Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

958
FXUS63 KDVN 220934
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
334 AM CST Wed Feb 22 2017

.SYNOPSIS...
Issued at 330 AM CST Wed Feb 22 2017

The moisture never did get very far away from the area yesterday
with the weak high pressure in place, and that left the stage set
for shallow moisture return on the developing south winds this
morning. Dense fog has spread throughout most locations southesat of
Mt. Pleasant to Maquoketa to Freeport Il line as of 2 AM.
Temperatures have risen slightly since mid evening, and with
dewpoints in the upper 40s to lower 50s working in, it looks like
we`ll have a very mild start to the day, but the fog will at least
create some negative impact to the initial rise in temperatures.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Wed Feb 22 2017

The HRRR has a great handle on the fog, and is on board with a 8-9
AM mixing out, and with clear skies above it, that looks accurate.

Yesterday, Omaha mixed to above 850mb.  Needless to say, it we pull
that off, we`re going to destroy records by 8 to 10 degrees. It does
look like there will be a 3 to 5 hour period from late morning,
where a combination of clear skies, southwest winds around 20 mph
gusting to 28 mph will bring ideal warming conditions. This supports
highs reaching the lower to mid 70s area wide. If we take full
advantage of today`s set up, I still can`t rule out upper 70s, but
again, that`s a best case scenario, and the morning dense fog will
create enough of an unknown for me to keep from going with that.

The rise in afternoon temperatures should also correspond with a
drop in humidity values to under 35 percent in the southwest 1/2 or
so. This will create GFDI values in the very high range for several
hours, and we`ll keep addressing this fire spreading threat in the
HWO and in today`s weather graphics.
ERVIN

.LONG TERM...(Thursday through next Tuesday)
ISSUED AT 330 AM CST Wed Feb 22 2017

Thursday...Latest suite of 00z run models suggest Thu to be a post-
frontal day with boundary laying out west-to-east along and south of
the CWA. Will have to watch for at least some patchy fog in the
northern third of the CWA Thu morning, then attention turns to
increasing lift signal acrs the area from the southwest to lee of
developing upper trof. Strong isentropic signal suggest overrunning
rains to spread up and over the boundary as the day progresses and
especially during the afternoon. Will keep it stratiform rain for
now through 00z Fri, but an embedded thunderstorm possible in the
west/southwest by late afternoon. Rain more widespread acrs the
south half of the CWA Thu afternoon in and just north of developing
prime LLj convergent zone...0.10 to 0.20 tenths of an inch of rain
possible by early evening in these areas. Despite easterly llvl flow
north of the front and increasing precip chances, still a seasonably
mild day with highs in the upper 40s north, to the upper 50s/around
60 in the south.

The models continue to vary with developing llvl cyclone and ejection
path northeastward out of the southern/central plains Thu night into
Friday.  00z run SREF placement has the sfc low center deepening
close to 990 MB acrs central into north central IA by 12z, while the
00z ECMWF continues to be a southern trender with the cyclone near
Kirksville MO at that time. But even the further south Euro`s thermal
parameters support all liquid precip even in the northwest thru Fri
morning. Several medium range models suggest strong warm moist
conveyor on nose of 50 KT LLJ converging just north of the LLVL
boundary targeting the northern 2/3`s of the DVN CWA Thu night.
Again, it appears this process to fuel a elevated/overrruning rain
band embedded with thunder or even a elevated cool season type of MCS
acrs the area. The NAM suggests a plume of 500-1000 J/KG MUCAPES to
push acrs the CWA THu night from the southwest supporting thunder
chances, but they should be rooted above strong llvl shear profiles
hopefully to limit the severe risk. But if they can tap into the
upper layer of the enhanced shear profiles, there would be at least
a hail threat. PWAT feeds of an inch or even more suggest rainfall
amounts of the same values possible under the prime convergent
swaths by early Fri morning. Thus seasonably heavy rainfall and some
run-off may produce rises on area creeks and rivers by Fri.

Friday...This day initially looks to be a dry slot/punch day from the
southwest for a part of the day, but lingering showers and even
some storms in the north and east through midday. Windy an mild
conditions in the dry slot with gusts up to at least 35 MPH, and
deep mixing in temporary WAA surging temps into the upper 50s or
even 60s acrs the east half of the FCST area. Interaction of dry
slot into warm moist tongue under strong diffluent southwesterly
cyclonic lift regime may spawn a severe weather episode/supercells
not all that far east of the CWA Fri afternoon, with southwestern
IL into NW Indiana looking like the prime axis currently.

Fri night...wrap around def zone band of precip still on track to
sweep east acrs the CWA, just some timing and thermal differences
still in the latest available medium range solutions. But the gist
is that strong in-wrapping cold conveyor should switches the rain
into wet snow with current model runs suggesting from a half inch
to 1.5 inches possible by Sat morning north of I80. The snow may
fall as northwest winds increase to 15 to 30 MPH making for reduced
VSBYS and tricky travel, but it may also occur lat Fri night and
early Sat morning. Warm ground from the recent warm spell also may
play as a snow accumulation inhibitor, unless rates can overcome
that.

Saturday and Sunday...The latest runs suggest Sat to be dry and more
seasonable, and will have to watch for a light isentropic precip
event on Sunday as return flow/lift impinges on lingering llvl
baroclinicity. The 00z ECMWF has remained more consistent with light
precip amounts and south track, while the 00z GFS has trended wetter
and further north. Somewhat moderating temps on Sunday as well.

Next Monday and Tuesday...Longer range signals suggest continued
thermal moderation into early next week, as well as a delay of the
next warm moist conveyor from the south fed precip event not til
late Mon nigh or more like Tue. The further the delay, the more
likely it will be mainly another rain event as opposed to snow or
wintry mix. Mild signal and another strong cyclone rolling acrs the
Midwest for mid next week.    ..12..

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
ISSUED AT 1131 PM CST Tue Feb 21 2017

Overnight LIFR/IFR conditions at BRL and MVFR/IFR at MLI due to
fog until 22/15Z. Then, mostly VFR conditions expected with clear
to mostly clear skies. Light southerly winds overnight will tend
to be southwesterly at 10 to 15+ MPH mid to late day on Wednesday
and then decrease to 5 to 10 MPH after sunset.

&&

.CLIMATE...
ISSUED AT 330 AM CST Wed Feb 22 2017

Record Highs for today February 22...

Moline.........66 in 1922
Cedar Rapids...64 in 1984
Dubuque........61 in 1984
Burlington.....66 in 2000

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Dense Fog Advisory until 9 AM CST this morning for Cedar-Clinton-
     Des Moines-Henry IA-Jackson-Lee-Louisa-Muscatine-Scott.

IL...Dense Fog Advisory until 9 AM CST this morning for Bureau-
     Carroll-Hancock-Henderson-Henry IL-Jo Daviess-McDonough-
     Mercer-Putnam-Rock Island-Stephenson-Warren-Whiteside.

MO...Dense Fog Advisory until 9 AM CST this morning for Clark.

&&

$$

SYNOPSIS...Ervin
SHORT TERM...Ervin
LONG TERM...12
AVIATION...Nichols
CLIMATE...Ervin



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.