000
FXUS63 KDVN 252349
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
649 PM CDT Thu Apr 25 2024

.KEY MESSAGES...

- There is a slight risk for severe storms in our western
  counties on Friday.

- The risk for severe storms continues on Saturday and Sunday.
  At this time, the best chance for severe storms looks to be
  Sunday afternoon/evening.

- The latest models have reduced the forecast rainfall amounts
  through the weekend.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 230 PM CDT Thu Apr 25 2024

Say goodbye to the nice weather for awhile as we get into an
active pattern beginning tonight. Deep low pressure (988 mb)
will be tracking from eastern CO to eastern SD. GFS/NAMNEST/HRRR
have slowed the progression of the showers and thunderstorms,
and now show the leading edge moving into our western counties
by dawn, and then our far eastern counties by noon Friday.
Should reach Dubuque and the Quad Cities by around 9 am. This
round of showers and scattered thunderstorms will be occurring
on the nose of a strengthening Low Level Jet bringing a nice
surge of moisture/warm air advection. Forecast soundings suggest
these storms will be elevated but MUCAPE is very limited, so
not expecting severe storms. Some of the models show a decrease
in the activity in the afternoon, then some re-development
possible later in the afternoon and evening. The bulk of the
severe storms should remain across western/central Iowa then an
arc of storms may enter our northwest counties overnight on
Friday night, but in a weakening fashion. Strong gradient
southeast winds will be gusting to around 35 mph.

Lows tonight in the 40s with highs on Friday ranging from the
mid 50s north to the mid 60s south. Lows Friday night in the
lower 50s north to the lower 60s south.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 230 PM CDT Thu Apr 25 2024

Saturday through Sunday night: Global models have really backed
off on pcpn for Saturday. Can`t rule out some isolated showers
and storms but not much in the way of forcing. We will be
between storm systems, as the first cyclone pushes to the
northern Great Lakes region, while another strong cyclone
organizes off the lee of the Rockies in eastern CO. This second
storm system will return strong forcing and with a frontal
boundary draped southwest-northeast across the forecast area,
numerous showers and thunderstorm should occur Saturday night
into Sunday morning. Heavy rainfall is likely with these storms.
Depending on how long the storms last on Sunday will determine
the severe threat. Any break in the action to allow sunshine
would increase the severe potential. SPC continues the SLGT risk
on Sunday afternoon into Sunday night. The pcpn should diminish
later Sunday night as the cyclone tracks to near the Twin Cities.
Highs on the weekend will be well into the 70s to lower 80s.

Rainfall amounts: Yesterday the model QPF total through the
weekend was around 3.50 inches for much of the forecast area.
However, the new model data this morning has backed off to
amounts of 2.50 inches west to 1.50 inches east. Is this a trend
that will continue or will the high rainfall amounts return in
later models? Time will tell.

Monday through Wednesday: Any lingering showers will end in the
morning on Monday with highs in the mid 60s to lower 70s. Zonal
flow Tuesday and Wednesday may allow for chances for showers and
thunderstorms but timing the disturbances in the flow is tricky
this far out. Highs will be in the 70s.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1238 PM CDT Thu Apr 25 2024

Currently TAFs are VFR at all sites to start the period.
Marginal LLWS is forecast to develop tonight after 06 UTC as
winds around 2kft increase to 40 to 45 knots. LLWS is forecast
to weaken by 14 UTC at all sites. A storm system developing in
Colorado and Kansas will lead to surface winds increasing after
06 UTC with speeds of 10 to 20 knots through the period and
gusts as high as 30 knots after 15 UTC.

VFR conditions are forecast to deteriorate between 12 to 15 UTC
as widespread showers and storms spread from west to east
across the area. Ceilings and visibilities will lower to MVFR
then IFR across the area during the morning hours as
precipitation moves in. Showers and storms are forecast to exit
the area during the afternoon but IFR ceilings will remain
through the remainder of the period.

&&

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

&&

$$

SHORT TERM...Haase
LONG TERM...Haase
AVIATION...Cousins