846
FXUS63 KILX 181041
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
541 AM CDT Fri Oct 18 2024

.KEY MESSAGES...

- Low relative humidity and dry fuels continue to create increased
  fire potential, especially west of the Illinois River where
  winds will be strongest this afternoon, gusting 15 to 25 mph.

- Dry weather prevails through Monday, along with gradually
  warming temperatures.

&&

.DISCUSSION...
Issued at 306 AM CDT Fri Oct 18 2024

A paltry October continues as the forecast period contains little
in the way of meaningful precipitation chances across central IL.
At the start of the period, the synoptic pattern was
characterized by an Omega block in the upper levels, with a ridge
over the Midwest and troughing on either side. At the sfc, a
1030-mb sfc high pressure was centered over WV but encompassed
much of the eastern third of the CONUS. This pattern will be very
slow to evolve over the next several days as a cutoff low develops
and meanders over the desert southwest.

Given the blocking pattern, the ensemble spread for forecast
temperatures is remarkably narrow (high confidence) through at
least Monday, with the probabilistic NBM depicting just a 2-3
degree temperature spread between the 25th and 75th percentiles
each day. Temps are also expected to gradually warm each day as
sfc flow maintains a southwesterly component, with highs rising
from near 70 today to the mid/upper 70s by Sun/Mon.

The forecast dewpoints from the NBM have been too high in recent
days, so a collaborative effort was made to lower the forecast
dewpoints, which resulted in the forecast minimum RH falling to
20-30% today (and potentially Sat-Sun as well). Winds today will
be strongest west of the IL River (gusts 15-25 mph), so if
unwanted fire spread was to occur that would be the most likely
area. Winds should become lighter over the weekend.

Into next week, the aforementioned closed upper low over the SW US
is expected to emerge and lift northeast, gradually weakening and
becoming an open wave as it does so. This could provide the CWA
with some light showers, but QPF amounts appear unlikely to put a
dent in the ongoing dry conditions. The GEFS ens has less than a
20% chance of exceeding 0.10" of rain. The EC ens is more bullish,
but I`ll need to see a stronger signal than a weakening wave
moving into a region with developing drought conditions to buy
into meaningful precip chances.

After that wave passes, a cold front is progged to sweep through
the CWA, ushering in a temporary cool down (highs in the 60s).
However, all three global ensembles (GEFS, EC, CMC) have a strong
signal for above normal temps during the final week of October,
generally showing a 70%+ chance for temps at least 5 degrees above
normal during that period. Normal temps for the final week of
October include highs near 60 and lows in the upper 30s. The
latest drought monitor showed moderate drought (D1) expanding to
encompass most areas north of I-74, and with the remainder of
October generally characterized by above normal temps and below
normal precip improvement in the drought conditions is
unlikely.

Erwin

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 541 AM CDT Fri Oct 18 2024

Clear skies and VFR conditions will prevail through the period.
SSE winds will increase to around 10-12 knots during the day,
then weaken to around 5 knots after sunset.

Erwin

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$