Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/06/23
Area Forecast Discussion
National Weather Service Indianapolis IN
1011 PM EDT Fri May 5 2023
.Forecast Update...
Issued at 1011 PM EDT Fri May 5 2023
Very little change was needed for the forecast and only minor
adjustments were made to the winds to adjust for current conditions.
Other than than, forecast is on track for cloud coverage to increase
overnight and lows dropping to the 50s.
&&
.Short Term...(This evening through Saturday)
Issued at 220 PM EDT Fri May 5 2023
- Mostly clear and pleasant this evening
- Increasing clouds overnight
- Partly Sunny on Saturday
Surface analysis late this morning shows a large area of high
pressure in place over the middle Atlantic States. The large high
had extensive influence of the weather, stretching west across
Indiana to the middle Mississippi Valley. Low pressure was found
across the TX/OK Panhandle. This pattern was resulting in warm
southerly flow across the Ohio Valley and into Central Indiana.
Aloft, water vapor showed a broad trough aloft stretching from the
northeastern States, across the Great Lakes to Central Canada.
Ridging was in place beneath the trough, stretching from Colorado
across the plains to the Ohio Valley. This was resulting in NW flow
aloft over Indiana along with weak lee side subsidence. Temperatures
across the area had risen to the lower and middle 70s under
plentiful sunshine.
This evening...
Dry and pleasant weather is expected this evening as little change
will be expected. Wind speeds are expected to diminish slightly with
the loss of mixing. Forecast soundings continue to suggest a very
dry column. ACARS soundings also show this trend. Thus a mostly
clear sky will be expected this evening with temperatures slowly
falling through the 60s.
Overnight...
The high pressure system over the east coast is expected to remain
in place as the surface low over the TX/OK panhandle begins to push
northeast toward Kansas. This will strengthen the southerly flow of
gulf air into the Ohio Valley. The 300K GFS Isentropic surface shows
upglide beginning overnight with the arrival of some high and mid
level clouds. Specific humidities begin to increase toward 5-6 g/kg
toward 12Z. Forecast soundings at that time continue to reveal very
dry air within the lower levels and dew point depressions near 12Z
area suggested to be 8-10F. Thus only some increasing high clouds
will be expected overnight. Given the increasing cloud cover along
with ongoing warm air advection, lows in the lower to middle 50s
will be expected.
Saturday...
The previously mentioned isentropic lift is suggested to continue
through the day on Saturday. Warm southerly winds ahead of the low
pressure system passing to the north will allow the continued flow
of gulf air into Central Indiana. Aloft, the ridge that was to the
west of Indiana will now be passing over Indiana, steering any
forcing dynamics well north of Indiana, toward and across the Great
Lakes. With the southerly flow in place, dew points are expected to
rise into the 50s on Saturday. This will allow for lower convective
temperatures along with a better set up for diurnal CU development.
Thus with high cloud invading with the isentropic lift along with
some afternoon CU, we will trend toward a partly sunny sky. Overall,
dry air within the lower levels along with a lack of forcing aloft
should prevent any precipitation. Given the clouds, will trend highs
slightly cooler than on Friday, as they should reach mainly the
lower 70s.
&&
.Long Term...(Saturday night through Friday)
Issued at 220 PM EDT Fri May 5 2023
Saturday Night Through Tuesday.
Rain chances will begin to increase Saturday night into Sunday as
the ridge moves eastward and a series of storm complexes potentially
impact the area. The overnight period Saturday night has the
potential to see the first of these systems, but details on the
initiation and development of the storm complex are beyond the more
synoptic pattern and will depend on mesoscale influences. Either
way, do think that light to moderate rain is likely during the
overnight hours with the better chance for heavier rain to the north
along the nose of the ridge.
Better chances for overnight convection arrive Sunday night, but the
pattern looks very messy with a lot of uncertainty as to how the
Saturday night storms may settle any outflow boundaries that would
then be areas of focus for additional development. Weak
northwesterly flow develops early next week with additional low
confidence potentials for storm complexes Monday night. Temperatures
will remain near to above average through the period with abundant
daytime CAPE and stout near surface caps in place which should limit
daytime convection coverage and potential.
Wednesday Through Friday.
The ridge begins to build back in Wednesday and Thursday with model
soundings showing dry air move in aloft which will bring a return to
the sunny skies and pleasant conditions. Highs near 80 will
continue into Thursday ahead of the next series of weak system that
may impact the area as early as Friday.
&&
.Aviation...(00Z TAF Issuance)
Issued at 728 PM EDT Fri May 5 2023
Impacts:
* VFR Conditions are expected this TAF Period.
Discussion:
VFR conditions expected through the period. Winds will start out
from the southeast and become more southerly through tomorrow. Winds
are still sustained at 10 to 12 kts at the start of the period but
will drop off once the sun going down to 5 to 7 kts. Current
satellite shows an increase of cirrus clouds moving in from the
west.
On Saturday, forecast soundings and time heights reveal the return
of mid level moisture overnight and lower level moisture during the
late morning hours. Southerly flow continues across the area as warm
air advection and isentropic lift begins. This will allow the return
of some low VFR ceilings after 061500Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...KH
Short Term...Puma
Long Term...White
Aviation...KH
Area Forecast Discussion
National Weather Service Louisville KY
936 PM EDT Fri May 5 2023
.Forecast Update...
Issued at 935 PM EDT Fri May 5 2023
Current radar mosaic tile shows weak reflectivity cores moving west
to east across the area associated with subtle isentropic lifting.
Although there have been a couple of light rain/drizzle reports over
south-central Kentucky, overall this activity should wind down
towards midnight. Otherwise, this warm advection regime will keep
the broken to overcast conditions on Saturday with a low chance of
light rain/drizzle over the Lake Cumberland region before sunrise.
Regarding tomorrow`s forecast, did noticeable adjustments to account
for a drier solution, more in line with latest CAM guidance. The big
question remains the conditional risk of isolated convection in the
southwestern corner of the CWA which seems to stem from upstream
boundary collisions in the Mid Mississippi Valley. So far from the
HREF model suite, HRRR has been the most aggressive output followed
by the HRW ARW as the rest does not show any kind of significant
development. Subsequently, low probabilities were introduced for the
area of concern during the late afternoon period.
&&
.Short Term...(Tonight through Saturday evening)
Issued at 240 PM EDT Fri May 5 2023
Weakening band of light rain showers is making slow progress
eastward into our southern KY counties this hour. KY Mesonet is
showing a delayed response to any measurable precip, as that
moisture runs into drier air to the east..per GOES Sounder
precipitable water gradient. Given location of band moving into our
southern KY zones, will maintain low-end (~20%) chances for
measurable rainfall into the evening hours.
As mentioned in the previous discussion, there`s no good trigger or
low-level jetting to focus activity overnight as a little more solid
moisture builds into the area. Still, we may get some weak
isentropic lifting to force a few showers, so have gone with some
more low-end PoPs over a bit larger area of southern KY by daybreak
Saturday.
For the day Saturday, that pwat gradient shifts east, with most of
our area getting up to around 1.2"...a little above normal for this
time of year. Still with expected low cloud cover, we shouldn`t have
too many triggers for shower development. Ensemble guidance, both
short-range CAM`s and global model...aren`t too excited about rain
chances either. Still, any good breaks in those clouds through the
day could allow for some instability to form and promote an isolated
thunderstorm or two in the afternoon...so will maintain that mention
in this forecast package.
&&
.Long Term...(After midnight Saturday night through Friday)
Issued at 350 PM EDT Fri May 5 2023
As we head into the long-term, upper ridging remains in place
overhead while surface high pressure sits off the coast of South
Carolina. Surface low pressure near the panhandle of Oklahoma will
slowly get pushed northeast, increasing the pressure gradient over
the Lower Ohio Valley. The will keep breezy winds from the south
over the region. Lows Saturday night will only drop into the upper
50s to mid 60s. Even with warmer temperatures and a rising dew
point, most guidance keeps the region capped and dry, but it is
possible that an MCS that develops over Illinois could continue
working southeast through southern Indiana and central Kentucky
through the evening hours into the overnight. The HRRR has the
region remaining less capped and has the MCS working through the
region.
On Sunday, the day will likely begin with a few breaks in the clouds
allowing sunshine to help the the southern breeze lift temperatures
to the upper 70s to low 80s. Dew points are expected to climb into
the mid to upper 60s. The upper ridge and high pressure will keep
shear values low, but the warm moist air will help MLCAPE values
reach 2,000-3,000 J/kg by the evening hours. Model soundings show an
inversion sitting just above the 850mb layer of moisture, but it
wouldn`t take much to overcome this cap and for scattered
thunderstorms to develop. These storms could produce strong winds,
but organized severe weather isn`t expected. The chance for
scattered showers and thunderstorms will remain until a weak cold
front pushes through the region on Tuesday.
Behind the cold front, mostly sunny skies and weak CAA will drop
high temperatures on Wednesday a couple degrees before WAA returns
on Thursday. Temperatures on Thursday are expected to reach into the
low to mid 80s.
&&
.Aviation...(00Z TAF Issuance)
Issued at 730 PM EDT Fri May 5 2023
Impacts/Confidence:
- Low confidence in MVFR ceilings between 6/12-18Z at HNB/BWG/SDF
Discussion...Mainly VFR conditions are expected at all terminals
through this TAF period with a low chance of MVFR ceilings at
BWG/HNB/SDF Saturday morning. As noted in the previous forecast,
moisture continues building into the area ahead of an approaching
warm front. Regional radar imagery shows some decreasing echoes over
BWG which could yield some light rain but uneventful whatsoever.
Further north, latest SDF ACARS depicts plenty of dry air to
evaporate any precipitation attempt. Conditions overnight will be
mostly dry accompanied by light winds gradually shifting to the
south. Last but not least, southerly flow will slightly strengthen
Saturday morning while increasing moisture advection with a low
chance of cloud bases lowering to MVFR levels.
Extended Outlook...A period of lowered cloud base could start
Saturday night into Sunday morning with possibility of MVFR/IFR
category.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...ALL
Short Term...RJS
Long Term...KDW
Aviation...ALL