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000
FXUS63 KDVN 280000
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
700 PM CDT FRI MAY 27 2016

.UPDATE...
Issued at 700 PM CDT Fri May 27 2016

Over the past hour thunderstorms have lit up along the nearly
stationary low level convergence boundary from DBQ through CID to
just east of OTM. With surface CAPES of 2000 to 2500 j/kg along an
axis from se to east central IA ahead of this feature, and the
slow moving boundary, there will be at least a low potential for
strong storms with heavy rainfall and possibly some small hail.
Also, over the past couple hours the SPC mesoscale analysis non-
supercell tornado parameter has had a maximum over the CID and IOW
area where the nose of the higher cape axis overlaps the low level
convergence and area of weak low level shear. This suggests the
potential for at least brief funnel clouds near strong updrafts.
Tornadoes are not likely, but Will be watching trends closely in
this area.

&&

.SYNOPSIS...
Issued at 330 PM CDT Fri May 27 2016

The latest SFC analysis was indicating a weak wave acrs central
IA...connecting into a warm frontal boundary arching up into
south central WI. South to southeast sfc flow into this boundary
was pooling mid to even upper 60 Dpts acrs the local area, but
these higher moisture levels and cloud cover keeping a lid on
afternoon ambient temp warming as well as SBCAPES. This sfc
wave/boundary feature acrs eastern IA a refection of a remnant MCV
rolling northward up along and east of the MS RVR Valley, with
isolated to sctrd showers and a few thunderstorms on its northern
flank. Other sfc troffiness and low pressure was noted acrs the
west central plains. Aloft...besides the MCV, another vort max was
noted upstream acrs northern AR in steep south-southwest steering
flow.

&&

.SHORT TERM...(THIS EVENING THROUGH Saturday)
ISSUED AT 330 PM CDT Fri May 27 2016

Tonight...Expect the isolated to sctrd showers and storms in the
north half of the DVN CWA to move north or diminish early in the
first period as the MCV rolls up into WI. But then eyes turn to the
vort max to the south acrs the Ozarks. As this feature propagates
toward the area, expect an increase of showers and embedded
thunderstorms to move in from the same direction(south-to-north) as
the night progresses. This activity already forming and taking place
acrs northern AR into the southern third of MO. Rather widespread
areas of showers and embedded storms should make it up to just south
of the I80 corridor by 10-11 PM CDT, and continue to spread north to
the Hwy 20 corridor by 1 AM CDT or so. Projected shear, instability
and saturation profiles all suggest a very marginal threat for any
type of severe weather tonight. But with PWATs of 1.5 to 1.6+
inches, some locally heavy rainfall will be possible. Progressive
nature to the more enhanced cells should limit any one area really
getting hit hard with heavy enough rain to produce flooding, and
most areas will get from 0.25 to 0.75 of an inch of rainfall by Sat
morning. Expect another night of rain cooling, sub-guidance sfc
dpts, or storm outflow to produce low temps generally below most of
the guidance lows, so will go with low to mid 60s.

Saturday...after some lingering showers exit the Hwy 20 corridor,
the rest of the morning will look to be a lull period with little or
no shower/storms acrs the local area as the overnight upper level
wave shears out acrs MN and WI. But cyclonic southwesterlies
pivoting acrs IA around the main wave acrs the MO RVR Valley will
then look to spark more sctrd showers and storms acrs the local FCST
area by Sat afternoon. With more clouds/LLVL moisture/ convective
debris in mind, will go with highs in the upper 70s to lower 80s and
limit the SBCAPES to 1500 to 2000 J/KG by afternoon. Vertical
deep shear profiles also look limited by Sat afternoon, thus
another marginal severe weather threat day. But if more insolation
occurs than currently expected and can boost higher temps/CAPES
during the afternoon, can`t rule out at least an isolated strong
to severe storm in the local area with damaging winds the main
threat.   ..12..

.LONG TERM...(Saturday NIGHT THROUGH next Friday)
ISSUED AT 330 PM CDT Fri May 27 2016

Main focus is with upcoming Memorial Day holiday forecast.
Overall, the signal appears to be toward limited precip chances
and mostly dry. Having said that, Saturday night harbors the best
opportunity for measurable rain with passing upper level trough,
although still kept at just moderate chances given boundary layer
stabilization, waning jet dynamics and weak positive vorticity
advection. Sunday will have just a small chance during the
afternoon mainly over northeast Iowa and northern Illinois in
lingering cyclonic flow on backside of departing shortwave. Highs
Sunday expected to be in the upper 70s to lower 80s. On Monday,
Memorial Day, another weak disturbance and diurnal heating should
bring about scattered showers and storms during the afternoon,
with the best chances /30-40 percent/ west of the Mississippi
River. Highs on Memorial Day look to be a tad warmer and mainly
around 80 to lower 80s.

Tuesday through Friday...confidence is poor on main features
especially late week with substantial run to run model
differences, more notable with GFS. GFS has a closed low over the
central plains by late week, with moisture streaming northward and
upper diffluence for continued day to day storm chances last half
of the week. Meanwhile, the ECMWF has the low over western
Ontario, which would place the region in drier northwest flow.
This would favor weak high pressure and pleasant conditions for
the region to start June. Forecast is attempting at a blend with
pops adjusted down to slight chance while temps nudged down to
near seasonal normals in the upper 70s to around 80.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z Saturday EVENING)
ISSUED AT 700 PM CDT Fri May 27 2016

A weak front will keep showers and thunderstorms in the CID and
DBQ area early this evening, then another upper level disturbance
is expected to send a wave of more organized thunderstorms through
the region later this evening. For the most part, conditions will
be VFR outside thunderstorms, but a period of MVFR cigs is
possible later tonight into early Saturday morning. This is low
confidence, but was included at DBQ and BRL. Saturday,
thunderstorms are again possible, especially late afternoon
onward. This has been handled with a broad brush prob30 mention
in this timeframe.

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

UPDATE...Sheets
SYNOPSIS...12
SHORT TERM...12
LONG TERM...05
AVIATION...Sheets





000
FXUS63 KDVN 271800
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
100 PM CDT FRI MAY 27 2016

...18z AVIATION UPDATE...

.UPDATE...
Issued at 509 AM CDT Fri May 27 2016

The convectively induced forcing that developed the band of rain
across the area earlier is now moving into Wisconsin. The
previously mentioned possibility of a minima in precip appears to
be occurring. Thus little if any precipitation now looks to be in
store for the area through mid-morning.

Another area of convectively induced forcing/precipitation is
moving northeast across western Missouri. If the RAP trends are
correct, this forcing should result in a new round of showers and
eventual thunderstorms across the area starting late this
morning.

&&

.SYNOPSIS...
Issued at 253 AM CDT Fri May 27 2016

06Z sfc data has a collapsing meso high from central Iowa into
northern Missouri. The main frontal boundary ran from southern
Kansas into central Missouri with a squall line across eastern
Kansas. Dew points were were in the 60s from the Great Lakes and
Ohio Valley to the Gulf coast. Dew points in the 40s and 50s were
across the central and northern Plains.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 253 AM CDT Fri May 27 2016

Through sunrise a band of showers with embedded thunderstorms will
move north through the area. This precipitation is a result of
forcing created by the thunderstorm complex across Missouri last
evening.

For Friday, boundaries left over from the overnight convection will
provide the focus for new convection to develop during the day. Thus
isolated to scattered showers and thunderstorms should be seen
through sunset. The possibility does exist that convection may be at
a minimum during the morning hours with most of the area being dry.

Tonight, stronger forcing will move through the area. Isolated to
scattered convection during the evening will become more widespread
during the late evening and overnight hours.

.LONG TERM...(Saturday THROUGH Thursday)
ISSUED AT 253 AM CDT Fri May 27 2016

Convective chances will continue in our forecast for Saturday and
Saturday night as the main upper system passes through the region.
This does not mean widespread rainfall is a guarantee. Models offer
a variety of convective mode transitions of scattered strong storms,
to a swing a miss of a linear mode system to the west.  In the end,
it`s only worth 40 to 60 percent pops during the period for Sat/Sat
night, and QPF will be forecast conservatively with locations
generally under 1/2 inch. That said, the pwat values are certainly
supportive of localized heavy rain from storms over 1 inch, but out
river "basin average" QPF will not resolve this possibility until in
the short term.

Sunday, the dry slot will be sweeping through early in the day, and
I have reduced pops to slight chance in the morning, and a dry and
warm afternoon is expected. Dry weather should last through Sunday
night before showers and thunderstorm chances return for Memorial
Day through Thursday. The 00z model consensus suggests the best rain
threats during that period will be Monday night, and Tuesday. In
other periods, there is great differences in the position of the
upper trof locations, with the GEM and GFS slowest, and the EC the
fastest. Given how slowly the upper trof has been to move from the
southwest this past week, I think the GEM/GFS should be favored
here, especially since convective contamination does not seem to be
a factor in the synoptic trof speed.  Never the less, the divergent
model solutions result in much lower pops for Wednesday and
Thursday.

Temperatures in the lower 80s for highs and upper 50s to mid 60s for
lows will last through mid week, before a slight cool down for
Thursday and Friday.

Like earlier forecasts have noted this week, the most difficult task
in this intermittent convective pattern may be to show that dry
weather is as likely as rain on many days. That is a challenge for
all communicating this forecast.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z Saturday AFTERNOON)
ISSUED AT 1248 PM CDT Fri May 27 2016

MVFR Cigs acrs the area should raise to low VFR except at maybe
DBQ this afternoon. Isolated to sctrd showers and a few
thunderstorms will be possible in the VCNTY of most of the sites
as well, but maybe more prevalent around CID. South to southeast
SFC winds of 10-15 KTs and some higher gusts, will become lighter
south overnight. Another upper level wave approaching the area
from the southwest will kick up more widespread showers with
embedded thunderstorms spreading up from south-to-north from mid
evening and into the overnight. Locally heavy rainfall may reduce
VSBYs to under 2 miles at times. As the rain lets up again late
tonight, some MVFR fog possible thru sunrise if sfc winds go light
enough. Increasing southwest winds and rising CIGs expected by mid
Sat morning.   ..12..

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...Ervin
AVIATION...12





000
FXUS63 KDVN 250847
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
347 AM CDT WED MAY 25 2016

.SYNOPSIS...
Issued at 239 AM CDT Wed May 25 2016

An area of thunderstorms continued across the Plains into
southwest Iowa during the early morning hours. Warm and moist area
remained in place across the area, with early morning temperatures
mainly in the mid to upper 60s.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 239 AM CDT Wed May 25 2016

The main forecast issues in the short term period involve
convective timing, coverage and intensity.

In the near term, various CAMS indicate a leading wing of showers
and storms developing early this morning and lifting northeast
across the forecast area. Based on recent radar trends and weak
deep layer shear, am thinking the main threat from the strongest
storms will be some small hail. However, by late morning into the
afternoon, an approaching H5 trough will enhance forcing and deep
layer shear. This feature, coupled with areas of enhanced moisture
convergence along a northward lifting warm front, should mean some
storm reintensification by late morning into the afternoon.
Forecast soundings suggest the main threat will be elevated storms
with large hail. However, there is some potential for a narrow
window of surface based storms with isolated damaging wind gusts.
Enhanced 0-1km shear of 20-25 kts near the boundary indicates that
an isolated brief tornado also cannot be ruled out. SPC has areas
east of a line from Dubuque, to Moline and Galesburg in slight
risk for today. Unseasonably warm and muggy conditions will
continue today with highs mainly in the low 80s, although not as
warm as Tuesday with the increased cloud cover.

For tonight, there is considerable uncertainty regarding favorable
areas for additional storms tonight. The 12km WRF is hanging up a
remnant boundary near the I-80 corridor with some heavy rainfall
amounts late. Certainly not sold on this scenario, and we will
have to see how the trends play out today before getting a better
handle on tonight`s weather.

.LONG TERM...(Thursday THROUGH Tuesday)
ISSUED AT 239 AM CDT Wed May 25 2016

Forecast focus on periods of active weather through the middle of
next week. Continued above normal temperatures.

Thursday, a brief lull in the action as operational models depict
weak ridging surface and aloft, due to subsidence in the wake of the
wave that moves through the night before. With sunshine and
southerly winds this should push temperatures into the mid to upper
80s at many locations. In addition, dewpoints will be well into the
60s to near 70 making for a summer-like day as heat index values
will push into the lower 90s.

Thursday night through Saturday, the active pattern resumes as the
main trough and surface low gradually pulls out of the Plains and
across the Midwest. There is a low risk of severe storms as the deep
layer shear just does not look that impressive, but it`s not zero
either. Also, this is a positive-tilt system and weak surface low.
Temperatures will remain somewhat above normal with highs in the
upper 70s to lower 80s, due to an increase in cloud cover this
period.

Sunday and Memorial Day, another lull as weak ridging surface and
aloft builds into the area. Will only have slights or small pops but
later shifts may be able to remove pops for one or both of these
days depending on model trends. With more sunshine expected
afternoon highs will push again well into the 80s.

Tuesday through Wednesday...Active pattern returns again as another
upper level trough swings out of the Rockies and into the Upper
Midwest. However, deep layer shear again not impressive as the main
cyclone will track well to our north and in a weakening fashion.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Wednesday NIGHT)
ISSUED AT 1152 PM CDT Tue May 24 2016

A large complex of thunderstorms in the plains is expected to
continue eastward tonight, reaching the eastern IA terminals
wednesday morning. These will likely be weakening considerably by
this time, but still result in MVFR if not brief periods of IFR
conditions. Once this moves eastward early in the afternoon,
confidence on subsequent convective trends is low and the current
forecast has VFR conditions in the afternoon with thunderstorm
chances waning. Another round of storms is possible Wednesday
evening, but this has been only included as a vicinity group for
now at the BRL site where confidence of impact is slightly
higher.

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

SYNOPSIS...RP Kinney
SHORT TERM...RP Kinney
LONG TERM...Haase
AVIATION...Sheets





000
FXUS63 KDVN 250452
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1152 PM CDT TUE MAY 24 2016

...AVIATION UPDATE...

.UPDATE...
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
sunrise.

&&

.SYNOPSIS...
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.

&&

.SHORT TERM...(THIS EVENING THROUGH Wednesday)
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 swaths...one 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-e airmass
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
level.

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..

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Wednesday NIGHT)
ISSUED AT 1152 PM CDT Tue May 24 2016

A large complex of thunderstorms in the plains is expected to
continue eastward tonight, reaching the eastern IA terminals
wednesday morning. These will likely be weakening considerably by
this time, but still result in MVFR if not brief periods of IFR
conditions. Once this moves eastward early in the afternoon,
confidence on subsequent convective trends is low and the current
forecast has VFR conditions in the afternoon with thunderstorm
chances waning. Another round of storms is possible Wednesday
evening, but this has been only included as a vicinity group for
now at the BRL site where confidence of impact is slightly
higher.

&&

.DVN Watches/Warnings/Advisories...
IA...None.
IL...None.
MO...None.
&&

$$

UPDATE...Sheets
SYNOPSIS...Uttech
SHORT TERM...Uttech
LONG TERM...12
AVIATION...Sheets





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