225
FXUS63 KDVN 182333
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Heat Advisory continues across the entire area through 8 pm this
  evening.

- Temporary bit of relief from the higher heat levels will come
  for some in the form of a cold front that will sink
  southeastward across portions of the area late tonight and
  Wednesday

- There is a Marginal Risk (Level 1 of 5) of severe weather for
  Wednesday across much of the DVN CWA.

- The pattern will remain rather active from Wednesday and
  through the upcoming weekend, with periodic chances of
  thunderstorms.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 249 PM CDT Tue Jun 18 2024


Tonight...With Heat Index readings in the mid to upper 90s ongoing,
will keep the heat headlines going although it is marginal. The
precursor isolated showers and storms now acrs central IA should
continue to fade as they try to push to the western fringe of the
CWA or continue to move northwest of the local area. Then eyes turn
to the MO RVR Valley or the central MN into the south central NE
area late this afternoon as many MCS spawning parameters come
together acrs these areas. Interesting fine line of convection along
the main front inn this favored region ATTM, while an EML is in
charge to the east acrs the local area. Right entrance region of
upper jet and digging short wave aloft will help be the synoptic
scale convection igniter upstream acrs the severe risk area, with
resultant linear MCS sweeping into the CWA from the west overnight.
The northeast portion of this feature should be making it into
northwestern CWA by around 10-11 PM. There may be some outflow gusts
ahead of this line reaching 40 KTs or so, but overall with ongoing
EML/CAP and less favorable mid level lapse rates feel the line will
be coming acrs in a weakening fashion late tonight into Wed morning.
Areas east of the MS RVR may not see much rain at all, while some
areas/swaths in the northwest may get up to a half inch by Wed
morning. Brisk south winds and DPTs to keep low temps up in the low
to mid 70s acrs much of the area, although rain-cooled outflow may
knock more down into the upper 60s especially west.

Wednesday... A few storms or showers may be ongoing/lingering out of
Tue night, but coverage and any intensity should continue to fade in
the morning. Then with the main incoming cool front or outflow
boundaries sagging acrs the CWA or laying out, they will act as a
focus for renewed storm development during the afternoon. Still some
uncertainty where these boundaries will lay out, as well as extent
of heating that we will get or rate of convective debris decay, but
at least moderate chance POPs warranted acrs much of the fcst area
during the afternoon and early evening. MUCAPEs may range up to 2000
J/kg, but storm layer shear profiles of 20-30 KTs and mid level
lapse rates under 6 C/km make for a limited severe storm threat.
BUt agree with SPC`s thinking there could be isolated wind gusts of
50-60 MPH or damaging rain loaded down bursts. Warm and moist
profiles should limit the max hail size to under severe limits.
PWAT`s of 1.6 to 1.8 inches will support locally heavy rain swaths
of over an inch. This while other areas receive only a trace.

High temps a challenge with all the boundary and cloud debris
questions, but will range them from highs only in the mid 70s in the
far northwest, to the low 90s in the east/southeast. Heat index`s in
theses 90 degree areas may range in the mid to upper 90s, but not
worthy of heat headlines with less true heat coverage and cloud
cover uncertainties.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 249 PM CDT Tue Jun 18 2024

Thursday...A day where we may have a few lingering thunderstorms out
of Wed night in the north, and then remnant outflow boundaries or
the quasi-stationary front itself may act as a focus for renewed
shower and storm development Thu afternoon and evening. Despite
decent looking CAPE profiles, weak shear and marginal mid level
lapse rates will hopefully limit any severe potential except maybe a
rain loaded isolated downburst again. Where these afternoon storms
may fire still uncertain, but ensemble placement is generally along
and north of the I-80 corridor with mid to upper ridging bulging
acrs the southeastern DVN CWA off the OH RVR/TN Valley high pressure
complex. These storms should fade diurnally as the evening progresses
and the upper ridge adjusts northward up the Upper MS RVR Valley
into Friday morning. Highs on THu will range from the low to mid 80s
north, to the lower 90s in the south.

Friday...Amplifying thermal ridge overhead will look to shunt the
storm track to the north as the day and night progresses, leaving
the local area in hot breezy conditions. But sfc DPTs are currently
progged to stay mixed out in the mid 60s, thus the lower humidity
may not warrant a heat advisory this day. BUt a better chance for
ambient temps to reach the mid 90s in some locations.

Saturday through Monday...A hot and more humid airmass with a ridge
flattening short wave digging acrs the region may spark strong,
heavy rain producing storms late Saturday or Sat night. Associated
cool front will also sweep through the area late, which could make
for a not as hot and less humid Sunday. Longer term ensembles
suggest a flattened steering flow/near zonal acrs the upper CONUS
early to mid next week, possibly placing the local area in or near
the thermal battle zone and thus MCS track.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 617 PM CDT Tue Jun 18 2024

A VFR, but warm evening will persist tonight through midnight,
before a slow moving line of storms approaches eastern Iowa
early Wednesday morning. These are expected to be dissipating as
they move into eastern Iowa. With timing pushed a bit farther
back compared with earlier issuances, but we`re maintaining a
rather long duration of Prob30, given the large, but dissipating
mode of the storms moving into eastern/northeastern Iowa between
06-12Z. There is likely to be MVFR in patches during the mid
morning hours behind this dissipating activity, followed by
generally VFR weather in the afternoon, but late in the period,
another round of developing storms is expected, closer to the
MLI and the Interstate 80 corridor. These storms could bring
lowered visibility in heavy rain and gusty winds into the early
evening hours Wednesday.

&&

.CLIMATE...
Issued at 249 PM CDT Tue Jun 18 2024

Record Warm Minimum Temperatures:

June 19:
KDBQ: 76/1931
KMLI: 78/1953

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Heat Advisory until 8 PM CDT this evening for IAZ040>042-
     051>054-063>068-076>078-087>089-098-099.
IL...Heat Advisory until 8 PM CDT this evening for ILZ001-002-007-
     009-015>018-024>026-034-035.
MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010.

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...12
CLIMATE...12