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Office: DVN

FXUS63 KDVN 172324
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
624 PM CDT Tue Jul 17 2018

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 225 PM CDT Tue Jul 17 2018

High pressure continued in place across the area today leading to
a lower humid day across the area. This high pressure will
continue to control the weather through the short term period.

&&

.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 225 PM CDT Tue Jul 17 2018

Little as far as forecast concerns expected through the period
with temperatures the main forecast issue. That said, the sensible
weather point of view is that the continued less humidity air will
lead to beautiful weather through the short term. An H5 wave west
of the area will begin to induce deep layer moisture return late
in the period and set up the beginning of the long term forecast.

.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 225 PM CDT Tue Jul 17 2018

Wednesday night through Friday, the area will see chances for
thunderstorms and rain, with a broadly forced warm advection event
followed by a cold front Friday. That system will be watched closely
as there is deep layer shear expected to be in place.  However,
there is also expected to be modest capping, and a lack of low level
focus for storms. Because of that, I am holding back both pops and
QPF from the higher potentials. The main convergence at the surface
and aloft by most models will be north into Minnesota and Wisconsin,
while we see some potential development on the south flank of any
ongoing convection Wednesday night into Thursday. That may be a
swing and a miss, if that the northern convection does not form much
of a cold pool. Thursday into Friday, the cold front will move
through, again with possibly little convergence for storms at the
surface. QPF could be quite variable, and may once again leave some
areas dry while being significant in others.

The entire forecast period, from Wednesday night through next
Tuesday will see pleasant temperatures in the lower to mid 80s for
highs and lows in the upper 50s to mid 60s. Initially, this will be
held down by clouds in the warm sector through Friday, followed by
very pleasant conditions for Saturday through Tuesday as Canadian air
moves over the region.

ERVIN

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 624 PM CDT Tue Jul 17 2018

VFR conditions will be seen through 00z/19 as high pressure moves
into the Great Lakes and Ohio Valley.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Ervin
AVIATION...08



Office: LOT FXUS63 KLOT 172324 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 624 PM CDT Tue Jul 17 2018 .SHORT TERM... 210 PM CDT Through Wednesday... A fairly quiet weather day continues across the region this afternoon. NW flow aloft and high pressure building into the region will keep nearly the entire area dry through the period. The one exception is the southwest half of the Chicago metro this afternoon where a lake enhanced boundary and resultant increased moisture convergence have forced a field of deeper cumulus. Convective cloud depths of at least 5kft should be sufficient to generate some sprinkles over the next several hours. Regarding the high swim risk in NW Indiana, stronger N/NNE winds have come in multiple waves throughout the day rather than remain continuous, so most buoys have struggled to record wave heights much above 3ft. While this falls just short of high swim risk criteria (closer to 4ft), webcams have indicated decent shoreline waves through the day. Will therefore maintain the Beach Hazards Statement through 03Z. Dry weather and mostly clear skies are expected tonight and Wednesday, with a decent cumulus field developing across the west half of the CWA Wednesday afternoon. Based off the upstream airmass and lower forecast 925/850mb temps, max temps should be at least a couple degrees cooler than today. Plan on highs in the mid 70s along Lake MI to around 80F inland. If enough high cloud cover filters overhead, temps may remain just shy of 80F inland. Kluber && .LONG TERM... 210 PM CDT Wednesday night through Tuesday... A more unsettled pattern will take shape through the latter half of the week and a closed upper low gradually makes its way across the region. Solutions from the GFS, ECMWF, and GEM remain in fairly good agreement with the evolution of the upper low across the region through Friday while the NAM becomes a southerly outlier Thursday night into Friday. Model consensus suggests the upper low will dig from the Dakotas into Minnesota on Thursday. Meanwhile, surface ridge axis will shift farther east into the eastern Great Lakes with return flow causing dewpoints to inch back up into the low to mid 60s Thursday. The GFS has had good run-to-run consistency past few days indicating the best shear/CAPE staying off to our West Thursday with the thunderstorm threat arriving later in the day Thursday. Barring any big changes in this expectation, appears that the severe threat should diminish east of the Mississippi River Valley later in the day Thursday. Upper low continues slowly east across Wisconsin on Friday and will provide additional chances for showers and thunderstorms. Dewpoints continue to become more uncomfortable with widespread upper 60s and low 70s expected. GFS has again been fairly consistent indicating the best shear and instability along with the highest severe threat will stay well to our south. While there will likely be instability locally under the influence over the upper low, it may be tempered somewhat by cloud cover. The 500mb trough axis should shift to our east over the weekend. Northwest flow aloft and cold air advection will support the possibility of additional diurnal showers over the weekend. The pattern will remain favorable for slightly below normal temperatures to continue into early to middle of next week. Deubelbeiss && .AVIATION... For the 00Z TAFs... Dry and VFR conditions are expected through the period with generally NE winds and some cirrus and diurnal cumulus. Winds will becm lgt/vrbl overnight and then increase to nely 7-10 kt late tomorrow morning. && .MARINE... 210 PM CDT A moderate north breeze is in place over Lake Michigan behind a cold front. Winds should very gradually diminish this evening and overnight as high pressure builds from the Upper Midwest across the western Great Lakes region. The ridge axis will settle over northern Lake Michigan during the day Wednesday allowing light and variable flow and afternoon lake breezes to produce onshore winds. Southerly flow will gradually pick up again Thursday into Friday behind the ridge and ahead of an approaching low. The low will very gradually meander east across the region over the weekend providing periodic chances of showers and thunderstorms. BMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...Beach Hazards Statement...INZ001-INZ002 until 10 PM Tuesday. LM...Small Craft Advisory...IN nearshore waters until 10 PM Tuesday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Office: ILX FXUS63 KILX 180152 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 852 PM CDT Tue Jul 17 2018 .UPDATE... Issued at 852 PM CDT Tue Jul 17 2018 High pressure to the north is bringing light north winds and mostly clear skies to central Illinois this evening. Mostly clear skies will continue overnight, with winds shifting more easterly. Lows should reach the low 60s in most locations. Current forecasts are on track with these features and no significant updates are needed this evening. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 242 PM CDT Tue Jul 17 2018 Pleasant weather will continue across the CWA as high pressure remains in-place through Wednesday. Temps will remain slightly below normal as well. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 242 PM CDT Tue Jul 17 2018 The flow will become more northwesterly for the remainder of the week with a sfc system dropping into the northern plains/Miss valley for later part of the week and possibly into the weekend. The models show some differences with the return of precip to the region with the NAM quicker than the GFS/ECMWF. The NAM seems to have a better defined warm-type front moving into the area late Wed night into Thur, keeping the precip west of I-55. The ECMWF/GFS are slower, so pops will remain on the low side for that time period. As models get into better agreement toward the end of the week, pops will become higher with likely pops for part of the area on Friday. This will be the main period that the front/sfc system moves through the CWA. Models differ on what the sfc will look like through this time period but have some agreement on outcome. Precip should begin to wane Friday night and Sat as the system/front moves east of the area. Remainder of the weekend should be dry, but with the pattern remaining northwest, the GFS has an upper level low situated over the Great Lakes region; and this brings precip back into far eastern parts of the CWA for Sunday. Beginning of next week will remain dry as well after this brief system moves further east. Temps will remain slightly below normal through rest of the week, through the weekend and into next week. A blend of the models looks good for this as well. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 607 PM CDT Tue Jul 17 2018 VFR conditions will prevail at all central IL terminals for the next 24 hours. Skies mostly clear other than high thin cirrus and limited afternoon shallow cumulus coverage. Winds north up to 7 kts decreasing and shifting eastward overnight. East-northeast winds up to 8 kts after 14Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Auten LONG TERM...Auten AVIATION...37