IND issues Area Forecast Discussion (AFD) at Nov 6, 9:15 PM EST508
FXUS63 KIND 070215
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
915 PM EST Wed Nov 6 2024
.KEY MESSAGES...
- Patchy fog expected tonight, mainly over SE and N portions of
Central Indiana
- Above normal temperatures to continue through the forecast period
- Rain and a few thunderstorms late Saturday into Sunday, with
additional rain chances mid week next week
&&
.FORECAST UPDATE...
Issued at 915 PM EST Wed Nov 6 2024
- Cloudy and Cooler Overnight
Surface analysis this evening shows a departed cold front stretching
across Ohio to Central KY and western TN. Strong high pressure was
found over the northern plains. Winds across Central Indiana were
from the northwest around 10 mph. GOES16 show cold air advection
cloud cover development the past few hours, resulting in low,
stratocu cloud cover. Dew points were in the upper 40s to lower 50s.
Forecast soundings and time heights across the area show lower level
moisture expected to be present through the night. HRRR also
suggests high RH values overnight at 925mb. Given our Cold air
advection and pressure gradient in place, this stratus development
will be expected to persist as opposed to fog. Given the expected
clouds, expect lows in the middle and upper 40s.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 256 PM EST Wed Nov 6 2024
Much quieter weather has settled in over central Indiana this
afternoon, as weak CAA and AVA in the back side of the decaying
trough has increased surface pressure and subsidence. Initially this
has lead to breaks in the stratus layer, with a broken strato-cu
deck now encompassing most of central Indiana. The one caveat is far
SE central Indiana where a weak low level boundary remains, as seen
on satelitte imagery. In this area, isolated showers may develop
this afternoon as a modest instability gradient develops. Any
rainfall should be minimal/isolated, but cannot be ruled out
nonetheless.
Overnight, the main forecast problem will be the potential
development of ground fog. This will work two-fold for central
Indiana. In the far SE, dew points are not expected to fall quickly
with the boundary just to the south. This boundary is also likely to
limit surface winds as a nocturnal inversion sets up. This
combination typically leads to patchy dense fog, especially over
river valleys. The other method of fog formation could occur over
northern portions of central Indiana, as model soundings have shown a
continuing towards an inversion reestablishing tonight underneath
clearing skies. A steady northerly wind at 5-10mph could limit
decoupling of the boundary layer and largely prevent any fog
concerns, but areas where winds fall below 5mph are expected to have
patchy fog.
Tomorrow, much of the same weather is expected in central Indiana,
just with slightly cooler temperatures as central Indiana's wind
flow becomes largely out of the N/NW overnight, including marginal
cold air advection. Any remaining stratus from overnight subsidence
inversions will likely mix-out by the late morning, with scattered
to isolated strato-cu remaining in the afternoon. This increased
sunshine may lead to slightly warmer than forecasted temperatures,
but given climatology of early November and consistent N/NW flow,
temperatures have been capped in the mid 60s as of this issuance.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 256 PM EST Wed Nov 6 2024
A fairly progressive pattern is expected is expected throughout the
period.
Broad surface high pressure will keep the area dry into the very
early portion of the weekend. An upper level low currently in the
process of cutting off over the Southwest will move quickly
northeast through the Great Lakes late in the week and over the
weekend, bringing first a warm front, followed by a narrow warm
sector and cold front through the area late Saturday into Sunday -
this will produce a period of widespread showers and perhaps a few
thunderstorms, primarily Saturday night into early Sunday, though
timing differences will necessitate chances lingering into Sunday
evening.
Ridging at the surface and aloft will reassert control thereafter,
with continued above normal temperatures and dry conditions early
next work week.
Guidance then suggests, though differs significantly in timing and
strength, that a much larger upper trough and stronger surface low
will develop across the northern CONUS and move into the central
Canadian provinces, with steady eastward progress of the upper
trough pushing a stronger cold front through the area mid week next
week.
Despite the cold frontal passage, temperatures are likely to remain
above normal throughout the forecast period, though depending upon
the strength of the cold front next week, there is at least some
chance of a brief drop to near or slightly below normal mid-month.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 542 PM EST Wed Nov 6 2024
Impacts:
- VFR at BMG/HUF/IND until around 06Z. MVFR overnight.
- MVFR conditions overnight at LAF.
- Patchy fog possible again late tonight BMG/LAF.
- Return to VFR all locations after 071400Z.
Discussion:
GOES16 shows IND/BMG and HUF caught in an area of clearing between
MVFR cloud decks over southern Indiana and over NW Indiana and
Central IL. HRRR 925mb surface shows increasing RH through the
overnight house as diurnal cooling takes place and the cold front
across Central Indiana pushes farther southeast. This will lead to
some brief VFR conditions in between these two cloud decks, but
eventual MVFR cigs overnight across the forecast area.
On Thursday, VFR conditions will return as high pressure arrives
across the area. Forecast soundings at that time show a dry column
with subsidence by late morning, returning conditions to VFR.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
SHORT TERM...Updike
LONG TERM...Nield
AVIATION...Puma
Source:
IND issues Area Forecast Discussion (AFD) at Nov 6, 9:15 PM EST---------------
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