Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/07/22
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
612 PM CDT Thu Oct 6 2022
...New AVIATION...
.SHORT TERM...
(Tonight through Friday night)
Issued at 133 PM CDT Thu Oct 6 2022
Latest GOES-16 Water Vapor imagery shows southwesterly flow aloft
and mid to high level clouds streaming into South-Central Texas. A
weak shortwave feature, as forecast by the latest CAMS and 18Z RAP
will swing through the forecast area this evening through Friday
morning, with perhaps enough lift to trigger an isolated shower or
two along the Rio Grande. However, with exceedingly dry surface air
and little to no CAPE to work with, believe that any showers that do
attempt to form east of the Rio Grande Plains will more than likely
produce virga and no measurable precipitation at the surface. That
being said, bumped PoPs up to less than 10% for most locations west
of I-35, but have kept mention of showers out of the forecast for
now. If anything does make it to the surface, it won`t provide any
sort of lasting relief to our ongoing drought conditions. More more
high clouds and broken skies overnight, expect less radiational
cooling to take place, with temperatures generally in in the lower to
middle 60s as compared to the widespread 50s we`ve seen most
mornings for the past week or so. Temperatures both this afternoon
and Friday afternoon will climb into the 80s west of US-281 and upper
80s to lower 90s east of US-281.
&&
.LONG TERM...
(Saturday through Thursday)
Issued at 133 PM CDT Thu Oct 6 2022
For the most part, quiet weather is expected to continue through the
long term.
At the beginning of the period, a cutoff low is expected to be
centered over Baja California, with longwave troughing aloft across
the northeastern CONUS. Through the weekend the longwave trough will
push east into the Atlantic and the cutoff low will gradually
diminish. This leaves fairly weak west to southwesterly flow over
south central Texas. The only potential weather maker through the
weekend would be a wave of vorticity that ejects northeast from the
cutoff low. This piece of energy could spark some isolated to widely
scattered shower and thunderstorm activity across the Rio Grande
Plains Sunday afternoon into Monday, but the low to mid levels of the
atmosphere will be fairly dry so some or much of this activity may
be virga.
Heading into the middle of next week, another longwave trough is
expected to move from British Columbia into the Upper Midwest. This
system could push a weak cold front into our region by the end of the
period which would be our next best chance for precipitation, though
unfortunately nothing widespread or significant is expected at this
time in terms of precipitation coverage or QPF.
A surface high will move into the southeastern CONUS from the
northern Plains by this weekend. This will bring a weak, reinforcing
shot of drier air to help maintain cool morning temperatures through
the weekend. However, once the high moves off further to the east,
we will see winds become southeasterly which will help advect greater
surface moisture into the region from the Gulf until the next front
arrives towards the end of the period. Consequently, mornings will
become increasingly muggy by the middle of next week. Highs will
remain more steady in the 80s to lower 90s, though the increasing
humidity may make it feel less comfortable.
&&
.AVIATION...
(00Z TAFS)
Issued at 605 PM CDT Thu Oct 6 2022
VFR conditions are expected across area terminals. Mid to high clouds
are forecast to arrive from the southwest as an upper level flow
dominates the region. Surface winds are forecast to be from the east
and southeast through the period. Light and variable this evening
through Friday morning and around 5 to 10 knots in the afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 64 91 66 92 / 0 0 0 0
Austin Bergstrom Intl Airport 63 92 62 90 / 0 0 0 0
New Braunfels Muni Airport 65 92 65 93 / 0 10 0 0
Burnet Muni Airport 63 90 63 88 / 0 0 0 0
Del Rio Intl Airport 64 86 66 85 / 10 10 10 10
Georgetown Muni Airport 63 91 62 89 / 0 0 0 0
Hondo Muni Airport 64 89 63 90 / 10 10 10 0
San Marcos Muni Airport 63 91 63 92 / 0 0 0 0
La Grange - Fayette Regional 63 93 64 92 / 0 0 0 0
San Antonio Intl Airport 66 90 67 90 / 10 10 0 0
Stinson Muni Airport 68 91 67 92 / 10 10 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...17
Long-Term...04
Aviation...17
Area Forecast Discussion
National Weather Service Gray ME
1025 PM EDT Thu Oct 6 2022
.SYNOPSIS...
A strong cold front brings rain showers and isolated
thunderstorms to the region tomorrow and tomorrow night with
much cooler temperatures over the weekend behind the front.
Another front passes through on Sunday afternoon, then a cool
area of high pressure builds in behind the front for the early
and middle part of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Latest 0222Z Update...
Temperatures continue to lower towards the current dew points
this hour. Fog will begin to develop rapidly late this evening
with mainly clear skies and light winds.
Shower activity remains well to the west over northern and
central New York State per latest radar imagery. This
precipitation may reach northern portions of our forecast area
late tonight into tomorrow morning.
Update...
Update this evening for the near term portion of the forecast.
Clouds remain primarily located over western Vermont and New
York state per latest satellite imagery. This will spring east
during the overnight hours. Latest HREF scenario suggests low
clouds may attempt to enter the coastline later tonight as well.
A few showers may enter far northern areas later tonight and
early tomorrow morning associated with a prefrontal trough.
Patchy fog expected to form as well ahead of the advancing
clouds.
Prev Disc...
Shortwave ridging through this evening is short-lived in the
progressive northern stream, which sends a trough through the
Great Lakes region tonight and across New England tomorrow. For
us locally, this means increasing clouds overnight along with a
warm and humid southwesterly flow... at least aloft. At the
surface, light flow goes calm in many areas, allowing decoupling
to occur with lows in upper-40s to low-50s and fog development.
Up into the mountains, height falls mark the approach of the
trough from the west, with increasing chances for rain showers
by dawn.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
A trough of low pressure swings from a positive to a negative
tilt as it pushes out of the northern Great Lakes region and
into Quebec on Friday, sending a cold front through New England.
While the stratiform baroclinic leaf portion of the storm will
be north of the region, closer to its parent forcing... a
trailing cold front will bring rain showers and perhaps line of
gusty convection to New Hampshire and Maine through the
afternoon into the evening hours, tracking quickly from West to
East.
Friday morning, rain showers will be increasing over the mountains,
with a few showers/sprinkles south of the mountains...forced by
a prefrontal trough as the front itself crosses Lake Champlain.
By about 12-2 PM the front crosses the Connecticut River
Valley... pushing out over the Gulf of Maine and Downeast by
about 7-9 PM. With surface/ML-based destabilization and
steepening lapse rates aloft... and adequate shear... am
expecting isolated to scattered thunderstorms to form along or
ahead of the front. The front itself is likely to bring some
gusty winds, with the HRRR showing 25-30 kt gusts for a brief
time after FROPA. Otherwise, expect greatest coverage of showers
and storms across the north although showers are still likely to
reach the coast as well... just not everywhere.
Cool and dry air quickly fills in behind the cold front Friday
evening and overnight. Upsloping showers will continue over the
mountains, but a transition to snow is expected at least across
the peaks before wrapping up entirely Saturday morning. A loss
of cloud ice may lead to some drizzle...or freezing drizzle...
as well. Low-level CAA looks to be strong enough through the
overnight to keep us relatively well mixed, with winds turning
west-northwesterly and remaining somewhat gusty. This should
prevent the bottom from entirely dropping out in terms of
temperatures... with lows in the low-30s toward the north and
closer to 40 near the coast.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Overview...
A ridge axis passes through the Northeast on Saturday as the
high pressure center moves across the southern tier of the
country. A cold front passes through New England later on
Sunday, with a cool high pressure following the front and
becoming centered across New England for the early to mid part
of next week. By Thursday, the high pressure center drifts
offshore with a moderating return flow bringing milder
conditions by the end of next week.
Details...
Some lingering rain and snow showers across the mountains
dissipate by the afternoon hours. Seasonably cool conditions are
expected on Saturday, with highs in the 40s across the north
and 50s across central and southern areas. Temperatures cool
into the 30s in most areas Saturday night, but with the ridge
axis transiting through it doesn`t look to be an overly strong
radiational cooling night. Still, with such a cool airmass in
place, some sub-freezing temperatures are likely away from the
coastline.
On Sunday, a cold front approaches and crosses through by late
in the day. This brings a brief warm up on Sunday on
southwesterly flow as temps warm back into the low 60s along the
coastal plain. A few showers are likely with the fronts`
passage across northern areas, which likely end as a few
snowflakes again across the higher terrain Sunday night.
High pressure builds into the area on Monday from Canada,
bringing a return to seasonably cool conditions for early next
week. Conditions Monday night and Tuesday night look good for
radiational cooling with the high pressure centered across New
England. Started to trend a little cooler than NBM for these
nights with this forecast, but held off on go too strong from
this far out knowing that any cloud cover could limit the
potential.
By late in the week the high drifts offshore and temperatures
climb back into the 60s across most of the area for at least a
couple of days.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...VFR prevails for the remainder of today with light
southerly flow going variable or calm overnight. LIFR fog
development may develop at some of the usual suspects tonight
including KLEB/KAUG/KRKD... and at KCON with stronger
decoupling. Conditions return to or remain VFR early Friday,
except at KHIE where off- and-on MVFR ceilings and SHRA last for
much of the day. Elsewhere, brief restrictions are possible as
a cold front with SHRA crosses. Southwesterly winds 5-15 kts
are expected ahead of this front, and will shift toward the west
behind the front with gusts to around 20- 25 kts possible. The
front itself could produce locally stronger gusts, along with a
few thunderstorms. Steady west- northwesterly flow continues
Friday night with VFR, except for in upslope flow at KHIE with
MVFR CIGS/SHRA... perhaps SHRASN late.
Long Term...VFR conditions are expected Saturday through midday
Sunday, then a few showers are possible late Sunday afternoon
and evening. VFR conditions return Sunday night and persist
through midweek as high pressure settles across New England.
&&
.MARINE...
Short Term...High pressure slips through the Gulf of Maine
tonight with light and variable flow turning southerly Friday
morning. Southerly flow increases through the day, gusting to
around 20 kts by the afternoon... before a cold front crosses
later in the afternoon and evening. The front brings a wind
westerly wind shift and rain showers with wind gusts around 25
kts, locally higher with showers and perhaps a thunderstorm
accompanying the front, persisting over the outer waters into
Saturday morning.
Long Term...Near SCA conditions are possible Sunday in
southerly flow ahead of a cold front. The front pushes through
Sunday night. High pressure follows the front and brings
tranquil conditions through midweek as it settles across the
waters.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR/SHORT TERM...Cannon
LONG TERM...Clair
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
939 PM CDT Thu Oct 6 2022
.UPDATE...
Issued at 939 PM CDT Thu Oct 6 2022
After an early evening lull in surface winds, the magnitudes are
re-increasing as a secondary push of lower tropospheric colder
air and surface pressure gradient tightening occurs. This
secondary push (i.e. cold frontal boundary) seen well on FAA TDWRs
has recently advanced inland along the lake front. Wind gusts on
marine platforms have gusted as high as 40 mph at Kenosha, WI and
to 38 mph at the southern Lake Michigan open water buoy. So would
expect similar along the immediate lakefront from ~10 PM through
early overnight, with a gradual tapering through lake adjacent
counties.
This secondary push of colder air is also resulting in a further
destabilized marine layer. Disorganized lake effect showers should
gradually become more sustained through daybreak as convergence
increases in the midst of lake-induced CAPE values of 150-400
J/kg. Equilibrium levels are forecast to peak Friday morning into
early afternoon, but it will be a race against drier column air
moving in. All-in-all, convection allowing models (CAMs) do
support a peak in lake effect rain shower footprint and intensity
during the morning. Some of these models even provide isolated
QPF values over one half inch in/near downtown Chicago. It`s
always difficult to predict the positioning of these "bands"
(whether rain or snow!) more than a few hours in advance unless
the convergence in the low-level wind field is already well-
defined, which it is not yet. So tough to get real precise, but
portions of central/southern Cook County, eastern Will County,
and Lake County, Indiana are most favored to have some showers
during the morning commute.
Otherwise, little changes made to temperatures which should start
Friday around 40F in north central Illinois to near 50F in
downtown Chicago.
MTF
&&
.SHORT TERM...
Issued at 255 PM CDT Thu Oct 6 2022
Through Friday...
A cold front is trekking southward through the northern CWA this
afternoon. A broken line of showers follows closely behind bringing
light rain to a good portion of Lake County, IL with a few very
spotty showers popping up further west. This line has not produced
any lightning since mid-morning when it was still pushing through
central Wisconsin aside from one lone cell pushing through McHenry
County. RAP guidance still shows a few hundred joules of CAPE near
the line through about 4:00 with low level lapse rates on the order
of 8 K/km or greater with plenty of moisture through the unstable
layer. The biggest contributor to the lack of convection appears to
be a lack of ascent. Lift along the boundary appears a bit too
gradual, for the most part, to produce thunderstorms given the
limited instability and the absence of any notable forcing aloft,
especially now that the broad deformation zone seems to have worn
away. Both the RAP and HRRR suggest that as many as 900 joules of
CAPE could build in the western CWA between 3:00 and 4:00 which
would likely promoted a couple of pulse thunderstorms and, as of
2:20, a few returns are beginning to pop up on radar out in Lee and
DeKalb Counties. With the instability and lapse rates both expected
to readily weaken heading into the latter part of the afternoon,
thunderstorm activity should be limited to areas near and north of I-
80. Not much has managed to form behind this line and with mid-level
instability being very marginal, the potential for post-frontal
activity should be very limited. This line will depart the CWA to
the southeast this evening. A large High approaching from the north
following the frontal passage will cause winds to accelerate through
the afternoon eventually featuring regular gusts to near 30 mph.
Winds will gradually die down through the overnight and Friday
morning as the surface pressure gradient loosens up with the front
departing to the south.
Tonight, a potential for some lake-effect showers arrives along
with a chance for a few waterspouts. Overnight into early Friday
morning, sfc-850mb delta-T`s will be approaching 20C over the lake
resulting in several hundred joules of lake-induced CAPE and steep
lapse rates through the lowest ~200mb. A stable layer at around
700mb will keep lake-induced EL`s capped at around 10,000 ft.
Guidance is suggesting an area of strong convergence setting up
along the Cook and Lake (IN) County lakeshore which looks to be
reinforced in the early morning hours of Friday as NNE winds onshore
back to NNW. Efficient rainfall could result with several convective-
allowing models throwing up a couple tenths of an inch of QPF. These
lake-effect showers should push primarily over NW Indiana by mid-
morning and fizzle away entirely by the late morning/early
afternoon. The rest of Friday will be dry with more sun out west
than over the metro and highs only reaching the lower and middle
50`s.
Doom
&&
.LONG TERM...
Issued at 255 PM CDT Thu Oct 6 2022
Friday night through Wednesday...
Strong cold air advection under a surface high expected to be
positioned across the mid Mississippi River Valley will be in full
effect at the start of the long term period. This will lead to
chilly temperatures to start our Saturday with lows expected to be
in the low to mid-30s across most of northeastern Illinois and
northwest Indiana. Couple these chilly temperatures with the mostly
clear skies and fairly light winds and widespread frost does look
likely Friday night into Saturday morning with isolated pockets of
freeze conditions. Guidance has continued to trend slightly warmer
with the overnight lows on Friday night which is leading to some
uncertainty in whether or not freeze conditions would be realized.
Regardless, measures should be taken to protect sensitive plants
Friday night due to the frost potential.
The surface high is expected to remain in control of our weather
through much of the weekend which will keep skies mostly sunny, but
temperatures will be on the cool side especially on Saturday as
highs will struggle to reach 60 degrees. Winds will also be breezy
on Saturday with gusts currently forecast to be around 20 mph with
higher gusts possible over the lake. The breezy winds are expected
to linger into Sunday as well, but should gradually begin to ease
Sunday afternoon and evening as the surface high departs the area.
Temperatures on Sunday will also be more mild with highs expected to
warm into the mid to upper 60s. Guidance continues to show a weak
cold front moving through Sunday, but the expected lack of moisture
in the lower levels should keep most areas dry with the small
possibility of a brief sprinkle overnight Sunday night though I have
maintained a dry forecast for now.
A gradually warming trend in temperatures is expected through the end
of the period with highs looking to be near 70 by the middle of next
week. However, a stronger cold front is expected to move through the
area sometime on Wednesday which will bring better chances for
showers. Guidance is showing uncertainty in the exact timing of the
frontal passage, but most guidance is hinting at the later portions
of the day on Wednesday. There is also a small chance that an
isolated rumble of thunder could also be possible given the decent
lapse rates aloft Wednesday afternoon, but given the potential late
arrival of the front the window of best instability looks to be
somewhat limited. For this reason I have maintained a mention of
just showers for now given the time range and uncertainty.
Yack
&&
.AVIATION...
For the 00Z TAFs...
The concerns with the Chicago area TAFs tonight and Friday are:
* A temporary lull in winds early this evening that will likely
cause some direction fluctuation between NNW and NNE
* Gustier winds returning late this evening and persisting
through midday Friday, with again some fluctuations between NNW
and NNE
* Lake effect showers and temporary MVFR conditions likely for MDW
and possible for ORD late tonight and Friday morning
The primary cold front has passed and some of the initial showers
behind it should largely clear the TAF sites by 01Z. There is a
temporary lull (2-3 hours) in the gustier winds that will envelop
the Chicago area through 02Z to 03Z. Confidence in specifics of
winds is lower than usual for a good portion of this TAF, and
that`s especially true this evening. The wind direction already
has and likely will continue to show some fluctuation in direction.
Through 03Z, when the wind direction is from 340-350 degrees,
it will likely will be 9 kt or less. After that time, including
even into Friday morning, fluctuations of more gustier winds is
probable. Both ORD and MDW look likely that they will see 350-010
directions during their morning push, and at this time confidence
is equal for NNW vs. NNE. So this will continue to be evaluated
through tonight and refined as needed in TAF AMDs.
As cooler air moves in aloft, instability will develop over the
warmer waters of the lake by late this evening and persist into
Friday. Enough moisture will be present for lake effect MVFR
clouds likely at MDW and GYY, as well as focused convergence for
rain showers. The signal in high-resolution guidance is for this
to be mainly an MDW and GYY concern, with the channel of showers
favored to remain to the east of ORD. Unfortunately the mesoscale
nature of such shower bands yield lower confidence on specifics
beyond a few hours. There is a signal that where this corridor of
showers is most persistent, temporary IFR visibility may occur.
By afternoon, the lake effect showers should be weakening as they
shift eastward over the southern part of the lake. Confidence
increases that the wind direction will turn more NNW in that time.
MTF
&&
.MARINE...
Issued at 939 PM CDT Thu Oct 6 2022
Have hoisted a Gale Warning into the overnight hours due to a
potent surge of north-northeast winds behind a second cold front.
Gusts upstream of 35 kt at Kenosha, WI and a 9 PM CDT ship
observation of 38 kt about 35-40 miles north of the Indiana
shoreline confirm that gales are being observed shortly behind
this front, and the environment supports these lasting for at
least a few hours. Waves accordingly are building sharply, and
would expect some double digit heights at the least occasionally
in both the Illinois and Indiana nearshores overnight and early
Friday morning. Winds will ease through mid to late Friday morning
into the afternoon, with waves slow to subside through Friday
night.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Gale Warning...nearshore waters until 4 AM Friday.
Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-
LMZ745...4 AM Friday to 10 PM Friday.
&&
$$
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