218
FXUS63 KDVN 090549
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1249 AM CDT Thu May 9 2024

.KEY MESSAGES...

- There is a Marginal or level 1 out of 5 Risk for severe storms
  over the entire area Tonight.

- Active weather continues through the period.

- Below normal temperatures are expected Thursday through
  Saturday with a warming trend starting early next week.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 205 PM CDT Wed May 8 2024

Surface analysis shows a warm front has lifted to along a line
from KALO to KSFY to near KSQI at 18 UTC. There are
southeasterly winds across the area of 10 to 15 MPH with gusts
up to 25 MPH. Temperatures are in the upper 70s to lower 80s
with dewpoints varying from 43 at Washington to 55 degrees at
Keokuk. Dewpoints have slowly been increasing this afternoon.
Visible satellite imagery shows some cumulus development near
the Interstate 80 corridor.

A 500 MB trough that stretches from Quebec westward into the
South Dakota is forecast to sink southward through 00 UTC
Friday. The trough axis will remain to our west through the
period. A piece of a closed 500 mb low will break off and move
into northern Iowa and southern Wisconsin through the period. At
the surface, a surface low and occluded front or inverted
surface trough will move eastward across the area tonight.

Scattered showers and storms will initially develop late this
afternoon into the early evening. the key question is how much
instability will be in place across the area. Models initially
suggest 500 to 1000 J/KG of CAPE but 0 to 6 km shear is very
strong at 50 to 60 knots. 0 to 3 km shear is 30 to 40 knots. The
instability may only support lower top storms late this
afternoon into this evening as higher storms may be quickly
sheared apart. Isolated severe storms are the main concern
across the entire area with hail, damaging winds and maybe a
tornado being possible. As we move later into the evening and
larger scale lift moves into the area, expect showers and
isolated thunderstorms activity to become more widespread across
the area. Sounding profiles at this stage support more of a
steady rain showers through tonight into Thursday. Scattered
showers will linger through much of the day on Thursday. High
temperatures on THursday will be cool and range from the upper
50s in northwest Illinois to the mid 60s in far southeast Iowa,
west central Illinois and far northeast Missouri.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 205 PM CDT Wed May 8 2024

Friday through the weekend: Pattern change to a northwest flow
as a deep trough sets up shop across the Great Lakes. Periodic
disturbances in the flow will bring off and on showers and a few
thunderstorms with chance pops every 24 to 36 hours.
Temperatures will be on the cooler side with highs in the 60s
and lows in the 40s to around 50.

Early to mid next week: Another pattern flip to a deep trough
diving into the Northern Rockies and then into the Plains. This
will warm our temperatures well into the 70s to lower 80s.
Also, chances for thunderstorms will also be on the increase.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1245 AM CDT Thu May 9 2024

Complex of showers and thunderstorms will continue into Thursday
morning, mainly along and north of I-80, but eventually will
develop farther to the south. There may be a brief break in the
rain later in the morning, followed by more showers and isolated
thunderstorms during the afternoon. Cold air aloft is expected
to produce widespread IFR/MVFR in low stratus and showers.

&&

.HYDROLOGY...
Issued at 911 PM CDT Wed May 8 2024

River flood watches have been issued for small parts of the
Cedar, Iowa and Wapsipinicon Rivers.

Rainfall expected tonight into Thursday will cause the Cedar,
Iowa and Wapsipinicon Rivers to rise over the next week.
However, there is uncertainty regarding the amount of forecasted
rainfall. If the rainfall is less than expected, rises will
still occur on these rivers but they could remain below flood
stage. If, on the other hand, rainfall is heavier than forecast,
more locations along Cedar, Iowa and Wapsipinicon Rivers could
go into flood.

&&

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

&&

$$

SHORT TERM...Cousins
LONG TERM...Cousins
AVIATION...Haase
HYDROLOGY...08