Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/04/20
Area Forecast Discussion
National Weather Service Caribou ME
917 PM EDT Thu Sep 3 2020
Weak high pressure builds into the region overnight while a
frontal boundary remains stalled along the coast. A cold front
will cross the region Friday. High pressure will build across
the region Saturday then exit across the Maritimes Sunday.
Another cold front could approach later Monday into early
.NEAR TERM /THROUGH FRIDAY/...
9:17 pm update: Showers with some embedded convection continues
to track northeast across eastern Hancock County and into
coastal and central Washington County. There have been a few
heavier showers with a report of 3/4" of rain near Jonesboro and
1/2" east of Machias this evening. The showers are along and
just north of a stalled out frontal boundary along the Maine
coast. It will remain quite muggy overnight along the coast with
dew points in the 60s and areas of fog. To the north, there are
a fair amount of mid levels north to Houlton, except across
northwest portions of the FA where it is clear to partly cloudy.
Made some minor adjustments based on the latest observations
and radar trends.
Clouds will thicken up tonight across the Downeast areas w/the
northern edge of the thicker clouds making their up in SE
Aroostook County per the 12Z NAM & RAP along w/the HRRR. The NBM
wanted to bring thicker clouds all the way up into northern
Maine w/85% coverage. This looked too aggressive and decided to
push back the northern edge to Patten and Houlton. There is a
stalled boundary along the coast and a disturbance is expected
to ride up along along the boundary this evening bringing some
showers and possible tstms. The 12Z UA showed a 40 kt jetstreak
residing in the lower OH Valley this morning. This feature was
picked up well by the RAP/NAM and HRRR and show this feature
pushing up into New England later this afternoon into the
evening aiding in the showers. Sounding data showed some MU CAPE
of 200-300 joules across Downeast pushing n into northern
Washington County and SE Aroostook County. Areas n and w of
those areas will remain dry. There is decent shear of 35 kts
w/PWS > 1.5 inches. So, convection is possible w/potential for a
cell or two to dump heavy rainfall and brief gusty winds. This
area of rain and isolated convection should move through fairly
quickly w/this area of rain reaching into NB by around 4 AM
Friday. Rainfall amts will be highest along the immediate coast
where >/= 0.25" is possible especially in any tstms. Due to wet
ground from last night`s rainfall and some more possible along
w/winds letting up and some cooling, fog will be a threat w/the
highest threat from Millinocket-Houlton region to the coast.
A cold front is forecast to slide across the region during the
day on Friday. A pre-frontal trof slides out ahead of the
boundary during the morning hrs on Friday. There is some forcing
aloft to support showers along the immediate coast, but the
atmosphere above 850mbs looks dry. So, any showers will be
isolated at best. Otherwise, SW winds will be increasing out and
veer to the W as a cold front slides across the region w/a
healthy 30-35 kt llvl jet. Sounding data does support gusts to
apch 25-30 mph across the open and higher terrain. The strongest
winds will be across the northern 3rd of the CWA. It will be
another warm day w/temps in the 70s to around 80F. Given the
warm temps and cold ocean water, a Beach Hazard was issued for
Friday for the entire coast.
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Stiff 250mb jet of around 130 kt will be overhead come Friday
night. The SW flow extends from aloft into the mid levels,
turning westerly in the lower levels. Because the longwave
trough is so broad, the westerly flow will actually bring in a
good deal of CAA overnight with lows expected to be around 10
degrees cooler than Thursday night. This passes along to daytime
high temps as well. Across the north, some cu will develop with
moisture pooling around 800mb. Given the CAA and instability,
chose to continue bringing in the chance of some rain showers
during the afternoon. The setup is reminiscent of a late Aug day
when there was one report of small hail in PQI with small
convective showers. The environment coming up is about 5C warmer
and the freezing level about 1kft higher this time around, so
chances are slim for a similar outcome.
Showers across the north taper in the early evening with the
loss of peak heating. Sat night lows will be about the same
across the north, with more Downeast locations joining in on the
cooler night temps. A slight south component will keep moisture
and mild temps nearby. Showers are again in the forecast across
the north during Sunday afternoon. A weak shortwave will
traverse north of Maine during peak heating. Chances taper south
of Millinocket, but a stray isolated shower cant be ruled out
given the moisture in the low levels. Daytime highs creep a bit
higher, towards 70 for much of the CWA, setting up a mild
warming trend into the beginning of the week.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
With high pressure overhead Sunday night into Monday, light winds
will persist. This will lead to patchy fog across the region
Monday morning, especially along coastal Downeast. A cold front
will approach the area from the west Monday afternoon, but will
get hung up in the St. Lawrence Valley. There remains a slight
chance of showers across the north Monday afternoon and evening.
The ridging influence will return to the area Tuesday,
decreasing the threat for showers. Temperatures mid-week will be
warmer than average. Another shortwave will begin to approach
from the west through the middle of this week. This will
increase the chance for showers across the region Thursday with
the possibility of another cold front. Uncertainty still remains
with the timing and intensity of this feature.
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: LIFR at KBHB overnight with VFR to lower to IFR late
this evening at KBGR, and likely north to KHUL.N of KHUL,
conditions should hold at VFR overnight.
Friday will be VFR for all terminals. There will gusty winds in
the afternoon of 25 knots, especially for KCAR and KFVE.
Friday night through Sun Night...Generally VFR. Slight chance
of afternoon showers across northern areas Saturday/Sunday.
Light SW winds, otherwise gusting to 15 kt during the afternoon.
Mon through Tues...VFR, except for MVFR/IFR in patchy fog near
northern valleys and coast Downeast Mon AM. SW wind shifts S
gusting to 20 kt during the afternoons.
NEAR TERM: No SCA expected. S winds less than 10 kt tonight
become SW on Fri and increase to 10-15 kt. Seas around 4 ft
will drop to 3 ft during the day on Fri.
SHORT TERM: Wind and waves below SCA through the period. Waves
will fall to 2 to 3 ft with light SW winds through Sunday,
shifting S Mon and Tues. Some patchy fog will be possible Monday
The high this afternoon in Caribou was 80F. This makes the 55th
day this year with a high of 80F or warmer in Caribou. The
previous record of 51 days was set in 1999.
ME...Beach Hazards Statement from 8 AM EDT Friday through Friday
evening for MEZ029-030.
Area Forecast Discussion
National Weather Service Glasgow MT
Issued by National Weather Service Billings MT
852 PM MDT Thu Sep 3 2020
Only minor changes for the evening update. Added areas/patchy
smoke to the forecast overnight as last visible imagery showed
smoke over the area, and KOLF reported 3SM HZ at 02Z. HRRR Smoke
model supported areas of smoke near the Huff Fire as well.
Adjusted cloud cover to increase it a bit due to the NW-SE jet
over NE MT. Also lowered temps slightly in some areas to line up
better with latest NBM. Arthur
Northeast Montana is now behind the cold front that arrived
overnight. A dry northwesterly or westerly flow aloft will control
the weather pattern here for the remainder of this week. Cooler
temperatures today will gradually climb back into the 90s by
Saturday. It should be noted that borderline fire weather concerns
may rise again for Saturday afternoon. Humidity will drop to 10
to 15 percent. Winds may be in the 10 to 15 mph range. Some
stronger winds are aloft in the model data, but it remains
uncertain if they will be able to be pulled down to the surface
for stronger surface winds. Neighboring office to our south wants
to get an early start on a fire weather watch for that timeframe.
Chose not to join them yet in order to get a bit more confidence
of conditions setting up for that day. Keep an eye on this and
reconsider for the next few shifts.
Another forecast challenge will focus on the next strong cold
front and organized precipitation taking shape from Sunday
afternoon through Tuesday afternoon. A cold extension of the
Hudson Bay low pressure trough, will quickly drop south from the
Canadian Rockies, all the way through the US Rockies, stopping at
the 4-corners region by Wednesday.
The resulting impacts for northeast Montana seem to include more
active and organized precipitation chances - especially Sunday
night through Tuesday morning. Models are beginning to depict a
band of NW to SE frontal precip that eventually expands to cover
the entire region in some decent rainfall accumulation. The EC
dries out quickly, but the GFS and the CMCnh fall in this wetter
On the trailing edge of this storm system, it should be noted that
low temperatures for Monday night / Tuesday morning are forecast
to be cold enough to allow a rain and snow mix, primarily on
Tuesday early morning, from midnight to around 9 AM. Obviously the
ground temperatures are expected to not allow any of this to
stick for snow accumulations (which would be very light anyway).
So, the forecast snow fall amount for this timeframe in the
forecast grids may not represent expected accumulation of 0 snow,
but for now, chose to leave it there to show next shifts where we
feel the best chances are for snow to mix in with the departing
Tuesday night and beyond, a dry pattern returns as temperatures
moderate warmer again.
VFR will prevail across the area tonight through Friday. Some
reduction to MVFR in smoke is possible overnight in the CIGS and
VSBYS. Surface winds will become gusty from the NW in KSDY on
Fire Weather Watch from Saturday afternoon through Saturday
evening for MTZ137.
Area Forecast Discussion
National Weather Service Wichita KS
946 PM CDT Thu Sep 3 2020
...Late Evening Forecast Update...
Issued at 944 PM CDT Thu Sep 3 2020
As of 9pm, the SFC cold front continues to slowly progress south
into northern OK. Meanwhile, satellite imagery and RAP analysis
suggests the upper level (850-700mb) front is just now approaching
southern KS. Lingering moisture/lift within the sloped frontal
boundary appears to be responsible for continued, and expanding, low-
level clouds across southern KS. Still have yet to see any showers
or thunderstorms develop ahead of the upper front, but short term
guidance continues to suggest at least some potential for
development before the frontal zone fully clears KS. The forecast
was updated to reflect these recent trends. Shear is very weak,
with only modest instability (1000-1500 j/kg MUCAPE), which should
keep the threat of strong/severe weather very low.
.SHORT TERM...(This evening through Sunday night)
Issued at 308 PM CDT Thu Sep 3 2020
The main challenge for the short term will be the speed and
intensity of the CAA this afternoon as a weak cold front moves
through the region. This cold front is currently moving through
Central Kansas this afternoon and slowly progressing to the south
and east. Moisture transport ahead and along this front is rather
weak and the short range models are in agreement that chances for
showers or thunderstorms with this front is rather small. Only
Eastern and Southeastern Kansas will have a slight chance at a
stray shower. The CAA behind the front is rather weak but the main
change will be the drier air that will be coming into the region
as well. Winds will kick around to the north for the afternoon and
the overnight. This will allow temperatures to retreat toward
normal for tonight and into Thursday.
Friday and Saturday, ridging will start to build back into the
region and southerly winds will once again return. Friday`s
temperatures are likely to remain near normal as it will take some
time for the dry air to be replaced by the more humid air that
will be advecting back into the region. Moisture transport will
slowly increase Friday night and through Saturday. This increase
in moisture transport will continue through the weekend as the
ridge builds into the region. The ridging will allow temperatures
to rise and be rather warm for Saturday. This ridging will also
keep the precipitation chances down with strong subsidence in the
.LONG TERM...(Monday through Thursday)
Issued at 308 PM CDT Thu Sep 3 2020
The extended range continues to look rather quiet with strong
ridging dominating the region. Sunday will be rather warm and
likely to be above normal. Moisture transport will be on the
increase as the next weather system will begin to approach the
region. Unlike the weak frontal system that came through today,
this frontal system is expected to be much more powerful. The
ECMWF remains the only model that slows this frontal system down
as it approaches and keep the area in the warm sector longer. The
GFS and Canadian families remain more progressive and bring the
front through the region Monday afternoon and evening. The CAA
behind this front is much stronger and temperatures are expected
to drop significantly and are likely to be below normal through
the remainder of the extended range. On the precipitation side,
all the long range models are pointing to a decent rain event. The
orientation of the front with the upper level winds is not very
conducive to severe weather. The amount of the low level moisture
advection, mid level shear and frontal forcing lends toward a good
chance for showers and thunderstorms. Confidence is increasing
for a significant cool down with a decent rain event next week.
Additionally, with the ECMWF shifting more toward a GFS solution,
confidence is also increasing on the timing.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 632 PM CDT Thu Sep 3 2020
* Mostly VFR conditions expected over the next 24 hrs
A cold front continues to sag south through southern Kansas at this
time. A narrow zone of SCT/BKN cumulus clouds has accompanied the
front, but thus far, no SHRA or TSRA have developed. Still cannot
rule out an isolated SHRA/TSRA across far southern Kansas through
early this evening, but the threat looks very low. Behind the front,
gusty N/NE winds will continue for another few hours, especially
southern Kansas. This evening`s front will return north tomorrow,
with S/SE winds developing once again. For now, we expect the
daytime hours to be dry, but FEW/SCT afternoon cumulus are
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 64 90 68 92 / 10 0 10 0
Hutchinson 57 86 65 91 / 10 0 10 0
Newton 58 86 65 90 / 10 0 10 0
ElDorado 60 85 66 89 / 10 0 10 0
Winfield-KWLD 65 86 67 89 / 10 0 0 0
Russell 55 89 66 93 / 10 0 10 0
Great Bend 55 87 65 92 / 10 0 10 0
Salina 56 89 66 93 / 10 0 10 0
McPherson 56 86 63 92 / 10 0 10 0
Coffeyville 64 87 65 89 / 20 10 0 0
Chanute 60 86 63 89 / 20 0 10 10
Iola 59 86 63 89 / 20 0 10 10
Parsons-KPPF 62 86 65 88 / 20 0 0 0
Area Forecast Discussion
National Weather Service Reno NV
1240 PM PDT Thu Sep 3 2020
Strong high pressure will bring well above average temperatures
with record highs likely through the Labor Day weekend.
Substantial cooling and breezy winds are possible next week.
Areas of smoke and haze from area wildfires will filter back
across the eastern Sierra and western Nevada for the next few days
as light afternoon and evening westerly breezes prevail.
* Heat: The heatwave is upon us, lasting through Monday. Very
impressive signals for extreme temperatures in ECMWF EFI across
much of Nevada and California this coming weekend. Given the
likely consecutive record temperatures including in mountain
communities, we`ve issued a blanket Heat Advisory for all zones
Friday through Sunday. These are the days where we have the
highest confidence in unusual heat, however Monday could be
close too. Night time temps will cool but not a ton, and even in
the mountains where 40s/50s are likely, people may not
necessarily be able to take advantage due to smoke/haze
lingering in the air.
* Smoke: Residual smoke and haze has been slow to clear today with
almost zero transport flow, relying solely on vertical mixing.
Should still see improvement by late afternoon but this is a low
confidence scenario with minimal winds. HRRR Smoke models show a
similar evolution tonight compared to last night, with plumes
from Quincy-area and Slink fires pouring east/southeastward by
Friday morning. So another day with reduced air quality from
smoke likely, with (gradual) improvement in the afternoon.
Probably a repeat of that Friday night into Saturday assuming
continued active fire behavior.
* Winds: Models trending to that cold front scenario for Monday
into Tuesday. This would bring breezy NW-NE winds with potential
for areas of critical fire weather each afternoon. Airmass
behind the front is super dry so widespread poor night
recoveries + single digit RH in the afternoons is feasible.
Still not a done deal with some models keeping the ridge more in
place. Example: NBM max temperature ranges for Tuesday at RNO
77-90. Could be a nice cooldown for mid-late next week compared
to what we`ve been dealing with, and assuming no new large fires
the wind shift should clear air out around the Sierra and W
Nevada for next week.
* Plan for more smoke and haze from the North Complex for KRNO
and locations north of Highway 50. KMEV and KTVL may continue to
see smoke impacts from the Slink Fire. Visibility should remain
VFR, but brief drops to 5SM at times will be possible near KMEV
* Weak late afternoon zephyr wind will return around 00Z today
with peak gusts 15-20 kts. Hot, dry and smoky conditions will
continue through the holiday weekend. Severity of smoke impacts
will depend on fire activity and suppression efforts. Breezy
west- southwest afternoon winds (G15-20 kts) will occur each
afternoon through the weekend. -Edan
* Hot and dry conditions will persist and worsen through the
holiday weekend along with low RH and poor overnight recovery
forecast for mid slopes and ridges. Winds will remain relatively
light with a weak zephyr likely to continue through the weekend
with peak gusts 20-25 mph. Could see localized critical wind and
low humidity in far NE California and NW Nevada.
* By Sunday afternoon and possibly Monday, an isolated
thunderstorm or two is possible if enough instability can build.
Chances remain 10% or less at this time. Late Monday and into
Tuesday, a cold front moving through the Great Basin will allow
winds to increase from the west to northwest. The majority of
the cooling will be across the eastern Great Basin, so the
chances for Red Flag conditions along the Sierra Front will be
20% or less at this time. Winds will become northeast behind the
front with locally gusty conditions over the Sierra. -Edan
Strong high pressure will bring well above average temperatures
through the Labor Day weekend with some records likely. Here are
the records and expected high temperatures for the area climate
* Current record highs and forecast highs for the Reno Airport
(records since 1893):
Sept. 3: 101 (2017) / 99
Sept. 4: 100 (2017,1988) / 103
Sept. 5: 99 (2017) / 102
Sept. 6: 96 (1944,1988) / 101
Sept. 7: 95 (2018+more) / 100
* Current record highs and forecast highs for South Lake Tahoe
(records since 1968):
Sept. 3: 88 (1988) / 87
Sept. 4: 94 (1988) / 92
Sept. 5: 94 (1988) / 91
Sept. 6: 92 (1988) / 89
Sept. 7: 90 (1988) / 88
For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
936 PM EDT Thu Sep 3 2020
A cold front will approach us tonight and arrive on Friday,
bringing significantly drier air for the Labor Day weekend.
Showers and thunderstorms will return by the middle of next
.NEAR TERM /THROUGH FRIDAY/...
As of 936 PM EDT Thursday...
Continued making reductions in pops to reflect radar and model
trends. HRRR and Namnest showed the diminishing convection this
evening with the loss of solar heating. Highres models indicated
that a few showers may linger in the western mountains overnight.
As of 820 PM EDT Thursday...
Made some minor adjustments to temperatures for this evening
into tonight utilizing the latest surface obs and blended in
NBM. A couple of lines of scattered showers and a few
thunderstorms will move east across the region tonight. With the
loss of solar heating expect this activity to slowly diminish.
Modified pops with latest radar images and their trends,
capturing the storms developing in the east. More changes later
As of 200 PM EDT Thursday
There is a broken line of showers along a slanted axis that is just
about to enter our WV counties. None of them has looked strong or
tall, and lightning strikes are far and few between. As they enter
an area of increased instability helped along by strong daytime
heating (Roanoke had already hit 90F as of 1PM) as well as some
upslope effects, these storms may strengthen a bit in our area.
Given their unimpressive organization and appearance, there is less
confidence that storms and showers will pass the Blue Ridge and
impact the Piedmont area. Downslope on the east side of the
mountains will likely weaken them and perhaps kill them off
entirely. Most of the CAMs tend to agree on a weakening or
dissipation of convection on the east side of the Blue Ridge.
The upper mini-trough that is driving these storms is moving quite
quickly, making the system progressive, and thus making the flood
threat minimal. There is a small chance that some of these storms
could reach severe strength, but the largest threat for severe
weather is further to our northeast close to the Delmarva. Winds
have already begun to pick up, and expect gusts of 15-25 MPH to
continue into the evening. Once nighttime arrives, expect any
ongoing convection to dissipate rapidly on Thursday.
Overnight the predominant flow becomes northwesterly again,
accompanying a drier air mass`s arrival. Overnight lows on Thursday
will be in the 60s/low 70s. On Friday a front will be pushed through
our area by a broad trough over Canada, drying us out further and
cooling things down considerably for Friday night. The frontal
passage Friday will kick up some isolated showers across the area,
especially in the mountains to the west, but coverage will be meager
in comparison to Thursday.
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 100 PM EDT Thursday...
A good and much needed extended break in the weather for the weekend
expected! High pressure builds in after Friday`s front, ushering in
cooler and drier weather to give a fall like feel. High temps
transition to maxing out in the 70s out west and 80s east. Lows will
generally be in the 50s, with some upper 40s occuring in valleys
west of the Blue Ridge. Dew points remain below 60 through the
weekend, with areas east of the Blue Ridge achieving mid 40
High pressure starts to break Monday with a trough digging into the
central U.S. While this starts to occur, it looks like we remain
dry for one more day. Temperatures start to push past the mid 80s
out east with 850 temps pushing near/past 16C.
High confidence in short range forecast.
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 100 PM EDT Thursday...
Upper level high begins to settles over the Carolina`s, down into
the southeastern U.S. for the middle of next week as surface high
from earlier in the week breaks. This will usher back in a warmer,
summer time like pattern. 850 temperatures are set to warm to +16 to
near +20 degrees by the end of the forecast period.
Return flow from the SW will open us back up to a more humid,
unstable airmass. Standardized PWAT anomalies climb to ~1.5
deviations above normal by Thursday afternoon. This means that
isolated to scattered storms that develop Wednesday and especially
Thursday will be heavy rainfall generators. While there`s certainly
room for change, guidance points to an in-situ wedge developing late
Thursday into Friday after a shortwave passes through the area.
Medium confidence in long range forecast.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
As of 735 PM EDT Thursday...
VFR conditions will prevail this evening into tonight, with the
exception of any sites that receive convection this evening. A
broken line of showers and a few thunderstorms from Covington
to Tazewell at 23z will move east tonight. This will lower cigs
and visibility temporarily as the line of storms passes
through. IFR conditions at KBLF will improve once the line of
storms moves east. A few storms are possible the next couple of
hours in the piedmont, but are less likely at TAF sites of KLYH
Overnight into Friday will be largely VFR, with the exception of
BLF and LWB, who will have MVFR/IFR cigs. There could be some
patchy fog, but given the arrival of a drier air mass, any fog
will be limited in its impact. Friday will be widespread VFR
conditions once low clouds mix out in the morning.
After the upper disturbance makes its way out of the area this
evening into tonight, winds will veer back to a northwest flow
and settle down to 5-10 KT.
Moderate confidence in ceilings,visibilities and winds during
the taf period.
.Extended Aviation Discussion...
Friday will be another day with MVFR thunderstorms along a cold
front that will pass across the area. VFR conditions are
expected Friday night through Sunday aside from late night fog.
Sub-VFR conditions are expected early next week as moisture
returns for diurnally driven showers and storms. Better coverage
for storms midweek.