fxus63 kdvn 212343 

Area forecast discussion 
National Weather Service Quad Cities Iowa Illinois 
643 PM CDT sun Oct 21 2018 

..aviation update... 

issued at 242 PM CDT sun Oct 21 2018 

Cool and dry conditions were found across the area this afternoon. 
Winds were gusty at times from the southwest in the pressure 
gradient between departing high pressure over the mid Mississippi 
River valley and a developing surface trough reaching from NE to 
Upper Michigan. Temperatures early this afternoon were in the upper 40s 
to lower 50s over the forecast area. Very dry air was in place and 
dewpoints were only in the 20s to lower 30s. This was resulting 
in a large expanse that was free of cloud cover over the central 
and northern plains. 


Short term...(this evening through monday) 
issued at 242 PM CDT sun Oct 21 2018 

Temperatures are the primary challenge as northwest flow aloft 
and advancing surface front have meager moisture to work with. The 
developing front to our northwest will push through the forecast 
area from northwest to southeast Monday morning. With a wedge of 
warmer air at 850 mb along and ahead of the surface front, 
temperatures will remain comparatively mild over much of the area 
tonight and Monday. 

Tonight, winds will diminish to less than 10 kts this evening and 
veer toward northwesterly in the northwest toward morning as the 
front approaches. This should be enough mixing to keep 
temperatures warmer than last night. However, the very dry air at 
the surface and cloud-free skies should still allow temperatures 
to cool into the lower 30s north to lower 40s south, which would 
be 10 to 15 degrees warmer than this morning. Stronger winds off 
the deck associated with an early evening 925 mb to 850 mb 35 kt to 
40 kt low level jet will result in low level wind shear this 
evening across the south, as mentioned in the aviation discussion. 

Monday, the weak front will push southeast of the area by afternoon 
accompanied by perhaps only few mid and high level clouds due to 
the dry air. Strong cold air advection will lag well behind the 
wind shift, allowing surface temperatures to recover into the 
upper 50s to lower 60s, as currently observed across the Dakotas. 
Considering the weak surface flow and model suggesting shallow 
mixing, have trended closer to the cool side of guidance highs 
which would be reached early afternoon, followed by a faster than 
typical mid to late afternoon cooling trend. 

Long term...(monday night through sunday) 
issued at 242 PM CDT sun Oct 21 2018 

Monday night through next sunday: 

Monday night through wednesday: dry and very cool northwest flow 
during this time frame. Temperatures will be below normal with highs 
generally in the upper 40s to lower 50s. Lows should bottom out in 
the 30s. 

Thursday through friday: models similar in lifting an upper level 
trough out of the southern rockies and into the Midwest. This will 
be quickly followed by a clipper system dropping southeast out of 
western Canada. Moisture looks limited for both of these troughs as 
sprawling high pressure will extend from the Great Lakes to the 
southeast United States. This will prevent Gulf moisture from moving 
northward. Pops will remain quite low at only 20-30 percent. 
There will be considerable cloud cover keeping temperatures below 
normal. Highs again will be in the upper 40s to lower 50s with lows 
in the 30s. 

Next weekend...northwest flow aloft returns with models similar 
dropping a rather potent trough into the area. Yet again moisture 
will be limited and the grids will have low chance pops. 
Temperatures will still remain below normal for late October. 



Aviation...(for the 00z tafs through 00z Monday evening) 
issued at 636 PM CDT sun Oct 21 2018 

Increasing SW winds aloft will result in low level wind shear 
at kbrl, kcid, and kmli tonight. Sustained west-southwest winds at 1500 ft 
above ground level are forecast between 35-40 kts. Otherwise, VFR conditions 
will prevail through the next 24 hours. Uttech 


issued at 110 PM CDT sun Oct 21 2018 

Minor to major flooding continues on several rivers in eastern 
Iowa and northwest Illinois. Little, if any, rainfall is expected 
over the next 7 days and forecasts are expected to remain 
relatively unchanged over the next several days. 

Coralville Lake Reservoir was at 710.7 feet and slowly falling. 
It will slowly fall over the next week, reaching 707 feet late 
this upcoming week. 

On the Mississippi River, routed flow resulting from rainfall 
earlier this month upstream over portions of WI and Minnesota is 
resulting in secondary rises, and in some locations, renewed 
flooding. A crest appears to be passing through Bellevue and this 
crest is forecast to be noticeable down river through Muscatine. 
Several sites along this stretch will continue to experience 
minor to moderate flooding over the next several days. From 
Muscatine to Gregory Landing, moderate to major flooding is 
expected through much of the upcoming week. Along this stretch, 
the advancing flow is not forecast to result in additional rises, 
but will prolong the on-going flooding. 


Dvn watches/warnings/advisories... 



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