IWX issues Area Forecast Discussion (AFD) at Nov 7, 3:39 AM EST822
FXUS63 KIWX 070839
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
339 AM EST Thu Nov 7 2024
.KEY MESSAGES...
- Cooler temperatures are in store today and Friday, but still
slightly above normal for early November.
- Mainly dry conditions through Saturday afternoon. Rain chances
return Saturday night into Sunday.
- Mild conditions with highs back into the 60s expected Sunday and
then again for middle of next work week.
&&
.DISCUSSION...
Issued at 338 AM EST Thu Nov 7 2024
Quiet weather conditions will persist through the first part of
Saturday, but a progressive pattern will allow for a few rain
chances late Saturday/Sunday, and then again by the middle of next
week.
A highly sheared, positively tilted upper level short wave is
allowing the pre-existing low level baroclinic zone to sag
southward this morning. Southward progression of this baroclinic
zone is also allowing stratocu deck across northwest
IN/southern Lower MI to also drop southeast. Water vapor imagery
this morning depicts this sheared vort max well north of the
local area across the northern Great Lakes. Still could see a
potential of some brief light drizzle across the northwest this
morning given shallow moisture profiles and being in the
vicinity of these sheared short waves, but overall setup appears
not favorable for measurable precip. Low level synoptic
subsidence should become more prevalent as we head into the late
morning hours, with expectation that diurnal mixing and
southeast advection of a drier low level air mass will allow
stratocu deck to erode. Mixing depths today will be somewhat
limited by stalled frontal boundary, but mixing up to 900 mb
should support highs in the 55 to 60 degree range.
For tonight into Friday, a low level anticyclone will build in from
the west as another sheared vorticity max tracks across the Great
Lakes perhaps bringing some low coverage mid-high cloud. A backdoor-
like cold front also is expected to drop across the southern/eastern
Great Lakes helping to anchor low level baroclinic zone across
the area, and also maintaining a dry low level airmass across
the region. Thermal profiles/mixing depths on Friday should be
very similar to that of today, with perhaps just a few degrees
of warming in comparison to Thursday due to the prospect of more
insolation.
For Saturday/Sunday, guidance is still supportive of previous
forecast in increased rain chances Saturday night into Sunday as cut-
off upper low lifts northeast across the Corn Belt. While this
evolution would be favorable good moisture transport from the
Lower MS Valley, duration of this moisture advection will be
somewhat limited by rapid progression of the forcing and by
increasingly veered low level flow by early Sunday that could
temper northward extent of moisture advection. This system also
will be quite mature and well into the occluded stage which
should limit strength/duration of vorticity advection. Will
continue to carry likely/categorical PoPs late Saturday night
into early Sunday, but precip amounts should be limited by above
factors. Mid level dry slot will overspread the area Sunday
eventually bringing reduced rain chances along with windy/mild
conditions. Cooler conditions back to near seasonable levels are
expected Sunday behind an associated cold front.
The first part of next work week will feature dry conditions and an
expected slow moderation in temps into Wednesday. Medium range
guidance is still onboard with a potentially stronger upper
level wave by Wednesday. Difficult at this forecast distance to
add too much detail, and will need to resolve timing over the
next several days along with just how far south stronger eastern
Pacific jet will dig. Deterministic guidance remains quite
varied in the amplitude of this wave which of course will have
big implications of magnitude of pre-frontal moisture
transport. Confidence does remain on the higher side of another
mild pre-frontal period toward end of this forecast valid period
before turning briefly colder behind this system by Day 8.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1208 AM EST Thu Nov 7 2024
As noted by the past few hours of observations at KFWA and KSBN,
ceilings are near the high end MVFR to low end VFR range.
Ceilings have predominantly been between 2000 to 3000 ft and
should stay that way through at least 12Z. This afternoon, VFR
ceilings should prevail as clouds clear out. Winds will remain
light out of the northwest at 5 to 10 kts. Have kept any
mentions of fog out of the TAFs for now, given the
aforementioned low clouds in place across the area, but wouldn't
be surprised if there could be a few patchy dense areas of fog
this morning (much like yesterday).
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Johnson
Source:
IWX issues Area Forecast Discussion (AFD) at Nov 7, 3:39 AM EST---------------
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