Author Topic: [Alert]IND issues Area Forecast Discussion (AFD) at Nov 16, 12:36 AM EST  (Read 92 times)

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IND issues Area Forecast Discussion (AFD) at Nov 16, 12:36 AM EST

575 
FXUS63 KIND 160536
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1236 AM EST Sat Nov 16 2024

.KEY MESSAGES...

- Low clouds tonight with temperatures remaining in the 40s;
  Potential for fog and low visibilities

- Wind gusts in excess of 30 mph next Tuesday and Thursday

- Potential for first snow Wednesday night into Thursday

&&

.FORECAST UPDATE...
Issued at 738 PM EST Fri Nov 15 2024

There is some concern of fog overnight, especially over the Wabash
Valley, where some clearing is possible. Currently, the clearing
line is knocking on the door yet not advancing much if at all, and
low level moisture progs and Hi-Res soundings at KLAF and KHUF
continue to keep appreciable moisture around from around 1-3K feet
underneath a strong inversion and the surface high center. Finally,
BUFKIT fog product and most Hi-Res models support stratus over fog.
So, will make little changes to the forecast and keep it cloudy to
mostly cloudy. The insolation from the stratus and lack of low level
winds should limit temperature drop with overnight lows expected to
match current dew points, in the lower to middle 40s.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 235 PM EST Fri Nov 15 2024

A rather cool and dreary weather pattern continues through the short
term over much of the state. Latest satellite imagery shows
widespread low stratus across the Great Lakes region and Midwest in
the wake of an area of low pressure east of Detroit. ACARs soundings
continue to depict a suppressed saturated layer around 1KM AGL with
subsidence induced dry air above. This will likely maintain the
stratus layer through the evening hours. There are some hints at
this stratus layer thinning out over portions of N/W central Indiana
early tonight, but most should remain within overcast skies.

Thick cloud cover throughout the day has significantly limited
diurnal warming leading to marginal dew point depressions this
afternoon and evening. This should allow for a nearly saturated
boundary layer overnight despite weak diurnal cooling beneath the
stratus layer. Surface high pressure also moves directly overhead
this evening creating peak subsidence and calming winds overnight.
The combination of elevated RH, calming winds and subsidence will
lead to lowering of the stratus layer, with some potential for this
stratus layer to reach the surface by tomorrow morning. If this does
occur, a widespread fog event is possible. For now, a near surface
level stratus layer is the forecast, including 3-5SM visibility
within misty conditions. We will closely monitor for trends
indicating further deterioration of visibility.

Tomorrow, temperatures will struggle to increase throughout the
morning, but by the early afternoon, high pressure moving off to the
east should create enough of a pressure gradient for mixing to
occur. This should lead to breaking of the stratus layer with
surface temperatures increasing into the mid 50s. There is a
scenario (mainly over eastern IN) that the stratus layer remains
intact, of which would significantly reduce expected high
temperatures (upper 40s).

&&

.LONG TERM (Saturday night through Friday)...
Issued at 235 PM EST Fri Nov 15 2024

Saturday Night Through Tuesday.

The warming trend will continue Saturday night into Sunday with
continued ridging across the Ohio Valley and strengthening southerly
flow near the surface as a low pressure system moves across Southern
Canada. Highs on Sunday and Monday will climb into the low to mid
60s.  Cloud cover will gradually begin to increase late Monday as
the next rain producing system begins to move northeastward from the
Baja Peninsula into the Plains. The low pressure system across
Canada will help to push the system in a more northerly direction
than would typically be expected of a system tracking from the Baja
Peninsula. This will keep the heaviest rain west of the forecast
area with precipitation onset late Monday night. The greater impacts
from this system will be from gradient winds Tuesday as the boundary
layer deepens to around 4kft which will allow the mixing down of
winds to around 30-40 mph. Total rainfall is expected to be around a
quarter of an inch.

Wednesday Through Friday.

Much colder air will move in Wednesday in the aftermath of the
Tuesday system with increasing confidence in a secondary low
pressure system quickly moves in on the backend of the exiting first
system. There is a fair amount of ensemble spread on the daytime
highs for Thursday, but there is increasing probabilities that highs
will struggle to rise out of the 30s. There is also the potential
for central Indiana to see snow for the first time this season, but
confidence remains very low on the precipitation aspect of the
forecast this far out. Looking to next weekend and beyond the
pattern then looks to become quieter with drier than normal
conditions along with temperatures staying near to slightly below
normal.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1236 AM EST Sat Nov 16 2024

Impacts:

- MVFR cigs through this morning, slowing lifting this afternoon


 Discussion:

Latest satellite imagery shows a large area of stratus across the
Great Lakes and Ohio Valley as moisture remains trapped in the
boundary layer under a strong subsidence inversion aloft.
Observations indicate cigs around 2000ft agl across the region early
this morning. Cigs should remain at MVFR levels through the morning
hours, with a slight possibility of them lowering to IFR levels in
some spots near sunrise. Patchy fog possible at KLAF, KHUF, and KBMG
through around sunrise; however with thick stratus around, not
expecting widespread fog and visibility reductions. As high pressure
shifts eastward today, expect cigs to lift and break up during the
afternoon hours.

Calm to very light easterly winds early this morning will become
southeast 6-11 kts by this afternoon.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...MK
SHORT TERM...Updike
LONG TERM...White
AVIATION...CM

Source: IND issues Area Forecast Discussion (AFD) at Nov 16, 12:36 AM EST

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