Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 270453

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1153 PM CDT THU MAY 26 2016


Issued at 840 PM CDT Thu May 26 2016

Building meso-high under the large, mainly stratiform rain shield
and rain cooled airmass over south central Iowa was producing
gusty W-NW winds from Marshalltown to Ottumwa. Marshall had a gust
of 41 mph in the past hour. Have updated the forecast to include a
period of strong gusty winds this evening in the far west and sw,
before this feature dissipates. Otherwise, have updated pops to
follow thunderstorms percolating along the northeast edge of this
precipitation shield that will stay mainly west of highway 218
through 10 pm and continue to dissipate as it moves into drier air
aloft over eastern IA. Looks like the severe weather threat this
evening will stay well to the south across KS and MO, closer to
the main synoptic surface boundary.


Issued at 355 PM CDT Thu May 26 2016

The latest SFC analysis was indicating low pressure with an arching
warm front acrs KS into Southeastern Neb back down into central MO.
A secondary trof was noted up into southwestern IA. A vort max was
noted acrs southeastern CO, with lee side southwesterly steering
flow sprawling out acrs the east central Plains.


ISSUED AT 355 PM CDT Thu May 26 2016

Tonight...will have to have some POPs this evening in the west
central to southwestern CWA for the potential for some of the
showers and storms in the current convectively active zone acrs
northwestern MO/IA border region, to propagate into the local FCST
area...probably into the southwestern and southern third of the
local area. But this activity will have to battle lingering mid
and upper ridge bulge from acrs southeastern IL...up acrs the
upper MS river Valley and thus may get eaten away at or decay
some as it tries to push east late this afternoon and into mid

But later on tonight, the upper wave currently acrs the southwestern
plains will roll up in steepening southwest flow acrs southwest into
central IA by midnight. This should help whatever congeals(MCS) out
of the current activity to the west/southwest...make it acrs the
local area. It may also spark new development in central Iowa mid
to late evening, which could also then come acrs the area as a
MCS-type feature. MCS forcing tools from the favored 12z run UKMET
and ECMWF target the northwest to northern half of the FCST area
from midnight on into early Friday morning. Other solutions hit
the south half of the CWA again. Although do think the UKMET/Euro
are hitting the right areas(northwest half or north half along and
north of I80)...not sure if there will not be convection in the
south as well and will go blanket Likely POPs after midnight into
Friday morning. With CAPES of 1500 to over 2000 J/KG lingering
well into the overnight, again see the threat of a storm cluster
developing it`s own cold pool and being able to produce damaging
winds. Large hail a secondary threat with marginal deep layer
shear to support bigger stones, but still not out of the question.
With PWATs increasing to 1.5 or even up to 1.7 inches, locally
heavy rain also a good bet with any enhanced storm cluster. A few
swaths of 1-2 inches of rainfall possible by Fri morning, but most
areas from 0.50 to around an inch. Ponding of water on
roads/drainage ditches possible.

Friday...convective system or clusters may still be ongoing through
mid morning, before the wave lifts north. Could have some strong
storms ongoing as well at this time around and a few hours after
sunrise despite the less then optimum time of day. Activity may then
wane into the afternoon and FCST POPs a bit high, but ongoing
southerly flow and moisture convergence may fester new development
as the afternoon progresses. High temps a challenge depending on
extent of convective debris and will do the middle of the road upper
70s to lower 80s.    ..12..

.LONG TERM...(Friday NIGHT THROUGH next Thursday)
ISSUED AT 355 PM CDT Thu May 26 2016

Active weather pattern of almost daily showers & storms the next 7
days with slightly above normal temperatures.

Long term forecast confidence assessment...slightly below average or
fair to poor with timing, coverage and intensity of precipitation
events the main issue.  American models are too moist which impacts
timing and evolution of convective events and propagation.  The most
significant impacts are subsequent events after tonight will be
very suspect.

Overview...Initialization and verification are fair with most
solutions underplaying evolution of developing complex in the
central plains.  Hi-res ECMWF slightly better suggesting a 70/30 mix
with GFS and importance of poor QPF reflection of evolution of
convective systems days 2-7.  Widespread 1 to 4+ rain amounts
expected which may result in water issues by the end of the forecast
period. Precipitable water of 1.5+ over most of the period will
ensure locally heavy rain totals will be an issue.

Friday Night...Local tools support a decent MCS event over at least
NW parts and possibly all CWA with widespread .5 to 1.5+ inches of
rain with some isolated severe of mainly bowing segments of winds to
around 60 MPH.  POPS in the likely category and lows mostly in the
middle 60s.

Saturday...lingering showers and storms with deep and fast south jet
ahead of rotating upper low in south plains moving into the upper
midwest.  Some risk of training of storms for locally higher rain
amounts of 2+ inches possible.  Highs should be mostly around 80
degrees with PM MUCAPES of 1000 to 1500 J/KG for marginal severe
risk in mostly in PM hours.

Saturday night into Sunday...Upper low to rotate northeast across
the region for a probable another convective event.  Timing most
likely for last convective event probably Saturday night with
possibly enough shear and instability for locally severe storms for
later shifts to consider as well as locally heavy rains.  Lows in
the lower 60s with highs mostly in the lower 80s.

Monday and Monday night...mostly dry with a chance of scattered
showers and storms with weak high pressure in southwesterly upper
level flow and slightly drier dewpoints.  Highs in the lower 80s
with mins in the lower 60s and possibly upper 50s.

Tuesday and Wednesday...Next upper level disturbance to impact the
region with poor confidence on timing and location of best forcing.
Large scale regime favorable for decent rains and isolated severe
once again.  Additional rain totals of 1 to locally 2 plus inches
seem reasonable which if get expected widespread rains the next 72+
hours of 1 to 2+ inches should cause water issue on some area

Thursday and Friday...Poor confidence with best estimate of weak
high pressure moving in with little or no chance of precipitation.
Highs should be per local thermal tools mostly in the upper 70s to
around 80 or near normal for late May.  Mins mid 50s to around 60
suggested.    Nichols


ISSUED AT 1153 PM CDT Thu May 26 2016

The potential for showers and thunderstorms throughout will
continue to be a challenge in the terminal forecasts. In the near
term, another round of rain with embedded thunderstorms will
spread north through the terminals overnight. Outside of the
stronger thunderstorms, conditions will remain vfr. Friday, it
looks like there will likely be a break in the precipitation from
mid morning through mid afternoon before another upper level wave
may trigger showers and thunderstorms late afternoon through
early evening. For now, this is presented with vicinity and
prob30 groups, which will likely be hit harder as forecast
confidence increases. The potential for thunderstorms could well
extend beyond the current 03z ending time mentioned at CID, DBQ
and MLI.


.DVN Watches/Warnings/Advisories...


LONG TERM...Nichols
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