Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/25/19
Area Forecast Discussion
National Weather Service Caribou ME
1056 PM EDT Thu Oct 24 2019
.SYNOPSIS...
A cold front will cross the area overnight and stall in the
Gulf of Maine. Weak low pressure will track along the stalled
front later Friday into Friday night. High pressure will return
Saturday. Low pressure from the Great Lakes approaches Sunday
and slowly crosses the Gulf of Maine Monday.
&&
.NEAR TERM /THROUGH FRIDAY/...
1050 PM Update...
A broken line of showers were sliding se across northern areas
this evening per the radar imagery. The showers were diminishing
w/the loss of any significant forcing. The 00Z NAM and RAP were
right in line w/the radar. 00Z CAR sounding showed decent LLWS
w/steep mid level lapse rates. SW winds did kick up this evening
as some the stronger wind was able to mix down at times w/some
gusts reported close to 20 mph in KFVE(Frenchville). Adjustments
were made to the wind fields to bring speeds up some for the
next few hrs and then winds will start dropping off after
midnight. This has keep the blyr mixed and keeping temps up
some. Adjustments were also made to the hrly temps to account
for the latest obs. Overnight forecast temps look in good shape
given clouds expected to move back in overnight.
Previous Discussion...
The cold front continues to weaken as it moves into northern
zones with little moisture above H700 and light precipitation
totaling just a few hundredths of an inch in northern Aroostook
County...and no measurable rainfall further south. Clouds with
the front will also tend to dissipate as it crosses the forecast
area, but there will be enough cloud cover and winds to prevent
substantial radiational cooling. Lows will range from the upper
30s to lower 40s for most of the area. The front is a fast
mover and will reach the Gulf of Maine later tonight before
stalling. The cold advection will result in tomorrow`s highs
around 5 degrees less than this afternoon`s readings. Weak high
pressure will ensure a dry Friday, but there`s enough H850
moisture for cu/stratocu cloudiness...and higher level clouds
will build towards the coast in the afternoon as a baroclinic
zone and resultant wave of low pressure moves eastward along the
stalled frontal boundary. Precip will hold off through early
evening.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
S/wv currently ovr the nrn Plains wl zip to the east and induce wk
sfc low dvlpmnt ovr New England. This low looks to dvlp close enuf
to the region to bring showers up into interior Downeast areas late
Fri night. System looks to be progressive enuf that it wl be near
Nova Scotia by 12z Sat with sfc hipres rapidly building in behind.
Cyclonic flow acrs the area conts thru the day on Sat with upr lvl
ridge dominating the wx pattern thru Sat night.
Temps wl run slightly blo normal thru the pd. Sat night wl lkly clear
out with near calm winds leading to good radn`l cooling, especially
acrs the nrn half of the area. Clds wl begin to mv into swrn areas
as upr trof digs into the Great Lakes Sun mrng.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Latest NAM is slower than rmng med range guidance as H5 pattern
is more amplified than GFS, EC and CMC. Expect that showers wl
enter the CWA by daybreak on Sunday. High pressure wl gradually
shift into the Canadian Maritimes on Sun which will allow
precipitation to overspread entire region drg the day. Secondary
low wl off of the coast of Cape Cod Sun evng and hv trended pops
to categorical acrs srn areas with high likely pops acrs the
north. Cannot rule out that widespread measurable rain wl occur
everywhere but uncertainty exists on how fast sfc low can dvlp
and prevent moisture surge into nrn areas.
Unsettled wx pattern conts thru the end of the week as moisture
conts to infiltrate region on srly flow. Temps moderate into
early next week ahd of cdfnt before fropa occurs on Wed night.
High pressure briefly builds in twd the end of the pd bfr next
significant system mvs in fm the west.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: The primary condition will be VFR. Temporary MVFR
cigs are possible this evening through Saturday morning north of
a GNR to HUL line. Low level wind shear is possible this evening
with southwest winds up to 40 kt at FL020 in contrast to light
southwesterly surface winds less than 10 kts.
SHORT TERM:
Sat-Sat night: Mainly VFR. Light winds from the nw becoming
southerly Sun morning.
Sun-Tue: MVFR/IFR cigs in rain at Downeast terminals Sun mrng,
lowering across the north on Sun afternoon. Restrictions will
continue thru the end of the pd. South winds 5-10 kts.
&&
.MARINE...
NEAR TERM: Longer period south swell continues into the evening
but the primary wave group will be shifting to a shorter period
SW wind wave reaching up to 5 feet. Southwest winds will pick
up this evening with a few gusts up to 25 kt, but then decrease
late tonight while shifting to the northwest.
SHORT TERM: Winds wl begin to gust to aoa 25kts on Sun into Sun
night. Question wl be how much mixing can occur with stable air
over the waters. Seas increase above 5ft Sun night, mainly
over the outer waters. Conditions drop blo SCA levels behind the
system and remain under advisory levels into early next week.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Dodge City KS
538 PM CDT Thu Oct 24 2019
...Updated Aviation Discussion...
.SHORT TERM...(This evening through Friday)
Issued at 328 PM CDT Thu Oct 24 2019
An 850-700mb layer frontogentic band extended across the panhandles
this afternoon where precipitation has been expanding from north of
AMA to the KS/OK line near Clark to Barber counties. The forecast
issue will be if the precipitation invading ht southern tier of KS
counties might be intense enough to overcome warmer low to mid 40s
surface temps and change over to snow. There are significant
differences in the models, with the NAM/NMM/ARW having a history of
developing snow for the southeast 3 counties or so - the latest
18Z NAM as well as the HRRR appears to offer no snow in the 3 hours
model snow accums. With this in mind it is likely some mixing of
snow and rain could be observed this late afternoon but any
significant pile up on surfaces like models have done in recent
days looks unlikely.
The system should exist later in evening evening hours with clearing
skies Tonight. Temperatures will be even colder than the night
before, from just sub freezing near Medicine Lodge to the mid 20s
from Hays to Liberal and possible some upper teens in the far west
as clear sky and light westerly winds develop.
A very fall-like day expected on Friday with full sunshine through
the day, light winds and temperatures varying from the mid 50 in the
lower Plains central KS counties to closer to around 60 in west
central Kansas where the drier air can heat more efficiently. Friday
night looks only marginally warmer than tonight.
.LONG TERM...(Friday night through Thursday)
Issued at 328 PM CDT Thu Oct 24 2019
A weak shortwave ridge passes across the central Plains on Saturday
before the westerlies become flat to southwest with a strong
shortwave diving into the desert southwest by the Monday timeframe.
At that point the upper flow looks to become amplifies with series
of strong upper shortwaves dropping through the western states and
into the Rockies through 168 hours (oct 31). Mesoscale features
this far out are usually impossible to have high confidence in,
however the pattern does look colder and possibly looking toward
rain/snow/windy conditions for parts of the central Plains by
early to mid next week.
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1213 PM CDT Thu Oct 24 2019
A frontogenetic forcing band of precipitation will develop
across the panhandles into south central Kansas later this
afternoon. This will have no effect on the local terminals
which will continue to see clouds clearing with time this
evening. North to northeast winds around 15 to 20 knots will
lose the 25 knots gusts toward 23 UTC and begin backing westerly
again with time. Light and variable winds, and no vsby or
ceiling restrictions are then expected overnight and through
Friday 18 UTC.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 532 PM CDT Thu Oct 24 2019
VFR conditions throughout the entire period for all TAF sites.
Any precipitation will be confined east of all terminals into
south central Kansas. Mid level clouds and breezy north to
northeast winds through 05Z with diminishing light and variable
winds and a few high clouds as high pressure builds into the CWA.
This will last throughout the rest of the period and into the
next couple of cycles. No other elements expected nor forecasted
during this period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 26 56 32 65 / 0 0 0 0
GCK 23 58 28 68 / 0 0 0 0
EHA 24 57 30 71 / 0 0 0 0
LBL 24 56 28 66 / 10 0 0 0
HYS 29 56 31 64 / 0 0 0 0
P28 32 56 33 62 / 30 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Lowe
Area Forecast Discussion
National Weather Service San Francisco Bay Area
620 PM PDT Thu Oct 24 2019
.SYNOPSIS...Critical fire weather conditions will persist through
Thursday afternoon with gusty offshore winds and low relative
humidity. Additionally, high pressure over the region will also
lead to above normal temperatures. Temperatures will cool over the
weekend and into next week. Another and likely stronger offshore
flow event is in the forecast late this weekend. The offshore flow
will bring renewed fire weather concerns and possible wind damage
concerns as well.
&&
.DISCUSSION...as of 03:45 PM PDT Thursday... Active weather day
across California as a 592dm high pressure ridge anchored just off
of the Northern California coast is being counterbalanced by a
564dm low pressure trough over eastern NM/Texlahoma panhandles.
Consequently, the SFO-WMC gradient (used as a proxy for offshore
flow strength) peaked at 16.7mb at 8am this morning but has since
eased to 13.4mb this afternoon. This steep offshore gradient led
to strong, gusty offshore winds, particularly across the North Bay
hills and ridges. Winds peaked around midnight near the
#KincadeFire with sustained winds 53mph and gusts to 76mph out of
the North East (11% RH). Extreme fire weather conditions prompted
by these winds and poor overnight humidities allowed for the
explosive fire growth on the Kincade fire which started late last
evening and expanded at around 1000 acres/hour into this morning.
Outside of the Kincade, a few smaller fires also popped up but
were rapidly campaigned by fire personnel (Muir fire in Marin,
Spring near Santa Rosa, a vegetation fire near Berkeley). Winds
began to taper off from early to mid morning regionwise though a
few stubborn spots remained breezy to occasionally gusty into the
early afternoon. As of 3pm, most winds have fallen into the light
category. As such, the current red flag warning is set to expire
on time at 4pm.
Fire weather aside, the high pressure system also has brought
oppressively warm temperatures along the California coast today.
Heat advisories are in effect along the coast from Sonoma all the
way to San Diego until 7pm today as the warmest air mass lingers
just offshore and over the coast. In addition, the high pressure
system has suppressed nearly all onshore cooling influences,
replacing them with warming and drying offshore flow.
Consequently, the usual suspects when it comes to heat -- extreme
inland areas -- were relatively mild in comparison to the usually
much cooler coastal areas. For example, Monterey topped out at
96F degrees, breaking the old record not only for the day, but
also for the month of October. Other notable coastal locations:
Dillon Beach 94F, Bodegahead 91F, Point Reyes 91F, Half Moon Bay
91F, Watsonville 97F, and slightly further away from the coast,
Corralitos tops the list at 98F. These afternoon high temperatures
not only are on pace to shatter records but are also roughly 16 to
25 degrees above seasonal normals for this time of the year.
Internal confidence statistics place these temperatures along the
coast at roughly 5 standard deviations above the norm (3.5+ is generally
record territory).
A cooling trend is expected through the next several days as this
high pressure system slides southward along the Pacific coast,
eventually dropping off of Baja through this weekend. Tomorrow`s
temperatures will be well above average once again (14 to 18
degrees above normal, generally), however, still a few to locally
several degrees cooler than today. Further cooling is expected
this weekend, with a return of near to only slightly above normal
temperatures on Sunday. The cooling trend continues into early
next week with nearly normal temperatures regionwide on Monday.
Now that today`s offshore wind event is winding down, all
operational focus has shifted towards this weekend`s offshore
wind event. Confidence is high that the strongest offshore wind
event yet this season will take aim at a broad swath of Northern
California late Saturday into Sunday. Internal confidence
statistics indicate offshore winds on the order of 4.3-5.2
standard deviations above the norm (3.5+ usually is record
territory) will occur late Saturday into Sunday. This aligns with
forecast model data which shows the development of 60-70kt low to
mid level offshore flow during the same time frame. 70kt roughly
translates to 80mph, which is currently the top of end of forecast
gust range overnight Saturday into Sunday across the highest
peaks. In addition, these winds are anticipated to cover a broader
area across most of the San Francisco Bay area and Santa Cruz
mountains, with a higher likelihood of seeing these winds make it
to the lower elevations. Winds are forecast to taper down in
intensity with elevation, however, downsloping/mixing down of
winds could bring rather gusty conditions to areas downwind of the
hills/peaks particularly into Sunday. This downslope/mixdown phenomena
was particularly evident today, with gusty winds along the lower
slopes of the East Bay hills, downwind of the Marin headlands, and
particularly near Half Moon Bay, which was gusting to 50mph
around 7am this morning. As a result, may see some wind damage
impacts from this weekends offshore winds across a broader area,
such as downed trees, localized power outages, debris in
roadways, difficulty driving high profile vehicles, etc.
Despite near normal temperatures... the combination of critically
low humidity, dry fuels, and very strong offshore winds will
bring extreme fire weather across the region once again this
weekend. As soon as the heat advisory/current red flag warning
expire today, expect to see a high wind watch and fire weather
watch for this weekend`s system to be issued. For what its worth,
do not see any significant precipitation on the horizon in the
mid to long range models.
&&
.AVIATION...as of 6:20 PM PDT Thursday...Local influxes of cooler
marine air at the immediate coast otherwise offshore winds easing
into Friday with onshore winds then returning by afternoon mainly
near the coastline and bays. With the ongoing wildfire in Sonoma
county, smoke will likely spread to the south reducing visibilities
to MVFR tomorrow morning for the terminals based on recent HRRR
model near surface smoke forecasts. Smoke will reduce slant range
visibilities to moderate to poor mainly on Friday.
Vicinity of KSFO...VFR. Light wind tonight, increasing to near 10
knots from the west Friday afternoon and evening. MVFR visibilities
and poor slant range visibilities in wildfire smoke on Friday.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR. Light/variable winds becoming light
E-SE tonight with late night and morning drainage winds increasing
over the Salinas Valley.
&&
.FIRE WEATHER...as of 4:55 AM PDT Thursday...Red Flag Warnings
remain in effect through this afternoon.
A fire broke out shortly after 9 PM last evening in Sonoma County
and was named Kincade Fire in the northeast corner of Sonoma
County. Wind speeds were gusting 60-70 mph during this timeframe
with RH values in the lower teens. The combination of strong NE
winds, low RH, and dry fuels led to a very rapid rate of spread.
Latest intel as of 4 AM says the fire grew roughly 10,000 acres.
Since then the winds have diminished, but definitely don`t want to
downplay it as gusts are still in the 40-50 mph. Latest short term hi-
res models drop the winds through day, but the very dry airmass
and above normal temperatures remain. Definitely not out of the
woods yet despite weakening winds.
Weaker winds over the next 24-48 hours, but not a lot of relief as
relative humidity values remain low and temperatures remain mild
to hot.
On to the next event slated for Saturday night through Sunday
evening...to alleviate any confusion will let first round of Red
Flags expire before issuing any new fire watches.
Now for the details...a very strong offshore flow gradient is
forecast to develop and peak early Sunday. The GFS and ECMWF put
this on par, strength wise, with the 2017 offshore flow event that
led to the devastating North Bay Fires. It will be interesting to
see what the 12Z WRF shows, but even the courser models of the
GFS/ECMWF show 50kt wind flags over the North Bay, 30-40kt over
the East Bay early Sunday. The weekend event has better upper
level support than today`s event, hence the stronger winds. Now
for some finer details, specifically focused on the North Bay.
Taking a look at a cross section over the North Bay Mountains
shows some signs of a downsloping wind event on the lee side of
the mountains. Hi-res WRF shows a nice theta-ridge on the lee
slopes with a horizontal wind max of 56 kts mid slope. A forecast
point sounding also shows potential for mountain wave development
as a nice inversion is forecast just above some of the peaks with
strong winds above the inversion. This thermal profile combined
with flow perpendicular to the ridge could result in a mountain
wave surfacing down slope or a hydraulic jump. Keep in mind this
is just a model and one tool in the weather tool box, but the
Sunday setup could be the real deal.
&&
.MARINE...as of 4:53 PM PDT Thursday...Light offshore winds
continue throughout the day before switching to northwesterly
Friday morning. Winds will increase, particularly for the Northern
outer waters, Friday afternoon, strengthening into Saturday
morning. The moderate northwest swell with light southerly swells
will persist through the forecast period, but the middle of next
week is expected a long period northwest swell is expected.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...Heat Advisory...
&&
$$
PUBLIC FORECAST: DRP
AVIATION: Canepa
MARINE: DK
FIRE WEATHER: MM
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