Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 250258

Area Forecast Discussion
National Weather Service Quad Cities IA IL
958 PM CDT TUE MAY 24 2016

Issued at 958 PM CDT Tue May 24 2016

Forecast has been updated to remove mention of showers and
thunderstorms over the next several hours. The next focus for
convection looks to be with an upper level shortwave linked to the
large complex over KS. With little other support, low level jet
assist, or significant theta-e advection suggested, will be
watching this system, which does not look to arrive until close to


Issued at 343 PM CDT Tue May 24 2016

Mid-level ridge axis has moved east of the Upper Mississippi River
Valley. SSW sfc flow finally pushed upper 50 to mid 60 dewpoints
into E Iowa/W Illinois. Temps ranged from lower 80s west to mid or
upper 80s central and east with a cool zone in the middle 70s
around Dubuque. Isolated showers have developed from time to time
but majority of the forecast area has remained dry.


ISSUED AT 343 PM CDT Tue May 24 2016

This Evening and Tonight...Weak forcing and lack of organized
low-level jet, but presence of 1000-2000 J/kg MUCAPE and little
SBCIN, supports the persistence forecast of isolated to sct
showers and storms with more areas missing out on the rain than
receiving it. Overnight lows influenced by higher low-level
moisture, for a change, will be quite mild in the mid 60s.

Wednesday...Clusters of convection will form across Kansas this
evening (Tuesday) and grow upscale into an MCS overnight as it
moves to the ENE. Pre-existing MUCAPE of +2000 J/kg across E
Iowa/W Illinois from the mid morning into the aftn should help
maintain this line of storms, in somewhat of a weakening phase,
into the DVN CWA. Weaker 0-6 km bulk shear of ~35 kts or less
lowers overall severe threat, but will have to watch for possible
reintensification of the convection by midday into the aftn as it
coincides with daytime heating.

Thunderstorm potential: A few strong to severe storms are
possible with marginally severe hail up to quarter size and wind
gusts up to 60 mph the primary threats. However, cannot ignore
high PWATS near 1.50 inches and potential for - localized - very
heavy rainfall rates. Storm motion vectors are generally greater
than 20 kts thus am not too concerned about training of storms.

Aside from the risk for more numerous showers and storms compared
to Monday and Tuesday, sfc dewpoints into the mid/upper 60s will
make it feel increasingly humid. High temps are forecast in the
lower 80s as clouds/rain/humidity keep them in check. Uttech

.LONG TERM...(Wednesday NIGHT THROUGH next Tuesday)
ISSUED AT 343 PM CDT Tue May 24 2016

Wednesday night...12z run model run ensemble using their MCS forcing
tools suggest the DVN CWA to lay mainly in between ongoing main
lift/forcing just to the southeast acrs mo into east
central IL/Indiana, and another along the IA/MN border on north into
MN and WI. These zones could very well be ongoing with convective
systems at the start of The period and then propagate east-
northeastward away from the local area by mid evening and into the
overnight. But with several models, including the 12z ECMWF having a
secondary warm front draped acrs the CWA off the MN wave, will have
to keep relatively high chc to likely POPs going for much of the
night. With projected PWATs of 1.3 to 1.5 inches, more of a locally
heavy rain threat while bulk shear of 20-30 kts and waning CAPES
makes for a marginal severe threat especially later at night.

Thursday...with both upper ridging and a lobe of sfc ridging in the
wake of the passing Wed-Wed night wave, much of the day may be dry
and thus allow to heat up into the upper 80s acrs much of the CWA
with some sunshine. A 90 may even be possible, although higher
humidity may limit that chance somewhat. Knocking back some of the
NAM and GFS sfc dpts which are in the low to mid 70s, down to mid
to upper 60s or around 70, still makes for a CAPE build up
3000-4500+ by late afternoon. MCS spawning parameters come
together late Thu afternoon and early evening acrs the east
central plains-eastern KS into NW MO/SW IA...with the potential of
portions of that system feeding acrs into the rich thta-eairmass
into the local area overnight into early Friday morning. With
better shear profiles off to the west and northwest Thu night,
probably another marginal severe threat but another round of heavy
rain with PWATs up to 1.5 inches. But a lingering high CAPE
airmass in place makes for an uneasy feeling with incoming
convection that may still produce damaging wind if it develops a
sfc cold pool. Also can`t rule out scattered storm cluster
development locally Thu evening as fcst soundings show a very
breakable llvl cap, or if it takes off at a slightly elevated

Friday and Saturday...for Friday, much will depend on lingering
convective debris and storm outflow pools from Thu night. But with
the Bermuda High complex setting up shop off the east coast
maintaining the warm moist conveyor up the MS rvr Valley, the air
mass should recharge to help produce/fuel more scattered storms
clusters later Fri afternoon and into Fri night. But better dynamics
for more substantial storms appears at this point will lay out acrs
the deep southern plains...up into western MO Fri evening. High
temps on Fri a challenge depending on amount of debris/cloud cover
with several ranges possible. Saturday the more optimum combo of
dynamics and instability will take place up the plains to MO rvr
Valley again, and locally we may have several dry hours in between
isolated to sctrd storms...ongoing above normal temp regime.

Sunday through next Tuesday...Assessing the latest run medium range
solutions, Sunday through early Memorial Day Monday will look to be
a lull period and mainly dry. But then afternoon isolated to sctrd
instability showers/storms may pop up Monday afternoon and into the
evening. A warm day with highs in the low to mid 80s. Broad
troffiness acrs the central and northern plains may bleed some of
it`s associated precip toward the local area later on Tuesday and
into mid next week.    ..12..


ISSUED AT 634 PM CDT Tue May 24 2016

Isolated showers may impact the MLI site early this evening, where
vicinity wording was included. Otherwise, VFR conditions are
expected through at least midnight with only a very small
potential for showers and isolated thunderstorms. Increasing
moisture may lead to light fog, which was included with 5 mile
visibilities at DBQ and BRL. Wednesday, the potential for showers
and thunderstorms returns from around mid morning onward. Forecast
models suggest an organized cluster of storms to move through from
late morning through early afternoon, but forecast confidence
remains low and only prob30 wording was utilized. Vicinity wording
for thunderstorms was then utilized for all sites through most of
the afternoon to convey the likelihood of scattered thunderstorms
in the area. Overall, conditions are expected to be VFR outside of
thunderstorms during the day.


.DVN Watches/Warnings/Advisories...


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