Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/23
Area Forecast Discussion
National Weather Service Boston/Norton MA
1007 PM EDT Mon Aug 14 2023
.SYNOPSIS...
Low pressure and associated warm front will approach the region
overnight into Tuesday morning with showers and a few thunderstorms
with localized torrential rainfall...especially south of the MA
Turnpike. The steady rain will exit the region by Tuesday
afternoon...but a few showers along with areas of drizzle and patchy
fog will persist. Can`t rule out hit or miss showers on Wednesday
although drier weather prevails more often than not. A mix of
sun and clouds on Thursday with seasonable temps, although
periods of rain showers and embedded thundershowers are possible
Thursday night through Friday night. Drier and seasonable
weather anticipated for the weekend.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
10 PM Update:
WAA light rain overspreading western MA/CT with -RA being
reported at PSF and DXR. Light rain falling from a mid deck, so
some of this activity is not reaching the ground yet, but it`s
just a matter of time before the column saturates. Thus, rain
will overspread the entire region after midnight from west to
east.
With dew pts in the 60s, increasing clouds and rain
overspreading the region, it will be a warm and humid night.
Previous forecast verifying nicely, therefore no major changes
with this update.
-----------------------------------------------------------------
&&
.SHORT TERM /MIDNIGHT TONIGHT THROUGH TUESDAY NIGHT/...
Key Points...
* Showers/isolated thunder with localized torrential rainfall Tue AM
* Localized flooding possible Tue AM...greatest risk near south coast
* Low probability of tornado/waterspout near south coast Tue AM
* A few lingering showers/drizzle and fog Tue afternoon
Details...
Overnight into Tuesday Morning...
The main concern revolves around heavy rain and a localized flooding
risk Tuesday morning along with a low probability of a
tornado/waterspout near the south coast. As for timing...we expect
the rain to overspread the region after midnight through 4-5 am from
west to east. The heaviest rain looks to occur between 5 and 10 am
which will result in an impact to the Tue AM rush hour. This
forecast is complex and it remains uncertain if the heaviest rain
will impact CT/RI/SE MA or remain just offshore. We will break it
down more below.
Heavy Rain/Localized Flooding Threat Tue AM...
Strong shortwave energy will be moving eastward across the Great
Lakes late tonight into Tue morning. This will induce a modest
southerly LLJ of 30-40 knots across our southern waters...which is 2-
3 standard deviations above normal for this time of year.
Meanwhile...at the surface a wave of low pressure and its associated
warm front will be pushing eastward in the vicinity of the south
coast. Pwats are extremely high on the order of 2 to 2.50 inches
which is a concern when you have a fairly strong LLJ impinging on
it. The problem is whether this torrential rainfall impacts our
region or remains to our south. Given various model convective
parameterization...there is uncertainty as to how far north/south
this warm front will get. This will determine whether or not a band
of torrential rainfall impacts areas near the south coast Tue am or
stays just to the south over our coastal waters. This will be more
of a nowcast type of forecast...but given the potential opted to
issue a Flood Watch for CT/RI/SE MA. Whether or not this comes to
fruition remains to be seen...but given the risk with the magnitude
of the LLJ/Pwats and potentially coinciding with the morning rush
hour opted to issue. Greatest risk is closest to the south coast
where potential for convection is higher. There then will probably
be an area of lighter rainfall amounts just north of the main band
with a secondary max possible somewhere across western or northern
MA. However...this is not expected to involve as much convective
elements so did not include in the Flood Watch. We certainly could
see 1-2" of rain with localized 3" amounts in under 2 hours during
the Tue AM commute if the heavier band comes onshore.
Low Risk for a Tornado/Waterspout near the south coast Tue AM...
The severe weather potential on Tuesday is low and if it were to
happen would be localized. That being said...there is the low risk
for isolated wind damage potentially in the form of a
tornado/waterspout near the south coast. If this were to occur it
would likely be on the warm front/triple point where low level
helicity can be enhanced. The Colorado State Machine Learning
Probabilities and the HRRR Neural Network do indicate some low probs
of this occurring near the south coast. So this is certainly
something will we will need to watch closely because some of the
guidance does indicate a really well defined triple point/warm
front. This will also be a nowcast type of forecast and will be
dependent on mesoscale factors as well as the track of the triple
point/warm front.
Tuesday afternoon and night...
The steady rain/localized flooding threat will come to an end by
lunchtime Tuesday. However...Low level light northeast flow will
continue to result in rather cloudy skies, a few showers along with
areas of drizzle and patchy fog. Will have to watch for a more
organized area of scattered showers and a few t-storms that may
impact parts of southeast New England late Tue night with another
shortwave. High temps mainly in the lower to middle 70s and a few
spots in the high terrain may not break 70. It will be rather muggy
though.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights:
* More of a pop-up/hit-or-miss shower coverage on Wed, but generally
drier weather prevails more often than not.
* Dry weather for Thu but with filtered sunshine.
* Cloudy with periods of rain to close the workweek; local downpours
may be possible but flooding and severe weather potential seem
low/unlikely.
* Generally dry and seasonable weekend.
Details:
Wednesday:
While primary frontal boundary will have shifted offshore, Wed still
looks unsettled with what may tend to be more spotty, hit-or-miss
showers across interior sections of MA, CT and RI focused mainly by
the primary mid/ upper trough passage. Won`t be raining everywhere
and not a washout but overall not likely to be a great day with more
clouds than sun. Highs should be near or just below seasonable
levels in the mid 70s to low 80s. Any pop-up showers to dissipate
around sundown with decreasing clouds. As that occurs, may have to
monitor for possible overnight radiation fog, being more favored
where we do receive areas of rain. Lows in the lower to mid 60s.
Thursday:
At least the first half of Thurs should be dry, but with a continued
pump of mid to high level moisture on deep layer SW flow, expect at
least partial cloudiness to result. Highs should be fairly
seasonable.
Thursday Night through Friday Night:
Amplifying midlevel height pattern takes place as a potent northern
stream trough coming out of the Canadian Prairies in central Canada
digs southward Thurs night into Fri; as it does so, it is likely to
draw on a stationary plume of subtropical moisture lying offshore
from the Tue/Tue night frontal boundary which returns back landward.
In addition, SW flow fields through entire depth of atmosphere
increase. Thus we should see better chances for at least rain
showers in background moisture profile characterized by precipitable
water values around 1.5 to 1.75 inches and favorable depth of warm-
cloud up to 12,500-13,000 ft; localized downpours are possible in
that setting but progged precipitable water values are lower than
we`ve seen in several heavy rain events this year. In addition, the
stronger flow aloft should keep any soaking downpours moving along
and fairly progressive. The extent to which we can destabilize is
also still unclear, given more clouds than not and rather poor
progged lower to midlevel lapse rates. At the moment, and certainly
good news, is that forecast instability values are too paltry to
support a risk for severe weather; given rather strong flow fields,
severe weather potential would then be increased if greater
instability values can materialize, though it would seem this would
have to be through more sunshine/warmer temps.
Timing will also need to be better refined as the GFS is more
progressive than the ECMWF; prefer the slower ECMWF given
amplification to the mid/upper pattern which often favors are slower
eastward progression.
Highs are somewhat cooler than normal due to the cloud cover and
periods of showers with lows around or slightly above normal.
The Weekend:
Gt Lakes upper low then stubbornly looks to hang around northern New
England and the U.S./Canada border Sat into early Sun. Thinking
better chance for pop-up diurnally driven showers in northern New
England; with NW flow allowing for downslope drying conditions in
SNE. Siding toward a more optimistic outlook for the weekend, with
more sun than clouds, lower humidity levels and core of heat
building over the center and southern parts of the country remaining
to our SW.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
02z TAF Update: VFR cloud bases with light rain already
overspreading western MA/CT at 02z. This trend will continue
overnight, with IFR in heavy showers and isolated TSRA toward
09z. Earlier discussion below.
----------------------------------------------------------------
Though Midnight: High confidence.
VFR. WSW winds 4-8 kt for most, though SW/SSW winds for
southeast MA.
Overnight through Tuesday Morning: Moderate Confidence.
Conditions deteriorate to low end MVFR-IFR levels from west to
east...roughly in the 6z to 12z time frame. This in response to
showers with locally heavy rainfall working northeastward across
the region and continuing into part of Tue morning. Greatest risk
for embedded thunder/heaviest rain will be near and especially
southeast of a PVD-TAN line...but an isolated rumble or two
possible anywhere. E-NE winds generally less than 10 knots...but
a period of southerly LLWS may impact the Cape/Island
terminals.
Tuesday afternoon and night...Moderate Confidence.
The steady rain will exit the region by lunchtime...but low end
MVFR-IFR conditions should continue Tuesday afternoon and night
with persistent light NE flow. Much of the time will feature
just a few showers or drizzle...but another cluster of showers
and t-storms may impact areas near the southeast New England
coast.
KBOS TAF...High Confidence in TAF this evening with moderate
confidence overnight into Tuesday.
KBDL TAF...High Confidence in TAF this evening with moderate
confidence overnight into Tuesday.
TAF Outlook /Wednesday through Saturday/...
Wednesday: Mainly VFR, with local IFR possible. Slight chance
SHRA.
Wednesday Night through Thursday: Mainly VFR, with local MVFR
possible.
Thursday Night: VFR. Chance SHRA.
Friday: VFR. Breezy. Chance SHRA, isolated TSRA.
Friday Night: VFR. Breezy. Slight chance SHRA.
Saturday: Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Tuesday night...Moderate Confidence.
A wave of low pressure and associated warm front will move across
the south coast Tue morning. This will be associated with a cluster
of heavy showers and a few t-storms. We also will need to watch the
potential for a waterspout. Areas of fog may also reduce vsbys for
mariners over this time. There is a low risk for a period of small
craft wind gusts across our southern most waters Tue
morning...depending on how far north the warm front gets. There also
could be localized stronger wind gusts Tue morning in any t-storms.
Outlook /Wednesday through Saturday/...
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.
Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft.
Thursday: Winds less than 25 kt.
Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers, isolated thunderstorms.
Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Chance of rain
showers.
Friday Night: Winds less than 25 kt. Seas up to 5 ft.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 2 AM EDT Tuesday through Tuesday morning for
CTZ002>004.
MA...Flood Watch from 2 AM EDT Tuesday through Tuesday morning for
MAZ017>024.
RI...Flood Watch from 2 AM EDT Tuesday through Tuesday morning for
RIZ001>008.
MARINE...None.
&&
$$
SYNOPSIS...Frank/Loconto
NEAR TERM...Frank/Nocera
SHORT TERM...Frank
LONG TERM...Loconto
AVIATION...Frank/Loconto/Nocera
MARINE...Frank/Loconto
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
624 PM CDT Mon Aug 14 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 224 PM CDT Mon Aug 14 2023
The sea breeze attempted to get going this afternoon, but some drier
mid-level air has, for the most part, kept showers and storms from
forming; one tiny shower was able to develop in northern Cameron
County before fizzling as it moved into Willacy County. The 12Z KBRO
sounding this morning showed precipitable water values (PWATs) near
1.5", but the GOES-16 Total Precipitable Water shows a plume of 2"+
values over our Gulf waters that is advecting inland this afternoon.
Therefore, will leave a 10 to 20 percent chance for rain along the
sea breeze the rest of the afternoon just in case anything is able
to develop.
A light to moderate southeasterly flow coupled with ample low-level
moisture means a passing streamer shower or two is possible,
especially across southeastern Cameron County, later tonight into
early Tuesday morning. That chance, however, is less than 10
percent. These will be mainly "splash and dash" kind of showers and
shouldn`t last terribly long.
Things could then get a bit more interesting Tuesday afternoon. Some
of the most recent Convection Allowing Models (CAMs), notably the
WRF-NSSL and WRF-ARW, have trended towards a more active day along
the sea breeze, and any subsequent outflows, Tuesday afternoon
across portions of the Lower and Middle Rio Grande Valley.
Meanwhile, the 12Z HRRR and WRF-FV3 keep most of the showers/storms
in Mexico. Both scenarios are on the table, so didn`t make any
drastic changes to rain chances with this forecast package other
than a slight upward trend to around 20 to 35 percent for most of
the CWA. Given ample moisture available (PWATs near 2") and energy
(CAPE values near 2500 J/kg), locally heavy rain and gusty winds are
possible within any thunderstorms that are able to develop. We will
continue to monitor these trends as this is the best chance for rain
we`ve had in weeks across the CWA.
Despite a few extra clouds along the sea breeze this afternoon, most
sites away from the immediate coast have already hit or are
currently above the 100 degree mark. Temperatures are forecast to be
a degree or two cooler Tuesday afternoon thanks to those elevated
rain chances, but didn`t make any major adjustments to what the NBM
had, so more upper 90s to middle 100s are anticipated tomorrow.
Calmer overnight winds should allow temperatures to drop into the
middle to upper 70s with lower 80s along the coast and southeastern
Cameron County the next couple of nights.
Elevated fire weather conditions are not anticipated at this time.
While relative humidity (RH) values are forecast to drop to between
25 to 40 percent for most of the Rio Grande Plains, Brush Country,
Upper and Mid Rio Grande Valley, 20-foot winds are expected to be
generally between 10 to 15 mph.
&&
.LONG TERM...
(Wednesday through next Monday)
Issued at 224 PM CDT Mon Aug 14 2023
Key Messages:
-Heat continues with Heat Advisories possible through the week.
-Periodic rain chances return.
Well, the long term forecast has become a bit more interesting since
last update.
First the easy part. High pressure will remain the main feature
through the forecast period. This means hot temperatures will
continue with highs primarily in the 100s, but as we head later into
the week we could see temps drop off by 2 degrees or so. The good
news is that while dewpoints remain moderate, Heat Advisories look a
bit more marginal through the period. This will be something we keep
a close eye one through the week.
Where the forecast becomes a bit more challenging is in rain
chances. Models are beginning to indicate rain chances remaining in
the forecast into Wednesday afternoon and again over the weekend. On
Wednesday moisture will wain just a bit as compared to Monday and
Tuesday, but models are beginning to show a bit of increased upper
level support for shower and thunderstorm development, mainly to our
north, but coupled with the sea breeze could lead to some
precipitation on Wednesday afternoon. While have added rain chances
to the forecast, confidence remains low and tops out at about 20%.
This forecast will likely continue to change a bit through the
upcoming days. Thursday and Friday look to remain dry before
moisture increases and rain chances return, primarily sea-breeze
driven, for the weekend. Chances once again top out about 20%, and
given this is near the end of the forecast period, confidence is not
very high on this activity at this time.
&&
.AVIATION...
(00Z TAFS)
Issued at 621 PM CDT Mon Aug 14 2023
VFR conditions are expected to generally prevail through Tuesday.
Brief MVFR ceilings are possible late tonight streaming off the
Gulf and near any showers or thunderstorms developing along the
seabreeze Tuesday.
&&
.MARINE...
Issued at 224 PM CDT Mon Aug 14 2023
Now through Tuesday Night...The pressure gradient has weakened some,
so Small Craft Exercise Caution (SCEC) conditions are not currently
anticipated for any of the Lower Texas Coastal Waters through the
period. Ample moisture and a passing inverted trough will enhance
rain chances over the Gulf waters with isolated to scattered showers
expected tonight through Tuesday. Slightly drier air begins to
return Tuesday night, lessening rain chances to end the period.
Wednesday through Sunday...Light to moderate southeasterly
winds will lead to generally favorable conditions along the Laguna
Madre and Gulf waters. With a stronger pressure gradient over the
weekend could lead to caution conditions, primarily on the Laguna
Madre. Periodic showers and thunderstorms could also lead to
localized increased winds and seas Wednesday and again friday
through Sunday. Otherwise, wave heights will generally remain
about 2 feet with 4 to 6 second periods.
&&
.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE 81 97 79 99 / 10 30 10 10
HARLINGEN 78 99 76 101 / 0 30 0 10
MCALLEN 80 102 78 103 / 0 30 10 10
RIO GRANDE CITY 79 102 78 104 / 10 20 20 10
SOUTH PADRE ISLAND 80 89 80 89 / 10 30 10 10
BAYVIEW/PORT ISABEL 79 95 77 96 / 0 30 0 10
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Heat Advisory until 7 PM CDT this evening for TXZ250-251-253>255-
351-353>355.
GM...None.
&&
$$
SHORT TERM...58-Reese
LONG TERM....68-McGinnis
AVIATION...56-Hallman
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
957 PM CDT Mon Aug 14 2023
...New UPDATE...
.UPDATE...
Issued at 936 PM CDT Mon Aug 14 2023
We allowed the Excessive Heat Warning and Heat Advisory products to
expire at 9 PM CDT as temperatures and heat index values dropped
below criteria. Also, the Fire Danger Statement product was allowed
to expire at 9 PM CDT.
A weak frontal boundary is pushing across the Hill Country. Latest
observations out of the Burnet Municipal Airport are showing a wind
shift from the north-northeast with gusts up to 21 mph within the
last 30 minutes. The temperature went from 95 degrees at 855 PM CDT
to 91 degrees at 915 PM CDT. So a bit of a cooler airmass spreading
across the local area tonight. Latest HRRR shows no rain across the
local area the rest of tonight into Tuesday morning.
A bit cooler on Tuesday due to the boundary lingering around but
still hot with heat headlines in effect from noon time. A few
showers and even a thunderstorm could occur along the Rio Grande and
south of San Antonio during the afternoon along and ahead of the
boundary.
&&
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 252 PM CDT Mon Aug 14 2023
(Tonight through Tuesday Night)
Synopsis: Upper level ridging will remain prominent through the
duration of the short term period. Currently evident to our north, a
cold front remains forecast to approach our Hill Country and
southern Edwards Plateau zones early this evening. Isolated
thundershowers remain possible over these areas as this occurs,
though most locations will remain dry. The boundary will continue to
sag south through the area tonight, and will likely extend from the
Rio Grande Plains east-southeast into the Coastal Plains by tomorrow
morning. Forward progress will be hindered moving into Tuesday
afternoon, thanks to southeasterly winds in the Rio Grande Valley
and the Coastal Bend. With the front stalled in the vicinity,
showers and thunderstorms will thus be possible once more on Tuesday
afternoon from the Rio Grande Plains southeast into the Coastal
Plains. Coverage may be a touch higher than that observed later
today, although widespread/meaningful rainfall continues to appear
unlikely in any activity. Post-frontal northerly winds will allow
slightly cooler air to filter into South-Central Texas tomorrow
afternoon, particularly over Hill Country and the I-35 Corridor.
Heat headlines will thus expire this evening in these locations.
Elevated to near critical fire weather conditions will continue
through the duration of the period, with Fire Danger Statements in
effect during the afternoon hours. Please refer to the Fire Weather
section below, as well as today`s Fire Weather Planning Forecast,
for additional details.
Rest Of Today: Evident in satellite imagery over the last 60-90
minutes, cumulus development has commenced along the approaching
cold front from San Angelo northeast toward Stephenville. It`s
likely that some of said cumulus will mature into showers &
thundershowers with continued surface heating, though it remains
uncertain if any of this activity will reach our far northern zones
as the boundary continues to drift south. Have continued to carry
slight chance PoPs over far northern zones through the mid-evening
hours, though most locations are likely to stay dry. With slightly
cooler temperatures forecast behind the front on Tuesday, heat
headlines will be allowed to expire over Hill Country and portions
of the I-35 Corridor at 9 PM.
Tomorrow: Isolated to widely scattered showers and thunderstorms
will be possible from the Rio Grande Plains southeast into the
Coastal Plains during the afternoon hours near/just north of the
stalled surface front. 12Z CAM guidance depicts slightly greater
convective coverage relative to today, likely due to enhanced
surface convergence from both the remnant frontal zone and the
advancing sea breeze. Coverage will nevertheless remain widely
scattered at-best, with many areas once again missing out on any
precipitation. Temperatures will remain elevated enough primarily
over the Coastal Plains to support additional heat headlines. Have
issued a Heat Advisory approximately along/south of I-10 from
Fayette County east into Bexar County, as well as in Frio and Medina
Counties between noon and 9 PM given forecasted 103 to 104 degree
high temperatures. Continue to practice proper heat safety in these
areas.
&&
.LONG TERM...
(Wednesday through Monday)
Issued at 252 PM CDT Mon Aug 14 2023
The weak front influencing the short term period should dissipate
into Wednesday. This yields to the return of a more southerly flow
at the surface and across the low-levels. The temperatures will
respond by warming a few degrees higher on Wednesday compared to
Tuesday. Additionally, low end rain chances also lower with any
stray shower confined to our western/southern areas. Thursday and
Friday then host our hottest temperatures of the week as the mid-
level ridge moves eastward and becomes centered from the Texas
panhandle into Arkansas. Temperatures could reach into the 103 to
108 degree range and additional heat headlines are very likely,
including returning Excessive Heat Warnings. No rain will be
expected with mostly sunny skies and low humidity levels through
each afternoon. The southerly winds increase slightly as well and
will result in some worsening fire weather concerns for late in the
week. Refer to the fire weather section down below for additional
details.
The weekend remains abnormally hot but as the center of the mid-
level ridge shifts northeastward into the Midwest, afternoon high
temperatures across the area may help to slowly shave off a few
degrees. Additionally, could not rule out for an isolated shower
along the seabreeze into our coastal plain counties. A glimmer of
hope for some slight relief in the heat and rainfall department
could arrive early next week as an inverted/surface trough could
approach the region from the Gulf underneath the strong mid-level
ridge centered over the Midwest. Will introduce slight chance to
chance PoPs for most of the region Monday with slightly cooler
afternoon highs.
&&
.AVIATION...
(00Z TAFS)
Issued at 641 PM CDT Mon Aug 14 2023
VFR conditions are expected across all area terminals. A weak frontal
boundary is forecast to push across the local area overnight. A wind
shift is forecast overnight into Tuesday morning with winds coming in
from the north and northeast around 4 to 8 knots with gusts up to 17
knots in the afternoon. Isolated showers and even a storm is possible
along the Rio Grande and south of the I-35 corridor on Tuesday
afternoon.
&&
.FIRE WEATHER...
Issued at 252 PM CDT Mon Aug 14 2023
Weaker wind speeds across the region this afternoon and tomorrow
will allow for an overall reduction out of the critical fire weather
conditions, however, with the low RH in place and dry to extremely
dry fuels fire weather conditions will be elevated to near-critical.
A Fire Danger Statement remains in effect through 9 PM this evening
across all of South-Central Texas. A Fire Danger Statement has also
been issued between noon and 9 PM Tuesday over the entirety of the
region given similar meteorological conditions and even drier fuels
behind the cold front. Southerly flow will increase once more from
Wednesday through the end of the week, which may support the re-
introduction of Red Flag Warnings across portions of the area.
Residents across all of South Central Texas are urged to continue to
exercise extra care with any outdoor activities that could
inadvertently ignite wildfires.
&&
.CLIMATE...
Issued at 252 PM CDT Mon Aug 14 2023
Record High Temperatures
8/14 8/15 8/16 8/17 8/18
Austin Camp Mabry 107 107 107 107 109
Austin Bergstrom 105 105 104 105 104
Del Rio 107 108 107 109 107
San Antonio 104 104 103 104 105
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 80 102 74 105 / 10 10 0 0
Austin Bergstrom Intl Airport 79 101 73 103 / 10 10 0 0
New Braunfels Muni Airport 79 103 75 104 / 0 10 10 0
Burnet Muni Airport 77 99 73 101 / 20 10 0 0
Del Rio Intl Airport 83 104 81 106 / 10 20 20 10
Georgetown Muni Airport 79 99 73 101 / 10 10 0 0
Hondo Muni Airport 77 103 77 104 / 10 10 10 10
San Marcos Muni Airport 78 102 73 104 / 10 10 0 0
La Grange - Fayette Regional 79 102 73 102 / 10 20 10 0
San Antonio Intl Airport 80 102 78 104 / 10 10 10 0
Stinson Muni Airport 80 104 79 106 / 10 10 10 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon to 9 PM CDT Tuesday for Atascosa-Bexar-
Caldwell-De Witt-Fayette-Frio-Gonzales-Guadalupe-Karnes-Lavaca-
Medina-Wilson.
&&
$$
Short-Term...17
Long-Term...Gale
Aviation...17
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
849 PM EDT Mon Aug 14 2023
.SYNOPSIS...
A weak cold front will drift slowly from Tennessee and across our
area tonight and reach the eastern Carolinas by Tuesday night.
Expect a few strong to severe storms ahead of the front. As drier
high pressure builds across our region in mid week, we will have
milder temperatures and lower humidity into late week.
&&
.NEAR TERM /THROUGH TUESDAY/...
Evening Update...A severe thunderstorm watch has been issued for the
NC mtns and Rabun Co in NE GA effective until 07z. Upstream
convection ahead of a cold front is becoming more organized and
widespread due to increasing effShear and large scale forcing.
Thunderstorm warnings have been issued by WFO MRX and expect this
activity to push into the NC mtns by 03z. Damaging winds, heavy
rainfall, and large hail will be the main threats with a tornado or
two possible into the overnight hours.
The front should push across the forecast area during the day
Tuesday, as a strong shortwave/upper low swings across the OH
Valley. The front is likely to be near the eastern edge of the
Blue Ridge around midday, when diurnal destabilization picks up and
convection initiates. MLCAPE will likely be over 2000 J/kg east of
the mountains, and effective shear around 30-40 kts, allowing for
some storm organization. The HRRR has been showing updraft helicity
swaths, with a quasi-supercell storm mode across the eastern third
of the forecast area. The updated Day 2 SPC convective outlook
has a marginal risk extended back west across our entire Piedmont,
with a slight just into Rowan and Cabarrus counties. If the frontal
timing slows much more, the slight risk may be extended further
west into our area. Temps should be a little cooler in the west
thanks to the fropa, while the southeast corner will see another
hot and humid day, with heat indices in the 100-105 range.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 213 PM Monday: Expect the frontal boundary to still be
lurking over the southeastern zones at sunset on Tuesday, with
some storms along the front primarily around metro Charlotte,
but this activity should continue to move out of the fcst area
thru mid-late evening. By daybreak Wednesday we should notice the
air mass change with a continental high building in from the west
with much drier air. The center of the high will remain to our
west and gradually weaken on Wednesday and Thursday while the old
front has stalled along the coast. The proximity of the front might
keep a few showers/storms just to the southeast of the fcst area
on Wednesday and Thursday afternoon and the fcst will keep that,
even though it is much more likely the convection will be to our
east both days. Temps will be a welcome relief on Wednesday...maybe
a category below normal with low dewpoints...and still a degree
or two below normal for Thursday.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 113 PM Monday: The latest model guidance shows a subtle trend
back toward more confidence in a dry solution for the end of the
week into early next week. The main player will be the sprawling
upper anticyclone over the Plains, the center of which may migrate
from OK to IA through the medium range period. The eastern extent
of the anticyclone is shown to gradually expand eastward over the
weekend to eventually envelop the entire forecast area in even
the slowest guidance. The immediate effect will be to suppress
deep convection with a formidable cap and relatively dry boundary
layer, such that even the usual ridgetop shower activity appears
unlikely through the weekend. By Monday, there could be enough
modification to the air mass to allow for some mountain afternoon
convection. For the time being, at least, temperature guidance
looks close to normal, with a warming trend as we start the new
week. Looking ahead, the big question is when/if the center of
the upper anticyclone will ever make it east of the MS River,
and it looks like the answer so far is...not yet.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conds this evening with little, if any,
in the way of convec renewal. Upper-level warm air has suppressed
deep tstm activity with only minor llvl triggering available. A band
of showers with embedded tstms will likely push into the NC mtns
overnight and have KAVL with VCSH and MVFR CIGs btw 09z-13z. A
decent chance of a convec organized line of tstms quickly traversing
the area Tue and have included PROB30s for thunder at all sites
except at KAND, which may be too far southwest of the better frontal
forcing. Winds remain aligned sw/ly outside the mtns and become low-
end gusty during the afternoon. Winds at KAVL will persist nw/ly
thru the period with a limited gust potential.
Outlook: A cold front is expected to stall just east of the area,
allowing drier air to filter in from the NW on Wednesday and beyond.
Mountain valley fog and low stratus will be possible each morning.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM to 8 PM EDT Tuesday for GAZ029.
NC...Heat Advisory from 11 AM to 8 PM EDT Tuesday for NCZ071-072-
082.
SC...Heat Advisory from 11 AM to 8 PM EDT Tuesday for SCZ009-011-
014-019.
&&
$$
SYNOPSIS...DEO
NEAR TERM...ARK/SBK
SHORT TERM...PM
LONG TERM...PM
AVIATION...SBK
Area Forecast Discussion
National Weather Service Gray ME
1120 PM EDT Mon Aug 14 2023
.SYNOPSIS...
Low pressure approaches from the south tonight bringing
widespread showers across southern New Hampshire with rainfall
decreasing as you move north. Periods of shower activity,
coastal fog and clouds will dominate the weather pattern through
the week. High pressure then settles into the area by the
weekend bringing breezy winds and cool temperatures.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
11pm Update...00z hires guidance continued a shift SE this
evening with much of the forecast rainfall, and have adjusted
rain chances through Tuesday. Evening RAOBs were in good
alignment with 18z GFS, and 00z HRRR initialized with a good
representation of ongoing precip from the Great Lakes into
PA/NY. These two guidance sources were used primarily for
tonight through Tues morning, with new HREF agreeing. Main
change was to focus the more consistent rain chances to southern
NH into southern ME (roughly from Lebanon, NH to Portland,
south) while reducing chances across the mountains. It will be a
rainy start to the day for these locations, but rates and
coverage should taper into the early to mid afternoon hours.
Also included some patchy fog as it will likely be a cool dreary
day here from the get go. It may be a very different day to the
north and east where stratiform rain doesn`t make much impact;
with warmer temperatures and potentially more sun.
8pm Update...Sfc moisture increasing across the area ahead of
wave now lifting into New York state. Will have 00z data to go
through shortly, but afternoon guidance suggests a rather flat
passage of low pressure late tonight through Tuesday morning.
This could limit the northward extent of precipitation. For
tonight, that means some of the thicker, lower clouds remain
further south. Could see patchy to areas of fog break out along
the periphery of the cloud shield, although clouds in general
will be messy tonight; no clear breaks to allow decent
radiational cooling. Forecast remains on track otherwise, and
will wait to see convincing changes in satellite obs or guidance
to make tweaks to tomorrow`s forecast if needed.
Previous Discussion...
Daytime instability clouds will diminish in areal coverage as
daytime heating is lost. At the same time high and mid-level
clouds will be on the increase tonight as a warm front and broad
area of surface low pressure move into southern New England
after midnight. Rainfall activity will increase after 3 am
across Southern New Hampshire will the remainder of the region
remaining dry through the night. Some patchy fog could develop
in the valleys tonight, but coverage will be limited compared to
last night due to the increasing cloud cover after midnight. It
looks to be pleasant temperature wise tonight with near
seasonal normals.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tomorrow morning will start off with rain across the south as
the warm front pushes into the area. All guidance is in
agreement that any moderate rainfall will stay close to the MA
border, with some spread still in the potential of receiving >1"
of rain. I capped the forecast to max out around three quarters
of an inch, which is slightly below NBM mean. Overall there is
no signal for heavy rainfall rates at this time, so flooding is
not a concern with this rainfall with a band of moderate
rainfall possible during the morning commute being the biggest
expected impact. Rainfall coverage and amounts will diminish as
you move further north with most areas across northern NH and
most of Maine only seeing a .10" or so. Widespread rain pushes
off the coast by early afternoon with isolated showers remaining
for the afternoon and evening hours with no concentrated forcing
expected. NE persistent onshore flow will keep cloud cover
prevalent even after the rain ends, this will also keep temps on
the cool side with highs mostly in the low 70s. A weakening
shortwave approaches during the overnight hours from New York
with will keep the chance for a few showers after midnight,
especially across northern New Hampshire. Fog and low stratus
will also thicken up along the coast.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
An exiting low pressure system crosses the gulf of Maine
Wednesday bringing onshore easterly flow and lingering showers
through the day. The coastal plain will likely remain socked in
with lingering low level moisture and little in the way of
mixing. To this end, temperatures may end up below normal under
the cloud deck. Showers taper off shortly after sunset while the
pressure gradient tightens to the west as another low pressure
system approaches from Hudson Bay. Deep southerly flow moves in
Thursday ahead of the trailing cold front gradually building
moisture throughout the day before showers begin in the
afternoon. These initial showers will likely stay more scattered
in their nature with residual shearing vorticity from the
previous low providing the forcing. More widespread showers move
in Friday morning as the cold front crosses the area. Global
models are still uncertain regarding the instability, however a
look at model soundings across southern New Hampshire keep the
mid-levels warm and therefore capped, limiting the threat for
severe storms. There is still quite a bit of wiggle room on the
timing and instability parameters that could shift to be more
supportive for severe weather. Showers gradually taper off
overnight with W/NW flow setting in Saturday ushering in drier
air for the afternoon as high pressure builds to the south.
Overall, this weekend looks breezy with high pressure to the
south and low pressure to the north. There is large uncertainty
in the location of these air masses with potential for the area
to see warm, sunnier conditions if the ridge ends up further
north, or showery conditions if the low drifts to the south.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...Aviation conditions will be trending downward
tonight as rain showers and moist onshore flow will drop
ceilings and visibility down to IFR conditions for most TAF
terminals by tomorrow morning. LIFR could also be possible by
tomorrow night at coastal TAF sites as a low marine stratus deck
is possible and should linger through Tuesday night.
Long Term... SHRA lingers Wednesday morning before conditions
improve to VFR in the afternoon. Another round of SHRA
restrictions then moves in late Thursday through Friday. VFR
conditions return for the weekend under northwesterly flow.
&&
.MARINE...
Short Term...Conditions will stay below SCA with generally light
onshore winds developing over the coastal waters tonight. A warm
front will push into the area later tonight with a round of
light to moderate rain by tomorrow morning, before ending my
mid-afternoon tomorrow. Marine stratus and fog formation will be
possible later tomorrow afternoon through the night. Lightning
threat is low tomorrow.
Long Term... Conditions look to remain largely below SCA criteria
through the extended period, however a couple low pressure systems
could bring some larger waves and gusty winds as they pass. Easterly
winds take a southerly turn Wednesday ahead of showers late Thursday
into Friday before westerly winds set in Saturday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Cornwell/Dumont
SHORT TERM...Dumont
LONG TERM...Thunberg
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
913 PM CDT Mon Aug 14 2023
.SYNOPSIS...
Issued at 909 PM CDT Mon Aug 14 2023
An upper low will bring isolated to widely scattered showers and
thunderstorms to portions of central Illinois the rest of today,
then dry weather will be favored through midweek. Expect overnight
lows around 60 degrees tonight, then temps will warm into the mid
to upper 70s Tuesday. A gradual warming trend will occur through
Thursday, then heat and humidity will return late this weekend
into next week.
&&
.UPDATE...
Issued at 913 PM CDT Mon Aug 14 2023
Current forecast is still looking good for overnight temps and
winds. However, isolated light showers or sprinkles are still
showing up on radar this evening. Several of the HiRes models
continue to show this for another few hours as the upper level
system moves across the Great Lakes region. Cyclonic flow
continues to provide just enough lift that these light showers are
being maintained. Have made some adjustments to pops/wx for hte
several hours til around midnight to keep these isolated sprinkles
and showers going. As already mentioned, rest of forecast looks
fine. Update will be coming shortly.
Auten
&&
.SHORT TERM... (Through Late Tuesday Night)
Issued at 207 PM CDT Mon Aug 14 2023
This afternoon, a well defined upper low is evident on water vapor
imagery spinning near Dubuque and is progged to continue pushing
east along the IL/WI state line through this evening. At the
surface, a weakly defined cold front is near the I-57 corridor
with scattered showers and storms near the front. Instability is
relatively weak ahead of the front. RAP suggests MLCAPE values
will peak around 600-900 J/kg this afternoon, but deep layer shear
is seasonably strong, peaking in the 40-50kt range. Low-topped
supercells will be possible, and couldn`t rule out an isolated
tornado this afternoon across east central Illinois. Given the
weak instability, and weak forcing along the front, expect storm
coverage to remain low through the evening.
Upper low is progged to track from northern Indiana Tuesday
morning to Lake Erie Tuesday evening while mid level height rises
and cold air advection overspread central Illinois in its wake.
This should keep the column subsident and suppress precip chances
through the day Tuesday, though couldn`t completely rule out an
isolated sprinkle across far east central Illinois Tuesday
afternoon in response to steepening low level lapse rates.
Deubelbeiss
.LONG TERM... (Wednesday through Next Monday)
Issued at 207 PM CDT Mon Aug 14 2023
The overall pattern will trend drier with heat and humidity
returning in earnest by this weekend. On Wednesday, a strong upper
ridge will be in place across the western CONUS while a strong
shortwave trough is digging across the Canadian Prairies and across
the Upper Midwest. At the surface, expansive ridging will be in
place over the Midwest and will remain in control of the weather
over central Illinois. Expect plenty of sunshine Wednesday with highs
around 80 degrees.
Aforementioned upper trough will dig across the Great Lakes Thursday
with attendant surface cold front sweeping across central Illinois
Thursday afternoon. Dew points pooling in the upper 60s to around 70
degrees along the cold front are expected, but will contribute
little to any notable instability due to poor mid level lapse rates.
Both the ECMWF and GFS indicate less than 300 J/kg MLCAPE will be
present with frontal passage. In addition, forcing will be weak
along the tail end of the cold front with central Illinois close
to the col area, and we will be well displaced from the upper
wave. Confidence in precip with frontal passage is low, but it
will be the best chance for any precip within the extended
forecast time frame.
Strong upper high will shift east across the Great Plains Friday and
then settle over the mid Mississippi Valley this weekend into early
to middle of next week. Under the influence of the upper ridge, dry
conditions should prevail while heat will build back over the region
with daily highs near or into the 90s starting Sunday and Monday
and likely continuing beyond the current forecast period.
Deubelbeiss
&&
.AVIATION... (For the 00z TAFs through 00z Tuesday Evening)
Issued at 641 PM CDT Mon Aug 14 2023
All sites will be VFR this evening, but lower MVFR clouds will
move into the area later this evening and into the overnight
hours. Clouds/cigs will drop into IFR category early morning, but
then rise back into MVFR category later in the morning. The only
site that will not see IFR cigs is SPI. MVFR cigs will remain
through the afternoon and then should begin to scatter out...from
west to east during the day tomorrow. Winds will be west to
northwest and be a tad breezy with gusts to around 20kft through
more of the period. When clouds clear tomorrow afternoon, wind
speeds will decrease.
Auten
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1130 PM EDT Mon Aug 14 2023
.UPDATE...
Issued at 1130 PM EDT MON AUG 14 2023
Convection continues to wane late this evening, with the bulk of
activity now south and east of the area. The one exception is for
a weakening swath of showers across northern zones, where
lightning has nearly vanished. As such, have largely dialed back
PoPs through early tonight with a diminishing trend expected from
west to east through 10z. Sky grids were edited toward the latest
satellite trends, with a quick load and blend of surface obs also
incorporated. Updated grids have been sent to NDFD and Webfarms.
UPDATE Issued at 900 PM EDT MON AUG 14 2023
The bulk of the forecast remains on track. Scattered convection
has fired up across Central Kentucky in the past hour, but has
struggled to grow very tall- likely a result of the more limited
instability but better shear. That said, better organized and more
widespread activity has developed across Middle and East
Tennessee, where mesoanalysis suggests MUCAPE exceeding 3000
J/kg. There lies an instability gradient primarily along, south,
and directly east of the Hal Rogers Parkway, which could aid in
better organization the next couple of hours nearer to the
Tennessee and Virginia borders. The latest HRRR is doing a fair
job in handling the on going activity, suggesting scattered to
numerous showers and storms form in the southeast before shifting
further east and out of the area into the night. Have blended in
CAM guidance with PoP to better fit in with this idea. Sky grids
were also tweaked to fit the latest trends on satellite, while a
load and blend of the latest T/Td/Wind obs was also done. Grids,
along with a fresh set of zones and an HWO with tonight wording,
were sent.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 350 PM EDT MON AUG 14 2023
Key Concerns:
*Slight chance of severe thunderstorms continues through early
this evening.
*A cooler and drier air mass moves in Tuesday and Tuesday night.
The latest upper level map shows a vigorous low pressure system
churning its way across eastern Iowa, with a strong sub-tropical
ridge still anchored over the majority of the Gulf Coast States.
At the surface, a wavy warm front is aligned from east to west
from Delmarva through the central Appalachians and north of the
Ohio River. An area of low pressure is noted across southern Ohio,
while a broader and slightly deeper low occupies northeastern
Illinois and northwestern Indiana. A cold front stretches south
along the Mississippi Valley, before bending southwest across
central Arkansas. A subtle pre-frontal trough is also noted near a
line from KSDF to KBWG. Eastern Kentucky sits in the warm sector
out ahead of the cold front, although leftover debris cloud cover
from the passing MCS has left us still under a decent amount of
ML CIN, with hampered heating thus far. Temperatures range from to
upper 70s to lower 80s.
The models are in excellent agreement aloft through the short
term, with the upper level low peaking as it crosses near the
Michigan/Indiana border tonight, with troughing and height falls
fanned southeast over the Ohio and Tennessee valleys. The low will
then lose punch as it moves over Lake Erie and eventually gets
absorbed into the flow by early Wednesday, as it heads downstream
of Lake Ontario, thanks to inbound troughing traversing
southeastern Canada. A positively tilted trough will be left in
its wake from the Ohio Valley through the lower Mississippi
Valley. At the surface, two areas of low pressure will shift east
and northeast with time, with one reaching the Michigan/Ohio
border by early Tuesday, while the other one moves in across
southern New England. The associated cold front will move through
eastern Kentucky tonight, with Plains high pressure spreading east
towards the Mississippi Valley on Tuesday, and then into the Ohio
and Tennessee valleys by late Tuesday night.
Scattered to numerous thunderstorms will redevelop across our
area late this afternoon into this evening. Some of these could
reach severe limits, given the ample effective shear in place of
40-45 kts. Damaging wind gusts will be the primary threat;
however, can not rule out a tornado and at least some small hail.
Large hail would be less likely given the high freezing levels
and notably weaker shear above 3 km. The latest trend in the ML
CAPE on the RAP data has been for a somewhat better gradient to
set up along and south of Highway 80 and Hal Rogers Parkway. This
would be an area to watch for cell development and eventual track.
Further north, instability dampens quite a bit, and while some
lower-topped supercells will be possible containing small hail
and perhaps some gusty winds, any impacts greater than this would
be much more limited.
Convection will wind down from northwest to southeast through
tonight as the cold front moves through the region. Some low
stratus and/or fog will set in overnight as the trough axis shifts
southeast over the area. Lows will range from the mid to upper
60s. A welcomed air mass will be in place on Tuesday, with low
stratus gradually burning off through mid-day. Highs will range
from the mid to upper 70s, with a few sites reaching the 80 degree
mark. High pressure will build in better Tuesday night, with lows
around 60 degrees, although low clouds/fog will likely set in
again, limiting a more significant drop off in temperatures.
.LONG TERM...(Wednesday through Monday)
Issued at 358 PM EDT MON AUG 14 2023
Key Concern:
* Potential for a heat wave beginning this weekend is increasing.
Analysis:
After one more day of September-like weather on Wednesday,
temperatures will be on an upward trend each day potentially
intensifying into a heat wave over the weekend and persisting for
much if not all of the following week. The 14/12z model analysis
beginning Wednesday morning shows a positively tilted trough axis
extending from Montreal, Quebec southwestward across the lower
Ohio/Tennessee valleys (a little further west than just 24 hours
ago). Another upstream trough is found over Central Canada from
northern Manitoba to southern Saskatchewan. To our west, an ~595
dam high is found across the Southern Rockies and Great Basin. At
the surface, a corresponding high pressure, centered over the
Ozarks, spans much of the Mississippi Valley as well as the Lower
Tennessee and Ohio Valleys.
With the trough axis now passing a little slower on Wednesday,
expect strato-cu deck to be more prevalent for much of the day. A
few of the deepest cumulus might even produce a sprinkle, but
strong capping above 700 mb should preclude much more than that.
Otherwise, it will cool with more of an early autumn feel as
temperatures peak in the mid to upper 70s at most locales.
Wednesday night will be cool with mostly clear skies and lows in
the mid 50s cooler sheltered valleys to lower 60s in thermal
belts.
Aloft, heights will be on the rise through the day on Thursday. The
second trough, over Central Canada at the start of the period, will
drop into the Ohio Valley late Thursday evening and night, dropping
a cold front across the Commonwealth on Friday. However, heights
will continue to rise and strong capping around or above 700 mb
should preclude anything more than some increased low cloud cover
and perhaps a sprinkle. Low-level flow will turn northerly behind
the cold front and the incoming air mass will be drier. The
boundary won`t substantially hinder the overall warming trend --
temperatures on Thursday are expected to reach into the middle 80s
at most locations and similar highs are expected on Friday.
The latest model suite has come in stronger and further north with
the strengthening upper high, now placing ~599 dam 500H levels
over the Missouri/Iowa border by Monday. Surface high pressure
will be firmly entrenched over the Ohio Valley. After a rather
tempestuous weather pattern this summer, this is a pattern which,
if it materializes as presently modeled, would bring a extended
period of hot and dry weather to eastern Kentucky. Ensemble
probabilities for high temperatures exceeding 95 degrees break 10
percent along I-64 beginning Sunday and increase to between 30 and
60 percent outside of the higher elevations (Pine, Cumberland,
Log and Black mountains) by next Wednesday. Of note, the 2m
temperatures currently predicted in the deterministic GFS
(exceeding 100 degrees for many locales on multiple days next
week) are outliers and represent a highly improbable scenario.
Even so, temperatures warming into the upper 80s and lower 90s are
likely on Sunday afternoon, further warming into the lower and
middle 90s on Monday. While beyond the end of the forecast period,
high temperatures in the mid or even upper 90s are plausible by
the middle of next week, if current projections hold.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 900 PM EDT MON AUG 14 2023
VFR conditions will start off the TAF period, but developing
scattered to numerous showers or storms will work through over the
next few hours ahead of an approaching cold front. As they do so,
brief CIG and visibility reductions will be possible, so a TEMPO
group for IFR was included at all terminals between the hours of
00z and 03z. Guidance suggests more organized development will
occur into tonight in the south/southeast, primarily south of any
terminals, before diminishing through 10z. Lower cloud decks will
follow the departing front, with MVFR or instances of IFR
ceilings/visibilities into early Tuesday morning. Fog and low
stratus will dissipate through 14z, where a return to VFR will
then prevail through the remainder of the period. Winds, outside
of any thunderstorms, of 5 to 10 kts can be expected out of the
south to southwest through the first part of tonight, becoming
more westerly behind the frontal boundary with time.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...BB
SHORT TERM...GEOGERIAN
LONG TERM...GEERTSON
AVIATION...BB
Area Forecast Discussion
National Weather Service Medford OR
902 PM PDT Mon Aug 14 2023
.DISCUSSION...A scorcher! And with five new record temperatures at
the climate sites of Montague, North Bend, Roseburg, Mt. Shasta
City, Medford, and probably more in the records of local weather
observers. That`s five of our six climate sites setting records!
Only the Klamath Falls station stayed below its record at 97
degrees, four lower than the 101 degrees recorded in 1933.
Tropical moisture will further dirty the ridge, brining
temperatures down a few degrees and introducing the presence of
thunderstorms in the forecast. This moisture has already produced
a some lightning activity along the southern County lines of Modoc
and Siskiyou County this evening. So far, there has been 25 cloud
to ground (CG) strikes observed with the storms (in Modoc and
Siskiyou County only). As the storms cycle between the mature and
decaying phase outflow boundaries can also be observed on the
-0.2 elevation scan from the KMAX radar moving north at about 20
mph. Today, these boundaries will do little, with dry air in their
path. But tomorrow and the following days, these gust fronts
could be more influential.
Over the next few days as moisture moves into the region,
thunderstorms are expected over a wider area. On Tuesday, areas
with at least a 15% chance for thunderstorms includes all of
Siskiyou, Modoc, and Klamath County. Storms are possible along the
south and east boundaries of Jackson County, in the Siskiyou and
Cascade foothills. With storm motions anticipated to be from the
southeast to northwest, it is possible storms move into the Rogue
valley. A 15+ percent chance also exists in eastern Douglas
County above Steamboat, and in Western Lake county west of highway
31. The chance for storms is highest in the Cascades between
Klamath Falls and Crescent Lake on Tuesday. The chances in these
same areas increase another 10-15% on Wednesday.
The main threat with these storms will be the lightning. Both from
the chance of striking a person and in starting new fires. a Red
Flag Warning is in place for the lightning potential on Tuesday in
the Cascades north of Klamath Falls. There is also a Fire Weather
Watch, again for lightning and the new fire start potential, for a
wider area including large portions of Norcal and in Klamath and
Lake County. More details can be found in the Red Flag text
product.
It`s worth noting the run-to-run consistency of the SREF model
indicating the potential for 100+ CG strikes. We saw today that
the storm activity was well electrified. What this suggests to me
is that even if coverage in storms remains isolated, the active
nature of a single cell could still deliver a number of CG strikes
above the normal anticipated lightning activity level.
There are two secondary threats with the storms. One is hail
potential. There is very strong instablity through the entire
troposphere, even down to the surface (as less common thing for
our region), as well as strong lapse rates. The limiting factor is
storm organization, with shear remaining low, but this only
suggests large hail (a quarter or bigger) is less likely.
Accumulating hail between dime and pea sized is still possible in
larger amounts. The secondary threat is rain. Today, radar
estimates place amounts under the core at 0.5" in three hours
(with most CG strikes outside of this core). While on Tuesday
storms should still be quite dry and comparable to these storms
today (8/15), Wednesday and Thursday may be different.
Precipitable water values will climb above 1" and slow moving
storms may quickly produce gully washing rains, especially in
mountains. We will have to watch going forward how these two
threats expand or contract.
-Miles
&&
.AVIATION...AVIATION...15/00Z TAFs..Across the area, haze due to smoke will be
widespread, with some modest reduction in visibility possible. Smoke
will be thickest downstream of the Bedrock Fire in eastern Lane
County into eastern Douglas and northern Klamath counties.
Along the coast and just offshore. Marine stratus is expected to
develop from around Bandon northward after 04Z this evening with
LIFR/IFR spreading into northern portions of the Coquille Valley,
including into North Bend, overnight. Improvement to VFR is expected
after sunrise, by mid-morning.
Otherwise...VFR will persist. There is a slight chance (15%) of
thunderstorms this evening in southwest Siskiyou County, and then
overnight a 5% to 10% probability across Siskiyou County. -DW
&&
.MARINE...Updated 800 PM PDT Monday, August 14, 2023...A combination
of northwest swell and a shorter period, fresh northwest swell will
continue steep seas in the outer waters tonight.
Winds and seas lower on Tuesday, but moderate to strong north winds
are expected to return early Wednesday. This will likely require a
Small Craft Advisory south of Cape Blanco at least into Friday. A
further increase in winds and seas is possible Friday. This may
produce steep to very steep seas across all of the waters, and an
area of gales south of Cape Blanco. The probability for wind gusts
to exceed 41 knots is 65% on Friday. Though winds are currently
forecast to peak on Friday, seas may remain steep to very steep
during the weekend. -Guerrero/DW
&&
.FIRE WEATHER...Updated 200 PM PDT Monday, August 13, 2023...The two
big weather concerns for the forecast period will be the extreme
heat expected today through much of the week and the thunderstorm
potential also continuing through much of the week.
A very hot air mass will be over the region through the week and
several days of 100+ degrees is anticipated west of the Cascades
with mid to upper 90s east of the Cascades. The heat peaks today
when temperatures are expected to exceed 110 in the valleys west of
the Cascades. This will also coincide with the lowest relative
humidities, with minimum RH values dipping into the mid to lower
teens for areas west of the Cascades and away from the immediate
coast. These low values combined with our fairly typical afternoon
breezes (10-15 mph with gusts 20-25 mph) will lead to some
borderline critical fire weather conditions this afternoon and Red
Flag Warnings are in effect for Fire Weather Zones 616, 620, and
622. Again, this is a fairly marginal event, but given the heat and
very dry air, decided to err on the side of caution given how close
the conditions will be. More details can be found at RFWMFR.
In addition to the hot and dry airmass, there will be instability
aloft over portions of the West Side including the Flat Fire in FWZ
619 and a Red Flag Warning remains in effect for this afternoon.
Temperatures will trend "cooler", or I should say less hot but still
very hot, Tuesday into the end of the week. We aren`t expecting
critical conditions Tuesday as minimum RHs trend higher,
temperatures trend slightly lower and monsoonal/tropical moisture
increases in the region...which leads us to the thunderstorm
concerns...
Thunderstorms enter the forecast this afternoon/evening with some
variation of thunderstorm chances continuing through much of the
week. Thunderstorm coverage is expected to be minimal on Monday and
focused across far southern Siskiyou County. There are some
indications of nocturnal thunderstorm activity continuing overnight
tonight into Tuesday morning across western Siskiyou County, which
could move northwestward into far southwest Oregon and clip southern
Josephine and Curry County. Coverage, however, is not anticipated to
be scattered enough to warrant any headlines. As we move into
Tuesday, thunderstorm chances expand northward, mainly from the
Rogue Valley and eastward.
Isolated to scattered thunderstorms are anticipated over the coming
days and the latest round of high resolution CAMs is pinpointing an
area of scattered coverage across across the Fremont-Winema National
Forest and westward into the Cascades. We`ve went ahead with a Red
Flag Warning for abundant lightning on dry fuels for FWZ 617/623/624
for Tuesday afternoon. Scattered thunderstorms are possible over a
broader area on Wednesday, so we`ve issued a Fire Weather Watch for
this potential that covers FWZs 624/623/621/280/281/284. Storms will
initially start out dry today/tonight then gradually transition
wetter Tuesday and over the week. Despite storms transitioning to
wet, strikes outside of storm cores remain a concern. Gusty outflow
winds are also a concern, especially for today and tonight as storms
remain on the dry side. Gusts of 30-40 mph will be possible with any
outflow winds. /BR-y
&&
PREV DISCUSSION... /Issued 255 PM PDT Mon Aug 14 2023/
DISCUSSION...The observation at Medford has already surpassed
100 degrees (approximately 106 degrees), and it isn`t even 3 PM
yet! Otherwise you`ll find many spots west of the Cascades in the
90s with east side locations in the 80s.
The HRRR smoke is doing well with picking up the smoke aloft from
the Bedrock and surrounding fires as the winds shift it to the
west. There is more uncertainty getting into Tuesday for what the
highest concentrations will be and if it stays on the east side or
moves westward again.
Tuesday morning is favored to be the one of the warmest this week
(along with Thursday). Looking at a threshold of 75 degrees, there
is a 25-30% probability to see this on Tuesday and Thursday
mornings. With the observed morning temperatures being lower in
previous days than forecasted, I have continued that trend by
lowering low temperatures a few degrees, but they will still be in
the 70-75 degree range in most west side valley spots.
The current heat hazards stand with all advisories and warnings in
effect until Wednesday or Thursday afternoon. Here`s a tidbit for
you: We could be in the top 5 for the most consecutive days at or
above 105 degrees in Medford! Based on records since 1911,
Medford`s longest streak where we got to 105 degrees or warmer was
6 days from August of 1981. Based on the current forecast, we
could tie the current third or fourth place with 4 days forecasted
to reach 105 degrees+. Roseburg is another noteworthy location!
Roseburg is forecasted to hit or exceed 100 degrees for four days
as the streak started yesterday with a high of 103. If this works
out, August 2023 could step into the top 3 for the longest streak
of highs at or above 100 degrees. Currently, August 2017 and July
1942 are tied for first place for that Roseburg streak.
Models are coming into agreement that there could be isolated
thunderstorms tonight, and relative humidities between 700-500 mb
are jumping to 60-80% for the area of western Siskiyou County.
Starting Tuesday, more portions of Northern California and East of
the Cascades will have slight chances for thunderstorms and this
will continue through most of the week. -Hermansen
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Wednesday afternoon through Wednesday
evening for ORZ621-623-624.
Excessive Heat Warning until 11 PM PDT Thursday for ORZ021>024-
026-028.
Excessive Heat Warning until 11 PM PDT Thursday for ORZ025-027.
Heat Advisory until 11 PM PDT Wednesday for ORZ027-030-031.
Red Flag Warning from 2 PM to 11 PM PDT Tuesday for ORZ617-623-
624.
Heat Advisory until 11 PM PDT Thursday for ORZ028-029.
CA...Excessive Heat Warning until 11 PM PDT Thursday for CAZ080>082.
Fire Weather Watch from Wednesday afternoon through Wednesday
evening for CAZ280-281-284.
Heat Advisory until 11 PM PDT Thursday for CAZ084-085.
PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Tuesday
for PZZ370-376.
&&
$$
Area Forecast Discussion
National Weather Service Pendleton OR
732 PM PDT Mon Aug 14 2023
.EVENING UPDATE...Minor change made to the tonight period regarding
sky and weather. Satellite imagery shows some smoke from the fires
in Lane and Linn counties moving down the east slopes of the
Cascades so have added some patchy smoke and haze to the central
Oregon forecast for overnight through Tuesday morning. The intrusion
of smoke into central Oregon will increase late Tuesday and Tuesday
night as winds aloft switch from the current offshore or easterly
flow to a westerly flow which continues rest of the week. As a
result, air quality in central Oregon is expected to decrease in the
coming days.
.AVIATION...00Z TAFs...VFR conditions are forecast through the
period with mostly clear skies. Aside from some intermittent gusts
to 15 kts this afternoon, winds will remain light and terrain-driven
through mid-afternoon Tuesday. A reversal in wind direction (to
westerly) through the Cascade gaps is forecast later Tuesday
afternoon and evening with some gusts of 15-20 kts for
KDLS/KRDM/KBDN/KYKM. The shift in wind direction will transport
smoke east of the Cascades with the highest likelihood in
visibility reductions at KRDM/KBDN late Tuesday through Wednesday
morning. Plunkett/86
&&
.PREV DISCUSSION... /issued 221 PM PDT Mon Aug 14 2023/
SHORT TERM...Tonight through Wednesday night...Strong high
pressure aloft remains over the interior NW with significant
heating across WA/OR. The inverted surface thermal trough has
been over western OR the past couple of days, and this has allowed
winds along the boundary layer to come from the NNE. Today`s winds
have been light. The thermal trough will shift eastward on
Tuesday for increasing temperatures and an uptick in winds in our
western zones. While the eastern CR Gorge will likely (60%) have a
couple of hours of winds gusting to 20-25 mph with RH`s in the
teens, the confidence is not has high (30%) in the Kittitas
Valley to have gusty winds due to the very shallow marine air over
western WA that will have more difficulty spilling through the
I-90 corridor. Therefore, there are no plans for any fire weather
highlights due to the localized winds and low confidence.
A Fire Weather Watch will be issued for fire zone 611 for late
Tuesday afternoon and evening for thunderstorms producing abundant
lightning. Now confidence is about 80% that there will be
scattered thunderstorms over south central Oregon late Tuesday,
but only about 60% that scattered storms will make it as far north
and produce enough lightning to warrant a red flag warning over
the southern Deschutes National Forest. Will review the upcoming
CAMS models to decide if a warning is needed. The Nam Nest and
HRRR are showing little to nothing in terms of convective
activity, and this is likely due to the lower dewpoints compared
to the other high resolution models. Storms will be associated
with an upper low over central CA edging northward, allowing a
weak circulation to travel across south central OR.
The overall pattern over the PacNW changes little on Wednesday,
although the cross Cascade gradient will be slightly weaker with
less marine influence, therefore less wind. Current forecast has a
20% chance of thunderstorms over the southern Deschutes NF. This
looks reasonable based on some lingering moisture and instability,
but most of the embedded circulations around the CA low are to the
south. The main concern for Wednesday will be another day of hot
and dry conditions with little relief in the overnight temperatures
and poor to moderate RH recoveries at night. Wister/85
LONG TERM...Thursday through Sunday...The long term will be
initially characterized by an upper level high which will keep the
region under warm and dry conditions. By the end of the week there
will be a pattern shift with an upper level trough swinging through
the region from the Gulf of Alaska while another low off the coast
of California will retrograde west and north bringing with it some
chances for some wrap around moisture. This pattern change will
bring with it increased chances of precipitation as well as some
reprieve from the heat and an uptick in winds through the Cascades
Gaps. With the extreme heat that has been over the area for a few
days, elevated fire weather concerns through portions of the Gorge,
southern Columbia Basin and the Cascades in northern Or are
expected. No highlights at this time but we will closely monitor
as the event nears.
Models are in firm agreement with the set up of the upper level
ridge over the region Thursday. Southerly flow aloft will continue
to dominate over the region through Friday morning. Clusters show
little to no variance between the ensembles. Thursday will be the
hottest day of the long term period with more than 65% of the
ensemble members showing temperatures greater than 90 degrees with
the NBM showing the most everywhere to be in the triple digits and
the higher peaks in the 80s (70-95%). The excessive heat warning
will remain in effect through Thursday night due to the very hot
daytime temperatures and high overnight lows. EFI is showing a very
strong signal of above average temperatures across the area through
Thursday. The NBM is showing a large portion of the Basin and some
of the surrounding areas to be in the major category with some
larger isolated locations reaching into the extreme. For more
information on heat risk categories and heat safety please go to
www.weather.gov/safety/heat and wrh.noaa.gov/wrh/heatrisk.
Models are again in firm agreement with the incoming round of upper
level lows. Variances in the clusters are lingering with the
amplitude of the troughs. A few members show the trough to be a bit
deeper while others show a bit more shallow. The more shallow
solutions are the members that are also showing a bit higher
potential for some wrap around moisture being pushed over the
eastern and central portions of the area. The deeper solution is
keeping the moisture to the south of the region. The NBM seems to be
somewhere in between both solutions so that was what was added to
the Forecast for Friday. EFI shows that on Friday temperatures seem
to regulate to nearing normal seasonal temperatures with the
ensembles showing over 90% agreement with temperatures between 85-95
degrees. Winds will also begin to increase as the trough from the
north begins to push closer to the region and the leading edge
begins to push towards the Cascades. The cross Cascade gradients
will begin to tighten increasing the winds through the Gaps and
along the southern Columbia Basin. NBM and the ensembles are showing
upwards of an 80% chances of those areas seeing winds up to 25mph.
Models continue to be in relatively firm agreement over the weekend
with the incoming upper level low that is expected to be in place.
This upper level low will bring with it ‘cooler’ temperatures and
increased chances of precipitation. NBM and >65% of the ensembles
have temperatures between 75 and 85 degrees with a few locations
seeing the upper 80s on Saturday and decreasing by about 2 degrees
each day with the coolest day of the period being Monday. EFI is
showing temperatures to be steadily dropping towards near normal as
the upper level trough continues to move eastward over the CWA
dropping temperatures into the upper 70s and low 80s by Monday (60-
80%). Precipitation will first wrap around from the low that is off
the coast of California bringing precipitation to much of Central Or
and along the eastern portion of the CWA. Ensembles are showing the
highest amounts of up to 0.1 inches of rain being shown by 36% of
the ensembles and mainly over the higher peaks with slight chances
of thunderstorms possible along the same areas mentioned above
(<10%) due to the increased instability associate with the upper
level low. Divergence in the models becomes a bit more noticeable by
Saturday night and into Sunday as some of the models show a deep
trough form as the two low pressure systems merge together while
others keep it broad and/or still separated. Regardless of the
solution, southerly flow aloft will dominate the region and
ensembles and NBM show increased chances of rain, especially over
the southern and eastern portions of the region as well as along the
Cascades of central WA. Ensembles are showing >20% chances of up to
0.2 inches of rain could be seen, especially across Wallowa County
on Sunday and >20% chances of up to 0.1 inches on Monday. Bennese/90
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 68 103 68 102 / 0 0 0 0
ALW 72 105 74 105 / 0 0 0 0
PSC 71 106 74 107 / 0 0 0 0
YKM 70 106 72 104 / 0 0 0 0
HRI 70 107 73 107 / 0 0 0 0
ELN 71 103 71 104 / 0 0 0 0
RDM 61 101 63 101 / 0 10 10 0
LGD 66 101 66 101 / 0 0 0 0
GCD 65 103 64 102 / 0 0 0 0
DLS 74 108 73 106 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 11 PM PDT Thursday for ORZ041-044-
505-507-508-510-511.
Heat Advisory until 11 PM PDT Thursday for ORZ049-050-502-503-
506-509.
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for ORZ611.
WA...Excessive Heat Warning until 11 PM PDT Thursday for WAZ024-
026>029-521-523.
Heat Advisory until 11 PM PDT Thursday for WAZ030-522.
&&
$$
SHORT TERM...85
LONG TERM....90
AVIATION...86