Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/31/21
Area Forecast Discussion
National Weather Service Boston/Norton MA
1019 PM EDT Sat Oct 30 2021
.SYNOPSIS...
A low pressure approaches from the southwest this evening with
a secondary low pressure that will bring locally heavy rain, a
few thunderstorms and gusty coastal winds across mainly eastern
New England late this afternoon and evening. Mainly dry and
cooler for much of the upcoming workweek, with temperatures
trending slightly below normal for early November. Monitoring a
potential coastal storm around Friday or next weekend, but this
is not set in stone and uncertainty in details on this system
remains large.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Just some minor tweaks to the forecast this evening. Still
looking at periods of rainfall as a series of shortwaves rotate
around mid level cutoff overnight. For some of the area, the
brief break in heavier rainfall will be just enough to prevent
significant flooding issues. Still most concerned across NE MA,
and will continue to monitor trends overnight.
710 PM Update:
Secondary low still is far offshore to our south (roughly
39N/71W) with deeper convection to its east well to the east of
Cape Cod. This secondary low looks to pass along our eastern
coast overnight into the pre-dawn Sunday hrs.
Arcing band of rain, at times heavy across eastern MA and
adjacent eastern RI, now extends north of the Mass Pike
offshore, then south across the waters east of Cape Cod.
Appeared there were a couple of in-cloud lightning flashes
earlier with the heavier rain band across southeast MA where
SPC`s mesoanalysis has a limited amount of most-unstable CAPE,
as dewpoints have risen into the low 60s here, with little to
nil noted elsewhere. This rain band also has increased low-level
flow as KBOX VWP showed an increase in 850 mb winds to around 35
kt upon its passage. ESE winds are now gusting into the 25-30
mph range across coastal southeast MA.
Current radar shows a brief lull across most of CT, RI into
southeast MA which should also expand in coverage northward
across remaining portions of MA in the next hour with rains
through late-evening confined to Cape Cod and the Islands. This
break in steady rains is brief, with the next slug of steady
rains now taking shape across the waters south of Long Island,
and HRRR shows this expanding into SNE between 03-05z into the
overnight.
Still are under a Marginal risk for severe weather across
eastern MA, but not thinking the overall risk is that high as
low-level profiles are no better than neutral to weakly
unstable. Likely will be tough to transport gusts to the surface
in that scenario, but there will still remain a small risk for
gusty winds until the strong LLJ lifts northward associated with
passage of secondary low.
Made a few minor adjustments to PoP to show a decrease in rain
coverage thru late evening, then interpolated to show PoP
increasing from SW to NE around late evening/midnight.
Otherwise, no other changes needed attm.
Previous discussion:
Mesoanalysis shows the secondary low center located east of the
Delmarva peninsula this afternoon. It will continue to strengthen
and move north through the afternoon and evening bringing a surge a
warm and moist air into southeast MA. Dewpoints are already in the
upper 50s and low 60s, well on our way to warm sectoring over
southeast MA/RI. Currently Newport, Providence, and and Pawtucket
all have dewpoints over 60F. The SPC has added a small Marginal risk
area to far eastern southern New England where we expect the warm
sector to move overhead with strong southeasterly low level flow and
those high dewpoints. Not expecting anything widespread but there is
a low chance that some of the thunderstorms this evening may mix
down through the marginal temp inversion some strong to severe
gusts, generally 5 pm to 10 pm. As for flooding potential, not
expecting any wide spread threat. The best chance for some urban and
poor drainage flooding would be beneath any particularly strong
convection. As for river flooding, not forecasting any at the
moment. One location we`re keeping an eye on is the North Nashua
River at Fitchburg; if the rainfall were to overachieve there`s a
low probability it could touch minor flood stage overnight.
Tonight the low level jet exits into northern New England along with
the heaviest rain and thunder chances. After midnight, still going
to see some showers around given our proximity to the exiting sfc
and mid level lows, but should be lighter and more scattered in
nature. Lows will be quite mild thanks to the humid airmass, from
the upper 40s in northwest MA to the upper 50s in southeast MA.
Winds also diminish through the overnight hours as the jet moves
away.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Overall quite a pleasant Halloween day in store, improving through
the morning. Bulk of the rain should be gone by sunrise, but some
scattered showers may linger, especially in the morning. Best chance
for showers will be the interior of NW Mass in closer proximity to
the cold pool aloft. Drier air filters in so clouds should be on the
decline through the day, but a mix of clouds and sun all day.
Southwest winds will be lighter on Sunday, pulling in well above
average temperatures, topping out in the mid to upper 60s! Overnight
high pressure starts to build in with clearing skies and dry
conditions. Lows will be cooler, in the 40s away from the immediate
coasts.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights:
* Overall dry through late week, though possible lake-enhanced
moisture could bring first snowflakes to the higher elevations
midweek with little accumulation as snow levels fall to around
2500 ft AGL.
* Temps trend cooler each day to near to slightly below normal
levels for early Nov.
* Possible coastal storm brewing around Fri night into the
weekend, though details and timing uncertain. Will have high
astro tides Fri into Sun.
Overview:
Deterministic and ensemble solutions continue to show strong
agreement in mid-level cyclonic flow/troughing to govern the pattern
aloft. A wider view indicates this troughing is part of a omega
block pattern across most of North America, with amplified ridge
over western Canada. As cyclonic flow aloft continues to spread into
Southern New England through the workweek, somewhat cooler than
average temps for early November look probable. Through late-week,
our temps look to fall a couple degrees each day compared to the
previous one. Active period of lake-enhanced moisture, along with
snow levels falling to around 2500-3000 ft could support the first
flakes of snow across the higher elevations in western/northwest MA
around midweek. But moisture being shallow and limited to nil QPF
suggest any accumulation would be in the trace-amount variety.
Confidence in the forecast then diminishes late in the week into
early next weekend. Models vary on the details, due to varied
handling of shortwave energy digging southward from northern Canada.
GFS remains the weakest and most progressive offering a dry forecast
under broad sfc ridge. On the other hand the Canadian GEM and the
ECMWF each show somewhat stronger vort energy around Thurs-Fri,
which in turn leads to a Miller Type B sfc cyclone near the Deep
South/Gulf Coast. There was pretty significant latitudinal variation
between the GEM/ECMWF regarding this potential system. While the 00z
GEM was more of a Carolinas storm, its 12z run now shows a solution
similar to the ECMWF in terms of mass fields and in bringing it
close for SNE for potential impacts; but it`s also about 24 hrs
slower than the ECMWF. Something to monitor as we move through the
week.
Details:
Monday:
Likely the pick of the workweek, with clearing skies and dry air.
Still fairly blustery given cold advection; mixing progs support a
period of WNW gusts late-AM to mid-PM in the 25-30 mph range in the
interior, and around 20-25 mph near the coasts. Mixing depth to
about 850 mb per model soundings should fully mix and support highs
mainly in the 50s, though a few lower 60s possible across the South
Coast/Cape and Islands. As winds slacken Mon night, should see
widespread mid to upper 30s lows for most, except low-mid 40s near
the coastlines. Could see a period of early lows near freezing in NW
MA if winds diminish, though will see higher clouds arrive by
daybreak.
Tuesday through Thursday:
Troughing becomes established over SNE this period, leading to
generally unsettled but dry weather. Do have to watch for any lake-
enhanced moisture that could support some higher-terrain snow
showers, with cooling profiles and snow levels falling. Tues
night may offer some potential though models have backed off to
an extent on moisture/QPF. Not expecting more than trace
amounts if any ensue at all and not convinced it would stick on
the ground even during the nighttime hrs. Overall more of a mix
of sun and clouds with the forecast generally dry much of the
time.
Cooling 925-850 mb temps leads to cooler and falling temps each day.
Highs upper 40s to mid 50s on Tuesday, and by Thursday highs are
more solidly in the 40s to the lower to mid 50s near coastal
southeast New England. Sub-freezing lows possible for much of the
interior Wed night, with values ranging from the upper 20s to mid
30s, and around mid to upper 30s for the coastal plain to low 40s
for Cape Cod and Islands.
Friday into Early Next Weekend:
While the GFS is cool and dry, as mentioned above the international
guidance hint at Miller B cyclogenesis and a coastal low riding up
the coast at some point in this period late in the week. Could bring
potential impacts to SNE late in the week into early next weekend if
mass field trends continue. There remains uncertainty on the
eventual track, timing of impacts (ECMWF is more Fri night-Sat
while the GEM is more of a weekend impact) and what the thermal
fields look like when precipitation begins. Tides also at their
astronomical highs Fri into the weekend (peaking Sat 1241 PM at
around 12.1 ft MLLW for Boston Harbor), so coastal flooding
would be a concern if the GEM/ECMWF coastal solution holds, as
would only need a half-foot of storm surge to reach minor flood
stage at Boston Harbor. Will keep Chance-level PoP for this
period with temps close to NBM in the 40s to mid 50s.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight: Moderate confidence.
LIFR to IFR for most terminals, though MVFR-IFR across western
terminals due to stratus, fog and rain. Brief lull in rains
late this evening, should fill back in around 04-05Z from SW to
NE at MVFR-IFR visibilities, before tapering off to intermittent
showers by daybreak. E/SE wind gusts to 20-30 kt along the
immediate coast, up to 35 kt possible across Cape Cod/Islands
airports. Winds start to diminish and shift to SW 07-09z, though
still somewhat gusty near the coastlines.
Sunday...Conditions improving to VFR. Local IFR across the
higher terrain during the morning.
Sunday night...VFR. Light west winds.
KBOS Terminal...Moderate confidence in TAF.
KBDL Terminal...Moderate confidence in TAF.
Outlook /Monday through Thursday/...
Sunday Night: VFR. Breezy.
Monday: VFR. Windy with local gusts up to 30 kt.
Monday Night through Tuesday: VFR.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Main change this evening was to replace the Gale Warning in
Cape Cod Bay and Nantucket Sound with a Small Craft Advisory
based on latest obs.
Gale Warnings continue across the eastern coastal waters this
evening. Winds diminish across all the waters late tonight into
Sunday, but seas will take longer to subside. Small Craft
Advisories will be needed for most waters Sunday and Sunday
night. Moderate to heavy rain comes to an end overnight leaving
dry weather on Sunday and Sunday night.
Outlook /Monday through Thursday/...
Sunday Night: Winds less than 25 kt. Areas of rough seas.
Monday: Winds less than 25 kt. Seas up to 5 ft.
Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.
Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Tuesday Night: Winds less than 25 kt. Chance of rain showers.
Wednesday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ231-232.
Small Craft Advisory until 8 AM EDT Sunday for ANZ233-234.
Small Craft Advisory until 2 AM EDT Sunday for ANZ230.
Small Craft Advisory until 8 AM EDT Monday for ANZ235-237-256.
Gale Warning until 4 AM EDT Sunday for ANZ250-254.
Gale Warning until 2 AM EDT Sunday for ANZ251.
Gale Warning until midnight EDT tonight for ANZ255.
&&
$$
SYNOPSIS...Loconto/BW
NEAR TERM...Belk/Loconto/BW
SHORT TERM...BW
LONG TERM...Loconto
AVIATION...Belk/Loconto/BW
MARINE...Belk/Loconto/BW
Area Forecast Discussion
National Weather Service Des Moines IA
1038 PM CDT Sat Oct 30 2021
...Updated for the 06z Aviation Discussion...
.DISCUSSION.../Tonight through Saturday/
Issued at 246 PM CDT Sat Oct 30 2021
The primary messaging highlights through the period include...
* Brisk NW winds tonight behind a cold front, then cooler below
normal temperatures well into next week
* Little if any precipitation through the period
* Frost possible south Sunday and Monday Nights
The biggest sensible weather change through the period will occur
tonight with brisk winds and cooler temperatures on the way. The
initial pressure trough and trailing cold front were just moving
through the Siouxland area this afternoon and should progress
south and east through the state this evening. The parent northern
Plains/Canadian upper trough will bring phased thermodynamic and
kinematic support as well, but it will be moisture starved with
nothing beyond some mid clouds on its back edge. Low level cold
advection will also produce a period of stratus behind the front,
but it will be brief. The degree of mixing tonight varies between
RAP and HRRR mixing projections, but have leaned toward the more
aggressive side considering what`s occurring upstream with at
least some 25 to 35 mph gusts anticipated.
There should be plenty of sunshine tomorrow with highs just
touching 50 in spots as sprawling surface high pressure settles
into the MO Valley. This will keep temps cool, and also introduce
frost potential south Sunday and Monday Nights were climatology
and past temperatures still deem vegetation potentially
susceptible. Headlines are possible south depending on future
adjacent office coordination. Remnants of the current CA/OR system
may traverse the MO Valley Monday as well, with low end chances
of light rain far southwest.
Otherwise, much of the work week will remain cool and dry with
highs in the 40s common as Iowa remains influenced by the Great
Lakes long wave trough. The models all agree that a short wave of
some form will drop into the mean trough midweek, but regardless
of timing and position, none have sufficient moisture for any
precip mention. Eventually the pattern is progressive enough for a
period of upper ridging toward the end of next week allowing for
SSW winds to nudge temps back toward normal.
&&
.AVIATION.../For the 06Z TAFS through 06Z Sunday night/
Issued at 1038 PM CDT Sat Oct 30 2021
Few changes to upcoming package expected. Stratus developing south
faster as cold air saturates the boundary layer. Winds picking up
as expected. As MVFR clouds give way to VFR cigs aft 12z, winds
will remain brisk through the balance of the day; relaxing aft
00z. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Small
AVIATION...REV
Area Forecast Discussion
National Weather Service Fort Worth TX
714 PM CDT Sat Oct 30 2021
...New Short Term, Aviation...
.SHORT TERM... /NEW/
/Tonight through Sunday Night/
As an area of low pressure from the west continues to move south
of our region, another surface trough will gently slide a weak
cold front toward North Texas from the north/northwest throughout
Sunday afternoon into Monday. The more recent model runs are
slowing down the timing of FROPA by a couple hours. Due to this
slower timing, have decided to increase Sunday afternoon
temperatures by using NAM temperature values, as the NAM seems to
handle this well. The timing of the front is still uncertain, and
future forecast updates will allow for a more fine-tuned FROPA.
As the surface low continues to move toward the region, a slight
increase in high cloud cover will be possible, generally for North
Texas, as the front and its accompanying higher moisture content
glides toward the Red River. Though the cloud cover will only
allow for partly cloudy skies, the same cannot be said for areas
in OK/AR/MO. A baroclinic leaf structure ahead of the incoming
shortwave, seen in the RAP upper level RH fields, will allow for
increased high cloud cover for areas northeast of North Texas.
Since this structure is north of our area, only minimally
increased cloud cover is expected for the CWA.
This front will not be overtly noticeable, aside from a
southeasterly to northeasterly wind shift. Speeds will generally
be less than 10 kts, though isolated spots of slightly higher
speeds are possible tomorrow afternoon. A lack of moisture will
allow the front to move through without any attendant
precipitation, and have kept PoPs near 0% through the entirety of
the short term.
Sunny skies with minimal cloud cover will couple with dry
conditions and allow for a nice end to the weekend. Sunday highs
will be in the low 70s to low 80s. Morning lows for both tomorrow
(Sunday) and Monday will range in the 40s and 50s, with the warmer
spots in the DFW metroplex and in isolated areas down in Central
Texas.
Prater
&&
.LONG TERM... /Issued 138 PM CDT Sat Oct 30 2021/
/Next Week/
The weak cold front discussed above will stall across the region
through the early parts of the week. This front should bring
cooler temperatures, mostly along the Red River, behind the front
with near to above normal temperatures remaining south of the
front across Central Texas. There still shouldn`t be much moisture
for this system to work for, so another rain-free day is expected
Monday. Moisture advection will start to ramp up Monday night and
continue through the middle to late parts of the week as zonal
flow aloft induces leeside cyclogenesis to our west. This will
develop a southerly nocturnal LLJ overtop of the front, triggering
isentropic ascent in the process. The added moisture and low level
ascent should begin developing widespread stratus Monday night
into Tuesday, eventually blanketing the entire region by Tuesday
night.
Meanwhile, a shortwave trough will move across the Desert SW of
the CONUS and eventually begin to overspread the Plains Tuesday
night. Increased thermal advection and mass response will deepen a
low pressure system along the stalled front over West Texas. This
low and its attendant warm/cold fronts will move across the region
Wednesday into Thursday. Added ascent in the mid levels will tap
into the low level moisture and develop widespread rain showers
with isolated thunderstorms across the region. The highest PoPs
will be in the direct vicinity of the low, most likely Wednesday
into Wednesday evening ATTM. There are some timing differences in
the globals in regard to this given the overall weak flow aloft,
however, they have been consistent with the timing over the
previous couple of runs. As the low/shortwave trough continues
east, a much cooler airmass will filter into the region to close
out the work week.
We are still unsure of exactly how cold this cold airmass will be.
The coldest guidance dips the H5 baroclinic zone as far south as
the Red River...sending a 1034 mb high into the region with it.
The warmer guidance keeps the H5 baroclinic zone in the Midwest,
sending a transitory shot of cold air south that modifies quickly.
The key difference between these two solutions is how deep a
trailing shortwave over the Great Lakes is able to get early this
week...a deeper shortwave would drive the coldest air south while
a weaker shortwave keeps the coldest air locked to our north. We
should gain more confidence of the extent of the late-week cold
air in the next day or two.
Bonnette
&&
.AVIATION... /NEW/
/00Z TAFS/
VFR will continue for all TAF sites during the next 24-30 hours.
A slow-moving cold front will slide into North Texas during Sunday
afternoon and evening, which will only impact our longer-fused TAF
site (DFW). Subsequent TAF issuances will account for this frontal
passage as it comes into the time frame.
The main concern for this current TAF period are changes in wind
direction, with speeds continuing to be less than 10 kts.
Throughout much of the TAF period, winds will be from the
southeast. The first distinct change in wind direction will turn
winds to the east around 12Z on Sunday morning. This shift will
generally affect the D10 sites and leave ACT unscathed.
The second wind shift is too far out for a majority of the D10
TAF sites, but is on the ending stretch for DFW. DFW will see
another direction change, this time turning to the northeast. This
shift is associated with the slow front moving into NTX.
Mostly clear skies will see a slight increase in North Texas along
with this frontal passage, but will stay in VFR criteria.
Prater
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 51 79 52 76 54 / 0 0 0 5 10
Waco 49 79 51 77 55 / 0 0 0 0 5
Paris 45 74 48 70 49 / 0 0 0 5 10
Denton 44 77 46 74 48 / 0 0 0 10 20
McKinney 46 77 48 75 50 / 0 0 0 5 10
Dallas 52 79 53 77 54 / 0 0 0 5 10
Terrell 46 77 48 77 51 / 0 0 0 5 5
Corsicana 49 79 51 78 54 / 0 0 0 0 5
Temple 47 80 51 78 54 / 0 0 0 0 0
Mineral Wells 46 78 48 76 50 / 0 0 0 5 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Green Bay WI
1036 PM CDT Sat Oct 30 2021
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 248 PM CDT Sat Oct 30 2021
The latest RAP analysis and satellite/radar imagery show eastern
WI is positioned between a weak surface ridge axis over northwest
Wisconsin and low pressure over the central Appalachians. With
cyclonic flow and north northeast winds continuing, broken cloud
cover remains blanketed over northeast WI early this afternoon. As
the low finally lifts to the northeast into Pennsylvania, winds
will back to the northwest and should see erosion of the clouds
accelerate for the rest of the afternoon. Looking further
northwest, a cold front is moving east over the northern Plains.
Strong pressure rises behind the front are leading to wind gusts
in excess of 30 kts over the eastern Dakotas. As this front slides
across the area tonight, small precip chances, clouds and winds
are the main forecast concerns.
Tonight...A period of clearing is likely to occur this evening
prior to the arrival of the cold front overnight. Moisture through
the column will be rather disjointed, with mid and high clouds
outpacing the clouds in the lower levels. But in general,
moisture will be quite limited. With some help from flow off
western Lake Superior, spotty light showers may occur over far
northern WI but most locations will remain dry. Pressure rises and
cold advection behind the front will help northwest winds become
gusty by late in the night. Lows will range from the middle 30s to
middle 40s.
Sunday...An upper trough will be digging across the region while
the cold front exits in the morning. Cold advection will be
occurring through the day with steepening lapse rates leading to
gusty winds. Gusts to 30 or 35 mph will be possible at times. A
few spotty showers will remain possible by the U.P. border, but
most locations will see decreasing clouds in the afternoon. Highs
will range from the middle 40s to lower 50s.
.LONG TERM...Sunday Night Through Saturday
Issued at 248 PM CDT Sat Oct 30 2021
Some light lake effect rain or snow showers could affect portions
of far north-central Wisconsin at times from Sunday night through
Tuesday evening with a favorable fetch from Lake Michigan and
fairly cold 850 mb temperatures allowing for delta T values to
rise into the middle to upper teens. The rest of the region will
remain dry during this period as surface high pressure builds in
across the Plains region, bringing below normal temperatures to
northeast Wisconsin.
Winds will turn to a more westerly direction by Tuesday evening as
the aforementioned high sinks south. This will keep the weather
dry across all areas for the rest of the forecast period as
temperatures remain below normal. Temperatures are expected to
moderate a bit by Friday and next Saturday, but will still be
below normal for this time of year.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1035 PM CDT Sat Oct 30 2021
A cold front will bring a period of MVFR ceilings to much of the
area late tonight through around 15 UTC Sunday. The lowest and
longest lasting ceilings will be over northcentral Wisconsin.
Some clearing is expected Sunday afternoon over parts of central
and east central Wisconsin along with Northwest winds gusting to
around 25 knots.
Lake effect clouds may remain across northcentral Wisconsin Sunday
night and Monday with partly cloudy skies elsewhere.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kurimski
AVIATION.......RDM
please see the previous forecast discussion below.
&&
.PREV DISCUSSION...as of 01:31 PM PDT Saturday...The big story of
the day is the weak boundary that was forecast and has moved
onshore over the North Bay bringing light precipitation. The
boundary is an extended branch off the low that is due west of
Ukiah, just offshore. Now, is this precipitation historic? No, of
course not. It is mainly drizzle drops and light sprinkles dotting
most walkways. But social media has been helpful reporting the
wet pavements around the North Bay, as far south as southeast San
Francisco, and the west side of I-680 in Contra Costa County. One
reporter in Sebastopol claimed to have received 0.06" and our own
gauge at the Santa Rosa airport got 0.01" as of 18Z. All of these
reports were enough to switch the radar into precipitation mode as
we saw the band come together just over Santa Rosa. It remains a
weak band that will likely dissipate in the next two hours, but
the slight chance for continued drizzle remains possible in the
North Bay into this early afternoon, as it moves farther inland.
As this low moves inland, it will work its way northward tonight
and into Sunday, wrapping around the parent low which is farther
out to sea in the Pacific. That low will work its way to the
California coast. In terms of timing, models have consistently
kept this system moving onshore on Monday morning. Check back in
on subsequent forecasts, but it is looking like Halloween should
be dry for any ghouls or ghosts that are planning on trick and/or
treating.
Once the low moves over the coastline, wide spread rain showers
remain in the forecast for Monday, with the bulk it expected in
the morning. Highest precip values are still forecast for the
Sonoma coastline mountains where around an inch is expected.
General North Bay areas can expect anywhere between a quarter of
an inch to just under an inch. San Francisco and the East Bay can
expect a quarter to a half an inch, with the Central Coast
receiving few tenths of an inch.
A weak ridge attempts to build on Tuesday as high pressure grows.
There is a chance for some lingering showers Tuesday morning from
residual moisture, but drier conditions are expected to move in.
Temperatures will likely remain cool and seasonal in the 60s each
afternoon.
The next upper level low moves toward the North Bay on Wednesday
night. Ensemble and deterministic models are staying on track by
keeping this system similar to Monday`s but have decreased total
precipitation amounts. A half an inch is possible in coastal
Sonoma Mountains, but the remainder of the Bay Area will likely be
a few tenths of an inch.
Beyond that looks to have drier conditions heading into next
weekend. Low temperatures will dip into the low 40s, but no
substantial cold snaps forecast just yet. The next long wave
trough grows over the weekend, but no real confidence for
additional precip for Veteran`s Day weekend at this time.
&&
.AVIATION...as of 04:34 PM PDT Saturday...For the 00z TAFs.
Patchy MVFR clouds across the region as a low pressure system
continues to pass to the north. Satellite imagery also shows an
additional layer of high level clouds at about 10,000 to 20,000 ft
AGL. Intermittent MVFR/VFR conditions will continue the rest of
the afternoon with scattered light drizzle along the coast and in
the North Bay. Lingering low level moisture will probably allow
MVFR/IFR conditions to persist overnight along with possible
patchy fog in the valleys. Additionally, high resolution models
show some possible light scattered showers around the SF Bay Area
and northward into mid Sunday morning. Conditions should improve
by late tomorrow morning and into the afternoon ahead of the next
system set to arrive into Monday. Light to moderate winds this
afternoon at about 10-15 kt at of the W/SW. Winds to diminish
overnight with onshore breezes returning Sunday afternoon.
Vicinity of KSFO...MVFR with intermittent cigs around 1,000 to
4,000 to persist into mid to late Sunday morning before cigs lift
and scatter. VCSH possible beginning late tonight (~07z) and
lasting through around 15z/16z Sunday. W/SW winds this afternoon
10-15 kt diminishing this evening. SW winds return Sunday
afternoon.
KSFO Bridge Approach...Similar to KSFO.
Monterey Bay...That patch of stratus over the Bay into Salinas
remains with observations placing cigs at about 1,200 to 1,500 ft
AGL. MVFR conditions to persist into the evening before cigs are
forecast to lower to IFR the rest of the night. Patchy fog
possible late tonight early Sunday morning around the bay.
Conditions to improve mid to late Sunday morning. SW/NW winds this
afternoon around 10 kt diminishing this evening. Light SE winds
for the Salinas Valley Sunday morning before onshore winds return
in the afternoon.
&&
.MARINE...as of 08:26 PM PDT Saturday...Generally light to
locally breezy westerly winds overnight. Winds will shift out of
the south to southwest tomorrow and increase ahead of an
approaching front. Southerly winds will then persist as another
frontal system moves in early this coming week. Northwest seas
will gradually subside the rest of the weekend before a long
period northwest swell arrives along with the next storm system
Monday morning.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm from 3 PM
&&
$$
PUBLIC FORECAST: RGass/DK
AVIATION: AS
MARINE: AS
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Area Forecast Discussion
National Weather Service Pueblo CO
345 PM MDT Sat Oct 30 2021
.SHORT TERM...(This evening through Sunday)
Issued at 343 PM MDT Sat Oct 30 2021
...Cold Front to bring big weather change to southeast CO...
Cold front is currently backdooring through southeast CO as evident
in KPUX radar loops extending along a line from KFLY to just east of
KLHX to roughly Kim, CO as of 21z. Initially, temperatures are not
all that cool behind the front so temperatures have still managed to
top out in the 70s across the plains as winds have picked up from
the northeast to east. Elsewhere, winds have been light and
temperatures warm for a late Oct day. Atmosphere will start to
saturate overnight across the southeast plains as temperatures cool
and dew points increase behind the front. Should see stratus
develop along the I-25 corridor after midnight with clouds lowering
and the possibility for some drizzle and patchy fog during the
morning hours on Sunday where southeast to east upslope flow
impinges along the lower eastern slopes. Overall, temperatures do
not look cold enough, or saturation deep enough, for widespread
freezing drizzle. Ground temperatures will likely stay too warm, and
surface layers don`t appear saturated enough for FZDZ to be a
concern even on elevated surfaces. HRRR is decidedly drier in the
short range models and even the wetter NAMNest keeps ptype as DZ.
Think any fog will be a narrow ribbon right up next to the mountains
and pretty patchy at best through Sunday morning.
Temperatures will be considerably colder across the I-25 corridor
and adjacent plains where upslope flow will keep clouds in most of
the day. Temperatures here will stay in the 40s most of the day,
and the high temperature for the climate day may actually be around
midnight and not really reflective of the day time highs. Meanwhile,
the mountains will be dry and mild...though a little cooler than
today as heights fall ahead of the next embedded disturbance. This
will bring some elevated Pacific moisture in from the west in the
afternoon with isolated showers developing over the mountains during
the late afternoon. Overall a much cooler day for Halloween over the
plains, with more mild 50s to around 60 across the valleys and 30s
and 40s for the higher mountains. -KT
.LONG TERM...(Sunday night through Saturday)
Issued at 343 PM MDT Sat Oct 30 2021
Tomorrow night...there will be some areas of light drizzle over
central and eastern El Paso County, as well as the northeast plains.
Light snow will be possible over the Sawatch and Rampart Range.
Monday...there will be areas of light snow changing to rain over the
far eastern plains in the morning, then later in the afternoon and
evening, light rain/drizzle over the plains and snow over the
mountains will develop. There could be areas of light freezing
drizzle over the Palmer Divide, especially along the eastern facing
slopes by late evening.
Tuesday...there will be areas of light rain/drizzle and even
freezing drizzle possible over the central and eastern plains during
the early morning hours. Some light snow will be possible over
northern areas of the I-25 corridor. This will all change over to
all light rain by later in the morning. Light snow will develop over
the mountains of the northern ContDvd earlier in the day, and then
light rain will develop over the plains later in the
afternoon/evening over the plains, and light snow over all of the
higher terrain.
Wednesday...areas of light rain/snow or drizzle will be possible
over the plains throughout the day and light snow over the
mountains, there is a slight chance of freezing drizzle possible in
certain locations of the plains during the early morning hours. Most
of the precipitation will change over to all light snow or a mix for
most locations of the plains by later in the evening.
Thursday...light snow will be possible during the early morning
hours over the Southern Sangre de Cristo Mountains and western Raton
Mesa. Snow showers will be developing late over the ContDvd.
Friday...light snow will be possible over the higher terrain, there
could be a rain/show mix in the San Luis Valley. Snow showers should
taper off by late in the evening.
Detailed discussion:
Sunday night...
A minor shortwave propagating over the northern CWA with mid level
winds turning southerly, along with colder air in place with
saturated lower levels will result in some overrunning and cause
some areas of light drizzle over central and eastern El Paso County,
as well as the northeast plains. Soundings show there being enough
moisture aloft to allow for precipitation to be more showery due to
a higher confidence of coalescence in the mid levels which will help
to keep precipitation in the form of either light rain or snow. This
should help to prevent the risk of drizzle along with a shallow
subfreezing layer at the surface, resulting in freezing light rain
and/or drizzle, however there is going to be a slight chance that
this could occur over some areas of the Palmer Divide. Light snow
will be possible over the Sawatch and Rampart Range.
Monday...
The longwave trough will remain in place over eastern half of the
CONUS with a low centered north of the Great Lakes, this, along with
a ridge over British Columbia will help to usher in colder air from
the north and allow for a some more cold air damming to settle in
over the plains and nearly isothermic profiles. Due to this, coupled
by a weak upper level minor shortwave passing over the area on
Monday, will provide just enough lower level saturation and weak
forcing to result in a very evasive stratus deck and some areas of
light rain/snow or drizzle over the plains and light snow for the
higher levels. Easterly winds will help also induce some upsloping
along the eastern facing slopes of the Sangre de Cristo and Wet
Mountains, and the Rampart Range.
Tuesday...
Another minor shortwave is going to be propagating towards southeast
Colorado, yet further to the south. The isentropic upglide over a
gradually sloped dome of cold air at the surface looks to be better
to the south of the CWA, yet there are going to be areas near south
of the Palmer Divide and along the southern I-25 corridor where this
could enhance development of drizzle and or a light rain/snow mix,
while other areas could still receive precipitation as well with the
passage of the wave, especially over the higher terrain where this
will all be in the form of snow. If enough cold air settles into the
lower Arkansas River Valley, it will allow for the possibility of
freezing drizzle to to occur where it is subfreezing at the surface
during the early morning hours. Soundings for areas such as Lamar
and La Hunta reflect enough saturation in an isothermic layer
greater than -10C of more than 1K ft above the surface for this to
be a possibility. Otherwise, enough omega forcing will allow for
light drizzle and snow to continue in areas where more ice is
present in the mid levels over other areas of the CWA throughout the
evening.
Wednesday...
Another weak perturbation in the longwave pattern upstream will help
to reinforce the overrunning with colder air remaining in place at
the surface. This will help to keep the lower stratus deck in place
over most areas of the plains and light rain/snow continuing
throughout most of the day. Soundings at this time reflect a lot
more moisture in the mid levels to be able to rule out the
possibility of drizzle, and therefore freezing drizzle to occur.
Snow will be possible over the higher terrain.
Thursday...
As the minor shortwave continues to move out of the area, light snow
during the early morning hours over the Southern Sangre de Cristo
Mountains and western Raton Mesa will continue to move out. Clearing
will take place over the CWA with warmer high temperatures as a more
southerly flow returns at the surface. Some slow showers will
develop very late in the evening due to another approaching minor
shortwave upstream.
Friday...
A minor shortwave will bring some light snow over the higher
terrain, and there could be a rain/show mix in the San Luis Valley.
The NW`ly flow in the mid levels will continue and more SWl`y winds
will return to the lower levels, which could increase and become
quite strong and gusty for the I-25 corridor, this weak chinook-like
wind pattern will allow for the plains to warm up quite a bit, with
lower to mid 60s returning over many areas. This wave will move
through rather quickly and snow showers should taper off by late in
the evening.
Saturday...
Ridging will begin to move back in over the region with warmer and
drier conditions returning to southeast Colorado. -Stewey
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 343 PM MDT Sat Oct 30 2021
VFR conditions will transition to MVFR to localized IFR
across the plains overnight with locations around KCOS expected to
drop into the IFR category towards morning with stratus. Some
patchy fog and even drizzle could occur at KCOS towards morning but
main contributer to IFR will be the CIGS. KPUB likely to stay dry
with MVFR cigs. Clouds will likely persist through the day for both
terminals but rise into the MVFR to VFR category in the afternoon
before some isolated showers spread into the KCOS area Sunday
evening.
KALS will remain VFR with some increasing high clouds overnight
into Sunday with winds under 10 kts. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...STEWARD
AVIATION...KT