857
FXUS63 KDVN 222339
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
639 PM CDT Thu May 22 2025

.KEY MESSAGES...

- Scattered showers south of Hwy 30 late this afternoon and
  early evening. A few brief funnel clouds may develop with
  these showers although latest trends had decreased this risk.

- Mostly dry holiday weekend, with near normal temperatures.

- Low confidence rain chances early next week, with a warming
  trend into the upper 70s/low 80s by the middle of the week.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 206 PM CDT Thu May 22 2025

After a chilly start in the upper 40s, temperatures have
struggled to climb today thanks in part to the cold pocket of
air aloft (+1 C at 850mb per 12z DVN sounding) and the BKN/OVC
sky. SPC sounding climatology shows +1C at 850mb near the daily
min for May 22nd, so it makes sense that we are hovering near
the coldest of temperature guidance today. Afternoon highs to
only reach the upper 50s/low 60s, which is normally what we see
in early April!

A weak shortwave will continue to drop south into southern IA,
supporting isolated to scattered shower development through the rest
of the afternoon and early evening. Steepening low level lapse rates
and very meager instability (less than 100 MLCAPE) near a weak
surface boundary could support a few funnel clouds occurring.
However, the latest NST parameter trends from the RAP have shown a
notable decrease since this morning and the movement on the showers
currently on radar has been faster thereby lowering the threat of
funnel clouds. IF they did occur, they would be brief and likely
forming south of Hwy 30. Shower activity will quickly wane after
sunset with the loss of heating, along with decreasing clouds.
Temperatures overnight to drop into the lower 40s. Light winds above
5 kts should keep any frost formation at bay, but some low lying
river valleys and poor drainage locations may see air temps drop
into the upper 30s.

Friday...upper low to move further east over the Great Lakes, but
still keeping us in cyclonic flow aloft. After a cold start, late
May sun, dry dewpoints in the 40s, and deep mixing over 850 mb will
help temperatures rebound nicely into the upper 60s/low 70s by the
late afternoon. An upstream shortwave tracking across the northern
Plains will bring an increase in clouds late in the day, with any
shower activity remaining to our west. All in all, a very nice day
to end the work week and start the holiday weekend.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 206 PM CDT Thu May 22 2025

This Weekend...northwest flow aloft and a large Canadian high to
drift over the upper Midwest and Great Lakes region. This will bring
slightly cooler than normal and mostly dry conditions for most. The
latest 12z deterministic and ensemble guidance is trending drier for
our CWA, with a storm system tracking east southeast across the
Great Plains Saturday night-Sunday. The 1000-500mb RH and 850mb
theta-e progs suggest the better moisture is still shown well south
of the area, from Kansas into Missouri. If precipitation occurs, it
will be confined to the southwest third of the CWA across northeast
MO, southeast IA, and west central IL. The current forecast has
slight chance to chance PoPs for this area, with QPF totals under a
tenth of an inch.

Memorial Day...model differences continue regarding the evolution of
several weak disturbances in the flow aloft owing to a low
confidence in any precipitation. The key factor for rain remains the
position and strength of the Canadian high over the upper Midwest.
If it is further south and strong, then dry or mainly dry
conditions will be seen. Most 00z ensemble solutions are
showing a dry forecast, but around 20% of the members still
have light QPF (namely the GEFS solutions). As a result, there
remains 15-40% chance PoPs in the forecast, but I suspect that
most locations will have a dry holiday, with temperatures
slightly below normal in the mid to upper 60s.

Tuesday-Thursday...most model solutions continue to show dry
conditions for this period, along with a warming trend. The
exception is the latest GFS and some of its 00z GEFS members that
have an upper low developing over the northern Plains that lingers
and becomes a closed low. However, doing a dprog/dt of the GEFS mean
QPF has shown a drying trend for this period. Needless to say,
uncertainty remains in the upper level pattern and any precipitation
prospects this late in the forecast.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 629 PM CDT Thu May 22 2025

Diurnally driven cumulus and showers are starting to dissipate
early this evening as a storm system departs and fast moving
high pressure builds into the area overnight. This will result
in VFR conditions through the period as skies clear. Winds will
become light and variable this evening. Winds will turn to the
west to northwest around 10 knots after 12 UTC on Friday.
Diurnally driven stratocumulus are foecast to redevelop after 15
UTC on Friday with ceilings around 5 to 7 kft.

&&

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

&&

$$

SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Cousins