Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/29/24
Area Forecast Discussion
National Weather Service Boise ID
828 PM MDT Wed Aug 28 2024
.DISCUSSION...Skies were clear this evening and northwest winds
were finally calming down over the region. There was a great
deal of smoke coming off area fires today, especially the
Wapiti. This smoke is expected to move south and then west
tonight into tomorrow morning, eventually entering the Treasure
and western Magic valleys. Temperatures will warm over the next
several days, getting back above normal Friday. All this is
handled well by the current forecast and no updates are planned
at this time.
&&
.AVIATION...VFR with clear skies, except localized MVFR/IFR due to
smoke near wildfires in central ID. Surface winds: NW 5-15 kt,
becoming less than 10 kt after 29/04Z. Winds aloft at 10kft MSL: NW
10-20 kt becoming north 5-15 kt after 29/06z.
KBOI...VFR. Surface winds: NW 8-12 kt, becoming SE around 5 kt after
29/04Z. Smoke and reduced visibility coming in from the east or
northeast around 29/17Z and potentially lasting 24 hrs or more.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...Clear and
cool tonight with decreasing winds. Low temps will be in
the upper 20s and 30s in the mountains and higher basins,
and upper 30s through 40s in the lower valleys. Skies will
stay cloudless through Friday night, but wildfire smoke
and air quality will get worse in western Idaho. HRRR
model expands the wildfire smoke in central Idaho
southward and westward tonight through Thursday, covering
all of western Idaho later Thursday through Friday.
Eastern Oregon should stay mostly clear but patchy smoke
will get into Baker and Malheur Counties. Meanwhile,
daytime temperatures will rise as higher pressure aloft
replaces today`s cool upper trough. High temps Thursday
will be in the mid 70s to mid 80s, and Friday in the 80s
to lower 90s. Lows will warm more slowly resulting in huge
diurnal ranges in eastern Oregon on Friday. For example,
at Burns and Baker the morning low will be about 40 degrees
and the afternoon high around 90.
LONG TERM...Saturday through Wednesday...A strong ridge
situated over the area will keep dry conditions across the
area with well above normal temperatures (about 10 degrees)
Saturday and Sunday. An upper low will approach the coast
Sunday evening with southerly flow ahead of the system
transporting monsoon moisture over the region. This will
bring increasing cloud cover and a chance (15-30%) of
showers and thunderstorms mainly Monday and Monday night.
This will also bring some cooling to the area Monday and
Tuesday but high pressure will return the middle of next
week for dry and warming conditions.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
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DISCUSSION...SP
AVIATION.....SP
SHORT TERM...LC
LONG TERM....TL
Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CDT Wed Aug 28 2024
.KEY MESSAGES...
- There is a level 2 out of 5 risk for severe weather over parts
of eastern North Dakota this evening and overnight, with the
main hazards being hail up to 1.75 inches and wind gusts to 70
mph.
&&
.UPDATE...
Issued at 955 PM CDT Wed Aug 28 2024
Thunderstorms from central ND starting to approach our western
counties. There has been an overall weakening trend as the cells
move into less instability. However, will continue to monitor a
storm in Stutsman county that has a history of nickel sized hail
and has shown a sharp cloud top cooling trend on IR satellite.
There is also the possibility of a second round of storms firing
along the nose of the low level jet, as the HRRR and several of
the other CAMs indicate. That does not occur until after 06Z but
should tap into some pretty rich moisture further south and
could still bring some strong to severe impacts after midnight.
Heavy rain will also be a problem with the slow movement of
storms, training cells, and PWATs over 1.7 inches moving east
into our area.
UPDATE
Issued at 637 PM CDT Wed Aug 28 2024
Storms have developed along the Missouri River to our west, but
have been very slow to move east so far. CAMs like the HRRR that have
been doing best on initiation have the convection getting into
our western counties around 04 or 05Z, and given motion so far
on the storms, this seems fairly reasonable. Some cells are
trying to get going in northeastern ND, but pretty capped and
only 25 kts of shear. Will keep an eye on the lead activity as
it gets going.
&&
.DISCUSSION...
Issued at 244 PM CDT Wed Aug 28 2024
...Synopsis...
The main 500mb low continues to slowly spin over north central
Montana, which will keep the strongest upper level winds over
western North Dakota tonight. At the surface, there are two
lows, one over south central Saskatchewan and the other over
western South Dakota. In between these lows, there is a cold
front extending from north to south. Since there is not much to
push this front eastward tonight (the upper flow almost
parallels the front), it is only expected to reach eastern North
Dakota by sunrise Thursday. Strong to severe storms are
expected along this boundary (and the low level jet) by late
this evening into the overnight hours. This boundary may still
lie somewhere east of the Red River Valley on Thursday
afternoon, which could spawn another round of strong to severe
storms. After this, the weather turns quieter again.
...The severe weather threat tonight...
The best moisture surge so far today has been from eastern
South Dakota into south central North Dakota, where dewpoints
are in the mid 60s to low 70s and precipitable water values are
up to 1.3 inches. CAPE is building quite nicely across this same
area, but 700mb temperatures of +10 to +12C have created an
initial cap. The latest CAMs are showing storms breaking out
along the frontal boundary somewhere between Bismarck and Minot
in the 6 to 7 pm time frame, where they would initially be
supercells. For most of the CAMs, this activity would remain to
the west of this FA until 10 pm or so.
In the 10 pm to 1 am time frame, the low level jet kicks up to
the 50 to 60 knot range. Initially (around 10 pm), this jet is
more focused into an area just east of Bismarck. By 1 am it
focuses more into east central or northeast North Dakota, and by
4 am into northwest Minnesota. This would provide the best
support for keeping storms around during the late evening and
overnight time period, when the storms may be more multicellular
or linear. If this occurs, strong winds may be the main hazard,
with isolated hail as well. The high precipitable water values
are also a concern, but the storms do look to be progressive.
Therefore think heavy rain rates are likely, but unless storms
train over the same areas, flooding type rainfall is less
likely. Would expect some weaker storm activity to be lingering
on Thursday morning, which may play into the severe weather
potential for the afternoon. Right now, the SPC Day 2 severe
weather outlook highlights a marginal risk (level 1 out of 5)
mainly east of the Valley.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 637 PM CDT Wed Aug 28 2024
Some lingering stratus around KDVL, but otherwise VFR in the
quiet before convection starts to move in later tonight. Should
see some thunderstorms moving west to east starting late evening
and continuing through the overnight, but may fizzle out before
reaching KBJI. Some MVFR ceilings along and behind the storms,
with visibility down to 3-5SM or even lower with the heavier
rain. Thunderstorms will decrease in intensity as they move east
and will become more VCSH towards the end of the period,
eventually tapering off from west to east. Winds that are
gusting to over 25 kts from the southeast this evening will
decrease but see some low level wind shear out ahead of the
thunderstorms as a jet gets going at around 50 kts. Winds will
eventually shift around to the southwest and then west to
northwest with gusts above 25 kts again by the end of the
period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...JR
DISCUSSION...Godon
AVIATION...JR
Area Forecast Discussion
National Weather Service Indianapolis IN
936 PM EDT Wed Aug 28 2024
.KEY MESSAGES...
- Heat Advisory Continues; Mild and warm tonight
- Heat Index values near 100 this afternoon...and again Friday
- Rain-free weather to oversee a slow transition to milder, and then
lower humidity conditions through the holiday weekend
&&
.FORECAST UPDATE...
Issued at 936 PM EDT Wed Aug 28 2024
- Partly Cloudy and mild
- Patchy Fog overnight
Surface analysis this evening shows a poorly organized and diffuse
boundary across southern Indiana, near where earlier thunderstorms
resided. A larger, stronger area of high pressure was found over
Ontario, providing easterly flow to the Great Lakes and weak
northerly flow to Central Indiana. The air mass across Central
Indiana remained rather humid, with dew points in the upper 60s and
lower 70s. GOES16 this evening shows some dissipating CU clouds
along with some mid and high clouds streaming well aloft due to a
tropical plume near the area and left over convective debris
clouds. SPC meso analysis pages shows falling CAPE across the area
and CIN developing and instability is being lost with a loss of
heating. The nears storm system to Central Indiana was near SW
Illinois.
Overnight, little forcing is expected to pass across Central
Indiana. Best area for possible convection would be near the surface
trough area near southern Indiana and the Ohio river, south of our
forecast area. Still the plume of moisture found across Indiana as
seen within the water vapor imagery will remain across Central
Indiana overnight. This will provide some high passing clouds from
time to time. Forecast soundings overnight maintain a very warm and
moist column, but fail to show deep saturation at any time.
Meanwhile the HRRR keeps the area dry through the overnight hours.
Thus will try and trend toward a dry forecast overnight under partly
cloudy skies. The weak surface pressure pattern across the area will
lead to light to calm winds. This along with the very high dew
points allow dew point depressions to fall to 2F or less. Thus
will trend lows in the upper 60s and lower 70s, with patchy fog
expected, particularly in more rural areas.
&&
.SHORT TERM (This evening through Thursday)...
Issued at 300 PM EDT Wed Aug 28 2024
Relatively benign weather has been observed this afternoon across
Central Indiana with only small chances for rain into tonight. An
area of dying convection this morning brought rain and a few storms
to areas along and west of the I-69 corridor in South Central
Indiana. Canceled the Heat Advisory for areas along and north of a
line from Putnam to Delaware Counties as clouds from this morning`s
storms has kept temperatures down in the upper 70s and low 80s in
those areas. There was concern there would be an area within Central
Indiana that this would happen to today, so this does not come as a
surprise. A Heat Advisory remains in effect until 8 PM EDT for
counties along the I-70 corridor and points south. Within the Heat
Advisory, temperatures are making a run for the 90s again by this
evening with dew points in the upper 60s to low 70s and heat
indices over 100.
Rainfall and thunderstorm chances have diminished somewhat across
the region for the rest of the evening and into the overnight hours.
While satellite imagery shows the remnant circulation from an MCV in
Central IL moving toward the IL/IN state line, the environment
ahead of it may be too dry and stable for convective development.
Satellite imagery does not show the presence of developing cumulus
across most of Indiana and ACARs soundings confirm dry air in the
lower and upper levels. Leftover clouds have made it difficult
for the low levels to destabilize through much of the day. Just
within the past hour it appears low level lapse rates have
steepened some with instability beginning to increase. Will have
to watch trends over the next couple hours as the potential is
there for a few showers or storms to develop as the MCV nears and
a front sags south from the north. Kept 20-30 PoPs in through this
evening (lowering them from 50-60) to account for the slight
chance of a stray shower or storm. Confidence remains low and most
places will likely stay dry this evening.
The aforementioned front will sag south across the region overnight
and become quasi-stationary with light winds shifting to the NE and
then E by tomorrow morning. Little change in airmass is expected
with relatively humid conditions persisting into the day tomorrow.
With the frontal boundary over the region, mid to high clouds should
stick around for a while keeping overnight lows elevated in the
upper 60s to low 70s.
Despite an increase in clouds tomorrow, another warm to hot today is
expected with highs approaching or exceeding 90 degrees in South
Central Indiana and mid to upper 80s further north. With the frontal
boundary hanging around the region, there is a very slight chance
for a rogue shower or storm to develop; however with ridging
building overhead ahead of the next approaching system in the Upper
Midwest, conditions may be too dry to support much convective
activity. Kept 20 PoPs for tomorrow afternoon and evening to account
for this, but at the moment most areas should stay dry.
&&
.LONG TERM (Thursday night through Wednesday)...
Issued at 305 PM EDT Wed Aug 28 2024
Thursday night through Sunday...
Summer`s final push of several humid days across central Indiana
will continue into Saturday under a retracted jet stream...with weak
surface low pressure approaching from the central US lifting towards
the southern Great Lakes Friday, which will help maintain the
oppressive flow from occasional southwest breezes. Maximum Heat Index
values Friday should again approaching Advisory criteria with
widespread 95-104 values. A faster arrival of clouds/convection thru
midday/early afternoon hours could mitigate this risk.
The boundary accompanying the weak wave Friday will bring another good
chance of rain to the region, especially during afternoon and evening
hours. Diurnally-driven convection Friday, courtesy of 1000 or so J/kg
of CAPE...will have the potential for marginally strong/severe wind
gusts amid a well-mixed boundary layer that should be sporting 1500
J/kg of DCAPE. This threat so far appears to be favored near/north
of the I-70 corridor.
Wind direction will shift to a light northwesterly flow for
Saturday, which will couple with slowly-clearing clouds to hold max
temperatures to only seasonably warm levels. However, the lack of
solid advection of drier air will maintain high humidity for one
more day, especially south of I-70. The arrival of moderate
humidity should be the rule for Saturday night and Sunday. Lower
dewpoints and light westerly breezes Sunday will attempt to bring in
the northeast corner of the hot, western ridge...which should result
in one final day of above normal temperatures with widespread mid-
80s giving a final taste of August. Rain-free conditions are
expected through the weekend amid this slow transition from hot and
humid to a more pleasant Labor Day.
Labor Day through Wednesday...
A secondary boundary is expected to cross Indiana around the Sunday
night timeframe...with subsequent Canadian high pressure`s
noticeably lower dewpoints completing the transition to early fall
conditions. The broad dome`s center will slowly cross the Great
Lakes...with the local region the benefactor of several days of
northeasterly to easterly surface winds, which should gust above 15
mph for most locations Monday afternoon. This flow will combine
with FEW/SCT daytime clouds to promote slightly below normal
afternoon highs, with mainly upper 70s through at least Tuesday.
Drier air should allow widespread morning lows in the 50s starting
Saturday morning, with the potential for isolated upper 40s across
the CWA`s northern tier Monday night. Lack of forcing and
precipitable water values generally suppressed below 1.00 inch will
maintain rain-free conditions into the mid-week. The long term
normal max/min at Indianapolis is 83/63.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 936 PM EDT Wed Aug 28 2024
Impacts:
- VFR expected most of the TAF period. IFR/MVFR fog possible near
daybreak at LAF/HUF and BMG
Discussion:
Cumulus clouds and isolated TSRA south of the TAF sites due to the
warm and humid air mass in place across Central Indiana will
dissipate as diurnal heating is lost this evening.
Weak high pressure across the area will remain in place as ridging
aloft begins to re-establish. High dew points across the area along
with clear skies and light winds will allow for the formation of
patchy fog overnight, particularly at BMG/LAF/HUF. A tempo group was
used to account for this.
After sunrise, heating and mixing will allow for fog burn off and a
return to VFR, as weak high pressure remains across the area.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
SHORT TERM...CM
LONG TERM...AGM
AVIATION...Puma
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
703 PM CDT Wed Aug 28 2024
.KEY MESSAGES...
- Showers and thunderstorms return tomorrow with severe storms
possible.
- Pleasant Labor Day weekend, with no major systems expected
through early next week.
&&
.DISCUSSION...
Issued at 340 PM CDT Wed Aug 28 2024
Tonight and Tomorrow... Partly to mostly cloudy skies continue to
keep parts of east-central MN and western WI about 5-10 degrees
cooler than other locations this afternoon. Widespread fog should
not be as big of an issue as last night with winds increasing out of
the southeast. Only locations that might see some patches of fog
look to be over NW Wisconsin where the winds will be slower to
increase.
All eyes shift to the approaching low over the western
US/Canadian border which could bring a round of showers and
storms, some possibly producing strong to severe wind, hail, and
isolated tornadoes. Let`s break it down...
Timing... Initial development of isolated to scattered cells along
the front is favored during early to late afternoon across the
eastern Dakotas. Shear vectors parallel to the front suggest a
linear convective mode is likely, especially as the front
approaches central and eastern MN during late afternoon. A well-
organized line of storms should develop by early evening as the
front passes through eastern MN and western WI. As such, if you
are planning on attending an event within the Twin Cities such
as the State Fair or MN Football home opener, it will be very
worthwhile to stay weather aware.
Severe Potential... While there seems to be largely solid agreement
in timing across the CAMS, the main difference to analyze will
be the potential of any pre-frontal convection. Models such as
the HRW FV3, NSSL, and NAM Nest continue to show scattered, pre-
frontal convection over portions of southern and central MN
during the late morning and early afternoon. If this were to
occur, it could potentially limit the risk of severe weather
associated with the line. On the flip side, the HRRR continues
to lack any sign of pre-frontal storms, favoring the
development of the well-organized line. In terms of
thermodynamics, there should be plenty of instability (CAPE
values of 2500+ J/kg) and moisture (PWAT values approaching 2").
Mid-level lapse rates are on the lower end, however there
should be enough ascent along the front as it marches
southeastward. Initial development of scattered cells would
support damaging wind and hail, as well as an isolated tornado
or two. As the line grows upscale and fills in, the main hazards
will be damaging wind and heavy rain, with large hail becoming
more isolated. Low level wind profiles suggest that an embedded
QLCS tornado is possible as well. Following the passage of the
line, showers and isolated thunder may linger, however the
threat for anything severe should quickly diminish.
Friday into Next Week... As the upper low moves east, high pressure
will start to build in over the Central Plains leading to mostly dry
and quiet conditions for much of this weekend. Some showers may
linger into Friday morning, otherwise expect cloud cover to
gradually diminish throughout the day. Highs will be in the mid-
upper 70s until a secondary cold front ushers in below normal temps
late Saturday. Northerly winds could pick up a little bit during the
day Sunday, but nothing too much higher than 10-15 MPH sustained.
NBM continues to suggest lows dipping their toes into the 40s,
especially Sunday night into Monday morning. A slow warm-up back to
normal temps is expected next week as the upper level ridging over
the western CONUS attempts to slide east.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 703 PM CDT Wed Aug 28 2024
VFR with MVFR and potentially IFR cigs possible. Over the
next few hours, the low bkn stratus stretching from AXN to near RNH
will erode.. Cloud cover is expected to redevelop later this evening
as system approaches from the west. Cigs are forecasted to reach
MVFR thresholds between 6-9z. Patchy fog IFR fog is possible for a
few hours near sunrise but mainly looks to be concern mainly for RNH
and EAU. Winds will increase out of the SE tomorrow morning between
13-15kts with gusts nearing 25kts in the early afternoon. TSRA is
expected to develop in the early afternoon near AXN and RWF and move
west to east across all sites into the evening. 40kt LLWS is
possible when the main line of TSRA moves through. Tempo groups
reflect latest timing. EAU precip will be introduced next TAF
period.
KMSP...Not much change since the last routine amendment. Cigs
expected to become MVFR late tonight and potentially IFR for a few
hours early tomorrow morning. SE winds will increase between 10-
15kts with gusts nearing 25kts after 18z. Delayed timing for TSRA by
an hour or so and introduced a prob30 starting at 18z in case
anything develops ahead of the main line of precip which should
likely arrive by 23z. LLWS exceeding 40kts is briefly possible
as the primary line of TSRA proceeds through.
/OUTLOOK FOR KMSP/
FRI...VFR. Wind WNW 10-15 kts.
SAT...VFR. Wind SW 10-15G18 kts.
SUN...VFR. Wind N 10-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...BED
AVIATION...Dunleavy
Area Forecast Discussion
National Weather Service San Francisco CA
852 PM PDT Wed Aug 28 2024
...New UPDATE...
.SYNOPSIS...
Issued at 1240 PM PDT Wed Aug 28 2024
Slight cooling trend begins Thursday as a trough develops, with
warmer temperatures early next week.
&&
.UPDATE...
Issued at 834 PM PDT Wed Aug 28 2024
Temperatures came down nicely today, especially in the coastal and
near coastal areas. For example, Redwood City reached 94 yesterday,
and only 83 today. This was caused by a disturbance that weakened
the ridge. The 00Z balloon today reached 500 mb at 5890 m while
24 hours ago it found the same pressure level at 5910 m. This
lower pressure allowed the marine layer to deepen from around 500
ft to over 1,000 ft and climbing. Moving forward, this cooling
trend is expected to continue through the next few days and we
are already seeing a good influx of coastal stratus signaling the
healthy marine layer.
In the longer range outlook, there is some indication that
offshore winds may accompany the warmer weather next week in the
North Bay. It`s too early to say for sure, but given the time of
year we will keep a close eye on this development and its impact
on fire weather.
&&
.SHORT TERM...
(This evening through Thursday)
Issued at 1240 PM PDT Wed Aug 28 2024
Satellite imagery shows an offshore stratus deck with impacts
limited to the immediate coast. Warm temperatures continue today,
especially in the interior, with highs in the inland valleys
reaching the 90s to near 100 in the warmest locations. The bayshore
sees highs in the mid 70s to upper 80s while highs in the 60s
continue along the Pacific coast. Breezy and gusty onshore flow will
develop each afternoon and evening with gusts up to 20 to 25 miles
per hour in the gaps, passes, and Salinas Valley.
A slight cooling trend begins on Thursday, as the upper level ridge
flattens and a cut off low approaches the coast. The cooling will be
gradual, with temperatures in the inland valleys in the mid 80s to
lower 90s, with little cooling in the most interior parts of the
East Bay and southern Monterey County. The Bayshore cools to around
the mid 70s to mid 80s, while the coastal areas stay in the 70s.
&&
.LONG TERM...
(Thursday night through next Tuesday)
Issued at 1240 PM PDT Wed Aug 28 2024
The cooling trend continues through the weekend as the cut off
low approaches and impacts the state. By Sunday, temperatures
should be close to or slightly below seasonal averages, with the
inland valleys seeing highs in the low to mid 80s, while the
Bayshore should see highs in the upper 60s to the mid 70s.
By the early part of next week, ensemble means and clusters are
converging on a ridge developing over the western United States,
bringing warmer temperatures back to the region. Exactly how warm
temperatures will get is an question for future me and my future
colleagues to clarify. CPC outlooks also suggest that temperatures
above seasonal averages are likely to continue into the second week
of September.
&&
.AVIATION...
(00Z TAFS)
Issued at 534 PM PDT Wed Aug 28 2024
A coastally trapped southerly wind reversal with stratus and fog
/LIFR-IFR/ continues, the SMX-SFO and SBA-SFO pressure gradients
are a robust 2.5 mb and 1.6 mb respectively; model forecasts continue
to struggle with surface pressure gradients, e.g. the 22z HRRR is
forecasting a slightly north to near flat gradient between SFO-SMX.
Visible imagery shows coastal stratus and fog holding together well
during the maximum diurnal mixing part of the day, thus there`s a
strong foothold in place for tonight`s radiative cooling and further
stratus and fog development. The marine layer depth is near 1000 feet
along the coast.
The STS-UKI pressure gradient is currently strong at 2.1 mb, this
should help usher stratus and fog /LIFR-IFR/ conditions earlier
this evening in the North Bay. Currently HREF IFR probability is
on the increase forecasting IFR between 04z-05z (after sunset); an
intrusion of stratus and fog into the Bay Area may be greater than
current models are forecasting. Highest confidence VFR holds through
mid evening away from the immediate coast, while LIFR-IFR prevails
on the coastline with lowering confidence in the areal coverage of
stratus and fog all locations tonight and Thursday morning. Will
monitor satellite and observations and amend 00z TAFs as needed.
Vicinity of SFO...VFR continues this evening, then by 08z IFR is
forecast continuing to 17z Thursday. Evening west to northwest
wind gusts to near 25 knots. IFR ceiling is forecast 08z-17z Thursday,
along with decreasing wind forecast tonight though caveat, it`s a
low to very low confidence forecast since recent model forecasts are
not resolving recent surface pressure gradients.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Visible satellite imagery shows stratus
curling around the Monterey Bay with the southerly wind reversal.
Stratus /MVFR-IFR/ is on the doorstep of SNS Airport while it`ll
take a while this evening for the southwesterly downsloping wind
at MRY to ease allowing stratus /IFR/ to fill in. The marine layer
depth is near 1000 feet. The southwesterly wind is advecting the
stratus to Jacks Peak which is subsequently downsloping, warming
and drying on the other side of the terrain. With nocturnal cooling,
winds will gradually ease allowing stratus and fog /LIFR-IFR/ to
fill in tonight and Thursday morning. Clearing /VFR/ is forecast
to return by late Thursday morning. Onshore winds 10 to 20 knots
easing to light onshore winds tonight, then onshore 10 to 20 knots
Thursday afternoon and evening.
&&
.MARINE...
(Tonight through next Monday)
Issued at 443 PM PDT Wed Aug 28 2024
Breezy northwesterly wind continues this evening over the northern
outer waters, while the rest of the waters remain relatively calm.
Northwesterly winds will redevelop over the coastal waters later
in the week and weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Pt Arena to
Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...SO
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Area Forecast Discussion
National Weather Service New York NY
958 PM EDT Wed Aug 28 2024
.SYNOPSIS...
A cold front sags south of the area tonight. High pressure gradually
builds from the north and northeast through Friday. A frontal system
will affect the area this weekend. Canadian high pressure builds in
thereafter and will remain in control through at least the middle of
next week.
&&
.NEAR TERM /THROUGH THURSDAY/...
A couple of showers, and possibly an isolated thunderstorm have
developed across eastern Long Island Sound and the eastern Long
Island bays at 0130Z. The other area of showers and
thunderstorms was moving south of western Long Island into the
adjacent marine waters. HRRR shows all the convection quickly
weakening in by 04Z.
The change in air mass appears to be a little more delayed
compared to previous NWP cycles. Now the drier air takes a few
hours longer to drain into the region. Dew point readings drop
gradually through the 60s. The more noticeable drop in humidity
and improved comfortability takes place into Thursday morning.
Clouds will linger behind the cold front, and thus temperatures
remain a bit more elevated despite a northerly flow. Slight
chance PoPs were kept for SW sections into the pre-dawn hours.
Low temperatures will be in the 60s region wide.
With the southern edge of high pressure attempting to nose in from
the north conditions should remain primarily dry on Thursday. Some
shower and convective activity takes place off to the west later in
the day over Central PA, and could get into Eastern PA late. Have
maintained slight chance PoPs for later in the day for the western
half of the area with 15 to 20 percent PoPs. Otherwise expect
variably cloudy to mostly cloudy skies and much more comfortable
conditions with temperatures likely getting to about 5 degrees below
average for the day Thursday. Daytime highs will be in the middle
70s for the most part due to more cloud cover and a prevailing
easterly flow.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
The forecast gets a little more complicated for Thursday night. The
evening should remain dry for the most part, with perhaps a few
showers getting into the western half of the region. Convective
chances will be limited with the boundary layer quite stable with an
onshore flow. An elevated warm front looks to slowly get slightly
further east through late Thursday night. Have slight chance to
minimal PoPs further east, with chance PoPs further west. Some
elevated convection cannot be completely ruled out for the western
periphery of the CWA later Thursday night into Friday morning, but
appears unlikely. An onshore flow will be locked in out of the east.
Temperatures will be a touch cooler with upper 50s to middle 60s
across the area.
High pressure builds along the New England coast and into the Gulf
of Maine on Friday. This should hold off precip throughout the day,
with more clouds further south and west, with less in cloud cover to
the northeast in closer proximity to the high. Skies will likely
average out partly cloudy for the most part with temperatures
running a few degrees below normal with the onshore flow
continuing.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The long term period starts off dry Friday night with shortwave
ridging aloft and also a surface ridge lingering over the area from
offshore high pressure. Off to our west, a cold front approaches the
area. By late Saturday morning the surface ridge will weaken and as
the flow becomes southerly a plume of moisture will spread over the
area. Some showers are possible with this warm front in the morning
hours, but the bulk of any showers/thunderstorms will likely move
through Saturday evening/Saturday night ahead and along the actual
cold front. The latest GFS run shows pwats around 2 inches right
ahead of the cold front, which could allow for some heavy downpours,
but at this time the system looks progressive enough for hydro
impacts to be minimal. Also, the late timing of the front is
favorable for our area, with the loss of daytime heating leading to
lower instability.
A secondary push of cold air is expected later on Sunday, but the
airmass will likely be too dry for any showers/thunderstorms.
Canadian high pressure then builds in, bringing a dry and cool
airmass to the region. Dewpoints look to drop to the mid and upper
40s Monday night and then could stay around there through at least
mid week. Highs will be around 10 degrees below normal for early
September on Tuesday and Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
A cold front continues to move slowly southward through the
terminals and will be south of Long Island 02Z to 03Z. High
pressure then builds in from eastern Canada through Thursday.
VFR. Area of showers and isolated thunderstorms was moving
through the NYC metro terminals at 0145Z and will be quickly
weakening as the area moves into the waters south of Long
Island. Forecast is on track and convection should be south and
east of the terminals by 03Z.
Southwest to west winds ahead of the front switch to the NNW to
NE with the passage of the front, and as the high builds
farther to the south and east. Winds then become easterly around
10 kt Thursday morning.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Showers and isolated thunderstorms will be south of the
terminals by 03Z, and weaken.
OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
Thursday night: VFR. A slight chance of showers western
terminals.
Friday: VFR. A slight chance of showers.
Saturday: VFR, a chance of showers, possibly thunderstorms with MVFR
or lower. Showers and thunderstorms likely at night with MVFR or
lower.
Sunday: Mainly VFR. Chance of a shower/thunderstorm,
mainly in the afternoon and evening.
Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Sub small craft conditions are expected to prevail tonight through
Friday. A period of marginal small craft gusts and potentially seas
is anticipated for the central and eastern ocean from the early
morning through the early evening on Thursday. But by and large seas
are not expected to remain above 4 ft.
Winds and waves will generally remain below Small Craft Advisory
criteria this weekend into early next week. There is a chance that
gusts may occasionally reach 25 knots ahead of and behind a cold
front. The best chances would be on Monday.
&&
.HYDROLOGY...
Any hydro impacts over the weekend appear minimal at this time.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip currents Thursday and Friday. With a
15-17 kt easterly flow on Thursday and 4-5 ft waves at 6s, there is
potential for an upgrade to a high rip current risk. Regardless, rip
current activity will be enhanced along jetties and groins both
Thursday and Friday with a strong E to W sweep.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JE/JT
NEAR TERM...JE/MET/JT
SHORT TERM...JE
LONG TERM...JT
AVIATION...MET
MARINE...JE/JT
HYDROLOGY...JE/JT
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Pocatello ID
149 PM MDT Wed Aug 28 2024
.SHORT TERM...Tonight and Thursday. Winds should continue to
diminish as the cold front and low pressure to our north pushed on
to the east. That will leave us with lighter winds, with a
downvalley/downplain wind across the area. We are looking a fairly
cool to chilly night, depending on location. Typical colder
mountain spots will be down into the mid 20s with 30s and lower
40s elsewhere. We will likely see some pockets of frost and freeze
conditions, but where issue any type of frost/freeze
headlines...we should see minimal (if any) issues with frost
tonight. Temperatures will be a bit warmer tomorrow and tomorrow
night, but we will still see afternoon highs that are below
average...in some cases closer to 10 degrees below average. Keyes
.LONG TERM...Friday through Next Wednesday. By Friday, high
pressure is back in place over Idaho with lighter winds and warmer
temperatures. Highs will be in the mid 80s for most on Friday
afternoon before we get even warmer for the weekend. By Saturday
afternoon, highs will be pushing 90 degrees, but we look more
likely to hit 90 on Sunday. It`s on Sunday that the NBM is showing
a 30 to 50 percent chance of reaching 90 degrees from American
Falls up to Idaho Falls. However, that jumps to about a 70 percent
chance our near Shoshone and through the lower Wood River Valley.
Sunday looks to be the hottest day, but Monday will only be a
couple of degrees cooler. It`s during the Sunday/Monday timeframe
that we see the return of some monsoon moisture to the area, too.
Though it will be very isolated activity on Sunday with a slight
uptick for Monday and continuing into Tuesday as an area of low
pressure moves through north-central Idaho. This will be a jump
from about a 20 percent chance of a shower or storm in the Central
Mountains on Sunday to a 20 to 40 percent chance CWA-wide for
Monday into Tuesday. QPF totals don`t look very impressive at this
time, unfortunately, but the increase in cloud cover will help
cool us off a few more degrees for Monday and Tuesday afternoon.
Wind gusts through the extended forecast are expected to remain
fairly light, but increase to around 20 to 25 mph on Monday and
Tuesday afternoons as that system moves through just north of us.
AMM
&&
.AVIATION...Wind gusts have been the main aviation weather impact today, but
gusts will begin to diminish this afternoon before becoming light
overnight into Thursday morning. However, we will continue to watch
for impacts to VIS due to smoke from regional wildfires moving into
our TAF sites tonight. The best potential will be for impacts at SUN
with the NBM advertising about a 20 percent chance for VIS of 5SM or
less from 02Z this evening through Thursday morning. The HRRR really
wants to tank VIS for SUN down to around 1SM, but the HRRR has been
a bit aggressive with VIS impacts due to smoke this summer. For now,
will go with 6SM HZ for SUN, but it will need to be watched. AMM
&&
.FIRE WEATHER...Winds will continue to subside through this
evening as any influence from this morniing`s cold front and low
move well east of us. The story until the latter half of Labor Day
Weekend is very dry air in place. With that, we are NOT expecting
much overnight humidity recovery. Even for some valley locations,
recovery by the weekend will only be from single digits/teens in
the afternoon to 35-45% at night. We will see some initial
inklings of monsoon moisture later Saturday with likely just some
afternoon cloud build-ups. The models are notorious for not
recognizing storms on the leading edge of the moisture surge, so
even though the Blend of Models has no storms Sunday...don`t be
surprise if some isolated dry storms develop that afternoon.
Better chances of storms arrive for Labor Day and beyond. Keyes
&&
.AIR QUALITY...The Air Quality Advisory for Custer County
continues until 3 PM MDT Friday afternoon due to degraded air
quality due to wildfire smoke. Air quality is in the "Unhealthy for
Sensitive Groups" and "Unhealthy" categories in parts of the Central
Mountains and forecast to remain there through Friday afternoon.
While the main areas of impact remain in the Central Mountains near
Stanley, breezy west/northwest winds will bring smoke back to much
of Eastern Idaho, though impacts are expected to be less the farther
east you are. AMM
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Salt Lake City UT
409 PM MDT Wed Aug 28 2024
.SYNOPSIS...A dry and gusty cold front will progress southward
through Utah this evening, with a warming trend kicking off
Friday through the weekend with continued dry conditions.
&&
.SHORT TERM (Through 12Z/6AM Friday)...With slightly more moist
air at the core of the mid-level trough clearly visible in this
afternoon`s water vapor imagery, continuing to track the push of
a weak summer cold front into northern and central Utah. Surface
observations across southern ID show gusts 20-25 mph, in good
agreement with HRRR and HREF mean wind gust forecasts. HREF
suggests upper limit for most of these gusts will be ~35 mph.
While this will drive some increase in surface humidity, will not
be enough to make an appreciable difference in sensible weather
or fire weather - with the saving grace being less than critical
fuel moisture in the majority of the forecast area. Gusty winds
may stick around as late as 09Z/3AM Thursday, ending earlier in
sheltered areas that quickly stabilize after sunset.
While cooler temperatures will set in for Thursday (with most
areas running 5-10 degrees below seasonal normals), expecting a
quick rebound into the upper 80s along much of the Wasatch Front
and touching 100F in the Saint George area by Friday afternoon,
kicking off a brief warming trend, discussed below.
.LONG TERM (After 12Z/6AM Friday), Issued 352 AM MDT...
A ridge of high pressure aloft will build over the Western US by
Friday, bringing mostly dry southwesterly flow aloft and a warming
trend. Global ensembles had previously indicated a potential
return to a monsoon-ish four corners high by late in the weekend
into early next week, allowing for moisture return to our area.
This morning`s 00Z runs have backed off somewhat on that favorable
position, still allowing for a little moisture increase with
southerly flow aloft but nothing substantial. Global ensemble
25th-75th percentile PWAT ranges from 0.5-0.75" over Utah, while
the ECMWF ensemble shows essentially a 0% chance of PWATs
exceeding an inch. This type of scenario would favor isolated to
scattered thunderstorms over southern Utah and isolated
thunderstorms in northern Utah / southwest Wyoming, largely tied
to the higher terrain. Thus, PoPs have trended downward somewhat
from what was depicted 24 hours ago.
Temperatures meanwhile will climb gradually, likely peaking
Sunday/Monday for the holiday weekend. That stated, these
temperatures are still only around 5 degrees above normal, which
translates to low 100s for the St George area and lower 90s for the
Wasatch Front. Looking ahead to next week, global models are in
relative agreement with another Pacific NW trough flattening the
ridge over our area and perhaps pushing another weak/dry cold front
through the northern portion of the forecast area by midweek. From
there on, ensemble clustering shows high confidence that ridging
will return, meaning more above normal temperatures and mostly dry
conditions for the 8-10 day outlook.
&&
.AVIATION...KSLC...The SLC terminal will see VFR conditions through
the evening with mostly clear skies. Due to the passing cold front,
the usual shift to southerly winds will be a bit delayed, most
likely between 06Z and 08Z. Wildfire smoke is expected to build back
in Thursday morning.
.REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR
conditions through the evening with mostly clear skies. A dry cold
front will stall over southern Utah this evening. In association
with this front, anticipate pockets of gusty west to northwest winds
behind the front and gusty southerly winds ahead of the front
through the early evening, with isolated gusts in excess of 30 mph.
Wildfire smoke is expected to build into northern Utah beginning
Thursday morning.
&&
.FIRE WEATHER...Axis of a broad trough will move through this evening,
bringing with it dry and gusty conditions. The impacts should be
short lived, ending by sunrise, and potentially earlier in areas
where surface conditions are able to become more stable. Peak
gusts with the front are not likely to exceed 35 mph, and no
precipitation or lightning is expected.
The bigger story will be the warming and drying trend through the
weekend into early next week as ridging yet again builds in over
the region. While there is a slight indication in ensembles that
moisture will tick up in the coming days for southwestern Utah,
expecting the remainder of the region to remain in the 5-15%
humidity range.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...Red Flag Warning until 8 PM MDT this evening for WYZ277.
&&
$$
Wessler/Traphagan/Van Cleave
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
816 PM EDT Wed Aug 28 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 815 PM EDT Wed Aug 28 2024
Busy afternoon and early evening continues to wind down across
the area, with a lingering area of rain along the immediate coast
from around the Tampa Bay area into parts of SWFL, and a small
cluster of storms across coastal Levy and Citrus counties, with
the remainder of the activity across the coastal and offshore
waters. This general trend should continue into tonight, with
another round of activity likely Thursday afternoon and evening as
we remain in an easterly flow pattern. No changes were needed to
the existing forecast package.
&&
.DISCUSSION...
Issued at 214 PM EDT Wed Aug 28 2024
A very typical late August weather pattern will persist through the
forecast period. Broad surface high pressure centered between
Bermuda and the Bahamas will ridge west-southwest across Florida and
into the Gulf of Mexico. This synoptic pattern will keep Florida in
a predominant easterly wind flow through the week and into the
weekend. This will favor late afternoon/evening showers and storms
forming along both the east and west coast sea breeze boundaries.
Abundant moisture with PWAT values ranging between 1.9-2.2 inches
will support scattered to numerous showers and storms each day with
the highest chances over southwest Florida. The latest HRRR guidance
has the bulk of these showers and storms over the west coast of
Florida between 4-8 pm later today moving from east to west. Some of
the stronger storms could produce gusty winds and localized flooding
in low lying areas. Seasonal temps are also expected with highs in
the low to mid 90`s and overnight lows in the 70`s. Heat indices
will reach 102-107 each afternoon. The tropics remain relatively
quiet with only a couple of low chance areas in the central Atlantic
at 20 percent and near zero percent chance of development for the
next 7 days. Neither of these areas pose a threat to Florida at this
time.
&&
.AVIATION...
(00Z TAFS)
Issued at 750 PM EDT Wed Aug 28 2024
Held on to VCSH/-RA for the opening hour or two of the cycle
followed by drier conditions prevailing until Thursday afternoon
when showers/storms once again develop and push west across the
peninsula bringing a period of MVFR/IFR conditions generally in
the mid-late afternoon into early evening period. Easterly flow
pattern continues, with period of onshore flow likely in the
afternoon in association with the W FL sea breeze before it is
overtaken by the E FL sea breeze and its convection.
&&
.MARINE...
Issued at 214 PM EDT Wed Aug 28 2024
Easterly winds around 10-15 knots will be in place across the waters
through the period, with a weak sea breeze possible near the coast
each afternoon. Showers and storms will be most likely in the late
afternoon and evening pushing offshore from land. No headlines are
expected.
&&
.FIRE WEATHER...
Issued at 214 PM EDT Wed Aug 28 2024
High pressure to the north ridges across Florida keeping a
predominant easterly wind flow across the region. Scattered to
numerous showers and storms can be expected each day through the
week and into the weekend. No fire weather concerns are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 92 76 92 / 30 70 20 70
FMY 76 93 76 93 / 30 70 20 80
GIF 75 94 75 93 / 30 60 10 70
SRQ 75 93 76 94 / 30 70 30 70
BKV 73 94 73 94 / 30 70 10 60
SPG 80 93 80 93 / 30 70 30 70
&&
Sea Breeze Thunderstorm Regime For Thursday: 2
Sea Breeze Thunderstorm Regime For Friday: 2
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Hurt
DISCUSSION/MARINE/FIRE WEATHER...Wynn
DECISION SUPPORT/UPPER AIR/CLIMATE...Delerme/Shiveley