fxus63 kdvn 142315 

Area forecast discussion 
National Weather Service Quad Cities Iowa Illinois 
615 PM CDT Tue Aug 14 2018 

..00z aviation update... 

issued at 330 PM CDT Tue Aug 14 2018 

Current water vapor loop was indicating upper low opening up acrs 
the Kansas/MO border region, with another upper level short wave noted 
digging southeastward acrs eastern Montana. The upper low to the 
southwest will get booted by the other wave and drift acrs the area 
overhead by Wednesday morning. This system will bring precip chances 
to the area tonight through Wednesday evening, with decreasing 
chances into the weekend except for maybe Friday. Another potential 
system with some strength lurks in the medium range models for early 
next week. 


Short term...(this evening through wednesday) 
issued at 330 PM CDT Tue Aug 14 2018 

Tonight...bands of showers, or sctrd areas will try and propagate 
northeastward in northeast flank of the upper wave this evening. The 
current activity having some trouble as it gets away from better 
support and coming in slower than earlier model run. But incoming 
higher precipital water(pwat) feed on 15-20 knots low level jet of 1.7 to 2 
inches, along with some elevated convergence should allow an 
increase in showers acrs the southwest half of the fcst area as the 
late afternoon and evening progress. Some instability to produce 
some lightning and thus thunderstorms, but increasing column 
saturation indicated by fcst soundings tonight as the upper low 
drags both monsoonal and west Gulf moisture up acrs the region may 
translate more of an isolated embedded thunder occurrence overnight. 

But until it does, incoming bands may be more of a sctrd thunder 
coverage especially south of I-80. Will decrease pops tonight in some 
areas for expected dwindling coverage of bands to sctrd or even 
isolated coverage. Despite very high incoming pwat's, lack of shear 
or forcing will limit a widespread heavy rain threat tonight, but 
any more enhanced cell or cluster will still produce very localized 
heavy downpours as they pass by. In general, will advertise most of 
the area getting 0.20 to 0.50 of an inch by Wednesday morning, with 
most areas on the lower end of that range. Where the rain lets up or 
is not occurring, with lingering high sfc dewpoints and convergent light 
winds around a developing sfc trof type feature under the 
approaching low may allow for at least patchy fog developing late 
tonight into early Wed morning. Will bank on thickening cloud cover 
aloft to limit widespread dense fog forming overnight. Most area low 
temps held up in the upper 60s. 

Wednesday...with the more significant rains/thunderstorm activity 
occurring on the southern and southeastern flank of the upper low 
acrs southern MO into the south half of Illinois tonight into Wed morning, 
some of that may be drawn up along and to the east of the County Warning Area Wed 
morning. Thus will go with higher coverage along the eastern fringe 
of the County Warning Area through 18z, but otherwise/elsewhere may be more of a low 
clouds, lingering fog, drizzle and spotty showers scenario through 
midday, before more sctrd showers and some storms pop up under the 
low Wed afternoon. Again expect marginal coverage with this afternoon 
activity, thus very limited/localized decent rain chances. 
Overall, am getting only widespread rainfall values of 0.30 to 
0.60 of an inch for tonight through 24 hrs/00z Thu...hardly a 
drought-denter. Although there may be some breaks in the 
afternoon, mostly cloudy skies and saturated column will make for 
temps limited to a warm up potential of mainly upper 70s, with 
some areas around 80 and others possible held in the mid 70s. Will 
also have to watch for non-supercell funnels on Wednesday with 
the upper low overhead and low lcl's in saturated lower layers. 

Long term...(wednesday night through next tuesday) 
issued at 330 PM CDT Tue Aug 14 2018 

An active pattern through early next week should lead to most areas 
receiving some much needed rainfall over the next 7 days. 

Wednesday night will see the departure of a shortwave trough into 
the Ohio Valley and lower Michigan. In it's wake weak high 
pressure will settle in providing about 24+ hours of mainly dry 
conditions. Weak winds and residual low level moisture may lead to 
some fog development overnight Wednesday - Thursday am. A 
secondary compact closed low will approach from the plains late in 
the day Thursday eventually shifting across the mid-Mississippi 
Valley on Friday. Rain prospects will be on the increase during 
this time, although it's possible to see the bulk of any rain 
delayed until Friday tied with the vort Max. Rainfall amounts 
mostly light to moderate of around one half inch or less, but 
potential for some areas to see an inch or more where repeated 
activity occurs. These heavier amounts would be most favored 
further south of I-80 as it looks right now. 

Great Lakes ridging then looks to take hold of the weather for most 
of the weekend providing generally dry conditions and seasonable 

Early next week is showing Promise for more widespread and potentially 
soaking rains, as phasing of northern and southern stream energy 
looks to bring the potential for a more organized low pressure 
system. Will continue to watch this system closely in the coming 
days, as it could have some increased moisture availability aided 
by Gulf and monsoonal components and with strength of forcing 
could lead to opportunity for widespread 1+ inch rain amounts 
Monday through Tuesday. 


Aviation...(for the 00z tafs through 00z Wednesday evening) 
issued at 612 PM CDT Tue Aug 14 2018 

VFR conditions will primarily be seen at all terminals through 
15/05z, with MVFR to IFR cigs possible with scattered evening 
showers and storms. After midnight, expect more widespread MVFR 
conditions to spread from south to north as additional rain 
showers and low clouds move across the area. Brief drops to IFR 
will also be possible, but have not included this in taf due to 
low confidence. 


Dvn watches/warnings/advisories... 


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