Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/10/22
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
850 PM PDT Sat Apr 9 2022
.SYNOPSIS...09/610 PM.
Expect periods of gusty northwesterly to northerly winds through
Tuesday evening across portions of the region. Temperatures will
be near normal on Sunday and slightly below normal Monday through
Friday. There is a slight chance of showers late Monday into
Monday night mainly for interior areas.
&&
.SHORT TERM (SAT-TUE)...09/849 PM.
An upper level trough is diving into the Great Basin tonight,
with a strengthening northwest flow aloft pattern over Southwest
California. Near the surface, pressure gradients have trended
sharply onshore today, with LAX-Daggett gradient peaking at
+5.5 mb. The combination of lowering heights and the stronger
onshore flow resulted in a significant cooldown from yesterday,
especially across coastal areas. Onshore wind gusts up to
45 mph occurring across the Antelope Valley this evening,
resulting in a wind advisory issuance.
For tonight, satellite imagery showing mostly clear skies
across the forecast area this evening. However, a strong eddy
circulation has generated a rapid return of low clouds this
evening across San Diego and Orange counties, which is quickly
lunging northwestward towards the LA basin. ACARS data already
showing a marine layer depth around 1800 feet this evening across
the LA Basin, with further deepening of the marine layer expected
by Sunday morning. As a result, expecting low clouds to expand
northwestward to the Ventura/southern Santa Barbara coastal areas
overnight, and also push inland into the San Gabriel/San Fernando
valleys. The increased marine layer influence and continued
lowering heights will result in additional cooling for all areas
on Sunday, with warmest valley areas climbing to around 80
degrees.
Other item of interest tonight is the continuation of
sundowner winds across southern Santa Barbara county, where
a wind advisory is in effect for western Santa Ynez range and
western coastal areas. Will be adding a wind advisory for the
eastern Santa Ynez range as well, since Montecito Hills just
came in with a gust to 49 mph as of 8 pm. Taking a look at
current sundowner pressure gradients, we are observing Santa
Barbara-Santa Maria at -4.5 mb and Santa Barbara-Bakersfield
at -3.2 mb. Winds are expected to taper off shortly after
midnight across the eastern portions of the south coast and Santa
Ynez range as the developing southeast winds from the eddy spread
up the coast. Strong northwest winds also pushing through the I-5
corridor tonight with wind advisory in effect for gusts up to 50
mph.
*** From previous discussion ***
The marine layer depth will increase further Sun night into Mon
morning, with low clouds expected to expand to much of the coast
and vlys, especially S of Point Conception. There will also be the
possibility of patchy drizzle over VTU/L.A Counties early Mon
morning from the coast to the lower coastal slopes. Altho the low
clouds should largely dissipate by early Mon afternoon, a
weakening cold front associated with an upper level trof will push
into SLO County Mon afternoon, with increasing clouds and a
chance of showers developing for much of SLO County into western
SBA County. Otherwise and elsewhere, partly cloudy skies should
prevail for the most part thru Mon.
For Sun night into early Mon, another round of gusty NW to N
winds can be expected across parts of southern SBA County and in
the mtns along the I-5 Corridor, where additional Wind Advisories
may be needed.
Temps across the region are forecast to cool significantly for
Sun, but still be near normal to a few degrees above normal for
many areas. Further cooling to a few degrees below normal is
expected for Mon. The warmest coast and vlys should reach the 70s
on Sun, and mid 60s to low 70s for Mon.
The upper level trof over CA will slowly move E Mon night and Tue,
with a broad WNW flow aloft persisting over srn CA, and H5
heights remaining rather low at around 558-564 dam.
There will be just a slight chance of showers mainly over interior
areas down to the VTU and S SBA County coast Mon evening, then be
confined to just the N slopes later Mon night. Any pcpn over the
area Mon and Mon night will be very light and should be less than
0.05 inch. Snow levels will lower rapidly to below 4000 feet Mon
night, and a dusting of snow will be possible on the N slopes.
Otherwise, skies will become mostly clear for most areas later Mon
night and Tue. Low temps Mon night will be quite chilly, with
patchy frost possible in the interior sheltered areas. Temps on
Tue will be only slightly warmer S of the mtns over VTU/L.A
Counties, but be several degrees below normal most elsewhere.
Conditions will be favorable for northerly winds to increase over
the area late Mon and Mon night. The strongest winds will likely
be in the mtns and over portions of southern SBA County. With
thermal and upper level support, wind gusts to warning levels may
be possible and a High Wind Watch may eventually be needed for
this event. Elsewhere, there may eventually be the need for Wind
Advisories for several wind-prone areas.
.LONG TERM (WED-SAT)...09/157 PM.
A broad westerly flow aloft will prevail Wed, then broad upper
level troffiness should move into the area Thursday and possibly
into early Sat. The GFS/EC mean ensembles differ in the timing of
the upper troffiness, with the EC a tad slower. The models do
bring in a weak front and some light pcpn mainly to SLO County by
Thu afternoon and linger the pcpn over that area at least thru
Fri, altho the EC mean ensembles keep pcpn over SLO and also SBA
County into Sat. Decided to go with NBM POPs for the extended
period, with just minimal POPs over SLO County Thu thru Fri. This
fcst will likely be adjusted as further model runs come in. Any
rainfall Thu thru Fri should be on the light side. Otherwise,
skies will be mostly clear Wed with partly cloudy skies at times
Thu thru Sat.
Temps will be near to slightly below normal Wed with a slow
warming trend thru Sat. Temps should be quite chilly Tue night as
well, with patchy frost not out of the question for sheltered
interior areas.
&&
.AVIATION...10/0041Z.
At 0110Z at KLAX, the marine layer depth is around 1700 feet. The
top of the inversion was near 3000 feet with a temperature of 20
deg C.
A strong Catalina Eddy will likely support low cig development
after 05Z for KLAX/KLGB/KSMO and after 09z for KOXR/KCMA. There
is also a 70 percent chance of low cig development after 09Z for
KBUR/KVNY/SGXKSBA. The ceilings will likely remain mostly in the
MVFR category with brief periods of IFR possible during the
initial onset of marine clouds. Gusty west winds of 30 to 40
knots will continue through this evening at KWJF and KPMD.
KLAX...Moderate confidence VFR TAF will prevail through 05Z. High
confidence that east wind component will not exceed 6 kt through
00Z. There is a 40-50 percent chance that the east wind component
associated with the Catalina Eddy will reach 8 kts or more
between 06Z-18Z. Mostly MVFR cigs tonight and Sun morning.
KBUR...High confidence in VFR TAF through 07Z. There is a 70
percent chance of IFR cigs after 07Z and MVFR cigs after around
12-15z.
&&
.MARINE...09/802 PM.
For the Outer Waters, a long duration Gale warning is in effect
through Tuesday. Winds may briefly fall below Gale levels each
morning. Large seas (10-16) feet will continue into early next
week.
For the Inner Waters north of Point Sal, SCA in effect for winds
and seas through Sunday morning. A Gale Warning is in effect for
Sunday afternoon through Monday night. Large seas above 10 feet
will likely continue into early next week.
SCA level NW winds will likely focus during the afternoon and
evening hours across the western Santa Barbara Channel this
weekend. Widespread Gale Force winds with large seas near and
above 10 feet will likely spread to remaining inner waters Monday
afternoon into Tuesday and a Gale Watch remains in effect for
Monday afternoon and night.
&&
.BEACHES...09/828 PM.
A combination of a large northwest swell and locally generated
wind waves will support high surf and dangerous rip currents for
the Central Coast through at least Monday. Ventura county beaches
will also likely experience high surf and dangerous rip currents
through at least Sunday evening. A beach hazards statement
is in effect for remaining beaches with an emphasis in dangerous
conditions for west facing beaches. High surf conditions may
spread to additional beaches early next week, and future shifts
will need to extend the CFWLOX into Tuesday, at least.
Ocean water temperatures in the mid 50s to near 60 can easily
cause hypothermia and immediate danger to those entering the
water. The combination of high surf, strong rip currents, and
cold water will be dangerous to unprepared swimmers or surfers.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 5 PM PDT Monday for zones
34-34. (See LAXCFWLOX).
Wind Advisory in effect until 3 AM PDT Sunday for zones
34-35-53-54. (See LAXNPWLOX).
Beach Hazards Statement in effect through Sunday evening for
zones 34>36-36. (See LAXCFWLOX).
High Surf Advisory in effect until 8 PM PDT Sunday for zone
35. (See LAXCFWLOX).
Wind Advisory in effect until 10 PM PDT this evening for zone
59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 11 AM PDT Sunday for
zone 645. (See LAXMWWLOX).
Gale Warning in effect from 11 AM Sunday to 3 AM PDT Tuesday
for zone 645. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 PM PDT Monday for zone
650. (See LAXMWWLOX).
Gale Watch in effect from Monday afternoon through late
Monday night for zones 650-655. (See LAXMWWLOX).
Gale Warning in effect until 5 PM PDT Tuesday for zones
670-673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Gomberg/Sirard
AVIATION...Gomberg
MARINE...Gomberg/Sweet
BEACHES...Gomberg/Sweet
SYNOPSIS...TF
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox
Area Forecast Discussion
National Weather Service Phoenix AZ
519 PM MST Sat Apr 9 2022
.UPDATE...00Z Aviation Discussion.
&&
.SYNOPSIS...Another hot afternoon with highs in the middle to upper
90s are expected across the lower deserts. A cooling trend begins
Sunday and continues through the first half of next week as a series
of weather disturbances move across the western states. Along
with the cooler temperatures, periods of breezy to windy
conditions can be expected. There is an opportunity for some
rain, especially over the higher terrain north and east of
Phoenix, on Tuesday. Lighter winds and a warming trend are
expected for the middle and latter half of next week.
&&
.DISCUSSION...
Latest objective analysis depicts a broad trough building
southeastward through the western U.S., breaking down the ridge
of high pressure responsible for the well above normal
temperatures observed during the past several days. However,
despite the ridge breaking down, boundary layer conditions still
remain very warm across the area with 850 mb temperatures running
about 1-2C warmer compared to 24 hours ago according to the
latest PHX ACARS sounding. Satellite imagery is also detecting a
batch of cirrus clouds moving across the region from west to east,
however, at this time this batch of cirrus does not appear thick
enough to limit the amount of insolation significantly. As a
result, given all of these factors, high temperatures later this
afternoon across most of the lower deserts should manage to top
out in the middle to upper 90s. Some breezy conditions can also be
expected at times throughout the afternoon with gusts ranging
between 15-25 mph.
As a shortwave trough embedded with the larger trough regime pivots
across the intermountain west region for Sunday, the pressure
gradient will tighten somewhat and thus result in higher breezes
with gusts across most areas in the afternoon ranging between
20-30 mph. With heights aloft lowering, boundary layer
temperatures will also cool with highs likely only topping out in
the upper 80s to lower 90s across most of the lower deserts. The
combination of the gusty winds and relative humidity values in the
teens may create periods of elevated fire weather conditions.
For Monday and Tuesday, a more potent shortwave trough will dig
across the western CONUS. This feature will tighten the pressure
gradient even further and thus result in stronger winds. Wind gusts
on Monday will likely be peaking during the daytime hours in excess
of 30 mph from the southwest out ahead of a cold front. The
combination of the gusty winds and relative humidity values in the
mid-teens may result in once again a period of elevated fire
weather conditions, especially across south-central Arizona. The
cold front will move through the region Monday night into Tuesday
morning and may introduce some rain opportunity. Given that the
core of the dynamics associated with the shortwave trough will
remain north of the area, the best QPF as well as PoPs will remain
to the north as well. Nevertheless, there is some chance of some
light showers, mainly across the higher terrain north and east of
Phoenix. The latest NBM guidance shows PoPs across the Phoenix
metro between 15-25%, across the higher terrain north and east of
Phoenix between 30-50% and across the western deserts at less than
10%. QPF amounts are expected to remain very light, at less than
0.10 inches across the higher terrain. Gusty post frontal winds in
excess of 30 mph from the west to west-northwest are likely
during the day on Tuesday.
In terms of temperatures through the first half of the week, much
cooler readings are expected. Highs on Monday are expected to top
out in the middle 80s, followed by below normal readings on Tuesday
and Wednesday with highs only in the lower to middle 70s. Ensembles
are in agreement that a broad trough will remain situated across the
western CONUS as we head towards the latter half of next week. As a
result, even though a warming trend is likely, the degree of warming
will be modest with readings gradually returning back to normal
as we head towards Thursday and Friday of next week.
&&
.AVIATION....AVIATION...Updated at 0019Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Breezy southwest winds will continue for the next few hours, with
gusts up to 20-25 kts, before subsiding. Elevated low level winds
aloft will delay the easterly shift tonight and may promote brief
LLWS concerns around midnight tonight, but for now expect this to
remain below TAF thresholds. A similar set up tomorrow but
slightly breezier conditions with gusts closer to 25 kts. Mid to
high level cloud cover will clear overnight and slightly increase
again tomorrow afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
Very breezy west to southwest winds will continue for the next few
hours at both terminals before subsiding. Gusts to 20-25 kts will
be common, but could reach up to 30 kts. Elevated low level winds
aloft may create some LLWS concerns later tonight, but expect
this to remain below TAF thresholds at this time. After winds
fully subside, KIPL will likely see a shift to southeasterly or
variable, while KBLH sees a northerly shift by later Sunday
morning. Overall, wind conditions Sunday will be very similar to
today with a breezy west to southwest component developing in the
afternoon. Can`t rule out some patchy blowing dust from localized
strong wind gusts. Mostly clear skies will persist aside from some
passing high clouds.
&&
.FIRE WEATHER...
Tuesday through Saturday:
A cold front is expected to pass through the region on Tuesday.
With it, there is a chance of rain, especially across the higher
terrain north and east of Phoenix where PoPs are between 30-50%.
Nevertheless, rainfall amounts are expected to remaining very
light at less than 0.10 inches. Behind the cold frontal passage,
gusty west to west-northwest winds in excess of 30 mph are likely.
Much cooler temperatures can be expected as well. However, with a
drier air mass expected behind the cold frontal passage, afternoon
relative humidity values will drop to between 10-20%. Therefore,
the combination of the gusty winds and low RHs will result
elevated fire weather conditions once again. During the rest of
the period, significantly lighter winds and a gradual warming
trend can be expected. Afternoon minimum RHs, however, will be
dropping into the single digits with modest overnight recovery.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 3 AM PDT Sunday for CAZ562.
&&
$$
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DISCUSSION...Lojero/Kuhlman
AVIATION...Benedict/Feldkircher
FIRE WEATHER...Lojero/Kuhlman
Area Forecast Discussion
National Weather Service Great Falls MT
814 PM MDT Sat Apr 9 2022
.SYNOPSIS...
Scattered rain and snow showers will move through the region
through this evening, then change to all snow showers by Midnight.
Temperatures will continue to cool each day over the next several
days, with scattered snow showers continuing for Sunday and
Monday. A spring storm will affect Central and Southwest MT Monday
night and Tuesday, with widespread accumulating snowfall.
&&
.UPDATE...
Moisture continues to spread across the region. All-in-all, the
forecast is working well. Relative Humidity (RH) values were a bit
low in some areas, so I bumped them up, where appropriate. Aside
from adjusting RH, I just tweaked a few elements to nudge them
closer to actual observations. Decreased overnight lows a little
bit, mostly through the valleys. Loaded observed wind and wind
gust grids for 10/00Z and 10/01Z, and interpolated for a few
hours our from there. Probability of Precipitation (POP) forecast
looks good, but with changes in temperature and RH, etc, I reran
snow amounts, as well as, Storm Totals.
- Fogleman
&&
.AVIATION...
633 PM MDT Sat Apr 9 2022 (10/00Z TAF period)
Early in the period, KHVR receives some rain, but generally,
precipitation falls as snow. Expect snowfall along The Great Divide.
Snow enters north central Montana and becomes more widespread as
moisture spreads south southeastward, and ultimately lingers across
the central part of the state. In coincidence with precipitation,
visibility and ceilings lower and most airfields fall into the MVFR
range, with possible IFR conditions. Mountain obscuration is
forecast. Light aircraft encounter poor visibility and gusty winds
in mountain valleys, as well.
- Fogleman
Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.
&&
.PREV DISCUSSION...
/ISSUED 633 PM MDT Sat Apr 9 2022/
Tonight through Monday...Scattered rain/snow showers will continue
to move southward through the region this evening, gradually
changing to all snow showers by Midnight. Scattered snow showers
will continue to move through the region on Sunday, along with
even cooler afternoon temperatures. Overall snow amounts will
generally be less than an inch from tonight through Sunday, with
many areas melting on contact.
Monday night through Wednesday...A strong spring storm will move
through Central and Southwest MT from Monday night through early
Wednesday morning. The heaviest precipitation will fall over
Central and Southwest MT. The 12z runs have lowered QPF a bit over
the region, but overall snow amounts look high enough for a winter
storm watch over Central and Southwest MT. Some areas might end
up with just a winter weather advisory if the QPF continues to
decrease. Blowing snow will also be an impact. For areas along the
Highway 2 corridor, from Cut Bank to Harlem, they will not receive
much precipitation from this event, as the bulk of the
precipitation stays south of Highway 2. Temperatures will be well
below normal, with a few record low temperatures are possible.
Thursday through Saturday...Expect drier conditions for Thursday
but by Friday, the next spring storm system will be approaching
the region. The GFS continues to be much colder/wetter, with
widespread accumulating snow over much of North Central MT.
Temperatures could start to warm a touch...but will still remain
close to 20 degrees below normal. Brusda
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 24 40 19 37 / 10 50 30 30
CTB 24 36 17 32 / 30 60 30 20
HLN 25 43 22 40 / 10 20 20 40
BZN 19 40 18 41 / 20 20 30 50
WYS 11 33 9 37 / 30 70 40 70
DLN 18 38 18 39 / 10 30 20 60
HVR 27 42 20 39 / 40 40 10 10
LWT 23 38 17 37 / 10 40 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Monday night through Wednesday
morning Broadwater...Cascade...Fergus...Judith Basin...Meagher.
Winter Storm Watch from Monday evening through late Tuesday
night Beaverhead...Central and Southern Lewis and Clark...
Gallatin...Jefferson...Madison...Southern Rocky Mountain Front.
&&
$$
http://www.weather.gov/greatfalls