 70s. Monday will again see low
chances for showers over especially the north and northeast.
Otherwise, a northwest flow under the upper low over Canada will
remain in place through most of the week, providing dry weather and
near to below normal temperatures with highs in the lower to mid 70s
and lows in the 50s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
ISSUED AT 1230 PM CDT Fri May 26 2017

Convective complex with embedded TSRA over eastern Iowa will move
across northern Illinois through 00z/27. Under this convective
complex MVFR/IFR conditions are common with VFR outside of the
complex. After 00z/27 VFR conditions will be seen across the area
through 06-09z/27. The models are suggesting the possibility of
fog developing after 06z/27 due to light winds. The 18z TAFs
introduced MVFR conditions after 08z/27 but IFR conditions are
possible due to the wet ground.


&&

.HYDROLOGY...
ISSUED AT 1230 PM CDT Fri May 26 2017

Convective complex with embedded TSRA over eastern Iowa will move
across northern Illinois through 00z/27. Under this convective
complex MVFR/IFR conditions are common with VFR outside of the
complex. After 00z/27 VFR conditions will be seen across the area
through 06-09z/27. The models are suggesting the possibility of
fog developing after 06z/27 due to light winds. The 18z TAFs
introduced MVFR conditions after 08z/27 but IFR conditions are
possible due to the wet ground.


&&

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

$$

SYNOPSIS...08
SHORT TERM...08
LONG TERM...Sheets
AVIATION...08
HYDROLOGY...Sheets