IWX issues Area Forecast Discussion (AFD) at Oct 8, 6:43 AM EDT842
FXUS63 KIWX 081043
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
643 AM EDT Tue Oct 8 2024
.KEY MESSAGES...
* Dry weather pattern continues through the rest of the work
week.
* Seasonable temperatures and large diurnal temperature swings
through Thursday, warming back well into the 70s to near 80 by
Friday.
* Some fire weather concerns possible on Friday, but of low
confidence at this time.
* Low rain chances return for the second half of the weekend and
turning much cooler for early next week
&&
.DISCUSSION...
Issued at 335 AM EDT Tue Oct 8 2024
An overall quiet weather pattern will characterize the rest of the
work week as a stable longwave pattern of central CONUS upper
ridging and northeast CONUS negative upper height anomaly persists.
A 110 knot upper speed max will drop across the western Great Lakes
this afternoon in association with a highly sheared upper level
wave. Low level temperature advection has become more neutral this
morning, but approach of this sheared vort max should allow some
slight backing of low level winds that will allow weak low level
warm advection across eastern IL/western IN. With full insolation
today and this very weak WAA, some slight moderation of temperatures
should continue today with highs from the mid-upper 60s
northeast to mid 70s southwest. A weak ridge of high pressure
will linger tonight in the wake of this sheared vort max from
western Ontario into the western Great Lakes. This weak low
level height gradient and dry low level airmass will be
conducive for good radiational cooling conditions again tonight
with lows around 40/lower 40s. Favored low lying cool spots
could dip into the upper 30s early Wednesday morning.
On Wednesday, an upper vort lobe currently across James Bay region
will rotate cyclonically through large scale negative upper
height perturbation and will drive a back door cool front type
feature across the southern/eastern Great Lakes. The strongest
reinforcing cold advection with this front should remain
confined to east of the local area with just weak cold advection
push across southeast Lower Michigan/northern Ohio. Stable
nature of longwave pattern should keep low level anticyclone
parked across the region which will allow for yet another night
of good radiational cooling conditions Wednesday night. Portions
of south central Lower Michigan into extreme northeast
Indiana/northwest Ohio could see mins drop into mid-upper 30s
early Thursday morning. Some patchy frost is possible across
south central Lower Michigan, but confidence in any frost is low
given tight nature to baroclinic zone associated with the
backdoor cool front.
For Thursday-Friday, upstream upper ridge axis will begin to show
more progression into western Great Lakes as more substantial
eastern Pacific energy overspreads Pacific NW/southwest Canada. This
will result in a steady moderating trend for Thursday and Friday.
Timing of the low level thermal ridge should provide Friday with the
warmest temperatures in the upper 70s to possibly lower 80s.
Dampening of the upper ridge by the eastern Pacific wave on
Friday will result in cold front emerging from southeast
Ontario into the Corn Belt by early Friday evening. Decent low
level westerlies preceding this front should allow for afternoon
gusts to around 25 mph on Friday. Breezy conditions coupled
with better low level moisture displaced west near the frontal
boundary could introduce some marginal fire weather concerns
Friday afternoon.
Surface cool front should sag into the area Friday night into
Saturday. This front will become more divorced from better initial
Pacific wave, and likely will be mainly dry as it stalls out across
the region. Medium range guidance remains consistent in a stronger
Pacific wave interacting with this baroclinic zone for a better rain
chance by Sunday. However, still a good deal of uncertainty
persists regarding the rate of amplification of this short
wave, and westward extent of the more amplified upper trough.
Deterministic/ensemble trends now in some better agreement in a
period of much cooler conditions early next week, but duration
of this cooler air remains an item of lower confidence due to
the large spread in the handling of the stronger Pacific trough
early next week.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 643 AM EDT Tue Oct 8 2024
With surface high pressure over missouri, plenty of dry air will be
across the area. As a mid level trough departs, shortwaves bringing
cloud cover will be fewer and further between allowing for VFR
conditions, especially with unfavorable cross-over temperatures.
West winds with a component veering from south to north through the
period are expected to gust 15 to 20 kts during peak heating this
afternoon, but will quickly drop off thereafter.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Roller
Source:
IWX issues Area Forecast Discussion (AFD) at Oct 8, 6:43 AM EDT---------------
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