FXUS66 KEKA 181119
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
419 AM PDT Sat Aug 18 2018
.SYNOPSIS...Dry weather will continue for the foreseeable future,
with hot weather forecast for interior northwest California.
Coastal clouds and fog will give way to some periods of clear
skies this weekend, but there will still be quite a bit of smoke
and haze around, especially closer to area wildfires.
.DISCUSSION...Satellite imagery this morning shows the coasts of
Humboldt and Del Norte counties free of stratus! However, it also
shows a thin layer of smoke with Crescent City currently reporting
reduced visibility and a layer of smoke at 3900 feet. Farther
south, along the Mendocino coast, there is some stratus, but it
has not penetrated as far inland. The good news is that we may be
in store for a sunny day here at the coast, but with easterly
winds at play we will also likely have hazy and smoky skies.
Conditions farther inland will probably be similar to yesterday,
although temperatures may be a few degrees warmer due to a brief
period of ridging building overhead. Smoke and haze are likely for
these areas too, especially as you get closer to the fires.
Sunday and beyond, models suggest that our weather will be
dominated by an upper level trough. Rain is not expected to come
from this, but temperatures will be slightly cooler for interior
areas with highs making into the 80s and 90s. At the coast, the
marine layer will likely redevelop and advance inland each night.
Patchy fog and perhaps even some drizzle will be possible each
.AVIATION...The primary forecast problem for today will be smoke
from wild fires. Smoke layers aloft have already spread out over
KCEC with ceilings around 4000 ft. The smoke appeared to be
spreading southwestward offshore over the coastal waters. Expect
layers of smoke aloft to spread over ACV and EKA. MVFR or IFR
conditions due to smoke or haze will certainly be possible today at
both coastal terminals today. The timing and duration of MVFR or IFR
conditions due to smoke are highly uncertain.
Another forecast problem is the coastal stratus. Stratus +decreased
significantly across the area yesterday and so far there has not
been much regeneration. Satellite imagery has been showing a few
slivers developing offshore west of Eureka early this morning.
Some stratus may push onshore shortly after sunrise. IFR or LIFR
ceilings may briefly impact KACV through mid morning.
Model soundings and profiles indicate marine layer conditions
redeveloping around Humboldt Bay tonight. Expect IFR or LIFR
conditions to impact KACV overnight into Sunday morning. Based on
high resolution model data, KCEC would stay clear tonight. Guidance
continues to indicate southerly winds developing tonight. Stratus
may advect into KCEC by daybreak Sunday.
Smoke from nearby wild fires will continue to impact KUKI with
periodic MVFR or IFR conditions. The timing and duration of the
smoke are highly uncertain.
.MARINE...Brisk northerly winds and steep hazardous seas will
continue across the outer waters through Monday. For the inner
waters, winds will generally be lighter but with rough and
uncomfortable seas. The GFS and ECMWF indicate a diminishing trend
in winds and seas Tuesday through Wednesday of next week.
.FIRE WEATHER...More or less of the same is expected for the
foreseeable future, with the exception being this morning due to
a thermal trough. This has brought some gusty easterly winds
across eastern Del Norte County. Gusts up to 25 mph will be
possible through the early morning hours up there, while RH
recoveries remain poor. Elsewhere, lighter easterly winds will be
possible for the higher terrain of eastern Trinity and Mendocino
counties. These winds will likely be accompanied with a variety of
recoveries with areas closest to the coast having the best.
Other than those winds, expect another hot day for interior
northwest California as temperatures will approach 100 degrees for
some valleys this weekend. Next week, temperatures will be still
be hot, but highs will likely peak in the 80s and 90s.
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 5 PM PDT Sunday for PZZ450.
Small Craft Advisory until 3 PM PDT Monday for PZZ470-475.
Small Craft Advisory until 5 AM PDT Monday for PZZ455.
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FXUS66 KHNX 181119
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
419 AM PDT Sat Aug 18 2018
Dry and hotter than normal conditions will continue through the
weekend as high pressure strengthens over the region. A low
pressure system will impact central California early next week,
lowering temperatures a few degrees to near normal but remaining
dry through the week.
Models drift the center of a strong upper ridge northwestward
over southern and central California during the next couple of
days, which will bring increasing temperatures and suppressed
mountain convection through the weekend. The higher max temps
combined with overnight lows a bit above normal will nudge heat
risk values up today and Sunday. Much of the SJ Valley and lower
foothill areas will experience moderate risk of heat related
illnesses for those sensitive to heat. Desert locales will see
moderate to high risk for much of the population without effective
cooling and adequate hydration. Persons experiencing these
conditions need to take precautions against the heat, including
drinking plenty of water.
Model solutions remain similar into next week as a trough is
progged to slide into the Pac NW and northern CA, weakening and
displacing the ridge over our area. This will bring increased
onshore flow with some gusty winds over the mountains and through
the passes. Some marine air should spill into the SJ Valley aiding
the synoptic cooling that will result from the approaching
trough, especially in our northern areas. By Tuesday, high
temperatures should be down to around seasonal averages.
With a troughy pattern to our northwest and the ridge remaining
centered to our southeast, we should not experience significant
warming during next week, with temps hovering just a bit above
climo. Best moisture is progged to remain to our east and south,
keeping our forecast dry through the period.
Areas of MVFR visibility in smoke and haze can be expected in the
foothills and higher elevations of the southern Sierra Nevada north
of Kings Canyon. Otherwise, VFR conditions will prevail across the
central CA interior during the next 24 hours.
.AIR QUALITY ISSUES...
On Saturday August 18 2018... Unhealthy for sensitive groups in
Fresno and Kern Counties and Sequoia National Park and Forest.
Further information is available at Valleyair.org
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is high.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.
FXUS66 KLOX 181618
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
918 AM PDT Sat Aug 18 2018
Above normal temperatures inland and weak onshore flow will
continue through this weekend and into early next week, as high
pressure aloft continues to build overhead. Night to morning low
clouds and fog will return to some coastal areas and coastal
valleys through Sunday.
.SHORT TERM (TDY-MON)...18/912 AM.
The marine inversion this morning ranged from near 1000 ft deep at
VBG to near 2000 ft deep at LAX. Low clouds were covering much of
the coast and adjacent vlys this morning, and are expected to clear
to or off the coast by midday. Otherwise, mostly sunny skies will
prevail across the region thru the afternoon, except for a few
afternoon cu buildups in the mtns and deserts. Temps today will be
several degrees above normal in all areas with highs in the 80s and
90s from the inland coastal areas to vlys and lower mtns, to low
100s in the Antelope Vly.
A 595-596 dm H500 high will prevail over central and srn CA today,
then weaken thru Sun before moving E into AZ and NM for Mon. The
marine layer pattern is expected to persist thru Mon, with varying
amounts of night and morning low clouds and fog expected mainly for
the coastal areas and perhaps into some of the adjacent vlys.
Otherwise, mostly clear skies will continue across the region.
A typical diurnal wind pattern will prevail as well, with weak flow
during the night and morning, followed by locally gusty onshore
winds in the afternoon and early evening.
Temps will continue to be several degrees above normal across most
of the area on Sun, then cool slightly but remain a few degrees
above normal on Mon. Highs Sun should reach the 80s and 90s from the
inland coastal areas to the lower mtns, then fall to the 80s to mid
90s in these areas on Mon. In the Antelope Vly, highs will be in the
101 to 107 degree range Sun, and in the upper 90s to near 104 on
.LONG TERM (TUE-FRI)...18/321 AM.
A very stagnant forecast pattern sets up next week with the upper
high to the southeast and a weak trof to the NW. Dry NW flow will
be over the state which will preclude any monsoon flow. Max temps
will change little across the coasts where the night through
morning low cloud pattern will continue. The inland areas will
cool some on Tuesday as hgts fall but then will change little for
the rest of the week as the pattern remains static.
The above normal sea sfc temps will continue to bring above normal
humidities and overnight lows.
At 1100Z at KLAX, the marine layer was around 1200 feet deep. The
top of the inversion was near 3600 feet with a temperature of 27
N of Point Conception...Moderate confidence with VLIFR/LIFR cigs
at coastal TAF sites early becoming IFR briefly before becoming
VFR by 17-18z this morning. 40% chance that cigs could scour out a
few hours earlier than 12z TAF suggest. High confidence for VFR
cigs at KPRB this morning. Not much change expected and will
continue with persistence forecast for this evening through Sun
S of Point Conception...Low to moderate confidence with high IFR
to low MVFR cigs for coastal sites. Better confidence for VFR
conds for inland TAFs. 20% chance for IFR/MVFR cigs between 14-16z
for KBUR this morning. Similar confidence for tonight with cigs
and stratus coverage into Sunday morning.
KLAX...Moderate confidence with 12z TAF for MVFR cigs through 17z.
30% chance that cigs could be at KLAX only briefly before scouring
out this morning. There is a 20 percent chc of IFR cigs through
13z. Good confidence that any east wind component will be under 6
kt. VFR transition should occur within an hour of fcst.
KBUR...Moderate confidence in 12z TAF through 14Z with 30% chance
for brief IFR/MVFR cigs. After that high confidence for VFR conds
through 10z Sun morning. 30% chance for IFR/MVFR cigs between
10z-15z Sun morning. Good confidence that VFR transition should
occur within 30 min of fcst.
For the Outer Waters... There is a thirty percent chance of Small
Craft Advisory (SCA) level winds tonight and tomorrow night near
Point Conception and a thirty percent chance across all of the
outer waters on Wednesday night. Otherwise conditions will be
below SCA levels.
For the Inner Waters... There is a twenty percent chance of SCA
level winds across the western portion of the Santa Barbara
Channel late this afternoon and evening. Otherwise conditions
will remain below Small Craft Advisory level through Wednesday.
Patchy fog... locally dense... will form in the overnight and
morning hours in portions of the coastal waters through Wednesday.
A south swell will result in hazardous conditions for mariners
through this evening, particularly near the surf zone.
Elevated surf will continue at Southern California beaches through
this evening as a long-period southerly swell moves across the
coastal waters. Strong rip currents and sneaker waves will be
common, especially across south-facing beaches.
Moderate to strong rip currents and sneaker waves could linger
into Sunday as the southerly swell will be slow to diminish.
Swimmers and anyone in the surf zone should remain vigilant
through the weekend.
CA...Beach Hazards Statement in effect until 9 PM PDT this evening
for zones 40-41-87. (See LAXCFWLOX).
.HAZARD POTENTIAL OUTLOOK (MON-FRI).
No significant hazards expected.
FXUS66 KSTO 181050
Area Forecast Discussion
National Weather Service Sacramento CA
350 AM PDT Sat Aug 18 2018
Above normal temperatures continue through the weekend, with
gradual cooling early next week. No precipitation is expected.
Areas of smoke and haze will continue, especially near wildfires.
Above normal temperatures continue today and Sunday, with highs
near 100 in the southern part of the valley and up to 102 over the
northern Sacramento Valley, similar to what we saw on Friday.
Smoke and haze levels today may increase even away from
wildfires, due to light northerly winds.
An upper level trough on Sunday will bring an increase in onshore
flow and some clearing in the smoke and haze near the Delta.
Cooler temperatures are expected late Sunday and into Monday. This
will also increasing southwesterly winds in the Delta, Sacramento
Valley and the Sierra, with northwesterly winds in the San
Joaquin Valley. Winds over high Sierra ridges could gust to 30-40
mph Sunday evening.
The slow moving upper trough will bring near normal temperatures
early next week. For the Valley, this means temperatures in the
90s. Higher elevation winds will remain breezy. Monsoonal
moisture will remain well east of the area and moisture associated
with the trough will remain well to the north. This will keep
dry weather across interior Northern California. EK
.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
Seasonably hot and dry weather will continue later next week as
interior NorCal will lie between high pressure over the Southwest
and a weak trough lingering along the West Coast.
Local MVFR/IFR conditions in HZ/FU near wildfires, otherwise VFR
continues over the area for the next 24 hours. Winds below 15
knots. Local SW surface wind gusts 15-25 kts vicinity Delta.
FXUS66 KSGX 181547
Area Forecast Discussion
National Weather Service San Diego CA
847 AM PDT Sat Aug 18 2018
High pressure will strengthen over the area today. There is still
enough moisture present for the possibility of a few showers to
develop over the mountains this afternoon. Moisture will decrease
further Sunday through Monday before monsoonal moisture returns
during the middle part of next week, rekindling the chance for
mountain and desert thunderstorms.
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
Satellite imagery this morning had a continuous marine stratus layer
covering all coastal areas. The layer extended up to 20 miles inland
across San Diego County. Elsewhere across SoCal, the skies were
clear. The 00Z Miramar sounding showed a sharp shift in winds below
8K FT from east to NW. Some drying accompanied the shift, but PW was
still 1.75 inch. There was a 5C inversion based near 2K FT MSL. The
sounding had stabilized considerably from yesterday. Except for the
desert passes where westerly winds were gusting to around 25 MPH,
winds were light.
Given the high PW values still present, a small chance of showers
seems warranted, but they will have to overcome continued drying and
stabilizing of the environment. No forecast changes.
From previous discussion...
Water vapor imagery shows a shortwave departing through the
intermountain west with upper level ridging building in overhead
Hi-res models are dry today with the WRF showing no cell
development anywhere today. HRRR shows a small light cells over
the Riverside mountains. Moisture levels are still sufficient
under the upper ridge. In fact, satellite-derived Precipitable
Water shows values ranging from 1.6 inches near the border to
1.2-1.4 inches across the mountains, highest south. Some
instability develops along the mountain crests this afternoon
with MUCAPE values of 500+ J/KG. These parameters suggest some
cumulus will develop over the mountains this afternoon with even
the potential of isolated showers. However, the suppressing ridge
should inhibit thunderstorm development. No flash flooding is
Tranquil days are expected Monday-Tuesday. Kept the forecast dry,
but there still could be just enough moisture present for cumulus
if not a few showers developing in the mountains. We can see the
latest hi-res runs and see how activity fares today to adjust the
forecast as needed. Either way, no significant impacts are
expected with no flash flooding anticipated through Monday.
Models show monsoonal moisture increasing Tuesday-Thursday, as the
upper high shifts east. This will bring a return to afternoon
mountain and desert thunderstorm activity then. How active it gets
though is uncertain and will assess in the days ahead.
Nighttime and morning low cloudiness will dominate at the coast
each day with sunshine each afternoon. It will continue humid as
well. Temps will continue to run above average through next week,
but not to excessive levels.
181530Z...Coasts/Valleys...Low clouds with bases 1200-1500 feet MSL
and tops to 2200 feet will scatter out by 18Z. Spots along immediate
coast may not clear fully or for very long. Clouds will redevelop
and spread inland after 01Z with bases 1000-1400 feet MSL and spread
not as far inland overnight. Local vis restrictions along inland
edge of cloud deck. Scatter out Sunday by 17Z.
Mountains/Deserts...Cumulus developing over the mountains this
afternoon with bases near 10000 feet MSL. There is a slight chance
of showers over mountain crests. Otherwise mostly clear with
unrestricted vis through Sunday morning.
No hazardous marine weather is expected through Wednesday.
Beach Hazard Statement will continue through this evening for
elevated surf and strong rip currents. A 3-4 ft/15-16 second period
swell from 180 degrees will bring surf of 3-6 ft, with isolated sets
to 9 ft, mainly along the south facing beaches of Northern Orange
County, and strong rip currents. Surf will lower tonight through
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Beach Hazards Statement through this evening for Orange County
Coastal Areas-San Diego County Coastal Areas.
FXUS66 KMTR 181543
Area Forecast Discussion
National Weather Service San Francisco Bay Area
843 AM PDT Sat Aug 18 2018
.SYNOPSIS...Very warm to hot conditions will persist inland
through the weekend. A persistent but shallow marine layer and
light onshore flow will maintain mild conditions at the coast.
Cooling is then forecast during the early part of next week.
.DISCUSSION...as of 8:45 AM PDT Saturday...A 596dm 500mb high
pressure ridge remains over the region this morning, contributing
to a compressed marine layer near the coast and mostly clear skies
elsewhere. Very little day to day change is expected for today
versus yesterday. That said, the weather pattern is forecast to
shift soon. An approaching trough will settle into Oregon/Norcal
by late tonight through early next week, which is expected to
flatten and thus weaken the ridge currently in place. This will
ease the suppression of the marine layer, allowing it to deepen,
and set temperatures on a slight cooling trend. Temperatures will
be their lowest on Tuesday, with afternoon temperatures 3 to 8
degrees cooler than normal nearly everywhere except the most
extreme inland locations, which may continue to run near to
slightly above normal. This translates to mid to upper 60s along
the coast and SF Bay shoreline, with 70s to low 80s just inland,
to mid 80s to low 90s for extreme inland locations.
.PREVIOUS DISCUSSION...As of 3:19 AM PDT Saturday...The marine
layer has compressed to around 1000 feet, per the latest Fort Ord
profiler output, and satellite imagery confirms with only limited
inland extent to the coastal stratus so far. The most appears to
be into the Salinas Valley, with Monterey and Salinas airports
both indicating visibility restrictions due to fog. The San
Francisco Bay area appears to be less impacted with no ceilings
currently being reported at Bay Area airports. With a high
pressure ridge still in place over the state, expect warmer
temperatures across the district but mostly across inland areas.
Highs today are forecast to range from 60s to mid 70s near the
coast, and 80s and 90s inland. Warmest inland spots could easily
exceed the century mark.
Warm/hot temperatures will persist through Sunday as the ridge
will remain in effect. Cooler temperatures are anticipated by
early next week, though, as an upper level trough displaces the
ridge over the west. Inland temperatures could be as many as 10
degrees cooler compared to weekend temperatures, however, coastal
temps should see less change. Medium range models keep a baggy
trough over the west through the remainder of the forecast period
maintaining the moderate temps.
.AVIATION...as of 4:45 AM PDT Saturday...Marine layer has
compressed as upper level ridge has built over the area. Stratus
extends along the coast but has made little inland progress.
Local stratus is possible at OAK but VFR is expected for the SFO
Vicinity of KSFO...VFR. West winds 16-18 kt after 21Z.
SFO Bridge Approach...VFR.
Monterey Bay Terminals...IFR cigs with local vsbys down to 1/2
mile through 15Z. Becoming VFR after 17Z at SNS and 18Z at MRY.
.MARINE...as of 08:23 AM PDT Saturday...High pressure persists
over the eastern Pacific with a thermal trough over inland
California. Northwesterly winds will remain generally light
through the week aside from locally gusty winds in the northern
outer waters through Tuesday as the trough over California
strengthens. Light to moderate mixed swell will continue along
with a longer period southerly swell.
.Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm from 5 PM
PUBLIC FORECAST: DRP
AVIATION: W Pi
MARINE: W Pi
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