Romeoville, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

857
FXUS63 KDVN 211140
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
540 AM CST Thu Nov 21 2024

...12z Aviation Update...

.KEY MESSAGES...

- Strong northwest winds will buffet the region today and a Wind Advisory
  has been issued for much of the area through this evening.

- Snow changing over to rain will sweep down across the eastern forecast
  area today, with light snow accumulations possible this
  morning before it transitions to rain.

- Cooler temperatures will dominate the region going into the
  weekend, with a brief warm up into the 50s on Sunday, with
  temperatures dropping again from there.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 315 AM CST Thu Nov 21 2024

Today and Tonight...Water vapor imagery and upper air observations
were indicating the large closed upper low center was located over
central LK MI ATTM, looking to spiral to northeast OH by midday.
Robust vort wing continuing to drive the current snow activity acrs
the area early this morning before moving mostly out by 12z Thu.
Then attention turns to another spiraling vort lobe now acrs the
northwestern GRT LKS that will pivot down acrs the western GRT LKS
and bring it`s precip swath with it wrap-around conveyor style down
acrs the east half of WI and IL as the day progresses. A nice TROWAL
fed precip process off the Atlantic. Short range ensemble handling
and extrapolation from upstream suggests this belt of precip to
sweep southward acrs the eastern quarter to third of the DVN CWA. It
will be mainly snow this morning with minor snow acumms up to a
half inch possible along and east of a Freeport to Princeton IL
line, before wrap around WAA(warm air advection) aloft and diurnal
processes turn it to mainly rain by midday. This rain may then flex
westward to the MS RVR into extreme east central IA mid afternoon
into early evening, before retreating back east through midnight.

Winds...of the most widespread impact will be the strong gradient
winds as the deep/sub-1000 MB sfc low drops south down LK MI. Extent
of MB gradient sprawl rule acrs the CWA agrees with most fcst
soundings and BUFKIT sfc momentum transfer with a lot of gusts
ranging from 43 to 47 MPH.  Some surges to 50 MPH still look
possible acrs portions of NW IL, which agrees with NBM 50th to 75th
percentile values by midday. Have issued the Advisory already
including some buffer counties off to the west and southwest, and
next shift will have to assess expansion if needed. With other
office collaboration, went with start times of 16z and ended by 02z
for our area, but some concern advisory values may be getting
tickled/reached in the north as early as 15z/9 AM CST.

Temps... With clouds and precip(in the east) and currently dragged
down cool air in place, see high temps having trouble getting out of
the upper 30s or just reaching 40 degrees.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 315 AM CST Thu Nov 21 2024

Friday through Sunday...Weak, lower amplitude upper ridging to get
pressed eastward acrs the mid CONUS for a fair wx regime for most of
this period in the wake of the cyclone. Mainly dry and near
seasonable to slightly above normal temps thru Sat, then some temp
moderation into Sunday with a better return flow push and pushing
temps back up into the 50s. Sfc feature progs on the latest suite of
medium range ensembles still sweep a cool front down through the
area Sunday night, but have trended drier and not much moisture to
work with to produce any precip along the FROPA.

Monday through Wednesday...Longer range prospects suggest a cooler
push in temps this period, with LLVl baroclinicity laying out in more
westerly steering flow along and south of the CWA by Tue. Any kind
of wave propagating through this more progressive flow may try to
kick up isentropic light precip in or near the local area Tue into
Wed with some precip type issues to be dealt with. Will have to
watch for the ejection of a larger wave out of deepening southwest
CONUS longer wave upper trof toward mid and late next week during
the holiday window. If the southern stream takes over and is
dominant, it may just clip our south with precip, but definitely a
high profile period to watch in the coming days and model runs.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 535 AM CST Thu Nov 21 2024

Wrap around MVFR CIGs today from the north today as large
cyclone shifts southeastward acrs the GRT LKS. The MVFR levels
will vary from 1000 to 3000 FT AGL at times and last well into
tonight. Of more of an impact will be the turbulent LLVLs with
strong vertical wind profiles. Sfc winds may gust up to 40 KTs
at times from the northwest through early evening. A swath of
precipitation will move southward down acrs WI and IL today,
but most of it should stay east of the TAF sites. A low chance
for MLI to get clipped by light rain this afternoon off this
activity if it flexes a bit more west than currently
anticipated.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Wind Advisory from 10 AM this morning to 8 PM CST this evening
     for IAZ041-042-052>054-064>068-078-089.
IL...Wind Advisory from 10 AM this morning to 8 PM CST this evening
     for ILZ001-002-007-009-015>018-024>026-034-035.
MO...None.

&&

$$

SHORT TERM...12
LONG TERM...12
AVIATION...12