790
FXUS63 KDVN 161032
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
532 AM CDT Mon Sep 16 2024

...Updated for 12z Aviation...

.KEY MESSAGES...

- High confidence on above normal temperatures this week.

- Confidence on timing of rain chances late week into the
  weekend is low, as an upper level ridge becomes reestablished
  across the region.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 200 AM CDT Mon Sep 16 2024

Pattern remains stagnant due to a Rex block out east formed
between Great Lakes to Mid-Atlantic ridging and a low (Potential
Tropical Cyclone 8 or PTC8) off the South Carolina coast. This
low per NHC has a high chance of becoming a Tropical Cyclone
while moving inland over the next 24+ hours. Please refer to
the National Hurricane Center (NHC) for further information on
this system.

Despite the lack of movement of systems in this blocked pattern,
we are tracking some changes (decrease) namely to moisture
levels. Water vapor imagery reveals a large reservoir of dry
air entrained in the mid/upper level ridge out east, and noted
in PWAT analysis (PWATs around 0.5 to 0.7 inch across the Ohio
Valley and Mid-Atlantic), which continues to make steady
progress toward the region. DVN RAOB PWAT at 00z was 1.3 inches
down from 1.6 inches 24 hours prior. We`ll continue to
gradually pull in drier air in a couple of surges through
Tuesday, as the mid level ridge edges a bit westward and low
level flow advective flow continues from the E/SE. This will
initially draw down the dew points with advection from the Ohio
Valley region later today and tonight, followed by a secondary
surge of drying to arrive Tuesday from the Appalachians. The
result will be a more comfortable late Summer warmth, which will
be noticed more in our eastern counties today (dew points
dropping into the 50s) and then areawide on Tuesday (dew points
lowering into the 40s/50s). The dry air will also support
increased diurnal ranges, which means more comfortable nights
with lows near or below deterministic NBM (MinT) into the 50s
and lower 60s. We`ll also continue to be above normal on daytime
highs with readings from the mid 80s to lower 90s today and
Tuesday. We`ll also have one more day with the low potential for
isolated weak convection this afternoon, mainly across SE Iowa
and NE Missouri within the low to mid level theta-e gradient.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 200 AM CDT Mon Sep 16 2024

The lingering Rex block in the eastern CONUS is progged to
finally weaken early on, which is great news for our rain
prospects right?!? Unfortunately, likely not so at least
early on in the period, as the models quickly reestablish and
amplify upper ridging over the region Wednesday and Thursday
ahead of a western CONUS trough, and possibly longer. Trends
from WPC cluster analysis of the 500 hPa pattern support the
influence of the upper ridge holding on longer. NBM has pushed
back PoPs to Thursday night through the weekend, but based on
the cluster analysis and trends of the 500 hPa ridge strength
and placement I wouldn`t be at all surprised to see further
delay/slowing of the PoPs. As a result, confidence remains
low with the timing of rain chances, until possibly sometime
next weekend when there`s a signal for the ridge shifting
eastward allowing for more influence of shortwave troughing.
While timing of our next rain chances remains low confidence,
what remains high confidence is a continuation of the
unseasonable late summer warmth through at least late week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 530 AM CDT Mon Sep 16 2024

VFR conditions and light E/SE winds will continue to dominate
through the TAF period.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...McClure