Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/24/21
Area Forecast Discussion
National Weather Service Burlington VT
1048 PM EDT Thu Sep 23 2021
.SYNOPSIS...
A strong frontal boundary will shift east across northern New
York this evening into tonight, and then into Vermont Friday
morning into the afternoon. Moderate to locally heavy rain
showers will be possible as this front moves east across the
region. A showery period with seasonable conditions is expected
for the first half of next week, followed by gradual cooling and
drying conditions.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 1040 PM EDT Thursday...Frontal rain band continues to make
very slow ewd progress across the St. Lawrence Valley and
Adirondacks at 0230Z, with the heaviest rainfall continuing to
remain south of the forecast area. These trends should change
overnight as the frontal rain band shifts ewd into the
Champlain Valley, with south to north channeling of moisture and
highest PW values (around 1.7") into western VT beginning
between 06-08Z. Have adjusted rainfall amounts upward into the
Champlain Valley, with amounts 1-1.25" generally expected in the
Champlain Valley area. Remainder of the forecast is on track.
Previous Discussion...The occluded boundary that has remained
at our doorstep for the last 24 hours is finally moving east,
and a bit ahead of schedule. It`s unseasonably warm, muggy, and
breezy. The forecast logic remains unchanged. Intervals of
moderate to locally heavy rain within a narrow band of
precipitation will amble across the North Country this evening
through Friday afternoon. Efficient transport of deep tropical
moisture with strong low-level inflow and favorable right
entrance region of a jet will allow for efficient showers. The
good news is that flow remains south to southeasterly up until
the frontal passage, so it`s not life we will see moisture peel
out ahead of this, which will limit the potential for multiple
rounds of convection. There could be some subtle enhancement, as
the previous 06Z NAM and occasional HRRR run depicts two
distinct deformation bands. Overall, high res guidance is
depicting faster motions, though. This means that the boundary
should be shifting east by mid- afternoon, which will limit
convective enhancement and reduce the likelihood of thunderstorm
activity, except across the easternmost section of our forecast
area. The potential for gusty winds ahead of the boundary also
appears limited by a narrow inversion around 2500 ft above sea
level, that should prevent efficient mixing of the 55 knot LLJ
at 850 hPa. Still, higher terrain areas near and above 2500 ft
will be blowing around 40 to 50 mph. We continue to see about
0.50"-1.25" of precipitation in the forecast, with locally
higher amounts possible in training convection. Antecedent dry
conditions should preclude any flood issues, but we will
maintain a close watch.
During the day on Friday, a non-diurnal temperature trend will
unfold as the dry slot beneath the upper low advects into our
area. Some areas might have their high temperature around
midnight, as cool air behind the occluded boundary shifts into
the region during the day. On Friday afternoon, temperatures
should climb at least into the mid 60s to lower 70s beneath the
south-southwesterly flow. Most areas will dry out, but some lake
effect rain showers are possible in southern St. Lawrence
County for a brief interval perhaps migrating into portions of
Franklin County, NY. It appears short-lived with a gradual decay
after sunset. Friday night lows will be in the 40s to mid 50s.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 311 PM EDT Thursday...Southwest flow aloft will exist
over the area on Saturday with developing upper trough over the
Great Lakes. Looking at a nice day overall with no precipitation
expected and high temperatures in the mid 60s to lower 70s. The
dry conditions will continue with high pressure over the area
Saturday night. Lows will generally be in the mid 40s to mid
50s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 311 PM EDT Thursday...Overall idea in the extended
forecast period...Sunday through Thursday...is for an upper low
or upper trough to develop over the region. At this time it is
looking like the upper system will be over the area in the
Monday time period and this may be our best chance for showers
before the upper system becomes established to our south and
east for the remainder of the period. In this scenario the best
forcing would also be south and east of the area. So have
trended with some lower precipitation with mainly dry conditions
or just a slight chance for showers. High temperatures through
the extended period will generally be a few degrees below
seasonal normals.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...Cold front will cross the region quite
slowly over the next 24 hrs. Will have showers as the front
pushes eastward, but much of the time conditions will remain
VFR. May see brief MVFR visibilities and possibly ceilings.
Winds will remain gusty out of the south ahead of the frontal
passage. Showers will slowly track eastward through northern New
York during the overnight hours and across Vermont on Friday
morning. IFR cigs are possible at KSLK and KMPV during this
time. After 12z, cigs will lift from west to east as skies clear
in the wake of the front. Strong wind gusts will continue
through late tonight, though expected to become less frequent. A
low-level jet will develop overnight, and low-level wind shear
is again expected tonight as surface gusts diminish from west to
east. Turbulence is also expected, especially around higher
terrain. Winds will begin to shift from the SW in the wake of
the cold front and decrease to less than 10 knots. This will be
the case for all terminals after 12z.
Outlook...
Friday Night: VFR. Slight chance SHRA.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Slight chance SHRA.
Sunday: VFR. Chance SHRA.
Sunday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Monday: Mainly VFR, with local IFR possible. Slight chance SHRA.
Monday Night: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Tuesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
&&
.MARINE...
South to southeast winds 15 to 25 knots, with some occasional
gusts up to 30 knots, will continue tonight into early Friday
morning. Winds will decrease Friday morning once moderate to
locally heavy rain begins once a frontal boundary moves
through. Winds will be under 15 knots after the frontal passage
midday Friday. Waves 1-3 feet today will build to 2-4 feet
tonight, then diminish back to 1-3 feet Friday afternoon.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Haynes
NEAR TERM...Banacos/Haynes
SHORT TERM...Evenson
LONG TERM...Evenson
AVIATION...Neiles
MARINE...Duell
Area Forecast Discussion
National Weather Service Caribou ME
1028 PM EDT Thu Sep 23 2021
.SYNOPSIS...
High pressure will slowly move east of Nova Scotia through
overnight. A cold front will approach the region from the west
Friday night and slowly move across the region into early
Sunday. Low pressure over the Atlantic will move east of the
region on Sunday. An upper level trough will cross the region
from Quebec on Monday and Tuesday. On Wednesday high pressure
will approach from the west.
&&
.NEAR TERM /THROUGH FRIDAY/...
1010 PM Update...
Pops and wx elements were adjusted to fit the latest radar
trends holding back the showers to the sw. Decided to push back
on the timing of showers into northern and western areas til
daybreak. Temps have cooled off into the 60s across the CWA.
Low clouds push up from the into the Bangor and Downeast region
per latest Microphysics satl imagery. The latest RAP and HRRR
bring low clouds further n overnight. Made adjustments to match
w/this assessment and brought thicker clouds up into ne areas
after about 2 AM. Also backed off on the timing of the fog by a
few more hrs. Rest of the forecast looks in line.
Previous Discussion...
High pressure east Nova Scotia is directing the flow off the
Gulf of Maine into Eastern/Northern Maine. This has caused an
increase in moisture with it feeling muggy across the FA today.
Expect areas of fog to develop over the waters and push into the
Downeast coast this evening. Patchy fog will develop over the
Highlands mainly southeast of the Longfellow Mtns and Katahdin
region. A large trough over the Great Lakes combined with an
Upper-Level low Northwest of Bermuda is directing an Atmospheric
River over western New England tonight. The trough over the
Great Lakes is lifting northeast slowly and tilting negatively.
At the surface a front will be pushing into the Champlain Valley
of Vermont. As moisture increases tonight with surface lift
expect a chance of showers to develop overnight. Best chances of
showers will be across southern & western zones. As the front
slowly pushes east tomorrow the funnel of moisture will increase
over western zones. Showers will increase to be scattered and
widespread during the day. Low-level jet increases and expecting
decent mixing so breezy southeast winds will develop. Expect 15
to 25mph wind gusts especially across the higher terrain.
Temperatures will increase into the upper 60s to low 70s thanks
to +15 to +17C 925mb temperatures pushing into the area. There
will be a few sunny breaks in the morning but not expecting much
sun during the afternoon. As those heavier showers to our west
get closer cannot rule out some isolated thunderstorms with just
a slight amount of instability. This would be mainly right
along our border with GYX CWA.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Models are starting to come into slightly better agreement on
the short term. Southeasterly flow will continue to bring a good
slug of low-level moisture ahead of the front. This should
enhance rainfall across the southern portion of the forecast
area initially. Friday night, some instability leads to showery
precipitation ahead of the front; however CAPEs are limited, so
am not expecting any thunderstorms as the front approaches.
Saturday afternoon may provide a brief break in precipitation
but skies will remain cloudy. As the upper level low shifts
closer to the area Saturday night, a surface boundary will
develop offshore, bringing another round of precipitation. The
models have not been in good agreement on how much rain is
expected with this second round. The potential of a surface low
developing offshore seems to be throwing a wrench in the works
with how much precipitation makes it onshore. Current thinking
is that southeasterly flow ahead of the developing low on Sunday
will provide some additional moisture, especially with upslope
flow over the mountains in the central portion of the state.
With warmer temperatures aloft and widespread upslope flow, this
should be more stratiform in nature, lingering through Sunday
into Sunday night. QPF amounts are still somewhat in question,
as it depends on how much enhancement from upslope flow occurs.
Current forecast brings widespread 0.5 to 0.75" Saturday night
and Sunday, but this may be a conservative amount.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
After Sunday, the forecast remains unsettled through the early
part of next week. Depending on how quickly the precip band
moves off to the east, precip may linger through Monday
afternoon for the eastern portion of the forecast area. On
Tuesday, the upper level low will pass off to the north. This
has the chance to bring some precipitation across the Crown of
Maine mid-week, but the track of this upper low is not very
clear at the moment, so forecast is just for a slight chance of
showers. Behind this low, high pressure will begin to build in,
bringing better weather for the end of the weak. Cooler
temperatures aloft are behind this low as well, so expect a
return to more seasonable night time temperatures for the end of
the month.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: Generally VFR through midnight. VFR cigs drop to
MVFR/IFR this evening with fog developing. A chance of showers
through the night. Winds S-SE 5-10kts. After midnight all
remaining sites cigs fall to MVFR/IFR. By daybreak cigs fall
to IFR/LIFR with fog/showers at BHB & BGR. Elsewhere, chance of
of showers with the low cigs. Tomorrow IFR/LIFR improves to low
end MVFR through late morning. MVFR with a chance of showers
becoming showers likely by late day. SE winds increasing
10-20kts with some gusts to 25kts possible.
SHORT TERM:
Friday night...MVFR becoming IFR in SHRA from W to E. SE winds
gusting to 20 knots at PQI/CAR/FVE. SE winds less than 10 kts
elsewhere.
Sat...MVFR early at BGR, BHB, HUL, becoming IFR by afternoon.
Light southerly winds.
Sat night and Sun...LIFR in -RA for all sites, lifting to MVFR at
BGR/BHB by Sunday afternoon. Light southerly winds.
Sun night...MVFR becoming VFR at BGR/BHB. MVFR tempo IFR in -RA all
night at HUL/CAR/FVE. Light westerly winds.
Mon and Monday night...VFR conditions south, MVFR lifting to VFR
Monday morning for the north. Light winds.
&&
.MARINE...
NEAR TERM: Winds/seas below SCA through early morning. By late
morning expect wind gusts to reach SCA levels with seas
increasing to low end SCA criteria. SCA in effect for the waters
from 11am through the end of the period.
SHORT TERM: Winds will drop below SCA Friday evening, but seas
will remain above 5 feet through midnight. On Saturday, seas
will begin to increase later in the day as some longer period
swell moves in from the south. Seas will reach 6 feet by Sunday
night, then gradually decrease through Tuesday.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory from 11 AM Friday to 5 AM EDT Saturday
for ANZ050>052.
&&
$$
Near Term...Hewitt
Area Forecast Discussion
National Weather Service Grand Rapids MI
1012 PM EDT Thu Sep 23 2021
LATEST UPDATE...
Marine
.SYNOPSIS...
Issued at 217 PM EDT Thu Sep 23 2021
- Diminishing rain and wind this evening
- Thunderstorms possible Friday evening with heavy rain and gusty
winds
- Drying out for next week
&&
.DISCUSSION...(This evening through next Thursday)
Issued at 217 PM EDT Thu Sep 23 2021
- Diminishing rain and wind this evening
The low pressure system centered near Detroit will lift slowly north
northeast into tonight. The pressure gradient will gradually weaken
across the CWA during that time. Also the mixing height will be
lowering during the evening. As a result the wind will become less
gusty and the sustained values will be lowering through the night.
We will likely hold onto some light rain/drizzle into the
evening...but as the low pulls away the moisture depth and lift will
diminish leading to conditions drying out. Models are in relative
agreement in showing no precipitation in the CWA after 09z.
- Thunderstorms possible Friday evening with heavy rain and gusty
winds
Models are in decent agreement in showing no precipitation for
Friday...through 00z Sat. Then the cold front pushes in for the
evening and overnight period. The main signal in the models is for
a band of more than a half inch of rain with some area potentially
seeing more than an inch. The southwest flow seems to be favoring
the Muskegon to Fremont to Big Rapids region for the heaviest rain.
Soil conditions are relatively dry in those locations so this should
result in no impacts other than some ponding of water near any
clogged drains. Some instability will be present along the frontal
zone and higher surface theta e values coming off of Lake MI could
support better instability closer to the lakeshore. The HRRR and
Namnest have been showing a risk for gusty winds around the frontal
zone. This seems reasonable given the strengthening temperature
gradient and winds at 850 mb as the front enters MI.
- Drying out for next week
The Gulf moisture stays to the south and west of the CWA next week
as a sharp mid level ridge develops just west of the MI. This
ridge is shown to stall out and continue to influence our weather
possibly into next weekend. Being on the east side of this
system...we will see subsidence and dry air advection. All this
should spell below normal precipitation. As for the
temperatures...some uncertainty exists there. Several models like
the 12z GFS and 00z High Res Euro are showing 925 mb temps
cooling off during the week. Thus a potential for gradual cooling
trend may exist. The incoming 12z Euro suggest the cooling trend
will not last long if it happens. We will start the week off with
above normal values.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 716 PM EDT Thu Sep 23 2021
We are expecting clearing to spread across our TAF sites after
06z and all TAF sites should be clear (or nearly so) by 09z.
Between then and now, conditions will slowly improve (cigs lift
and precipitation come to an end) over the next 3-4 hours.
PRECIPITATION THIS EVENING...There is band of showers over Lake
Michigan coming on shore south of South Haven at 23z, this area of
showers will slowly break up and lift north over the next 2-4
hours but while the overall area lifts northward, the individual
showers are moving south southeast. However as the large scale
system lifts northward dry air comes in from the west and up from
the south so all of the precipitation will dry up from south to
north as that happens.
WIND..With the system lifting north northeast the wind gradient
will also lift north northeast too. That will mean decreasing
winds overnight. However there is a band of higher winds on the
south edge of the mid level system lifting north with it, so in
the 2000ft AGL to 10000 ft AGL here will be a period of 30 to
40 knots winds but that should be north of our TAF sites by 09z.
Friday...Skies should be sunny most of the day and winds will turn
to the south before noon. Clouds, showers and thunderstorms return
after 00z ahead of the next frontal system.
&&
.MARINE...
Issued at 1012 PM EDT Thu Sep 23 2021
Since winds will keep waves mostly greater than 4 feet through
Saturday afternoon we have extended the small craft and beach
hazard through Saturday afternoon. Winds may be close to gale
force Friday night but it is marginal and we have warm air
advection at that point, so that decreases the risk of the winds
mixing down anyway. So, we decided for now, not to go with gales
or a gale watch for Friday night. This may yet change on the
overnight shift of on the day shift Friday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Saturday evening for MIZ037-043-
050-056-064-071.
LM...Small Craft Advisory until 8 PM EDT Saturday for LMZ844>849.
&&
$$
SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...WDM
MARINE...WDM