718
FXUS63 KDVN 020500
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1200 AM CDT Sun Jun 2 2024

.KEY MESSAGES...

- Areas of fog are likely tonight into early/mid Sunday
  morning, especially for counties along and west of the
  Mississippi River. The fog could become dense at times and a
  Dense Fog Advisory may eventually be needed.

- Active/Unsettled Sunday night through Tuesday night with
  several chances for showers and storms. Some potential for
  stronger storms Monday PM (conditional upon development) and
  Tuesday night ahead of a cold front.

&&

.UPDATE...
Issued at 1151 PM CDT Sat Jun 1 2024

Visibility is already starting to drop across portions of E Iowa
and vicinity of the Mississippi River where stratus has cleared
out. Web cams and obs indicate already some areas of dense fog
with visibility at or below 1/4sm. Expect fog to continue to
become fairly widespread with additional BL cooling and near
calm winds, and as such we`ve issued a Dense Fog Advisory until
10 AM Sunday for the area along and west of a line from Freeport,
to Savanna, to the Quad Cities to Carthage IL.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 135 PM CDT Sat Jun 1 2024

Nothing quite like starting off your first day of meteorological
summer with a deformation zone rain and temperatures 10 to 15
degrees below normal! The persistent rainfall today, fell at
0.10 to 0.30 per hour in most locations where it was found, and
resulted in total amounts of 0.25 to 1.25 in observed rainfall.

This rain seems to have fallen at a slow enough rate that run
off will be low for the actual amount of rain received. Anyhow,
the most wet soils will be in the Iowa counties, while the
driest tonight will be in the west central Illinois and
Missouri. This is one of several factors in a potential dense
fog forecast for tonight, as low level dewpoints remain in the
lower 60s through sunset, with damp top soil conditions.
Clearing is the lowest confidence feature in this forecast, as
there is extensive cloud cover in place, and we don`t have much
dry advection or downward motion expected this evening. It
appears we will at least thin our cloud cover this evening, with
areas of fog forming, but should any total clearing occur this
evening, fog will be possible anytime after sunset. Lows tonight
are forecast in the mid to upper 50s, well past crossover
temperatures around 60. Thus, we will hold off an advisory
issuance, but steer our messaging towards fog for tonight. Once
sky trends are confident, an advisory is more likely.

Sunday, following lifting/clearing of the fog, we will see dry
day of moderate humidity, and at least partly cloudy by
afternoon. Any thunderstorm activity appears to hold well west
of our area until later Sunday night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 135 PM CDT Sat Jun 1 2024

A shortwave and cold front look to provide the focus for convection
Sunday PM/evening across the Plains. This will advance into the
region primarily overnight Sunday night into Monday morning, while
likely weakening as it outpaces the better moisture transport
and instability. Depending on the timing of the shortwave, we
may need to keep an eye on Monday PM for any redevelopment and
at least a low threat for a few strong storms. Soundings show a
stronger deep layer shear potential likely augmented by the
shortwave for some concerns over organized multicell storms with
gusty winds should PM convection occur. Latest CSU machine
learning probabilities for Monday do reach the equivalent of a
Slight Risk for severe weather for wind across south/west
portions of the service area. Largely south/southwest low level
flow/ warm advection will foster above normal warmth, which
coupled with increasing humidity will continue to make it feel
summer- like heading into midweek.

Toward mid to late next week the guidance continues to support
a pattern change with an eventual deepening northern stream
trough shifting into the eastern CONUS. An initial shortwave
driving this pattern change will evolve eastward across the
Northern Rockies and along the International border with ND/MN
Tuesday into Wednesday. This will drive a cold front through
the area Tuesday night into Wednesday bringing the potential
for strong storms due the above normal warmth and moisture
fostering greater instability. 00z ECMWF deterministic QPF
has the look of a mature MCS developing to our northwest on
Tuesday and diving E/SE into the instability across the region
Tuesday night with wind potential given ramping deep layer
shear, and this potential certainly bears watching over the
next few days. Beyond, there`s quite the uncertainty in the
deterministic and ensemble guidance on strength and position
of the upper trough heading into late next week and next
weekend. This owes to lower confidence on temperatures, as
illustrated by NBM with Interquartile ranges as much as 10-15
degrees on highs over several days from Thursday through
next weekend ranging from the lower 70s to the lower to mid 80s.
Confidence in precipitation chances late week into next weekend is
also low, modulated by the location of the upper trough.

In general, we`re looking at "windows open and AC off" weather
returning for the end of the week and upcoming weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1151 PM CDT Sat Jun 1 2024

Low level moisture aided by recent rainfall, light winds, and
thinning low clouds will continue to promote areas of fog
developing overnight. The fog will become dense at times
leading to VLIFR conditions (visibilities at or below 1/4SM)
into Sunday morning. Improvement to MVFR/VFR is anticipated by
the mid to late morning hours on Sunday as the fog dissipates.
There are low chances for a shower or storm west of the
Mississippi River late this afternoon and evening, but low
coverage and uncertainty on impacting terminals precludes any
mention at this time.


&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 10 AM CDT Sunday for IAZ040>042-
     051>054-063>068-076>078-087>089-098-099.
IL...Dense Fog Advisory until 10 AM CDT Sunday for ILZ001-002-007-
     015-024-025-034.
MO...Dense Fog Advisory until 10 AM CDT Sunday for MOZ009-010.

&&

$$

UPDATE...McClure
SHORT TERM...Ervin
LONG TERM...Ervin/McClure
AVIATION...McClure