Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/11/23
Area Forecast Discussion
National Weather Service Indianapolis IN
1002 PM EDT Tue Oct 10 2023
.Forecast Update...
Issued at 958 PM EDT Tue Oct 10 2023
Quiet weather conditions will continue overnight as weak surface
high pressure builds into the region. Forecast soundings show a dry
column with subsidence and a sharp radiation inversion. Winds have
diminished considerably over the past few hours as surface
ridging builds in. Light winds and clear skies over central
Indiana will allow for efficient diurnal cooling to continue,
which is supported by the sharp radiation inversion on forecast
soundings. A frost advisory is in effect late tonight into
Wednesday morning as temperatures will likely fall into the 30s
for much of the area.
&&
.Short Term...(This evening through Wednesday)
Issued at 236 PM EDT Tue Oct 10 2023
- Cool again with Patchy Frost again Tonight
- Increasing clouds and slightly warmer on Wednesday
Tonight...
...Frost Advisory Tonight for much of Central Indiana...
Surface analysis early this afternoon shows cyclonic flow in place
across Indiana due to a deep low pressure centered over eastern
Ontario and western Quebec. Aloft, an associated deep low pressure
system was found nearly in the same location in this stacked system.
Strong surface high pressure was found near the confluence of the
Mississippi and Ohio Rivers, and this was resulting in a moderate
pressure gradient across Central Indiana. Water vapor continued to
show dry and subsidence filling into Central Indiana from the
northwest. Skies across Central Indiana were clear. A few clouds
were found across northern Indiana associated with the cyclonic
flow. Heating and mixing today has allowed dew points across the
area to fall into the lower 30s
The models keep the broad cyclonic circulation in place across the
Great Lakes and northern Indiana tonight. However the surface high
pressure system to our southwest is expected to drift east across
Kentucky and provide weak surface ridging across Central Indiana
overnight. This should allow lighter winds tonight than we saw
early this morning. Forecast soundings and time heights show a dry
column in place overnight, providing clear skies. Dewpoints in the
lower 30s and even a few upper 20s this afternoon reveal a very dry
condition across Central Indiana, favorable for radiational cooling.
Thus with many of the same elements in place tonight that are
favorable for frost, we will once again issue a frost advisory for
much of the forecast area.
The area least likely to get frost would be across the southwest,
where eventual backside flow around the high will allow for some
slightly warmer low temperatures at that location. Much of Central
Indiana will see lows in the middle to upper 30s, with lows around
40 in the southwest.
Wednesday...
Warmer air is expected to arrive on Wednesday. Models suggest a warm
front pushing across Central Indiana on the back side of the surface
high. Weak ridging aloft is suggested to develop as the deep upper
low to the northeast begins to slide east. A weak upper disturbance
is noted within the flow aloft, pushing toward Indiana on Wednesday
afternoon. HRRR responds to the feature showing some showers
developing, mainly across the western and northern Central Indiana
late in the afternoon. Moisture remains questionable. Forecast
soundings show saturation within the middle and upper levels of the
atmosphere, but a prominent dry layer within the lower levels. Pwats
appear to be only around 1 inch as this forcing feature passes. Thus
as the warm front and disturbance arrive and pass, will trend toward
increasing clouds with small chances for very light rain. Most rain
will probably end up as virga as evaporation occurs within the dry
layer. Given the clouds and warm front along with winds becoming
southerly, we will trend highs to the mid 60s.
&&
.Long Term...(Wednesday night through Tuesday)
Issued at 236 PM EDT Tue Oct 10 2023
Thursday...
A deep upper level trough and associated low pressure system will
continue to approach Thursday with the bulk of central Indiana in
the warm sector by Thursday morning. A broad, but very cold core low
will continue to sit over SE portions of Canada, limiting mid to low
level WAA over the area, but there should be enough surface-850mb
advection for temperature to exceed normal values for early to mid
October. There has been a significant warming trend out ahead of
this system on Thursday due to low pressure track trends shifting to
the NW. Without much moisture in the warm sector of this system,
conditions should remain dry during the day and through Thursday
night. The combination of dry low level air and southerly winds,
could lead to an overachieving temperature day; current forecast is
for mid to upper 70s, but low 80s are not out of the realm of
possibilities.
Winds on Thursday are likely to be higher as the pressure gradient
sharpens out ahead of the low. This in combination with a deep
mixing profile should lead to 20+ MPH gusts Thursday afternoon,
especially over western portions of the area.
Friday and Friday night...
The aforementioned low pressure system will pass through on Friday,
leading to some unsettled conditions. The initial concerns will be
related to gradient wind Friday morning through the afternoon. As
mentioned previously, the warm sector out in front of this low will
be rather dry, leading to an efficient layer for mixing stronger
wind from aloft. The low will also deepen Thursday night through
Friday leading to a stronger pressure gradient over the region. In
all, sustained winds are expected to be around 15-25 MPH with gusts
up to 35-40MPH. Peak gusts are likely to be between 4-7PM over
western central Indiana as the cold front nears from the west. As
dusk arrives, surface temperatures should cool enough to combat WAA,
suppressing mixing and non-thunderstorm wind gust strength.
The secondary concern will be rain/thunderstorms along the cold
front Friday evening into Friday night. Moisture return looks to be
condensed along the boundary. Outside of this narrow moisture
corridor, instability looks to be heavily limited as the low
pressure system begins to occlude keeping cold air aloft west of
central Indiana. This should place 850-500mb lapse rates around 6.3-
6.8 C/km, of which would need fairly high surface dew points for
surface based instability to be present. Lift will not be an issue
along the front however, so there will likely be scattered
showers along the boundary. If convection does initiate along the
boundary, there would be enough mixing to tap into a fairly strong
LLJ, leading to high wind gust concerns. Uncertainty is still
very high at this point, but this is something to monitor in the
coming days.
Saturday through Tuesday...
The upper low will move into the Appalachians and then New England
late in the weekend with cyclonic northwest flow over central
Indiana. Embedded waves in the NW flow could result in more periodic
showers through the remainder of the long term along with more below
normal temperatures (highs in the low 60s).
&&
.Aviation...(00Z TAF Issuance)
Issued at 736 PM EDT Tue Oct 10 2023
Impacts:
* VFR Conditions expected through the period
* Winds will become S/SW overnight into Wednesday
Discussion:
VFR conditions will prevail through the TAF period. Forecast
soundings show a continued dry column with subsidence. Thus mostly
clear skies are expected.
Weak high pressure arriving from near the Mississippi and Ohio river
confluence will result in light to calm winds overnight. Winds will
be out of the S/SW tonight into Wednesday, but speeds should
increase to around 10 kts during the day. Mid-high level clouds will
stream in from the west on Wednesday, leading to increased cloud
cover.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 3 AM to 9 AM EDT Wednesday for INZ021-
028>031-035>042-046>049-054>057-064-065-072.
&&
$$
Update...Melo
Short Term...Puma
Long Term...Updike
Aviation...Melo
Area Forecast Discussion
National Weather Service Nashville TN
751 PM CDT Tue Oct 10 2023
...New UPDATE...
.UPDATE...
Issued at 748 PM CDT Tue Oct 10 2023
A pleasant fall evening across the midstate with current
temperatures and dewpoints mainly in the 40s/50s. Satellite
imagery shows considerable cirrus clouds over our far southern
counties, and models indicate high clouds will continue to
increase and thicken over our entire area as the night goes on.
Despite the light winds and dewpoint depressions getting low
towards sunrise, the increased cloud cover is expected to keep fog
formation minimal - although cannot rule out some patchy fog here
and there. Forecast remains on track and no notable changes were
made.
&&
.SHORT TERM...
(This afternoon through Friday)
Issued at 130 PM CDT Tue Oct 10 2023
Nice day with mostly sunny skies and current temps in the lower to
mid 70s. A larger shield of cloud cover is located to our south.
This is in response to a little bit of tropical activity along the
western Gulf and also southeast of Baja Cal.
A disturbance off the east coast of Mexico could develop into a weak
tropical cyclone as it heads northeast. For middle TN, only an
increase in cloud cover is expected. Hrrr does hint at perhaps a few
sprinkles south during the afternoon on Wednesday. Otw, the NBM is
keeping the moisture south. Wednesday night could feature some
patchy fog across our Plateau.
Thursday night and Friday, another weak disturbance will track
across the northern Gulf while a frontal system approaches from the
west. This will increase our shower chances but rain amounts should
remain on the lighter side. Instabilities look weak in the pre
frontal area so not anticipating any tstm activity.
For the near term temps, a slow warmup into the lower 80s will be
possible by Thursday as some upper ridging builds in. Lows will
climb back into the 50s.
&&
.LONG TERM...
(Friday Night through next Tuesday)
Issued at 130 PM CDT Tue Oct 10 2023
In the extended forecast, good shower chances will still be in play
for Friday night with the front moving through. This will be
followed by a series of disturbances, the strongest of which will
occur early next week. Thus, look for shower chances to persist
through the extended.
For the extended temperatures, turning much cooler following the
Friday night fropa. With the clouds and precip coexisting with the
backside troughing pattern, our high temps will hold in the 50s for
the Plateau next week, slightly warmer west. Lows generally will be
in the 40s but perhaps a few upper 30s Tuesday morning along the
Plateau.
6 to 14 day outlooks are showing below normal temps and below normal
precip.
&&
.AVIATION...
(00Z TAFS)
Issued at 648 PM CDT Tue Oct 10 2023
VFR conditions continue. High clouds will begin to move in
overnight with light, variable winds. Winds will settle into S/SE
by the afternoon through the remainder of the TAF period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 50 77 54 79 / 0 10 0 0
Clarksville 47 78 54 79 / 0 10 0 0
Crossville 44 68 49 72 / 0 10 10 0
Columbia 51 77 53 77 / 0 10 10 10
Cookeville 46 71 52 75 / 0 10 10 0
Jamestown 43 68 50 74 / 0 10 10 0
Lawrenceburg 52 76 52 76 / 0 10 10 10
Murfreesboro 49 78 53 79 / 0 10 0 10
Waverly 51 76 53 77 / 0 0 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Shamburger
SHORT TERM...21
LONG TERM....21
AVIATION.....Adcock