359
FXUS63 KDVN 301638
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1138 AM CDT Sun Jun 30 2024

...Updated for Hydrology and 18z Aviation...

.KEY MESSAGES...

- Pleasant weather into Monday with low humidity.

- Thunderstorms return to the area Monday night into Wednesday
  morning. These storms will likely lead to heavy rain as
  humidity increases. There is a chance for strong to severe
  storms Tuesday PM.

- Independence Day forecast looks wet with potential
  thunderstorms.

- Moderate to Major flooding is expected on several area rivers.
  Crests could be delayed or altered with any heavier rainfall,
  depending on where it occurs Tuesday through Friday.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 306 AM CDT Sun Jun 30 2024

High pressure will continue to overspread the area today leading
to clear skies today. Dewpoints in the low 50s with highs in the
low to mid 70s will result in a beautiful Sunday across the
entire area. These highs will be 10 to 15 degrees below normal
for this time of year. Tonight, cooler temperatures are expected
again. In fact, the lows tonight are getting near record lows
for July 1st. Current forecast is on the low end, however if we
start to see some clouds move in late, lows in the west may end
up being a few degrees warmer. The high pressure will slide
east of the area by Monday morning as winds will begin to
increase ahead of an active pattern to start the workweek.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 306 AM CDT Sun Jun 30 2024

Active weather continues through the long term as we see
multiple chances for rain and storms across the area. Monday
starts with H5 ridging that should keep the area quiet. This
ridging is short lived as an energetic SW flow returns to the
area. Moisture return will begin in earnest Monday night tied to
the H85 jet. The jet is setup just to our west. Tuesday the main
wave moves into the area and with it the LLJ for Tuesday night
into Wednesday. PWATs skyrocket and there is pooling of moisture
ahead of a `cold` front that moves through the area. Wednesday
looks to be quiet before a leading wave ahead of closed upper
level low moves through the area on the 4th of July. This
pattern looks extremely active even into the next week. This
additional rainfall will not just affect the river crests, it
will likely bring chances for flash flooding as well.

Monday night into Tuesday AM: Looks like the better forcing and
moisture will start out west of the area. As the LLJ veers into
the area, some storms are expected to move into the area. The
best area for these storms will be across our NW CWA. PWATs
close to 2 inches are forecast to be in the area. Looking at the
CAMs that are in for that time period, it looks like most of the
rain will fall just NW of us until early Tuesday. Around 12Z it
looks like the storms should be in the area. MUCAPE doesn`t
really move in until 9z Tuesday. WPC has a slight risk for
excessive rainfall across our NW. Does not look a severe threat
and SPC agrees as the mrgl is just west of our area.

Tuesday PM into Wednesday AM: This looks like the best chance
for heavy rain across the area. PWATs in excessive of 2 inches
are likely Tuesday PM. This is in the 99% percentile for PWATs
this time of year. Looking at individual models, there is
a hint of even higher PWATs pooled ahead of a front Tuesday PM.
By 06z the LLJ ramps with a strong SW feed of moisture into the
area. Between 09z and 12z, the moisture transport weakens and
shifts east. Looking at all things, it looks like between 00z
and 06z Wednesday is when the setup for heavy rainfall is. This
is again maximized across our NW CWA. As the front and forcing
moves through the area, the heavier rain should shift east
through 12z.

Looking at severe weather on Tuesday PM. SPC has the area in a
slight risk, this seems appropriate as instability builds across
the area. The approaching wave leads to increasing shear. Deep
layer shear of 40-50kts will lead to updraft organization. The
shear vector is nearly parallel to the front, while supercells
will be favored at first, we can expect rapid upscale growth
into a line of storms. These storms will likely form west of the
area and move towards us in the late afternoon. One factor we
need to think about is whether or not there are any OFBs from AM
convection. If these create thermal gradients, we could see
redevelopment in our area in the afternoon as well. This could
increase our severe chance and also flash flood threat for the
evening and overnight.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1135 AM CDT Sun Jun 30 2024

VFR conditions expected through the period. Scattered diurnal
cumulus with bases of 3000-4000 ft AGL will continue to lift
and dissipate by sunset. Winds near 10 kt from N/NE will
become near calm to light easterly tonight, as a surface high
pressure ridge shifts into the western Great Lakes by 12z Mon.
Some shallow fog is possible in river valleys and other low
lying areas from DBQ to MLI and into NW Illinois, but confidence
on occurrence and impacts at either terminal is too low for
mention at this time. On Monday, increasing mid/high cloudiness
is expected. SE winds will increase to 10-15 kt by mid to late
morning, with occasional higher gusts possible at CID.

&&

.HYDROLOGY...
Issued at 1135 AM CDT Sun Jun 30 2024

New forecasts this morning for the tributary rivers have come in
slightly lower for the Cedar River at Conesville, Iowa River at
Wapello, and the Wapsipinicon River near De Witt. However, no
changes to the expected flood category were made. The crest on
the Cedar River has gone through Cedar Bluff and should reach
Conesville by Monday morning. A return to an active weather
pattern will bring a heavy rain risk Monday night through
Wednesday that may result in renewed rises on many tributary
rivers. Those with interests along the tribs should monitor
future forecasts, especially Monday evening when the bulk of the
1-3 inch rainfall will be incorporated into the river model.

On the mainstem Mississippi, no change to the expected flood
categories with the new forecasts this morning. Broad crests are
now shown from Dubuque to Fulton LD13 late in the 7 day
forecast. A widespread heavy rain event (1-3" amounts across
much of eastern IA into southern WI) is anticipated in the
Monday evening through Wednesday time frame which may have an
impact on expected rises and delay the crest downstream.
Residents and interested individuals/businesses should monitor
future forecasts for any changes to the river rises.

&&

.CLIMATE...
Issued at 145 PM CDT Sat Jun 29 2024

Record low temperatures for July 1

Burlington......51 in 1918
Cedar Rapids....43 in 1924
Dubuque.........47 in 1995
Moline..........48 in 1988

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Gibbs
LONG TERM...Gibbs
AVIATION...Gibbs
HYDROLOGY...Gross
CLIMATE...McClure