Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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855
FXUS63 KDVN 201942
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
242 PM CDT Thu Jun 20 2024

.KEY MESSAGES...

- A chance for isolated storms this afternoon and evening. Severe
  weather not anticipated. Locally heavy rainfall possible.

- Hot and humid Friday and especially Saturday.

- A chance for severe thunderstorms Saturday and Saturday night.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 241 PM CDT Thu Jun 20 2024

Tonight...Light sfc flow with several embedded boundaries seen on
sfc observations and RADAR loops. Afternoon heating has made for
2000+ J/kg MUCAPEs, and with convective temps of mid to upper 80s,
weak ridge-riding vort aloft, the buoyancy will be allowed to
translate into isolated to widely sctrd showers and thunderstorms
through mid evening. While widespread severe storms not expected
with weak shear and lapse rates, can`t rule out pop and drop
isolated downburst winds doing some shenanigans here or there. Also
an environment favorable for non-supercell funnels. PWATs remain very
high from 1.8 to 2 inches acrs the area, thus any more substantial
cell will be very heavy rainer`s as they drift by. After some cloud
thinning and evening storms fade, ongoing light sfc wind flow and
juiced sfc DPTs there may be some patchy fog in spots, especially
along any lingering boundary. Will place patchy fog wording in the
north for now. Low temps in the upper 60s to low 70s for most of the
area.

Friday...High pressure aloft will look to bump up acrs the
southeastern CWA, while periphery thermal ribbon-storm track
setting up around this feature from the northern plains over to the
Great Lakes, keeping the brunt of the MCS storm track northwest and
north of the local area possibly into Sat morning. But lingering
boundary north of I-80 or even Hwy 30, or possibly outflow from
convective activity to the north or northwest, may be enough to bump
up buoyancy-driven isolated storms in these areas Friday afternoon.
Thermal profiles support highs in the upper 80s to low 90s, but sfc
DPTs are still looking to mix out in the mid to upper 60s, thus the
lower humidity should not warrant a heat advisory. But with the
somewhat reduced humidity, there may be a better chance for ambient
temps to reach the mid 90s in some locations with full sun or
limited CU.  Friday night, a low chance of upstream MCS activity to
bleed down toward the northwestern CWA late night or just before
dawn Saturday morning.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 241 PM CDT Thu Jun 20 2024

Saturday and Sunday...A hot and more humid airmass Saturday with
highs in the low to mid 90s. Of course any cloud or convective
debris lingering out of Friday night or coming in the form of
initially decaying storms from upstream in the morning may make
temps warm up potential tricky in some locations. Sfc DPTs may hang
closer to 70 thus making heat indices push the upper 90s or near
100. Synoptic flow ensembles still keep the same signal of a
vigorous northern stream short wave digging against the upper ridge
and heat dome, with an associated sfc cold front acrs the region on
Saturday. Stronger forcing/shear breaking the EML and plowing into
high CAPEs likley will spark strong to severe, heavy rain producing
storms later Saturday and into Saturday night. It`s still early but
currently indicated CAPE and shear profiles would support damaging
winds, large hail and isolated tornadoes. In the wake of the
Saturday cool front and storms, incoming upper MO RVR Valley ridging
and northwest flow may make for a dry, not quite as hot and less
humid Sunday. Still looking like the best day of the weekend. Sunday
night still under the influence of the sfc high and we may have low
temps cool well down in the 60s by Monday morning.

Monday through Wednesday...Latest run medium range ensembles and
upper jet patterns suggest broad upper ridge amplification acrs the
Rockies and western CONUS early next week. Resultant northwesterly
steering flow acrs the upper MS RVR Valley into the GRT LKS may
place the DVN CWA close to the ridge-riding short wave storm track,
thus possibly subject to occasional convective systems. Thus may be
a unsettled stretch this period especially Tue or Tue night. But one
change in the latest runs was being more bullish in pumping up the
Rockies upper ridge out west, resulting in more of a southward surge
in LLVL ridging dumping down the upper to mid MS RVR Valley and
western GRT LKS, for a cooler and dry reprieve from the early week
warmth/storms.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1249 PM CDT Thu Jun 20 2024

Some lingering MVFR CIGs through mid afternoon, but most areas
should lift to VFR by 3-4 PM. Isolated to widely sctrd showers
and thunderstorms may pop up mid to late afternoon, and linger
through at least mid evening. Hard to time and pin-point
location with the low coverage, but just covered the suspected
timing windows with VCNTY periods in the TAFs. Light and
variable sfc wind regime this afternoon and much of the night.
There may be some patchy fog under any clear skies late tonight,
but not enough confidence to place in the TAFs at this time.
VFR Friday morning away from any fog, with south to
southwesterly sfc winds increasing to 5-10 KTs by late morning.

&&

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

&&

$$

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