206
FXUS63 KDVN 120750
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
250 AM CDT Fri Jul 12 2024

.KEY MESSAGES...

-  Isolated to scattered showers and thunderstorms are possible
overnight into Saturday morning, and again Saturday night.

- Becoming very warm and humid this weekend and into next week, with
heat indices in the upper 90s and low 100s. Heat headlines seem
eventually be needed Sunday and Monday.

- Ring of fire pattern early next week may bring strong/severe
thunderstorms close to the forecast area and temporary relief from
the heat, prior to the arrival of a significant cold front by mid
week.

- Moderate to major river flooding continues on the Mississippi
  River with most sites crested or cresting in the coming days.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 243 AM CDT Fri Jul 12 2024

Pleasant summer weather will continue through today, as the clear
skies tonight have allowed for lows to drop to the lower to mid 60s
in most areas as of 2 AM. The moist ground/and maturing crops are
helping patchy fog formation in some of our favored areas. We`ll
keep an eye on that, and may need to address this in short term
graphics today.

In any case, any fog will quickly burn off in the strong sunshine
this morning.  With surface high pressure from the Great Lakes,
extending to eastern Iowa today, we`ll have plenty of sun, light
winds and humidity that`s not so bad.  Certainly, today is the most
pleasant day through Monday.

Tonight, the heat and humidity forecast to build into the region
will begin to move in, mainly aloft during the evening.  By
Midnight, a 25-35kt low level jet LLJ, will be aimed into Iowa, with
strong moist warm advection spreading into the state. 1500+ J/KG
MUCAPE is forecast by some CAMs tonight, with the terminus (nose) of
the LLJ aimed towards eastern Iowa between midnight and mid morning
Saturday, and diffluent flow at upper levels (potentially a weak
short wave trof as well). So, it appears that the location and
widespread nature of storms is not going to be very high
confidence, but the zone in which they occur is, and we`ll time
that through our area from west to east between Midnight and
late morning Saturday. Spotty qpf of 1"+ is possible, through
like yesterday, over all amounts would be much less.

Saturday could see storms lingering through the morning hours
in the east 1/2 of the area, which is expected to help keep
temperatures from getting above 90 in the northeast 1/2. Farther
southwest, afternoon temperatures in the lower 90s are
expected, with dewpoints in the lower to mid 70s, resulting in
heat index readings of 95 to 99 southwest of Cedar Rapids to
Peoria IL.

This is very warm, but should fall short of a need for a heat
headline Saturday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Issued at 243 AM CDT Fri Jul 12 2024

Saturday night into Sunday, the heat dome over the western states is
expected to shift east, with another potential round of storms
overnight. This strong warm advection, is more likely to be
associated with a nocturnal MCS, initiating in Minnesota. Thus,
while tonight`s storms offer a small hail and isolated heavy rain
threat, Saturday night`s storms are no more predictable in
occurrence, but if they do, the have a much more significant
potential for damaging winds, as they would arrive with an
established cold pool from upstream.

Sunday, heat and humidity will combine for a dangerously hot day.
Heat index readings of 100 to 105 are expected, as highs reach the
lower to mid 90s, with dewpoints of 73 to 76.  Some locations could
see dewpoints in the upper 70s, if any mesoscale convergence along
outflow boundaries happen from activity Saturday night. A heat
headline is looking to be in place from Sunday through Monday, when
similarly conditions are in place. Models forecasts of 850mb
temperatures of 23-26C, which corresponds to our climatology
for reaching the mid 90s. Of course, given our moist conditions
of late, maturing crops, and potential for convective debris
clouds in the area will potentially limit our highs, but these
same factors do add confidence to the dewpoint reaching levels
over 75.

Monday late afternoon, through the evening, a strong cold front will
move into area, which is tied to a seasonally strong low pressure
sweeping across southern Canada. This will bring shear, as well a
strong trigger for storms through our region, but given the hot flow
of air aloft, an EML/capping inversion is expected to be in place
over our area. This could prevent all storms from happening with
Monday night`s fropa, but if it breaks, we`re looking at potential
for severe storms, and very heavy rain during the evening. The
strong westerly/northwesterly flow aloft Monday night should quickly
veer the LLJ into the Ohio Valley with an end of activity and dry
cool advection arriving.

Much cooler weather will sweep in for Tuesday afternoon through
the end of the week! Highs may only reach the 70s Wednesday
through Friday, with lows in the 50s to low 60s! Thus, thus heat
wave that`s expected should be quite short lived.

ERVIN


&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1218 AM CDT Fri Jul 12 2024

A quiet day and evening are expected for aviators before some
thunderstorm chances arrive overnight. High pressure over the
area through daybreak with moist boundary layer conditions will
allow for the likelihood of some fog. Spotty IFR visibility is
possible (20% chance at TAF sites), though fog will not be as
noteworthy in coverage or density as yesterday morning.
Southeast winds will be primarily less than 10 kt today.

&&

.HYDROLOGY...
Issued at 232 PM CDT Thu Jul 11 2024

The Mississippi River continues a broad crest or just starting
to fall from crest at major levels from upstream of Camanche,
IA, and through Illinois City. The crest may take 1 to as much
as 3 days to pass. From south of IL City to Burlington, the
respective crests will commence within the next 1 to 2 days.

Keokuk is now forecast to crest within Moderate Flood category
Friday night into Sat. Gregory Landing is forecast to remain
near 19.5 feet through the week.

Tributary Rivers:

On the Cedar River at Conesville, minor flooding will continue.
It is starting to fall from it`s recent crest early this
morning.

The Wapsipinicon River at Dewitt is forecast to remain in
moderate flooding category through late Friday.

The Iowa River at Oakville continues to experience high water
levels due to backwater affects from the Mississippi River. It
is forecast to rise to near 12.1 feet into Friday.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...Ervin
LONG TERM...Ervin
AVIATION...Friedlein
HYDROLOGY...12