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fxus63 kdvn 151751 
afddvn

Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
1251 PM CDT sun Sep 15 2019

..aviation update...

Update...
issued at 916 am CDT sun Sep 15 2019

Thunderstorms have moved east of the dvn cwa with a few lingering
showers, mainly east of the MS river.

Update issued at 839 am CDT sun Sep 15 2019

Thunderstorms have moved east of the dvn cwa except in Bureau and
Putnam counties so we have cancelled the Flash Flood Watch. As
soon as the storms moved out of the cwa entirely the remainder of
the watch will be cancelled.

&&

Synopsis...
issued at 245 am CDT sun Sep 15 2019

As of 2 am, two distinct areas of convection were noted on GOES
infrared imagery, one across NE Iowa into SW Wisconsin and the other
over east- central Iowa into northwest Illinois. The trend over the past
few hours has been increasing storm coverage and intensity per
cooling infrared cloud tops. Mrms radar estimates 1-2.5 inches of rain
has fallen in the past 12 hrs from NE Iowa County through central
Johnson, and into central and southern Cedar co. Another hard hit
area was central Clinton co. Into portions of Whiteside co.
(About 1-2"). Luckily we haven't had to deal with too much
training of storms as they have shifted slightly to the south of
this hard hit zone.

Late tonight into early this morning

Latest rap analysis indicated a favorable setup for numerous
elevated showers and thunderstorms on the eastern periphery of
impressive 925-850mb WV transport and a low-level jet. Efficient
rain producing storms, with rates up to 1-2 inches per hour, can
be expected due to deep warm cloud depths (2-2.5 km warmer than 0
c) and pwats up to 1.50-1.70 inches. Additionally, mid-level lapse
rates of 7-7.5 c/km and 1000-2000 MUCAPE will provide ample
instability for robust updrafts. Storm motion vectors and mean
850-300mb flow are showing storm speeds of 20-30 mph from west to east.
Although, corfidi vectors suggest some potential for backbuilding
meso-Beta elements and threat for localized heavy rain totals of
2-3+ inches.

Hi-res models have come into better agreement on the most likely
location for the highest quantitative precipitation forecast to be over the central to east-
central sections of the cwa, probably staying to the south of the
Freeport area.

The Flash Flood Watch remains in effect in the north and northeast
where recent heavy rainfall has led to saturated ground and
has lowered 1 hr flash flood guidance to 1-1.5 inches. Since the
heaviest rain axis has shifted a little to the south, the watch
was expanded to include the counties along I-80 from the Quad
Cities and points to the east.

&&

Short term...(today and tonight)
issued at 245 am CDT sun Sep 15 2019

Today

Scattered showers and storms will linger in the east and
southeast through the mid morning before completely diminishing
and moving east of the forecast area. The rest of today will be
very warm and humid with highs in the low 80s north to upper 80s
south, and dewpoints into the upper 60s to low 70s. There could be
an isolated shower or storm that develops in the east this
afternoon near peak heating but chances are very low.

Long term...(monday through saturday)
issued at 245 am CDT sun Sep 15 2019

Little change to the extended forecast with hot (for mid
september) and humid conditions likely through the week ahead. An
expansive upper ridge will be in control over the central U.S.
Forecast highs are in the 80s and dewpoints into the low 70s at
times, which will yield peak heat indices in the upper 80s to
lower 90s making it feel more like mid Summer than mid September.

A shortwave trough, tracking through the northern plains into
southern Canada, will flatten the northern edge of the upper ridge
mid to late week. A weak front associated with this system is our
next chance for showers and thunderstorms. Have low chances in
the forecast from Wednesday evening (in the west) through Friday,
which is reasonable due to expected low areal coverage and limited
influence from the shortwave due to its northern track.

Models are in better agreement on the front either washing out or
not making it completely through the central or southern forecast
area before retreating north again on Thursday and Friday. Main
message is the unseasonably warm and humid conditions look to be
locked in through at least next Saturday. Uttech

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1247 PM CDT sun Sep 15 2019

VFR/LCL MVFR cigs this afternoon then areas of dense fog are
expected to form later tonight and lasting into Monday morning.
IFR/LCL LIFR cigs/vis in the dense fog. For now I have
kbrl/kdbq/kmli having the worst conditions due to calm winds and
plenty of low level moisture from heavy rainfall from last night.

&&

Hydrology...
issued at 1144 am CDT sun Sep 15 2019

Moderate flooding is now expected on the Rock River near Joslin.

The Pecatonica and Rock River basins received another round of
heavy rain overnight of around an inch or a bit more. This
additional heavy rain will result in further rises on the Rock
River near Joslin and at Moline, with moderate flooding now
expected near Joslin and crest levels up a few tenths of a foot
at Moline and minor flooding. Meanwhile, on the Pecatonica at
Freeport the local runoff from the heavy rain is leading to a
bit of a rise this morning. There does remain uncertainty in the
amount of local runoff and response, thus uncertainty with how
high this initial crest will be. Right now the forecast is for
minor flooding to continue, but this will be watched closely as
it is nearing moderate flood stage. Still expect the river to then
drop some/level off by tomorrow in wake of local runoff, with a
secondary crest still slated for the middle of the week.

Otherwise, routed water moving through the river systems coupled
with the swaths of heavy rain overnight will lead to many within
bank rises across the area.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

Update...haase

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