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000 
FXUS63 KDVN 230926
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
426 AM CDT Sun Jul 23 2017

...HYDROLOGY UPDATE...

.SYNOPSIS...
Issued at 303 AM CDT Sun Jul 23 2017

06Z surface data has a stalled frontal boundary running from 
northern Ohio into northern Oklahoma. Dew points were in the 70s 
from the southern Great Lakes into the central Plains with 50s and 
60s from the upper Great Lakes into the northern Plains.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 303 AM CDT Sun Jul 23 2017

Through sunrise, quiet but humid conditions will continue.

The question for Sunday is when does the diurnal convection develop. 
The large thunderstorm complex across Missouri and its associated 
cloud cover will briefly hold temperatures down for part of the 
morning.

The arrival of an upper level disturbance combined with diurnal 
heating and the next cool front is expected to initiate isolated to 
potentially scattered showers and thunderstorms across the southeast 
half of the area starting around mid-day and continuing through the 
afternoon.

Heat index readings will be in the 95 to 100 range for part of the 
afternoon for areas south of a Sigourney, IA to Kewanee, IL line. 
Once the cold front passes those areas around mid-afternoon, heat 
index readings should drop back into the mid 90s. At this time there 
are no plans for any heat headlines. However, an SPS will be issued 
for the area at risk.

Tonight, the showers and thunderstorms will either move out of the 
area or dissipate by sunset across the far east and south areas. 
Otherwise, expect quiet conditions as less humid air moves into the 
area. 

.LONG TERM...(Monday through Saturday)
ISSUED AT 303 AM CDT Sun Jul 23 2017

Dry and comfortable conditions are expected over the area Monday 
into Tuesday with northwest flow aloft and a large area of surface 
high pressure settling in over the region.

The weather will become active again late Tuesday night through 
thursday as an upper trof traverses southern Canada, forcing a cold 
front into the region.  The 00z model runs are suggesting a more 
progressive system than earlier runs depicted.  Although the 00z 
ECMWF was slowing the front at it moved into northern MO Wednesday 
night.  A good fetch of PW's just over 2 inches is progged to 
precede the front, so any storms that occur could produce heavy 
rainfall rates.  The progressive nature of the system though, should 
limit rainfall amounts in any one area.

An amplifying ridge in the west and eastern U.S. trof will put 
the region in northwest flow again for the end of the week and 
weekend, resulting in a return of mild temps and lower humidity.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
ISSUED AT 1133 PM CDT Sat Jul 22 2017

Areas of MVFR cloud bases will slowly give way to fair skies as high
pressure moves in. VFR conditions will then prevail through Sunday
with cumulus clouds with light northwest winds of 5 to 10 MPH. Patchy
light MVFR ground fog is possible overnight with light northwest winds
and is included as a tempo group at each terminal since dewpoint depressions
are 2 degrees or less at 11 PM.


&&

.HYDROLOGY...
Issued at 426 AM CDT Sun Jul 23 2017

Heavy rain fell across eastern Iowa and northern Illinois Friday 
night which has resulted in flooding on some area rivers. The 
potential exists for some fluctuations in the crest forecasts over 
the next 24 hours as runoff from the rain becomes better known. 
Little or no rain is expected across the area for the next 2 to 3 
days.

Maquoketa River...

Based on the way the heavy rain fell across this basin, the flood 
crests on the individual forks of the river are out of sync with 
each other. The river is near crest at Manchester at just over 15 
feet...minor flood stage. At Maquoketa, the crest forecast has been 
lowered significantly. With the individual flood crests out of sync, 
the river may only crest at 23 feet...or below flood stage Monday 
evening.

Wapsipinicon River...

Major flooding is expected along the river. There are still unknowns 
regarding routed flow and how much flow may get lost to off-channel 
storage. Confidence is high in regards to flooding but there is 
lower confidence regarding the crests.

Pecatonica River...

Freeport is cresting just short of 16 feet. Routed flow from 
upstream will keep the river between 15 and 16 feet until Thursday 
afternoon.

Rock River...

Major flooding will be seen along the Rock river. Como looks to 
crest shortly after sunrise today and then begin falling. Joslin 
looks to crest between 18.5 and 19 feet Monday evening. At Moline, a 
crest is expected Monday night that will be 16 to 16.5 feet.

Mississippi River...

A flood watch remains in effect from Camanche south to Gregory 
Landing. The exceptions are a flood warning for Lock and Dam 15 and 
crests below flood stage at Le Claire and Keokuk.

Most locations on the Mississippi are forecast to reach flood stage 
in the next 24 to 48 hours. Several of the current flood watches for 
the Mississippi may go to a flood warning later today.

&&

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

$$

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