Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/04/17
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
550 PM MDT Sun Sep 3 2017
.AVIATION...
00Z TAF CYCLE
Isol to Sct TS and SH will shift southward during the eve hrs.
SAF/LVS/AEG and ABQ could potentially be impacted. Biggest impact
would be gusty outflow wind to at least 40 kt. A particularly
stronger cell could affect SAF with even higher gusts early eve. Most
of the activity should die off by midnight or shortly after. Hit and
miss drier cells will affect western and northern areas Mon
afternoon. Gusty winds will remain the main impact with that
activity.
50
&&
.PREV DISCUSSION...300 PM MDT Sun Sep 3 2017...
.SYNOPSIS...
High pressure aloft will dominate northern and central New Mexico
this week. Showers and storms will be focused over the northern and
western high terrain through Labor Day with temperatures near to
above average. A vigorous cold front remains scheduled to plunge
into northeast and north central New Mexico Monday night, then
advance south and westward to the Continental Divide Tuesday on
gusty northeast to east winds. The front will spark showers and
storms along it`s path with locales along and west of the central
mountain chain more likely to be affected Tuesday, while the east
experiences cooler and more stable conditions. Thereafter, isolated
to scattered showers and storms will be focused over the northern
and western high terrain. High temperatures over the east will
rebound by Thursday.
&&
.DISCUSSION...
Less cumulus overall compared to this time yesterday afternoon but
isolated storms have developed sooner than yesterday over the
highest terrain of the northern mountains. Models indicate there
will be a few more developing as the afternoon progresses but how
far south through central NM and for how long they will persist is
where there is some model disagreement. RAP13 and HRRR seemed a bit
over enthusiastic with Saturday`s convection, so not confident
activity will hold together through the evening and into the
overnight hours as depicted, reaching the Lower Rio Grande Valley
and South Central Mountains. Decided to pencil in some dime sized
pops into those areas though dew point at KABQ has fallen into the
upper 30s and similar values stretch southward. Therefore any shower
or storm would likely be more gusty and dry with lightning than
rainy.
Labor Day will feature mainly afternoon and evening showers and
storms over the western and northern high terrain. Temperatures will
be above average.
A cold front is expected to push into north central and northeast
New Mexico Monday night then spread south and westward on vigorous
northeast to east winds. High temperature guidance for northeast NM
on Tuesday varies by about 10 degrees, went with a blend with a
little more weight given to the warmer ECMWF mos. The west will
remain above average temperature-wise with potential for showers and
storms but the east will see highs about 5 to 15 degrees below
average Tuesday, and will be more stable, which would diminish
potential for convection.
Hazy skies look to persist through mid week at least though there
may be some temporary improvement with the gusty winds expected with
Tuesday`s front. Went with mostly generic mountains pops for mid to
late this week as the upper high wanders around the central and
southern Rockies. Temperatures in the east rebound by Thursday.
&&
.FIRE WEATHER...
Weak disturbances embedded in the broad mid-level high pressure
system will continue to sink southward over NM this afternoon and
Monday with scattered to isolated showers and thunderstorms favoring
north central areas, and spottier convection mainly over the
mountains farther south. The lower atmosphere is fairly dry so small
wetting footprints are expected with erratic wind gusts potentially
reaching 50 mph near virga showers and drier variety thunderstorms.
High temperatures are expected to vary around 4 to 10 degrees above
normal on Monday with falling humidities across the east. Haines of
5 is also expected across the northwest two thirds of the forecast
area. A pocket of poor ventilation may linger across the east
central plains on Monday before improvement there Tuesday.
Look for showers and thunderstorms to increase in coverage and
wetness Monday night across the northeast as a gusty back door cold
front arrives, then Tuesday across central and western areas as the
front pushes southwestward to the continental divide. With the broad
upper high centered over the Great Basin, these storms will move
south and southwestward off the high terrain while lingering into
Tuesday evening. High temperatures will fall a few to 10 degrees on
Tuesday from Monday`s readings, and as much as 23 degrees farther
east, before falling further across central and western areas on
Wednesday. Haines Indices will plummet with Tuesday`s front and
remain low for the remainder of the week. Poor ventilation will
favor the Sangre de Cristo Mountains on Tuesday before spreading to
include central areas Wednesday and Thursday.
Daily rounds of mainly isolated showers and thunderstorms will favor
the mountains Wednesday through the end of the week as the Great
Basin high pressure system migrates southeastward over NM.
Humidities will generally trend downward and temperatures upward
after Wednesday causing wetting footprints to shrink.
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Gaylord MI
1147 PM EDT Sun Sep 3 2017
.UPDATE...
Issued at 1023 PM EDT Sun Sep 3 2017
Earlier diurnal convection in eastern upper MI has faded out. Next
precip event starting to take shape upstream. Surface wave along
incoming cold front is over the western tip of Superior. Showers
are developing in the warn advection zone e-ne of the low, over
central/northern Superior, with precip developing se-ward with
time. Light showers will re-enter the picture in eastern upper MI
toward or just past midnight. Better rain chances will arrive
from the nw after 3 am, as the cold front/surface wave and
stronger mid-level forcing arrive. Some embedded, non-svr storms
with this activity. Shower chances could get as far south as M-72
by 8 am. Unfortunately, per recent HRRR guidance, could be a
couple of waves of activity impacting the Straits region through
8-9 am. HRRR runs have not been particularly consistent though, so
not going to place a ton of confidence in any one solution.
UPDATE Issued at 436 PM EDT Sun Sep 3 2017
A few showers have been able to develop in interior eastern upper
in lake breeze convergence. Fcst soundings revealed a cap at
around 15kft with at most 200j/kg. Guess that was enough. Will run
them until daytime heating fades.
&&
.NEAR TERM...(Tonight through Monday)
Issued at 307 PM EDT Sun Sep 3 2017
High impact weather potential: None.
Pattern synopsis and forecast:
Early this afternoon, morning low clouds have been thinned and
lifted into a scattered cumulus field as drier air swept into nrn
Michigan. Temperatures have been responding to the emergence of some
sunshine by climbing into the upper 60s and 70s. The focus is now
shifting to a shortwave activity across western and central Canada
that was inducing low pressure in western Montana and the Dakotas.
No precipitation there as the air mass is fairly dry, but spotty
showers were seen in south central Canada, ahead of an ill-defined
warm front extending east of the low pressure. Mid level clouds were
thick north of this warm front, and quickly eyeing eastern upper as
they advect eastward from western Lake Superior.
The scattered cumulus will fade with loss of heating, and a period
of mostly clear skies is expected across the region, with the
exception for eastern upper where those mid level clouds are likely
to roll in early this evening. These clouds will continue to thicken
and lower through the night and Monday morning as the aforementioned
low pressure and warm front move into nrn Michigan, which will then
be followed by the system cold front. While forcing increase through
the overnight and Monday morning, via frontal convergence, WAA and
DPVA, instability will be rather minimal with CAPES only a handful
of J/kg. While showers are likely, especially in eastern upper in
stronger forcing, only a thunderstorm or two seems possible. Much
better chances for storms will reside downstate Monday afternoon
with diurnal heating leading to much more impressive instability
ahead of the cold front. Low level moisture will remain thick enough
for nrn Michigan through the day for clouds to hold firm for a good
portion of the daylight hours, but some late day clearing is
expected, more so across eastern upper.
Lows tonight will be fairly mild in the upper 50s and lower 60s.
Highs Monday will have a good range from NW to SE as the cold front
is moving through, the upper half of the 60s NW to the mid and upper
70s more toward Saginaw Bay in downsloping NW flow.
&&
.SHORT TERM...(Monday night through Wednesday)
Issued at 307 PM EDT Sun Sep 3 2017
...Turning cool with showers at times...
High Impact Weather Potential...Minimal.
Pattern Synopsis/Forecast...Highly amplified upper ridge/trough
pattern will develop over the CONUS towards midweek as a deep trough
settles into the Gulf of Alaska. High confidence that this will
result in deep longwave troughing entrenched over the Great Lakes
region for several days. 500mb heights will steadily fall Monday
night into Tuesday, dropping 2 to 3 standard deviations below the
mean. At the same time, 850mb temps will fall from +7 to 8C 00Z
Tuesday to around +3 to 4C by Tuesday afternoon. Thus, cold air
advection will be ongoing through the period, though weakening with
time. Some lake-induced rain showers will likely develop given the
warm water temperatures and influx of colder air aloft, with further
enhancement coming at times from lobes of vorticity swinging through
the upper trough.
Primary Forecast Concerns...Temperatures and shower chances through
the period. Possible thunderstorm or two?
Despite the anomalous trough and colder air building in aloft,
ensemble data suggests the airmass won`t be /significantly/ cold for
this time of the year, as 925mb and 850mb temperatures are only
about -1 to -2 standard deviations over northern Michigan. A little
more impressive further aloft with 700mb temps at -2 to -3 sigma.
Still, considering normal highs for early September are in the low
70s and normal lows in the low 50s, most of the area will be running
about 5 to 10 degrees below normal.
Showers will be possible at times through the period thanks to the
deep trough overhead as well as from lake induced processes given
the chilly Canadian airmass and warm lake waters. By no means a
terribly dry airmass for early September settling into northern
Michigan, as PWATs will only drop to around 0.7 inches...not too far
off from the median. As per the usual, tough to pinpoint the timing
of scattered showers tied to the upper trough, but Monday night
through Tuesday night would be the most favored timeframe. By
Wednesday, the trough axis will be pivoting east of our forecast
area with heights starting to slowly rise again.
Chances for lake-induced showers will gradually increase Tuesday
into Wednesday as 850mb temps steadily drop and delta Ts increase.
Wind direction veers from WNW Monday night to N on Wednesday, so
Lake Michigan will be the main contributer...possibly Lake Superior
to a lesser extent (cooler Superior waters only yielding delta Ts
around +13C). Looks like favorable low level moisture comes into
play both days as well. Wouldn`t entirely rule out a waterspout, but
parameters look to only be marginal through the period and not
always coinciding well. Would like to see deeper EL-LCL depths,
which look to range from 10 to 15 kft at best, depending on the
model.
Finally, given the ongoing CAA aloft, steep low-mid level lapse
rates will yield some instability at times that could result in a
thunderstorm or two. This would be mainly along Lake Michigan Monday
night and over northeast Lower Tuesday afternoon.
.LONG TERM...(Wednesday night through Sunday)
Issued at 307 PM EDT Sun Sep 3 2017
Scattered shower activity is possible as we begin the extended
period, as a sharp trough extending from Quebec through the
Tennessee Valley lifts out of the region through the day Friday.
High pressure will begin to build into the region Friday, and remain
in control through the weekend, and possibly into early next week.
This will bring us quiet weather, with the low temperatures probably
the biggest concern as good radiational cooling could bring some
chilly nights and perhaps some frost concerns again.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1147 PM EDT Sun Sep 3 2017
MVFR to IFR cigs Monday morning.
Incoming cold front will cross northern MI Monday morning. Shower
activity is expected ahead of and along the front, with a
thunderstorm or two possible as well. Vsbys will decrease as
precip arrives, with cigs to follow. MVFR to IFR cigs will be in
place Monday morning, with PLN the most likely spot for IFR
conditions. Improvement to VFR will take place north to south
Monday afternoon.
Sw winds will increase tonight, with LLWS also developing. Winds
veering nw to n Monday and decreasing.
&&
.MARINE...
Issued at 307 PM EDT Sun Sep 3 2017
Sfc low pressure and it`s warm front will lift into the region
tonight, tightening the pressure gradient and allowing skies to
thicken with clouds. The system cold front follows for Monday
morning, resulting in a wind shift out of the NW. Wind speeds will
be high enough for widespread advisories later tonight through
Monday evening. Winds fall below advisory levels later Monday night
and into the work week as large sprawling high pressure slowly moves
into the Great Lakes over that time.
Showers and possibly a few non-severe storms are likely later
tonight through Monday with the low pressure.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...BEACH HAZARDS STATEMENT through Monday afternoon for MIZ020-025-
031.
LH...SMALL CRAFT ADVISORY until 2 PM EDT Monday for LHZ346-349.
SMALL CRAFT ADVISORY until midnight EDT Monday night for LHZ347-
348.
SMALL CRAFT ADVISORY until 8 AM EDT Monday for LHZ345.
LM...SMALL CRAFT ADVISORY until 2 PM EDT Monday for LMZ323-342-
344>346.
SMALL CRAFT ADVISORY until 8 AM EDT Monday for LMZ341.
LS...SMALL CRAFT ADVISORY from 8 AM to 8 PM EDT Monday for LSZ321-322.
&&
$$
UPDATE...JZ
NEAR TERM...SMD
SHORT TERM...MK
LONG TERM...AM
AVIATION...JZ
MARINE...SMD
Area Forecast Discussion
National Weather Service Denver/Boulder CO
804 PM MDT Sun Sep 3 2017
.UPDATE...
Issued at 758 PM MDT Sun Sep 3 2017
No changes needed to previous fcst.
&&
.SHORT TERM...(This evening through Monday)
Issued at 203 PM MDT Sun Sep 3 2017
Strong upper high entrenched over the region with very warm and
dry airmass over Colorado. Record breaking heat this afternoon as
record high temperature already broken at Denver and trying to
break the all time September high of 97 degrees. Integrated PW
trends from GPS continue to drop with readings down another
quarter of an inch in the past 9 hours. No chance of storms
through tonight over plains and even much of the mountains. The
only exception would be over Park county with an isolated shower
possible through early evening.
Main impact tonight and Monday will be the smoke and haze expected
to increase over Northern Colorado tonight and Monday. GOES16
Geocolor imagery showing thick smoke over much of Wyoming this
afternoon. With the flow aloft and a weak frontal boundary, smoke
will be increasing over the northeast plains this evening and
overnight. Experiment HRRR concurs with some increasing smoke tonight
and this may linger through much of the day on Monday. A bit
cooler on Monday in prefrontal airmass before main front poised to
move into northeast Colorado Monday evening. Still mainly dry on
Monday and maybe just slightly better chance of storms over
mountains and higher terrain of Palmer Divide.
.LONG TERM...(Monday night through Sunday)
Issued at 203 PM MDT Sun Sep 3 2017
Monday night the large upper level ridge of high pressure will
stretch from the Pacific Northwest into the Desert Southwest...with
an upper level trough of low pressure deepening across the central
and eastern United States. A strong short wave on the back side of
the upper trough will push a strong cold front across northeastern
Colorado Monday night...with north to northeast winds gusts up to 30
mph possible. Moisture with the front looks limited...with inverted
V forecast soundings suggesting only light rainfall and gusty winds
with any showers and storms that do develop. Tuesday should be
cloudy and much cooler across northeastern Colorado due to a stratus
deck lingering through much of the day. The GFS has trended warmer
with Tuesday`s high temperatures while the NAM12 had trended lower.
If the NAM12 is correct...many locations across the plains and
Palmer Divide may only have high temperatures in the 60s. The cloud
cover and cooler temperatures should also result in a very stable
airmass with dry conditions expected. The mountains south of
Interstate 70 and the southern foothills should see more sunshine
and daytime heating. Therefore...these areas could see a better
chance for afternoon and evening showers and storms. The dry air
combined with mostly clear skies overnight should allow Wednesday
morning temperatures to drop into the 40s across most plains
locations.
A gradual warming trend is expected Wednesday through Friday as the
upper level ridge of high pressure shifts eastward over the Rocky
Mountain Region. This may allow some subtropical moisture to flow
into Colorado from the south and southwest. The increase in moisture
combined with daytime heating should result in increased
precipitation chances by late in the work week...mainly across the
high country.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 758 PM MDT Sun Sep 3 2017
One bndry has moved across DIA which will keep winds
nely the next few hours. Overnight winds may eventually just
transition to drainage between 06z and 08z. Meanwhile areas of
smoke/haze will spread across the area with visibilities
eventually dropping to 3-5 miles late tonight.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Entrekin
LONG TERM...Kalina
AVIATION...RPK
Area Forecast Discussion
National Weather Service Taunton MA
914 PM EDT Sun Sep 3 2017
.SYNOPSIS...
Remnants of Harvey and a Midwest cold front will move through
the region this evening. Weak high pressure brings clearing and
drier weather overnight. A trend to warmer weather follows on
Labor Day and Tuesday. A cold front will slowly push toward the
region, bringing showers and scattered thunderstorms with
locally heavy rainfall late Tuesday into Thursday. Slowly
improving conditions move in during Friday, then continue into
next weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
900 PM Update...
Upper level trough over the region will continue to push to the
north and east during the overnight hours. At the surface,
surface low is currently located off of Cape Ann and the NH
Seacoast. Thus winds will generally be from the west for the
overnight as the low moves towards the northeast.
Bulk of the showers have moved out of southern New England and
into NH/Maine. However on the backside of the low pressure,
showers have continue to fester. This is in conjunction with
the higher 700 mb moisture moving into the area as well as
upper level jet. Added the risk for a slight chc across the CT
valley as these showers continue to move into from the Berks.
The combination of the westerly winds bringing in drier air,
these showers will not last very long and appears that they will
dissipate around 3-5z.
The other item to watch tonight is the potential for radiational
fog. Clearing skies and winds going light in sheltered valley
locations could result in some fog. See the MMK is down to 1sm.
The only caveat once again is the dry air. Also the HRRR and
the NARRE are not pinpoint the fog potential. Still cannot rule
out the potential so will mention patchy fog for the overnight
hours. The risk for dense fog appears low at this time.
Previous Discussion...
Drier air moves in behind the departing weather system. Expect
clearing skies and winds from the west southwest. Overnight
lows in the lower to mid 50s except 55 to 60 in the urban
centers and on Cape Cod and the Islands.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday...
High pressure south of the region extends across our area on
Labor Day, with the ridge axis shifting east of us by afternoon.
That will allow winds to shift from the southwest. This will
provide plenty of sun, with sufficient mixing to reach 850 mb.
Temps at that level are forecast at 14C, which would support max
temps 80 to 85, with cooler spots in the hills and along the
South Coast where winds will come off the water.
Monday night...
High pressure in place to our southeast with a light south-
southwest flow over southern New England. This brings a return
of dew points in the 60s. Expect min temps in the low to mid
60s. With temps and dew points close to equal, expect areas of
fog to develop.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...
* Warm and humid Tuesday with sct strong t-storms possible
across the interior
* A slow moving front will bring showers/scattered
thunderstorms, locally heavy rainfall Tuesday night into
Thursday
* Drier conditions Fri and Sat but still the risk of a few
daytime showers inland
Overview...
12Z model suite continues to signal development of digging H5
long wave trough out of Hudson Bay and Ontario S to the mid and
lower Mississippi valley by mid week in response to yet another
high amplitude ridge building across the western U.S.
Cold front will tend to stall across central and western areas
as it becomes parallel to the eastern side of the mid level long
wave trough. Also noting Bermuda high extending westward into
the western Atlantic, a bit higher than its normal position.
This deep SW flow setting up will allow plumes of high PWAT air
working toward the region. Continued concern for a prolonged
period of heavy rainfall along with the potential for localized
flooding/flash flooding.
By late this week into next weekend, models and ensembles
continue to signal the long wave trough lifting NE across New
England, but some question on timing and whether it tries to
cutoff across Quebec or the Maritimes. At this point, will
continue with previous forecast trend of drying conditions
moving in by next weekend as high pres pushes E out of the Great
Lakes. Will continue to closely monitor the progress of Irma as
it approaches the western Atlantic in the Friday-next Sunday
timeframe at least.
Details...
Tuesday...
Dewpoints will continue to rise with the developing SW flow,
which should reach the mid to upper 60s during the day. Warm
temperatures ahead of slowly approaching cold front out of
central NY/PA with forecasted H85 temps remain in the +16C to
+18C range, so expect temps to top off in the 80s across most
locations away from the immediate S coast.
Noting SB CAPEs rise to the 800-1000 j/kg range and K indices
rise to 30-35 during Tue afternoon across central and western
areas. Otherwise, decent instability also moves in as well as
increasing PWATs. However, some question as to how far E the
cold front will reach during max daytime heating to bring in the
best instability. Could see some strong thunderstorms develop
across central and western areas, mainly from about Worcester
and Windham counties westward during Tue afternoon and evening.
SPC keeps mention of general thunder for now.
Tuesday night into Thursday...
The upstream mid level trough continues to amplify to the W,
causing the cold front to stall across the region with weak low
pres waves moving along it. Noting steadily increasing PWATs
during this timeframe, upwards to 1.8 to 2 inches by Wed
night/Thu with persistent SW flow. So, will start to see
training showers/scattered thunderstorms allowing for not only
heavy downpours but persistent rainfall for potential of flash
flooding. Current thinking is the best shot for this would be
Wed into Thu, but exact timing as well as where the training
precip to set up remains in question. Forecasting a general 1.5
to 2.25 inches of rainfall, but again could see localized higher
amounts.
Will see POPs increase to categorical by Wed morning across the
western half of the region, but will spread E during the day
and continue into early Thu before slowly shifting E.
Friday through Sunday...
H5 trough will lift NE across New England, which should push
the front offshore but timing is a bit in question amongst the
model suite. Some showers may linger across portions of the
region into Friday, but should end Fri evening with drier air in
place. Could still see some diurnal showers on Saturday as
moisture lingers across the interior. Carrying a dry forecast
for next Sunday for now.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...
Tonight...High confidence.
Band of showers may bring brief MVFR-IFR CIGS/VSBYS moving E
across the region, mainly N of the MA/RI/CT border through 03Z-
04Z, then should dissipate. Otherwise mainly VFR conditions.
Leftover W-SW wind gusts up to 20 kt should weaken by around 03Z
as well. Otherwise, expect clearing skies and west southwest
wind.
Monday and Monday night...High confidence.
VFR. Areas of IFR cigs/vsbys in fog late Monday night.
KBOS Terminal...Moderate to high confidence in TAF. May see
brief MVFR-IFR CIGS from around 02Z-04Z with batch of -SHRA
moving across. Otherwise VFR.
KBDL Terminal...Moderate to high confidence in TAF.
Outlook /Tuesday through Friday/...
Tuesday...High confidence. Mainly VFR. Will see scattered
afternoon/evening showers/TSRA develop across the interior with
lower conditions. Patchy fog developing after midnight with
local MVFR-IFR VSBYS.
Tuesday night through Thursday...High confidence in overall
trends, but lower confidence in exact timing and details. Expect
areas of MVFR-IFR conditions in showers and sct TSRA, initially
focused across the interior through Wed, then shifting slowly E
Wednesday night into Thursday. Patchy late night/early morning
fog with locally MVFR-IFR conditions each night.
Thursday night-Friday...Moderate confidence. Lingering
showers/scattered TSRA early Thu night, will slowly push E late
Thu night. A few daytime showers may develop across the interior
late Fri morning into the afternoon.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...
Tonight...High confidence.
East winds in the evening become variable, then shift from the
west-southwest. Showers and fog should diminish with the wind
shift. Wind speeds of 20 to 25 knots linger much of the night,
but trend lower after midnight. Seas 5 to 7 feet linger, mainly
on the outer waters overnight. A Small Craft Advisory is in
effect through tonight.
Monday...High confidence.
Southwest winds to about 20 kt. Seas subside through the day,
but seas of 5 feet may linger along the seaward edge of our
outer waters. Small Craft Advisory lingers on the outer waters
through the afternoon.
Monday night...High confidence.
Southwest winds may reach 20-22 knots. Steady south-southwest
wind will help seas re-build to 5 feet on the outer waters and
possibly RI Sound.
Outlook /Tuesday through Friday/...
Tuesday...High confidence. S wind gusts up to 20-25 kt, highest
across the eastern outer waters. Seas up to 4-6 ft, highest on
the outer waters. Good visibility.
Tuesday night through Thursday...Moderate confidence.
Persistent S-SW winds may gust to 25 kt at times. Vsby will be
reduced at times in showers and isolated thunderstorms. Patchy
late night/early morning fog with reduced vsby mainly on the
nearshore waters.
Thursday night and Friday...Moderate confidence. Winds shift to
W Thu night as cold front passes. Showers/isolated
thunderstorms will end from W-E mainly around or after midnight,
but may linger into Fri across the eastern waters. May see
patchy late night fog with locally reduced vsby, otherwise
mainly good vsby.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ231>234.
Small Craft Advisory until 8 AM EDT Monday for ANZ235-237.
Small Craft Advisory until noon EDT Monday for ANZ250-251-256.
Small Craft Advisory until 4 PM EDT Monday for ANZ254-255.
&&
$$
SYNOPSIS...WTB/EVT
NEAR TERM...WTB/Dunten
SHORT TERM...WTB
LONG TERM...EVT
AVIATION...WTB/EVT
MARINE...WTB/EVT
Area Forecast Discussion
National Weather Service Burlington VT
1008 PM EDT Sun Sep 3 2017
.SYNOPSIS...
Widespread rainfall will taper off tonight as upper level low
pressure pulls east of the region. A brief period of fair and
seasonably warm weather returns for Labor Day before a slow
moving cold front brings a renewed threat for showers from
Tuesday onward into the late week time frame.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 1006 PM EDT Sunday...Minor update to fine tune steadier
rain ending from the CPV into parts of central/northern VT.
Based on latest radar trends still thinking steady rain ends
across the NEK around midnight with just a few leftover
scattered showers. Additional qpf will be a tenth or two at most
with highest values over northern VT. Temps remain nearly steady
overnight in the 50s with south/southwest winds 4 to 8 knots.
All covered well in grids/forecast.
Current radar continues to show light to moderate rainfall from
the eastern dacks into most of central/northern VT. Utilizing
the time of arrival tool has the back edge to precip in the BTV
area around 01z...and thru the NEK by midnight. Have tweaked the
pops toward this thinking and integrated the latest HRRR model
reflectivity progs. Otherwise...additional qpf will range from
0.10 to 0.25...with some isolated higher amounts toward the NEK.
Large pictures shows negatively tilted 5h/7h trof with deep 850
to 500mb southerly flow associated with warm conveyor. This
deep moisture and favorable upper level divergence pattern is
slowly shifting north...as 925mb to 850mb winds shift to the
southwest as drier air advects into our cwa. Temps will remain
steady or climb a few degrees especially aft the heavier showers
move east...with lows mainly in the 50s. Winds and mixing
should limit fog potential to higher trrn...where summits are
obscured in clouds.
Previous discussion below:
Widespread showers and periods of steadier rainfall continue
across the area as expected this afternoon as the remnant
moisture from former Hurricane Harvey interacts with a
negatively tilted, though progressive upper trough.
Precipitation efficiency is on the higher side of average with
current 12-hr MRMS totals generally ranging in the 0.25 to 0.75
inch range as of 200 pm. Global and hi-res model output remain
in excellent agreement showing this trough and associated
rainfall to continue pivoting through the region through the
late afternoon and early evening hours before exiting east with
better dynamics. So the idea of conditions trending gradually
dry later this evening into tonight looks on track at this
point. Low temperatures a consensus blend of available guidance
with some bias- corrected MOS output thrown in for good measure
offering near steady readings in the upper 40s to mid 50s. This
seems reasonable given near-neutral advective processes under
developing southwesterly flow.
The best weather day over the next 3-5 day period by far will be
tomorrow (Labor Day) as weak surface ridging builds across the area
under deepening southwesterly flow aloft. This is in advance of
another longwave upper trough developing to our west across the
Upper Great Lakes. Skies should trend partly to mostly sunny through
the day with highest coverage of sunshine across southern counties.
High temperatures respond nicely as model-averaged 18Z 925mb
temperatures climb into the 18-20C range - mainly 70s to a few spot
low 80s in favored warm spots of the Champlain Valley and southern
VT. As the boundary layer deepens, southwesterly winds will trend a
tad breezy through the day, especially across the western slopes of
the Adirondacks into the St. Lawrence Valley where channeled flow
will develop. Here mean gusts from 25 to 35 mph will be likely with
a few spots hitting 40 mph. While below advisory criteria, this
could lead to a few downed branches and an isolated power outage or
two as trees remain fully leafed out.
By Monday night the upper trough continues to approach from the
northwest along with a slowly advancing surface front tracking into
the St. Lawrence Valley. Showers will be forecast to overspread our
western counties overnight as the frontal zone approaches, with much
of VT remaining mainly dry. I did introduce an outside threat of
thunder across northern New York after midnight as a band of steeper
mid-level lapse rates advects ahead of the boundary into this
region. Low temperatures will remain on the mild side as deep
southwest flow continues - mainly upper 50s to mid 60s.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 350 PM EDT Sunday...Upper trof digs into the Great Lakes
Tues and Tuesday night with height falls while a cold front
moves into the region and provide a focus for showers and
thunderstorms. The front should be in northern NY around 12z Tue
with showers concentrated there. The front will move slowly
eastward across Vermont on Tuesday. It looks like southern and
eastern VT will destabilize mainly south and east of BTV/MPV. An
blend of MUCAPE gives 500-1000 J/kg perhaps a bit higher in the
immediate CT river valley around 21z Tue. 0-6km shear will also
be in the increase with 30-50kt so a strong to severe storm is
a possibility over SE VT in the afternoon or evening. 850 temps
will range from near 8C at MSS to 13C at VSF. There will be
quite a few clouds with highs on Tuesday will range from the
lower 70s at MSS to around 80 at VSF, though if there is enough
sun could be a bit warmer there.
Instability wanes quickly Tuesday evening with loss of daytime
heating but still some chance of showers mainly over SE VT as
the frontal movement slows to a crawl over southern VT or MA
overnight. Lows mainly in the 50s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 350 PM EDT Sunday...The large scale upper trof becomes
established over the eastern third of the country through Sunday
with a number of short waves moving through it. This will help
to keep the threat of precipitation going over the area through
much of the extended along with temperatures trending below
normal.
The frontal boundary will become quasi-stationary orientated from
southwest to northeast over southern New England Wed and be the
focus for a potential wave of low pressure moving along it Wed
into Thu. As a result, we will see the threat for showers be
greatest over Vermont with slightly less chance over northern
New York Wed and Thu. Eventually the front moves off the coast
as the upper trof axis moves over the area Friday into Saturday
with the latest models indicating it cutting/closing off
somewhere over the Northeast though the timing and location are
a bit uncertain as well as when it moves out. The dynamics and
instability associated with the upper trof will enhance the
potential for showers. Showers will be mainly driven by diurnal
instability with the highest chance in the afternoon and evening
hours.
With the clouds and precipitation through much of the extended
time period high temperatures will generally be in the 60s and
lows trending into the 40s to lower 50s. In fact the latest
ECMWF shows 850 temps near 0C along with 540dm thicknesses by
next Sat which means it may be cooler than what we are
forecasting but the GFS is a bit warmer, so we`ll wait and see
what later forecasts trends bring including what happens with
Irma which is just way too far out to say.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Low pressure continues to produce rain
and low clouds across much of the North Country. Mix of IFR to
VFR conditions for the first half of the night. Gradual
improvement expected after 06Z as system pulls east. Winds
mainly south to southwesterly at 3 to 8 kts should inhibit
widespread fog development outside of rain showers. Low cigs
will be main concern through the early morning hours, at which
time expect the low to move far enough east with cigs lifting to
VFR after 09Z at all sites but KSLK and KMPV. Expect these
terminals to improve to VFR during the late morning. VFR
conditions expected throughout the day Monday. During the late
morning throughout the afternoon, winds will pick up out of the
south southwest at 8 to 15kts with gusts generally between 20
and 30 kts possible.
Outlook...
Monday Night: VFR. Breezy. Chance SHRA.
Tuesday: VFR. Chance SHRA...Slight Chance TSRA.
Tuesday Night: VFR. Chance SHRA.
Wednesday: VFR. Occasional SHRA.
Wednesday Night: VFR. Chance SHRA.
Thursday: VFR. Chance SHRA.
Thursday Night: VFR. Chance SHRA.
Friday: VFR. Chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG/Taber
SHORT TERM...Sisson
LONG TERM...Sisson
AVIATION...KGM
Area Forecast Discussion
National Weather Service Grand Forks ND
1000 PM CDT Sun Sep 3 2017
.UPDATE...
Issued at 952 PM CDT Sun Sep 3 2017
The cold front has now passed through the FGF CWA with a brisk
northerly wind following closely behind. Winds are settling down
nicely as the pressure gradient relaxes further behind the front.
A light northwest wind should persist overnight...with the a
trailing system likely to bring in some scattered showers through
Monday morning.
UPDATE Issued at 638 PM CDT Sun Sep 3 2017
No significant updates planned for the forecast package. Updated
Aviation Discussion is attached below.
RAP analysis at 23z shows a surface low pressure system centered
just west of BJI with a trailing cold frontal boundary extending
back through Ada, Grandin, and Valley City. Winds turn fairly
sharply from the north following frontal passage. At 2330z Radar
shows thunderstorms beginning to develop over far northcentral MN
ahead of the surface low. CAP strength is slowly eroding near the
low and scattered strong thunderstorms remain possible over
northcentral MN through early evening.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 341 PM CDT Sun Sep 3 2017
Manitoba short wave forecast to move into southeast Ontario by
Mon morning. Short wave will send cooler air into the area tonight
and Mon. Upper level jet was across southern Canada with showers
occurring over northern Lake of the Woods county. Water vapor
loop indicated an upper level ridge was rotating through the area.
Showers and storms will be possible mainly on the MN side with
frontal boundary moving through. Gusty northwest winds may be
possible this evening as cooler air moves into the area.
Water vapor loop indicated a short wave over central MAN. Another
short wave was located over central BC. 500 hpa height falls
mainly over southern Canada today will shift south into the area
Mon morning as BC short wave digs into the area and concurrent
ridge building occurs over western North America. 140M height
falls expected by 12Z Mon over the forecast area and ahead of main
short wave.
Another upper level jet will occur on the south and west periphery
of the BC short wave Mon. light showers are expected to occur in
the left front quad of jet.
Flow aloft becomes much more northerly Mon night. North flow aloft
will remain across the Northern Plains through Wed.
.LONG TERM...(Wednesday night through Sunday)
Issued at 341 PM CDT Sun Sep 3 2017
It will remain dry through the end of the week as an upper ridge
builds into the northern high plains and high pressure at the sfc
sits over the Great Lakes. ECMWF/GFS/GEM remain in good agreement
with this scenario. Temperatures will rebound back to above
normal levels by the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Updated at 958 PM CDT Sun Sep 3 2017
Expect VFR conditions with loight northerly blayer flow across
the area through the midnight period. Aft 07Z expect increasing
mid level clouds spreading from northern ND southeastward and
across the FA through the morning hours. Scattered showers and
patchy MVFR CIGS and VSBYS will push through the DVL Basin by
12Z... through the RRV from 10Z through 14Z... and through
northwest MN aft 14z. Scattered showers and isolated Thunderstorms
are possible across northwest MN aft 16z.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Gust
SHORT TERM...JH
LONG TERM...Riddle
AVIATION...Gust
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
542 PM MDT Sun Sep 3 2017
.SHORT TERM...(Tonight through Monday night)
Issued at 332 PM MDT Sun Sep 3 2017
High pressure will remain firmly situated over the western CONUS
over the next several days, keeping conditions generally dry and
warm. Temperatures will be well above seasonal as a result; at
least 5 to 10 degrees. Residual moisture trapped underneath the
ridge will continue to be recycled each afternoon, resulting in
isolated to scattered showers and thunderstorms over the higher
terrain. As has been the trend the past few days, the San Juans
will be favored for convection with activity subsiding after
sunset. The overnight hours will be benign with mild lows and
mostly clear to partly cloudy skies.
As northerly flow remains overhead we can expect hazy conditions
to persist, generally over areas north of I-70, into Monday. Did
not make any alterations to the inherited haze grids coverage
wise, though I did extend the duration through 15Z Monday morning
in accordance with the latest HRRR smoke dispersion model.
.LONG TERM...(Tuesday through Sunday)
Issued at 332 PM MDT Sun Sep 3 2017
For Tuesday, the continued area of high pressure will be
sandwiched between two upper level troughs - one located over the
Pacific Ocean and the other, much stronger trough digging into the
eastern CONUS. After the midweek point the high will begin to
shift to the southeast as the aforementioned Pacific trough moves
inland. Here, extended models begin to diverge on potential
solutions with the GFS introducing subtropical moisture underneath
the retreating high late Wednesday while the Euro lags behind
some 36 to 48 hours. Regardless, the progression of the high
further east should allow for moisture to trickle back into the
region from the south, so we can expect to see an increased chance
for showers and thunderstorms as well as cooler temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 542 PM MDT Sun Sep 3 2017
Storms will be laying down for the night as sunset approaches
leaving minimal flight operation concerns over the next 24 hours.
Winds should be mainly influenced by the terrain with any cigs
aoa 120kft agl. VFR dominates the forecast.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...MMS
LONG TERM...MMS
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Gray ME
1011 PM EDT Sun Sep 3 2017
.SYNOPSIS...
Low pressure will lift north out of New England overnight. A
shallow ridge of high pressure will move east through the region
on Monday. A cold front will approach from the northwest Monday
night and will gradually stall over the area on Tuesday. Several
weak waves of low pressure will track northeast along the front
Wednesday through Wednesday night before the front shifts
offshore on Thursday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
10 PM...Forecast still on track for the most part. Heaviest RA
should lift NE and out of the CWA by midnight. Latest HRRR runs
showing a little bit of surge of showers moving across central
NH into central ME, associated with cold conveyer belt of
developing low just to the east. These will mainly be light and
should be gone by early morning if they survive that long.
7 PM...Tweaking the grids to mach up with current grids, but
general forecast thinking remains mostly the same. One more slug
of steadier, and maybe moderate to heavy precip moves through
during this evening from SW-NE. Any mod-heavy rain will
probably not last much longer than an hour in any given spot.
Then rain should wind down quickly around mid night as flow
shifts to WNW and should dry things out quickly.
Previously...Low pressure associated with the remnants of
Harvey will lift north through the region this evening. Heaviest
of this precipitation currently pushing into southwest New
Hampshire and will be overspreading the remainder of the
forecast area through the afternoon and early evening. QPF not
changing much with a half to one inch still expected for storm
totals. Looking for gradual clearing from west to east after
midnight as winds kick into the west but shelter valley may hold
on to fog and stratus into Monday morning. Lows overnight will
range from the mid 40s to mid 50s.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Shallow ridge of high pressure will build east through the
region on Monday.Looking for a mix of sun and clouds in the
mountains and mostly sunny skies elsewhere. Should see
temperatures closer to normal with upper 60s to mid 70s north
and mid 70s to near 80 south.
Cold front will approach from the northwest Monday night
bringing increasing clouds to northern zones and a chance of
showers toward daybreak on Tuesday. Remainder of forecast area
will be just partly cloudy. Lows overnight will range from the
mid 50s north to the mid 60s south.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
To start the extended the region will be under the influence of
an amplifying pattern across North America. Seasonably strong
ridge building will occur across Wrn North America and over the
Wrn Atlantic. Between those two ridges a trof will deepen across
the Ern CONUS. This will set up Sly flow along the East Coast
some 2 standard deviations greater than normal. This will keep
things mild in general...clouds and precip will keep real warmth
from being realized. However deep moisture will be transported
up the coast...and that could result in locally heavy
rainfall...especially if any elevated convection develops.
Forecast soundings continue to show plenty of elevated
CAPE...perhaps some surface based Tue depending on
insolation...so thunder will remain in the forecast thru
midweek.
Because of the large ridges to the E and W...this front will be
slow to move. Several rounds of rainfall are possible as weak
waves ripple north along it. The upper trof is not forecast to
start edging E of the region until Fri or so...and even then the
low heights aloft could lead to diurnal showers into the first
part of the weekend. Then ridging is expected to build over the
forecast area from the W.
Looking well beyond the weekend...little has changed regarding
the track of Irma. The hurricane remains well out in the
Atlantic...with several days to go before any potential impacts
to the Lesser Antilles. Its current position in the Atlantic
Basin continues to suggest the likelihood of impacts to the
Northeast are low...however a SW push over the next couple of
days may bring Irma into a more favorable location. Ensemble
guidance continues to show a wide range of solutions...so any
forecast you see is low confidence at this time. Continue to
follow the National Hurricane Center for the most up to date
information...and regardless of eventual impacts or lack thereof
from Irma it is always a good idea to review your hurricane
preparedness and emergency kits.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Short Term...IFR/LIFR ceilings and vsby overnight. VFR Monday
through Monday night.
Long Term...An extended period of MVFR or lower conditions is
likely to begin Tue. As the front moves into NWrn zones during
the day conditions will deteriorate in the mtns first. Coastal
locations will likely see VFR conditions linger into the
afternoon Tue before deteriorating overnight. Areas of IFR or
lower are possible Tue night into Wed as RA intensity increases.
Especially during the day Tue and Wed...heating of a moist
environment may allow for some isolated TSRA to form...though
confidence in more widespread convection is low.
&&
.MARINE...
Short Term...Have extended this SCAs into Mon afternoon outside
of the bays, as seas will remain high, even if winds hover at or
just below borderline SCA. Should see winds drop below SCA in
the bays as winds shifts to WNW later tonight. Winds quickly
pick up from the SW Monday night, and will likely need SCAs
again Mon at some point Mon night.
Long Term...Deep SW flow develops Tue ahead of the next front.
The pressure gradient may be enough for some 25 kt gusts outside
of the bays...but more likely is that seas build to 5 to 7 ft.
Hazardous seas look to continue into the latter half of the week
before diminishing.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ151-153.
Small Craft Advisory until 3 PM EDT Monday for ANZ150-152-154.
&&
$$
SYNOPSIS...
NEAR TERM...Cempa/Sinsabaugh
SHORT TERM...Sinsabaugh
LONG TERM...Legro
AVIATION...
MARINE...
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
629 PM CDT Sun Sep 3 2017
.SHORT TERM... (Through Late Monday Afternoon)
Issued at 328 PM CDT Sun Sep 3 2017
Weak cold front has pushed through the forecast area this morning
leaving dry and warm conditions for this afternoon and evening. Warm
temps will push to near 90 as most areas will see plenty of sunshine
with just scattered high and mid clouds south of I-70 and light
winds from the southwest.
Dry and warm conditions continue into tomorrow with highs into the
mid 90s in the St louis area and low 90s elsewhere. The light
southwesterly winds will begin to increase late morning into the
early afternoon as a new cold front pushes its way into the region.
Precip chances increase as front approaches but will remain minimal
through this period. Areas to the west of the Mississippi River
look to remain capped so any convection will be limited to the
eastern CWA.
Walsh
.LONG TERM... (Monday Night through Next Sunday)
Issued at 328 PM CDT Sun Sep 3 2017
(Monday Night)
Convective initiation along the front appears probable by early
Monday evening. As alluded to by the short-term forecaster above,
initiation appears most likely east of the Mississippi River
where combination of weaker capping and stronger mid/upper level
forcing for ascent will reside. Development further southwestward
along the front, particularly across south-central Missouri, is
far more uncertain. Some CAMs such as the NCAR WRF and the ESRL
HRRR show very little to no development west of the Mississippi
River while the NMM and hi-res NAM show a line of storms all the
way into western Missouri. Global models are also split, with the
NAM/GFS more bullish with the ECMWF not showing much in the way
of storms along the front. Leaned a little bit more toward the
ECMWF and ESRL HRRR/NCAR WRF as conceptually it makes the most
sense. As alluded to above, the further southwest you get, the
weaker the mid/upper level forcing along with more of a capping
inversion between 700 and 800 hPa. Therefore have highest PoPs
across portions of south-central Illinois during the evening
hours. Some weakening of the convection is expected late evening
into the overnight hours as instability weakens. However, there
could be a few strong to severe storms with the frontal passage
during the evening before the expected weakening occurs. Slightly
better chances of strong to severe storms would be across the
Mississippi River where highest PoPs will reside. Further
southwest, a more conditional threat will exist. Gusty winds
appear to be the primary threat.
Cold front is expected to exit the CWA by 0600 UTC, with a band of
frontogenetically enhanced showers possible moving from north to
south very late Monday night. Should be a gap of dry weather behind
the front however and ahead of this potential band of showers.
(Tuesday - Next Sunday)
Post-frontal showers will remain a threat into early Tuesday, mainly
for portions of southeastern Missouri. After that threat passes
to the south, see little to no chance of rain through next
weekend.
Everything remains on track for the well-advertised period of well
below normal temperatures behind the cold front. A reinforcing shot
of cold air comes in behind a shortwave trough Thursday
afternoon/evening. A broad area of anomalously strong high pressure
will remain nearly anchored across the central CONUS, aided by
confluent flow aloft. Temperatures will run 10-20 degrees below
normal, especially at night with a clear sky, light winds, and very
low dewpoints. Made very little changes to temperatures for the
middle of the week, and lows likely will still need to be nudged
downward in future forecasts. Did however slow down the
moderation in temperatures late next week into early next weekend.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 603 PM CDT Sun Sep 3 2017
VFR conditions are expected for the majority of the TAF period.
Initially light and variable winds will become southwesterly
overnight ahead of an approaching cold front. Southwest winds will
gust to near 20 kts after 12z, then diminish and become northerly
after fropa. SHRA/TSRA will develop near the front towards the
end of the valid TAF period and may affect KCOU/KSTL/KSUS/KCPS
after 21z.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Medford OR
700 PM PDT Sun Sep 3 2017
.DISCUSSION...
Smoke is rampant this afternoon with visibilities in most of the
west side valleys around or below a mile. High pressure will
continue to remain in control through the Labor day weekend and
Tuesday bringing abnormally warm temperatures to California and
Oregon. Smoke is having very little impact on temperatures
pushing towards 100 degrees in locations outside of western
Siskiyou county this afternoon, so the concentration of smoke
does matter. Look for most areas to under shoot guidance by about
3 to 5 degrees in southern Oregon where as areas near very active
fires in Siskiyou county may undershoot guidance by 10 to 20
degrees tomorrow Monday. We tried to make adjustments to high
temperatures in western Siskiyou county for Monday to account for
the massive smoke concentrations.
High pressure will continue to remain in control but gradually
break down as tropical storm Lidia travels up the coast of
California Tuesday into Wednesday. Right now, we did introduce a
slight chance for thunderstorms Tuesday afternoon and evening.
There appears to be a healty amount of instability along the
Cascade crest, but forcing is really lacking for Tuesday. The best
chance for storms will be Wednesday evening as Lidia becomes
negatively tilted just west of Eureka California. This should
allow for scatted thunderstorms given enough moisture coming up
from the south. The other important things to note here is the 0-6
km shear is showing 45 to 55 knots over southern Oregon. In
addition, potential instability near the Cascades are around 2200
J/kg. Given these variables, we`ll really have to keep an eye on
some potential for severe thunderstorms. Should be interesting to
watch.
Thursday into the weekend...Eventually a long wave trough will
approach Oregon and Washington. The models differ on what exactly
will happen, but in general we can expect temperatures to cool off
to around seasonal normals with westerly flow. In addition, both
models are bringing a dry cold front to the coast around mid day
Saturday. This is good news in a few ways because the west flow
and the cold front should be cooler and carry some moisture to
help fire fighting. In addition, the flow should be strong enough
to help with smoke dispersion if we want to believe with what the
GFS is showing. The ECMWF doesn`t show as great of a solution
with the long wave staying a bit farther north into Washington. In
the end, next weekend is a welcome change of pace in the weather.
-Smith
&&
.AVIATION...04/00Z TAF CYCLE...Wildfire smoke will limit visibility
to less than 2 miles at times west of the Cascades today (including
KMFR/KRBG). Visibility will be as low as only a few hundred feet in
portions of the lower Klamath River Valley in western Siskiyou
County where vertical mixing will be negligible. However, north to
northwest breezes will pick up this afternoon in the rest of the
west side valleys, which should raise visibility in some areas, but
likely not all locations. The northwest winds should bring some
thicker smoke east of the Cascades too, which may impact the
terminals at KLMT. Visible satellite imagery also shows that the
smoke layer is much thicker than the current cloud layer, with the
tops of the clouds being obscured by the top of the smoke. aS THE
asos ceilometers are reporting ceilings and some are even showing VV
am using the reports as a VV designation for the smoke.
A shallow marine layer will redevelop north of Cape Blanco for a few
hours late tonight into Monday morning with the potential for IFR
fog, but confidence in this is moderate at best. Sven
&&
.MARINE...Updated 305 PM PDT Sunday 3 September 2017...Overall,
expect light to occasionally moderate northerly winds today through
Tuesday morning, strongest south of Cape Blanco on Monday.
Relatively low seas can also be expected during this time frame,
though seas will be slightly steeper Monday due to the increased
wind speeds south of Cape Blanco. Winds are likely to reverse to
light southerly Tuesday with seas then expected to become westerly
swell dominated. Seas will likely range from 4 to 6 feet at least
into early Friday.
&&
.FIRE WEATHER...Updated 230 PM PDT Sunday 3 September 2017...Hot
weather will prevail into early next week. Dense smoke shading will
occur in some areas, especially western Siskiyou County valleys,
portions of southwest Oregon and around the Umpqua Complex, where it
will be markedly cooler. A few of the local RAWS sites in the lower
Klamath Valley like Dutch Indy, Sawyers Bar and Somes Bar failed to
break the strong inversion and only reached the upper 70s for highs
Saturday afternoon and it looks like we`ll have similar conditions
this afternoon and early this evening. Typically in this type of
pattern, these sites would easily reach into the 100s in the absence
of smoke.
The water vapor image shows high and mid level moisture moving north
along the California/oregon coast. At the same time the visible
image shows cu starting to build over the Warners and higher terrain
in Fire zone 285 and points south and also in portions of Fire zone
624. On a bigger scale, cu is developing and building over the
Sierra Nevada crest and northwestward in east to northeast
California. The latest HRRR model shows some returns late this
afternoon and evening in southeast Siskiyou county and portions of
Fire Zone 285. Currently we have a slight chance for thunderstorms
mainly over the higher terrain in Siskiyous, but could not rule out
a strike or two in parts of Fire zone 285, so we`ll had a slight
chance there.
Note: Even though we have a slight chance of thunderstorms this
afternoon and evening, there`s a chance the smoke may limit the
amount of instability, perhaps enough to preclude thunderstorm
development altogether, this is especially the case in Siskiyou
County.
Tonight, east to northeast winds will develop over the upper slopes
and ridges of the Coast Range in Curry and western Josephine
Counties and also portions of western Siskiyou County. They`ll be
gusty at times and combined with poor humidity recovery will cause
critical fire weather conditions. Thus the Red Flag Warning remains.
The models also suggest Red Flag warning could be met in portions of
Fire Zone 621 including the Miller Complex. Overnight relative
humidities will be low enough. It will be a close call on the wind.
However there`s a higher concern for winds to exceed criteria near
and above 4000 feet. Given the sensitivity of the situation, we`ll
lean on the side of caution and issue a Red Flag Warning to include
portions of Fire Zone 621.
With the upper ridge overhead east of the Cascades on Monday, dry,
unstable conditions will develop there resulting in the potential
for plume-dominated fire with any existing fires. Therefore we have
upgraded the Fire Weather Watch to a Red Flag Warning for fire
weather zone 624 for this potential including the Jade Creek Fire.
Details on all the Red Flag Warnings can be found at RFWMFR.
The models have backed off on the thunderstorm potential late Monday
afternoon and evening. Moisture and instability are marginal at best
and there is little or no trigger. Also if the smoke remains thick
enough, this will also limit the amount of instability further.
Therefore have removed them from the forecast.
There is a slight chance for thunderstorms in northern California
and up the Cascades Tuesday afternoon and evening, but I don`t have
a good feel of where or if any storms will develop.
Wednesday afternoon through Wednesday night could be problematic in
terms of thunderstorms. The models are in fairly good agreement
showing the remnants of Lidia getting advected into our region
Wednesday. At the same time the upper trough (remnants of Lidia)
will become negatively tilted as it moves north in response to the
upstream upper trough from the eastern Pacific. The pattern that the
models suggest could be one that could lead to a thunderstorm
outbreak from Wednesday afternoon through Wednesday night. There is
even some evidence that we could get an increase in activity
overnight Tuesday. Keep in mind this is not a slam dunk as were
still a few days out and the details on this are likely to change,
but it`s something that we need to be aware of.
The focus for thunderstorms should shift north of our area Thursday
and we will end up cooler with a few instability showers mainly west
of the Cascades. Next Friday into the following weekend could end up
cooler if the GFS is right. The ECMWF shows a cutoff low west ofthe
Bay area and a less pronounced trough which would suggest warmer
temperatures. -Petrucelli
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 2 PM to 8 PM PDT Monday for ORZ624.
Red Flag Warning from 8 PM this evening to 9 AM PDT Monday for
ORZ618>621.
Heat Advisory until 11 PM PDT Monday for ORZ021>028.
CA...Heat Advisory until 11 PM PDT Monday for CAZ081-082.
Red Flag Warning from 8 PM this evening to 9 AM PDT Monday for
CAZ280.
Heat Advisory until 11 PM PDT Monday for CAZ080.
Dense Smoke Advisory until noon PDT Monday for CAZ080.
Pacific Coastal Waters...Small Craft Advisory from 11 AM Monday to 5
AM PDT Tuesday for PZZ356-376.
$$
CZS/SBN/MAP
Area Forecast Discussion
National Weather Service San Francisco Bay Area
447 PM PDT Sun Sep 3 2017
.SYNOPSIS...The strong ridge of high pressure that brought two
consecutive days of oppressive heat to the region is exiting into
the Great Basin today. As a result, a cooling trend has begun,
however, above average temperatures will persist for the day. In
addition, remnants of Tropical Storm Lidia will begin to spread
across our region from the south today into Monday and bring a
slight chance of showers and thunderstorms to southern portions of
the region. Additional cooling is forecast on Labor Day and into
the first half of the upcoming workweek.
&&
.DISCUSSION...as of 2:00 PM PDT Sunday...Overnight low
temperatures were anything but low last night, with many
locations reporting overnight lows similar to or higher than
their normal daily high temperature. Temperatures have steadily
crept upwards from this warm start so far today for most inland
locations, with triple digit readings already coming in from the
deepest inland locations. Despite this heat, temperatures inland
are generally 3-8 degrees cooler than yesterday. Closer to the
coast, temperatures are generally 15 to 35 degrees cooler than the
same time yesterday. For example, Linda Mar is 33 degrees cooler
(112 vs 79) versus the same time yesterday. Despite this cooling,
temperatures are still 5-20 degrees above normal today, thus, an
excessive heat warning remains in effect for higher elevation
locations and a heat advisory remains in effect for all remaining
lower elevation locations through the end of the day.
The high pressure ridge responsible for the last two days of
oppressive heat is now transitioning out of the area and into the
Great Basin. To the south, the remnants of once tropical storm
Lidia is replacing the hot, dry air mass under the ridge with a
more tropical (yet cooler) air mass. The synoptic scale pattern
change will bring many changes to the local weather over the
coming days. First, the depth of the marine layer will increase
gradually which will create a reservoir of cool, moist air for the
onshore winds to advect inland. Marine stratus is not anticipated
to return on a large scale until at least Tuesday morning, if not
later. Second, temperatures will be much cooler, with the cooling
trend beginning today and persisting through the week. Near normal
temperatures will return by Tuesday, with below average
temperatures coming in for the latter half of the week. Third, the
tropical air mass will result in humid and hazy conditions and
reduced visibility (especially in conjunction with the smoke).
Finally, elevated moisture and energy will promote a slight chance
of high based convection starting over Monterey and San Benito
counties today, before spreading northward to cover most of the
area Monday afternoon through Tuesday afternoon. Nocturnal
convection may be possible on Monday night if the core remnants of
Lidia remain to the southwest as model guidance currently
suggests.
The initial mid to upper level moisture and energy on the
vanguard of Lidia`s northerly excursion from the south is
bringing partly to mostly cloudy conditions to most areas of the
Monterey and San Francisco Bay areas. KMUX radar is detecting some
minor radar returns within this band of elevated moisture,
indicative of the energy in that layer and the convective
environment that is arriving.
Numerous wildfires continue to burn across northern California,
southern Oregon, and the Sierra Nevada today. These fires are
generating a tremendous amount of smoke, some of which filtered
into the region over the last few days. The latest HRRR smoke
model suggests that we wont see much additional smoke arrive
locally through this afternoon, however, smoke from both the north
and from the east is being modeled to arrive beginning this
evening and through the night. As a result, Labor Day will see
extremely poor air quality for many locations throughout the
forecast area. Be sure to check with your local air quality
district or the California Air Resources board for more
information.
&&
.AVIATION...as of 4:30 PM PDT Sunday...Upper level low off
southern California is bringing mid and high clouds into the area
from the south. Stratus continues to stay well away from the area
and will provide another night of VFR. Models indicate increasing
mid and high level moisture Monday which could possibly bring a
few showers to the Santa Lucia mountains and the MRY Bay Area.
Vicinity of KSFO...VFR.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR. Cannot rule out the possibility of a
shower in the MRY Bay Area Monday.
&&
.FIRE WEATHER...as of 8:50 PM PDT Saturday...Very hot and dry
conditions persisted across the entire district on Saturday and
elevated overnight temperatures are expected again tonight. In
addition, expect very poor humidity recoveries in the hills
tonight with RH values expected to remain below 30 percent.
However, winds overnight are forecast to be light. Therefore, will
allow the Red Flag Warning to expire at 9 pm this evening.
Even though the Red Flag Warning will expire this evening, fire
weather concerns will continue through at least Sunday evening.
Temperatures will be trending downward starting tomorrow, but
inland areas and the hills will remain hot and dry. Also,
southerly winds will begin to increase across the far southern
portion of the district late Sunday and then across most of the
rest of the district on Sunday night. Moderate and gusty southerly
winds are expected in the hills and locally in the valleys on
Sunday night. However, relative humidity values are forecast to
increase significantly on Sunday night.
Also, increasing moisture from the remnants of Tropical Storm
Lidia will result in a slight chance of showers and thunderstorms
beginning in the southern portion of the district by Sunday
afternoon. These chances will remain across the south through
Monday morning. Shower and thunderstorm chances will then advance
northward into at least the southern half of the San Francisco
Bay Area by Monday afternoon and evening. When thunderstorm
chances first develop late on Sunday, the sub-cloud layer will
still be very dry and so conditions could be favorable for dry
lightning across Monterey and San Benito Counties. But with time
the lower levels should moisten and any thunderstorms that develop
from Sunday night onward will most likely be accompanied by
wetting rains.
&&
.CLIMATE...The following is a list of daily record high
temperatures for the next 3 days at the selected cities.
San Francisco Bay Area....Sun Sep 3
..........................Temp/Year
...............Kentfield 104/1950
..............San Rafael 104/1950
....................Napa 105/1950
......San Francisco Dtwn 92/1961
...San Francisco Airport 93/1961
.........Oakland Airport 95/1961
................Richmond 89/2004
...............Livermore 115/1950
...........Moffett Field 93/1961
................San Jose 99/1950
..................Gilroy 104/2002
Monterey Bay Area.......
.................Salinas 94/1961
.........Salinas Airport 94/1961
...............King City 103/1955
The following is a list of All-time record high temperatures for
the selected cities. Note the period of record for each individual
site will vary from one to the other.
San Francisco Bay Area....All-Time Record High
..........................Temp Date
...............Kentfield 112 Jul 11 1913
..............San Rafael 110 Jun 15 1961
....................Napa 113 Jun 14 1961
......San Francisco Dtwn 106 Sep 01 2017
...San Francisco Airport 104 Sep 01 2017
.........Oakland Airport 104 Jun 14 1961
................Richmond 107 Sep 15 1971
...............Livermore 115 Sep 03 1950
...........Moffett Field 106 Sep 01 2017
................San Jose 109 Jun 14 2000
..................Gilroy 115 Jun 15 1972
Monterey Bay Area.......
.................Salinas 106 Sep 14 1971
.........Salinas Airport 105 Sep 01 2017
...............King City 113 Sep 02 1955
&&
.MARINE...as of 4:45 PM PDT Sunday...A southerly flow will
persist over the coastal waters through Monday. Remnants of
Tropical Storm Lidia will bring a slight chance of showers and
thunderstorms to the southern waters early this week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...Heat Advisory...CAZ006-505-506-508-509-513-516>518-528>530
Excessive Heat Warning...CAZ507-510>512
&&
$$
PUBLIC FORECAST: DRP
AVIATION: W Pi
MARINE: Sims
CLIMATE: Rowe/Dykema/BAM
FIRE WEATHER: Dykema
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Area Forecast Discussion
National Weather Service Paducah KY
640 PM CDT Sun Sep 3 2017
.UPDATE...
Issued at 640 PM CDT Sun Sep 3 2017
The AVIATION section has been updated for the 00Z TAF issuance.
UPDATE Issued at 343 PM CDT Sun Sep 3 2017
Enhanced CU taking on more definition near KFAM moving SE. The
airmass has become slightly unstable in this area, with lapse
rates slowly steepening. One tiny return perhaps NW of our area.
There is some convergence in this region as well. The HRRR is not
completely in sync with placement. But it is still suggestive of
isolated shra (maybe some lightning) through early evening. An
update to the very near term portion of the forecast may be
required to add the isolated mention.
&&
.SHORT TERM...(Tonight through Tuesday night)
Issued at 239 PM CDT Sun Sep 3 2017
Still monitoring weak boundary from KOWB to KSAR for potential
very isolated convection through the evening. Until something
develops, will leave PoPs silent 10`s for now. Otherwise quiet
tonight. Breezy and quite warm Labor Day. May be near Lake Wind
Advisory criteria for some areas. Night crew can determine the
need.
Convective chances arrive with front Monday night and progress
south Tuesday, over Tuesday night and cooler with high pressure
building in. Used a GFS/EC/NAM blend for timing.
.LONG TERM...(Wednesday through Sunday)
Issued at 239 PM CDT Sun Sep 3 2017
High confidence in drier and cooler conditions for Wednesday and
into the next weekend for the extended forecast period.
Regionally blended model guidance a little warmer than expected, so
weighted toward EKD MOS, as well as the ECMWF/NAM-WRF guidance for
temperatures. Given the drier air mass, diurnal temperature will
likely remain in the 25-30 degree.
No precipitation expected through extended period. Will be
interested to see how NHC handles Irma`s track, given some of the
varied model solutions from the Canadian, GFS, and ECMWF for the
following week.
&&
.AVIATION...
Issued at 640 PM CDT Sun Sep 3 2017
A band of showers has developed along a weak surface boundary.
The showers are comfortably south of KEVV and KOWB and are
expected to dissipate this evening before reaching KCGI or KPAH.
The boundary is expected to wash out overnight as pressures lower
across the region in response to a rather strong storm system
moving southeast toward the Upper Midwest and Great Lakes. The
entire area should see light south winds developing overnight.
Winds will veer to southwest with mixing Monday morning, and will
become gusty by afternoon. Strongest winds will be at KEVV and
KOWB where gusts 20-25kts are expected.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...DRS
AVIATION...DRS
Area Forecast Discussion
National Weather Service Reno NV
356 PM PDT Sun Sep 3 2017
.UPDATE...
Low level instability associated with very warm temperatures and
weak low level boundary forcing is helping to development showers
and a few thunderstorms north into western Lassen County late this
afternoon. A few cells are also trying to develop in far eastern
Churchill County. Will update to account for some isolated
development into the early evening hours.
&&
.PREVIOUS DISCUSSION... /Issued 1259 PM PDT Sun Sep 3 2017/
SYNOPSIS...
High pressure will provide unseasonably hot temperatures and light
winds into the early part of the work week. Areas of wildfire smoke
and haze will occur as well. Moisture will increase each day
through midweek with showers and thunderstorms spreading north
across the Sierra Monday and Tuesday and then into western Nevada
Wednesday. A few stronger storms are possible Wednesday afternoon
and evening.
SHORT TERM...
For this afternoon/evening...observed and modeled soundings show a
cap to deep convection so thunderstorms are not expected. Latest
runs of high-resolution HRRR model do show a few showers possible
through this evening for Mono and Mineral Counties and near the
crest of the Sierra as far north as the Tahoe Basin.
For the upcoming work week, no change to the expected evolution
of slowly increasing moisture and atmospheric instability over the
eastern Sierra and western Nevada through Wednesday. This
evolution means the potential area for isolated showers and
thunderstorms for Monday afternoon/evening expands across Mono
County into western Mineral County and also north across the Tahoe
Basin. Storms are expected to be isolated but a few new fire
starts due to lightning are possible.
For Tuesday afternoon/evening, an offshore low becomes a bit more
of a factor and the slight chance for thunderstorms extends north
to the Oregon border and west into central NV. However, southeast
flow will still focus the best chances over the Sierra.
Wednesday looks like the peak day in terms of intensity and
coverage of thunderstorms. As the offshore low moves north along
the coast towards the Pacific Northwest, there is potential for
weak upper impulses to track north from the Tahoe Basin north
across Plumas/Lassen/Modoc/northern Washoe Counties. These
impulses could aid in developing a few stronger thunderstorms in
those counties. The south to southeast steering flow across the
Sierra, western NV and northeast CA also strengthens -- creating
an environment that increases the potential for (1) new fire
starts because quicker moving cells means less time for a wetting
rain over any lightning strikes, and (2) a few stronger storms
with up to 1-inch hail, gusty outflow winds and/or flash flooding
possible (especially over burn scars and if cells train along the
same path).
Another possible fire concern for Wednesday is breezy winds: a
late day zephyr could create westerly gusts 25-30 mph which could
fan any existing or new fire starts, especially along the Sierra
front range. JCM
LONG TERM...Thursday through Sunday...
A stable air mass is expected to begin moving in from the southwest
on Thursday, with weak southwest flow aloft bringing in drier
air. However, lingering afternoon/evening thunderstorms may still
be possible across Mono county and in western NV generally east
of highway 95. Friday and Saturday are looking to be drier as the
southwest flow continues to push moisture north and east of the
area. By Sunday, there is some indication that an offshore low
could develop and bring a return of moisture and thunderstorms to
the area. Recent model simulations have varied greatly on this
feature, and for now we are forecasting a slight chance for
thunderstorms across the Sierra and western NV for Sunday
afternoon and evening. JCM
AVIATION...
Areas of Haze and smoke from area wildfires may cause some slight
reductions in visibility, especially slantwise visibility for
landings and takeoffs. These reductions will be most prominent
late in the night and during the morning before heating allows for
smoke to mix/vent. Otherwise, VFR conditions will persist.
A general increase in afternoon cumulus is expected as moisture
works slowly northward around upper ridge. Conditions remain too
stable for more than isolated showers along the Sierra this
afternoon but instability will increase Mon-Wed with isolated
thunderstorms in Mono County Monday spreading farther north each
day. Right now Wednesday appears to be the best day for coverage
and intensity of storms.
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
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http://weather.gov/reno