Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/26/21
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
537 PM CDT Mon Oct 25 2021
.AVIATION...
Southerly winds overnight will be around 15 knots. South to
southwest winds will pick up by late morning into the 25 to 30
knot range with higher gusts. Any low clouds tonight are expected
to remain east of the TAF sites. VFR conditions are expected to
prevail through this forecast.
&&
.PREV DISCUSSION... /Issued 256 PM CDT Mon Oct 25 2021/
SHORT TERM...Tonight through Tuesday Night...
High pressure over the central CONUS will amplify with enhanced very
warm southwest flow heading into Tuesday. As a result high
temperatures will be in the 80s to lower 90s yet again. Record
highs not currently forecast, but will not rule that out as models
have trended cooler than the actual highs in this mid fall warm
pattern. While there is a stacked jet, it doesn`t appear to
perfectly overlaid for the best wind potential, as the stronger
winds aloft tend to be displaced slightly to the west. Right now
sustained winds look to be in the 25 to 35 mph range across the
western 3 stacks of counties in the Panhandles with maybe 35-39 mph
winds in the far northwest Panhandles. Right now gusts look to be
around 40-45 mph. Dryline expected to setup east of Amarillo and
progress into Oklahoma later Tuesday evening. East of the dryline
will have plenty of dynamics for Severe Weather. The main question
will be if the cap hold and keeps storms from forming in the easter
TX Panhandle, or if we manage to get some supercells develop over
the eastern counties. It really has been a toss up between the
models. ML CAPE values just east of the dryline expected to be in
the 1800-2200 J/kg range with 0-1 and 0-3km SRH values exceeding
250m2/s2. All hazards will be possible with storms that form, again
it will just be if storms manage to form in our area or just east of
the Panhandles. Max hail looks to be in the 2" range with wind gusts
up to 70 mph and can`t rule out a tornado. Overall the only model
that suggest storms to form in our area has them as elevated storms,
so it`s a very low chance that tornados will occur. If the storms
are surface based, then "yes" the chances of a tornado will be much
more likely. The storm time looks to be in the 6 to 9 pm time, if
they even occur. West of the dryline we can expect elevated to
critical Fire Weather conditions (See Fire Weather Discussion). Cold
front behind the system will move through overnight on Tuesday night
with windy conditions expected to follow through into Wednesday.
Weber
FIRE WEATHER...Tuesday...
Elevated and critical Fire Weather expected on Tuesday as warm and
dry southwest flow over the Panhandles brings minimum RH values down
in the 10-15 percent range as well as winds ranging from 20 to 35
mph. Strongest winds are expected in the west and northwest, but it
will still be breezy in the central Panhandles, which happens to
coincide with the potential for the lowest RH values. Although it
does not appear that the worst winds will combine with the worst RH
values, there will be enough of a combo to get RFTI`s of 4 to 5
across the central and western Panhandles with isolated RFTI`s of 6.
Confidence is pretty high that there will be critical Fire Weather
in the west and northwest, with elevated to maybe critical Fire
Weather in the central Panhandles. &&
Weber
LONG TERM...
Current satellite and RAP analysis depicts a mid to upper level
low sitting over northwest Vancouver Island with a high amplitude
trough extending south just off the WA, OR, and CA coastline. By
Wed the axis of this trough will be taking on a negative tilt with
the base of the trough passing through west Texas. Upstream of the
H2 trough base, will be a strong jet of 140 to 170 kts. Part of
these stronger winds at H2 will be over the Panhandles by Thursday
morning. This system will influence strong low pressure and jets
throughout the troposphere all the way down to H7 and H85. These
lower level jets will mix down helping to create strong winds not
only behind the front on Wednesday, but also a day later on
Thursday as the H5 and H7 lows strengthens over eastern OK.
For Wed, the western extent of the H7 low will be over the
western FA where the strongest northerly winds will be. Models are
hinting at the H7 jet being upwards of 60 kts over the western OK
Panhandle and NW TX Panhandle early Wed morning. The strongest
winds aloft will of course propagate east as the low does so leaving
the eastern half to third of the FA under strong winds on
Thursday afternoon as well. Around H85 winds will be around 40 to
45 kts. After examining Bufkit soundings confidence is high that
these higher winds aloft will be mixing to the surface and adding
to the gust potential. As of right now only a Wind Advisory, not
Warning, is looking like it may be needed behind the front. With
the NBM being so low on winds have used a blend of the 90th
percentile NBM and CONSMOS for the forecasted wind speeds both on
Wednesday and Thursday.
Temperatures will be in the 60s for a high on Wed and Thu with
maybe a brief warm up into the 70s on Friday and Saturday. Also,
on Saturday the next real push of CAA will be moving down the
northern Rockies and Northern Plains. By Saturday the next cold
front will move through possibly bringing the next chance at a
good overnight freeze across much of the area. For now the NBM is
only giving overnight lows of 32 or below, for the northwest FA. By
the looks of the models this will all be thanks to an upper level
low strengthening over Manitoba and Ontario and ejecting some
Canadian air our way.
36
Fire Weather...
Early Wednesday a strong low pressure system will be introducing
strong northerly winds behind a front. A stacked jet where H7
winds will be near 50 to 60 kts will be able to mix to the surface
introducing even stronger winds than what gradient winds would be
alone. This front will not be introducing super cool air as
daytime highs will still be in the 60s. However, Tds will be low
keeping dropping RH values into the teens especially in the west.
RFTI`s will be mainly wind driven though with 20ft winds in the 30
to 40 mph range. Elevated fire weather conditions are a given
every where in the Panhandles with these winds. Critical fire
weather conditions will most likely be present for areas with very
dry fuels, mainly the western half of the combined Panhandles.
For Thursday, surface winds will still be influenced by the strong
low pressure system mainly in the east on Thursday. Winds may not
be quite strong as on Wed. However, elevated to possibly isolated
critical fire weather conditions look to be present on Thursday
afternoon.
36
AVIATION...18z TAFS...
VFR conditions will prevail at all TAF sites over the next 24
hours. Winds will be mostly south southwest 10-15kts through 15z
with winds increasing southwest 25-30kts after 15z. Possible low
cloud intrusion at KAMA and KGUY between 10-15z, but confidence
is very low, however will not rule out a BKN/OVC MVFR/IFR cig.
Right now no mention in the TAF of category changes, will defer to
future TAF packages to see if it needs to be introduced.
Weber
&&
.AMA Watches/Warnings/Advisories...
TX...Red Flag Warning from noon to 7 PM CDT Tuesday for the following
zones: Dallam...Deaf Smith...Hansford...Hartley...
Hutchinson...Moore...Oldham...Palo Duro Canyon...Potter...
Randall...Sherman.
OK...Red Flag Warning from noon to 7 PM CDT Tuesday for the following
zones: Cimarron...Texas.
&&
$$
15/77
Area Forecast Discussion
National Weather Service Boston/Norton MA
957 PM EDT Mon Oct 25 2021
.SYNOPSIS...
A developing strong coastal storm will bring the potential for
heavy rain, flooding, and damaging winds into Wednesday.
Much quieter and mainly dry weather returns Thursday into at least
part of Friday. Another system will likely bring more rain to the
region late Friday into Saturday, but it does not look near as
strong or impactful as the upcoming event. Dry weather returns
sometime Sunday and probably continues into next Monday with
temperatures averaging a bit above normal.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Made some tweaks to the forecast this evening. Tried to work
out the timing for rainfall redeveloping overnight. Thought the
time-lagged HRRR ensemble and the latest runs of the RAP were on
the correct track. Thinking the brunt of the rainfall tonight
will be after midnight. Overall instability is not the greatest.
However, the latest SPC mesoanalysis showed steep mid level
lapse rates, which is enough to keep a mention of isolated
thunderstorms in the forecast overnight.
Minor tweaks to temperatures to bring them back in line with
observed trends.
750 PM Update...
* Showers and isolated t-storms with heavy rainfall will expand
northward across the region as the night wears along
Previous forecast is on track. The vigorous upper trough over
the Eastern Great Lakes was beginning to take on a negative
tilt. This will allow for an intensifying 700 mb to close off to
our southwest and also result in rapid cyclogenesis off the
mid-Atlantic coast. Showers and thunderstorms were expanding
across the outer-Islands early this evening. This activity will
work northward across the rest of the region as the night wears
along. There is elevated instability along with Pwats near 1.5
inches. Therefore...showers and isolated thunderstorms with
heavy rainfall will work northward across the region as the
night wears along. Pockets of torrential rainfall may result in
street flooding too. Before the heavier activity arrives, areas
of drizzle and fog will persist.
Previous Discussion...
Robust mid level trough from the Gt Lakes to the OH valley will
take on negative tilt as it approaches the mid Atlc coast late
tonight. Impressive height falls off the coast will result in
low pres developing along the Delmarva coast late tonight with
increasing forcing for ascent spreading northward across SNE.
Rain will redevelop and overspread SNE from south to north
tonight, starting along the south coast this evening then moving
north during the night. The main focus for rainfall overnight
will be in the interior with likely just some spotty light rain
across SE New Eng after midnight.
Soundings show some elevated instability and steeper lapse
rates developing above the inversion and hi-res CAMs indicate a
convective nature to the precip as it lifts north across the
region. As a result, some locally heavier showers are likely
with an isolated t-storm possible.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday into Tuesday Night...
* Strong to damaging winds late Tue into Wed
* Heavy rainfall will produce areas of street flooding
* Minor coastal flooding possible during early Wed high tide
Neg tilt upper trough will evolve into vertically stacked
closed low south of New Eng. Rapid cyclogenesis of offshore low
pres will get pulled back to the NW toward SNE as it get
captured by the upper low. Still some uncertainty with the track
of this main low but strong wind anomalies remain focused
across SNE which increases confidence of a potentially high
impact wind event for the SNE coast, along with a heavy rainfall
event.
Strong to damaging wind potential...
Wind will be the biggest concern with this storm and likely have
the greatest impact as 70+ kt low level jet pivots west across
eastern New Eng. This jet is around 4SD above normal. An
examination of soundings show enough low level BL mixing to
support wind gusts 60-70 mph across the Cape/Islands to coastal
Plymouth county with low risk for hurricane force gusts. Wind
damage may overachieve given trees in this region remain fully
leaved combined with wet ground from heavy rainfall. Power
outages are likely. The low level wind field drops off the west
of the main axis with 50-60 mph gusts expected across rest of
eastern MA and coastal RI, with 40-50 mph gusts along and a bit
west of the I-95 corridor.
Winds will ramp up Tue afternoon with the strongest gusts
occurring Tue night.
Heavy Rain/Flood Potential...
Strong forcing for ascent with fire hose of moisture aided by
long trajectory of easterly low and mid level jet will result
in periods of heavy rainfall for SNE. The heavier rainfall will
initially be focused across western and SW New Eng through 18z
assocd with enhanced convergence ahead of first low pres along
the mid Atlc coast. But the heavy rainfall will shift to
eastern New Eng later Tue and Tue night as main low pres
begins to back in toward SNE with increasing low and mid level
jet providing deep moisture and strong forcing. Additional
rainfall through Wed morning will be 2-4 inches with highest
amounts likely focused in eastern MA with secondary max
possibly into the hilly terrain of CT/RI and Worcester Hills,
as strong NE inflow provides upslope rainfall enhancement.
Lesser amounts are expected in the CT Valley.
The heavy rainfall will result in areas of urban and poor
drainage street flooding. However, rainfall rates are not
expected to be excessive and forecast rainfall amounts will be
occurring over a long duration so risk for flash flooding is
very low. No changes to flood watch area.
Will discuss coastal flooding potential in section below.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights...
* Damaging Wind Gusts continue into Wed across eastern MA/RI with
lingering rain and Minor coastal flooding/Beach erosion
* Quieter weather returns Thu into early Fri with generally dry
weather other than a few lingering showers Thu across southeast MA
* Another system likely brings more rain later Fri and Sat, but
should not be nearly as impactful as the upcoming event
* Dry weather likely returns sometime Sun and continues into Mon
Details...
Wednesday...
The powerful coastal storm will become vertically stacked and slowly
move east of the region. A potent NNE LLJ of 45 to 60 knots will
persist across the coastal plain into Wed afternoon. While winds
will not be quite as strong as late Tue night, still expecting gusts
on the order of 40-50 mph along and southeast of I-95 with 50-60 mph
gusts lingering across the Cape/Islands. Given winds of those speeds
and fully leafed trees, damaging wind gusts along with the risk for
additional power outages will continue. We also expect rain to
persist across eastern MA/RI albeit not as heavy as Tuesday and
Tuesday night. However, given closed mid-level low to our southeast
coupled with continued moist inflow we do expect rain to continue
across the coastal plain for a good portion of Wednesday.
Meanwhile, across western MA and CT conditions will not be as bad on
Wednesday. Still may see a few showers, but the steady rain shield
should be east of that region. While it will be breezy to windy,
expect gusts mainly in the 30-40 mph range.
Thursday and Friday...
The major storm system will have finally lifted well to our
northeast by Thu. This coupled with a ridge of high pressure
building down from eastern Canada will result in mainly dry weather
Thu into early Fri...despite lingering clouds and a few left over
showers possible on Thu across southeast MA. This a result of
lingering NNE low level flow. High temps should mainly be in the 50s
Thu and Fri. We will have to see if we get some lighter rain moving
in sometime on Fri in advance of the next system. The GFS/CMC keep
us dry, but the ECWMF and even some GEFS ensembles indicate onshore
moist flow to allow some light rain to break out during the day Fri
ahead of the next system.
Friday night and Saturday...
Another low pressure will approach from the southwest Friday night
into Sat. This will likely bring another round of rain Fri night
into Sat. This system does not look nearly as strong as the upcoming
event and it also is more progressive. This should result in much
less impacts than what we are expecting to see with this upcoming
storm Tue into Wed.
Sunday and Monday...
There still is uncertainty if some rain lingers into Sunday given
the time range. We do expect improving weather though sometime Sun
and continuing into Mon as high pressure builds in from the west. So
favoring mainly dry weather and high temperatures probably in the
upper 50s to the middle 60s...a bit above normal for this time of
year.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight...High confidence.
IFR/LIFR across much of the region, except areas of MVFR/VFR
over the Cape/Islands. Increasing coverage of showers/isolated
TSRA currently across the islands as they lift south to north
across SNE as the night progresses. Heavy rainfall is expected
with some of the activity.
Tuesday and Tuesday night...High confidence.
Widespread IFR/LIFR. Periods of rain, heavy at times especially
in the afternoon through the night. Increasing NE winds during
the afternoon, with winds peaking Tue night with gusts 50-60 kt
east coastal MA and Cape/Islands, 40-50 kt back to I-95
corridor and 25-35 kt CT valley. LLWS across SE MA and Cape Cod
Tue night.
KBOS Terminal...High confidence in TAF trends.
KBDL Terminal...High confidence in TAF trends.
Outlook /Wednesday through Saturday/...
Wednesday: Mainly MVFR, with areas VFR possible. Strong winds
with gusts up to 55 kt. Chance RA.
Wednesday Night: Mainly VFR, with local MVFR possible. Strong
winds with local gusts up to 40 kt. Slight chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 35 kt.
Thursday Night: Mainly VFR, with local MVFR possible. Breezy.
Friday: Mainly VFR, with areas MVFR possible. Windy with local
gusts up to 30 kt.
Friday Night: Mainly MVFR, with local IFR possible. Windy with
local gusts up to 30 kt. RA likely.
Saturday: Mainly MVFR, with areas IFR possible. Windy with
local gusts up to 30 kt. RA likely.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Storm Warnings continue for all waters from Tue afternoon into
Wed morning. Winds ramp up during Tue, with worst of the wind
and seas during Tue night. Max wind gusts to 60-65 kt possible
over waters east of Cape Cod Tue night. Dangerous seas develop,
peaking 20-25 kt east of Cape Cod to outer NE MA waters. A
dangerous storm for mariners. Vsbys will be reduced in rain and
fog.
Outlook /Wednesday through Saturday/...
Wednesday: gale force winds with gusts up to 45 kt. Rough seas
up to 22 ft. Rain likely.
Wednesday Night: Moderate risk for gale force winds with gusts
up to 40 kt. Rough seas up to 19 ft. Chance of rain showers.
Thursday: Low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 16 ft. Slight chance of rain showers.
Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 12 ft. Slight chance
of rain showers.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 10 ft. Slight chance of rain
showers.
Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 11 ft. Rain likely.
Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 12 ft. Rain likely.
&&
.TIDES/COASTAL FLOODING...
* Minor Coastal Flooding with significant erosion possible
The high tides of main concern are the early Wed morning and Wed
afternoon tide cycles. Thankfully, astronomical tides are quite
low which will limit the magnitude of flooding. A 3 to 3.5 ft
surge is possible with seas 20-25 ft offshore which will be
enough to produce areas of minor coastal flooding around the
time of high tide. We are not as concerned with the Tue
afternoon high tide as winds, waves and surge will not likely be
built enough to cause flooding.
However, persistent easterly wind wave over multiple tide
cycles may result in areas of significant beach erosion.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 2 AM EDT Tuesday through Wednesday evening
for CTZ002>004.
Wind Advisory from 6 PM Tuesday to 2 PM EDT Wednesday for
CTZ004.
MA...High Wind Warning from 2 PM Tuesday to 2 PM EDT Wednesday for
MAZ007-013>024.
Flood Watch from 2 AM EDT Tuesday through Wednesday evening
for MAZ003>021-026.
Coastal Flood Advisory from 3 AM to 7 AM EDT Wednesday for
MAZ007-015-016-019-022>024.
Coastal Flood Advisory from 3 PM to 7 PM EDT Wednesday for
MAZ007-015-016-019-022>024.
Wind Advisory from 6 PM Tuesday to 2 PM EDT Wednesday for
MAZ005-006-012.
RI...High Wind Warning from 2 PM Tuesday to 2 PM EDT Wednesday for
RIZ005>008.
Flood Watch from 2 AM EDT Tuesday through Wednesday evening
for RIZ001>008.
Wind Advisory from 6 PM Tuesday to 2 PM EDT Wednesday for
RIZ001>004.
MARINE...Storm Warning from 5 PM Tuesday to 11 AM EDT Wednesday for
ANZ231>235-237-250-251.
Storm Warning from 8 PM Tuesday to 8 AM EDT Wednesday for
ANZ230-236.
Storm Warning from 2 PM Tuesday to 11 AM EDT Wednesday for
ANZ254>256.
&&
$$
SYNOPSIS...KJC/Frank
NEAR TERM...Belk/KJC/Frank
SHORT TERM...KJC
LONG TERM...Frank
AVIATION...Belk/KJC/Frank
MARINE...Belk/KJC/Frank
TIDES/COASTAL FLOODING...Staff
Area Forecast Discussion
National Weather Service Charleston SC
855 PM EDT Mon Oct 25 2021
.SYNOPSIS...
A cold front will move through the area tonight, followed by
high pressure through mid week. A low pressure system will then
impact the region late week. High pressure is expected to
return early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
The forecast is on track and did not require many adjustments
for the late evening update. 27/00z surface analysis showed the
pre-frontal trough is still running several hours ahead of the
cold front. The forecast is on track.
A pronounced pre-frontal trough will cross the area later this
evening with the actual cold front pushing offshore overnight.
The pre-frontal trough shows up rather well on late afternoon
GOES-E visible imagery stretching southwest-northeast across
southern Alabama, northwest Georgia and into the North Carolina
Mountains. A band of convection accompanies the trough and
there are signals this line could survive as it passes through
later this evening as a broken band of isolated showers. Pops
around 20% were maintained across southern South Carolina and
expanded into Southeast Georgia with the early evening update
per latest RAP and H3R. Dewpoints will not really fall until
well after midnight as the actual cold front pushes east. Lows
from the mid-upper 50s inland to the lower 60s at the coast
looks on track.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday and Wednesday: The forecast area will be positioned between
a mid-level trough along the eastern CONUS and a ridge along the
Mississippi River Valley. The ridge axis will shift to overhead of
the region on Wednesday. Subsidence and dry air associated with the
ridge will support a rain-free forecast for both days, with sunny
skies and seasonable temperatures. High temperatures are expected to
be in the mid 70s both days. Low temperatures in the mid 40s to low
50s Tuesday night will then warm a few degrees Wednesday night, with
low to mid 50s expected.
Thursday: An anomalously deep mid-level trough and associated
surface low pressure will approach the region Wednesday night.
Associated with the low pressure system, a warm front will lift
north followed by a cold front approaching from the west. The cold
front will bring a line of showers and thunderstorms, impacting the
southeastern GA counties in the morning hours before moving eastward
and impacting the southeastern SC counties in the afternoon.
Instability looks to be very limited, with models only showing 200-
400 J/kg of CAPE. However, other convective parameters show the
potential for strong to severe wind gusts with some of the
convection. The severe potential will need to be ironed out with
future forecasts. Temperatures for Thursday are forecast to be in
the low 70s inland with mid 70s along the direct coastline.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The region will remain positioned under an anomalously deep mid-
level trough through Saturday. On Sunday the trough will push
offshore and zonal flow will prevail over the southeastern states.
Model soundings are indicating dry air will be prevalent aloft,
leading to mostly dry conditions. Temperatures through the period
are forecast to be below normal.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
VFR. Isolated showers could meander around KCHS, KJZI and KSAV
roughly 02-05z as a pre-frontal trough pushes through. Direct
impacts are unlikely and would be rather brief should they
occur.
Extended Aviation Outlook: Prevailing VFR. Flight restrictions are
possible in showers and thunderstorms Thursday, possibly lingering
into Friday.
&&
.MARINE...
Winds will quickly shift westerly late this evening after the
cold front sweeps through. Solid 15-20 kt winds expected over
all of the waters between midnight and daybreak Tuesday.
Frequent 25 kt gusts are expected over the nearshore SC waters
and offshore GA waters so a Small Craft Advisory has been
issued for these waters.
Northwesterly winds will likely remain elevated Tuesday
morning, with wind gusts to 25 knots possible through mid
morning. Tranquil marine conditions expected Wednesday, with
prevailing northerly winds, 10 to 15 knots and seas 3 to 4 feet.
A cold front will pass through the region Thursday, bringing
elevated northeasterly winds and increasing seas. Small Craft
Advisories will likely be needed for most, if not all, of the
marine zones for both winds and seas.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory from midnight tonight to 10 AM EDT
Tuesday for AMZ350-352-374.
&&
$$
Area Forecast Discussion
National Weather Service Grand Forks ND
1012 PM CDT Mon Oct 25 2021
.UPDATE...
Issued at 1012 PM CDT Mon Oct 25 2021
Wind gusts are starting to increase once again after the previous
lull earlier in the evening as expected, and the highest gusts
are in the Devils Lake Basin where they are around 35 mph.
Strongest winds aloft are in the 45-50kt range according to RAP
where the LLJ is beginning to slide east. This is expected to
remain above the BL in our CWA, with less momentum transfer due
to unfavorable direction (SE flow) and limited nighttime mixing.
However, as the day progresses Tuesday a dry adiabatic mixed
layer increasing in depth may begins to allow for higher winds to
reach the surface and there is an increasing signal for potential
gusts 45 mph or higher especially in the southern RRV and west of
the RRV. This is most favored by the GFS, with NAM showing a
shallower BL (common biases of both models). As there is a lack
of CAA (instead WAA) and a less traditional direction for peak
momentum transfer I will hold off on decisions regarding potential
"Wind Advisory" issued Tuesday. Based on data later this
evening/overnight, this may need to be considered though.
UPDATE Issued at 649 PM CDT Mon Oct 25 2021
There is a brief lull currently with the strongest gusts at sunset
at daytime heating ends, however as LLJ transitions east gusts
should once again increase by mid evening. High clouds ranging
from sct-bkn are streaming across the region currently and trend
should be for this to increase overnight. This is all in line with
forecast, so only minor adjustments were necessary.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 252 PM CDT Mon Oct 25 2021
Gusty southeast winds will continue tonight into early Tuesday,
with the strongest winds expected by mid to late Tuesday morning
through the afternoon. Overall, not expecting these to cause too
much impact, but there will be some for anyone out on Devils Lake
or hunters along/west of the Red River Valley out on small
wetlands.
As of mid afternoon, some cumulus had formed from Baudette to
Bemidji and from Cando to Valley City. At times this has been a
little thicker, but for the most part it remains mostly sunny in
all areas. Wind speeds have become breezy to the west of the
Valley, and continue to pick up within the Valley. Think there may
be a slight lull in the winds around sundown, but they should
pick back up again by mid evening, and remain steady for the rest
of the night. These southeast winds will really start to crank up
by mid to late Tuesday morning, maybe even a little faster around
Devils Lake. Most guidance products indicate speeds right around
wind advisory criteria along and west of the Valley at least
through late morning and afternoon. Some of reasons that advisory
criteria may not be met are that the forecast soundings do not
show perfect alignment on wind directions in the low levels. Also,
there is warm advection ongoing, so there is not a strong push of
cold air. Although there are a few negatives, the positives are
there too. Iowa State wind meteograms show good clustering around
25 mph for sustained winds (Valley and west) with gusts to around
40 mph or so. Will defer to the midnight shift to make the call on
any advisory, as impacts should be minimal. Speeds will decrease
Tuesday night as the next batch of rain starts to move toward the
FA.
.LONG TERM...(Wednesday through Monday)
Issued at 252 PM CDT Mon Oct 25 2021
Overview...
The main opportunities for impactful weather will be tethered to the
chance for rain on Wednesday and generally persistent breezy
conditions across much of the long term period. Otherwise, warm
above normal temperatures look to prevail from the end of the week
into the weekend, before a potential return back to normal to round
out the weekend.
Wednesday...
An upper level trough is progged to eject out of the Four Corners
region into the central and southern Plains on Wednesday. A
secondary embedded wave within this upper trough is expected to
traverse the northern Plains around the same time as well. Ensemble
guidance is beginning to paint a clearer picture of how this system
will progress, but is still struggling to resolve the exact
progression due to the subtle nature of the wave. A slower
propagating wave would bring rain impacts further westward, while a
more progressive wave would tend to push rain further eastward
quicker. Current consensus is indicating that rain will begin to
work into the southern forecast area by Wednesday morning and
continue east-northeastward throughout the day. As a result, the
highest rainfall amounts are outlined over the far southern Red
River Valley and into west central Minnesota.
Thursday through Sunday...
As the main upper level trough continues its eastward progression,
rain may still linger over portions of west central and northwestern
Minnesota into Thursday. Cluster analysis is indicating that the
upper level trough will deepen as it reaches the SE CONUS and and
allow for an upper level ridge to begin to build into the Plains by
the late week period. Where cluster analysis falters, however, is on
the strength of the building ridge. A stronger ridge would yield
more zonal flow over the northern Plains and a continued warming
trend, while a weaker ridge would induce more northwesterly flow
aloft. Regardless, consensus seems to favor a rather stagnant
weather pattern with warm, above normal temperatures and breezy
conditions persisting from the late week into the early weekend
period. By Sunday, ensemble guidance is hinting at an upper trough
swinging through the area. This may bring with a chance for some
precipitation, but most notably will introduce a shot of colder air
as we return back toward more normal temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 649 PM CDT Mon Oct 25 2021
VFR conditions should prevail through at least midday Tuesday
across eastern ND and northwest MN, with MVFR ceilings possibly
arriving near the end of the TAF period though chances are better
Tuesday evening. A low level jet (40-50kt) will support potential
low level wind shear from the south through the night, while winds
at the surface remain southeast and gusty (generally 25-30kt).
Stronger gusts are possible during the daytime period Tuesday
(30-35kt), and may occasionally gust over 35kt (best chances at
KDVL).
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
UPDATE...DJR
SHORT TERM...Godon
LONG TERM...Rick
AVIATION...DJR
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1038 PM CDT Mon Oct 25 2021
.SHORT TERM...(This Evening through Tuesday)
Issued at 410 PM CDT Mon Oct 25 2021
Lower cloud band has backed into south central SD along the Missouri
River at mid afternoon, with various wisps of higher clouds moving
past the ridge axis downstream over the remainder of the area.
Increasingly strong southeasterly gradient becoming established over
the area, with just a small window for radiational cooling into the
mid 30s to occur over areas near/east of highway 60 during the
evening before winds start to increase there to 10 to 20 mph late.
Elsewhere, likely to see a small diurnal drop early on, but mainly a
gusty 15 to 30 mph especially later tonight with temps upper 30s to
lower 40s. Trends in HRRR temps are best of the fairly sorry sort,
so based the eventual steady to rising temps with both the
increasing wind and/or increase in higher clouds. Lower clouds
likely to remain mainly west of the James River into the morning
hours.
Main feature Tuesday will be the strong and gusty surface winds.
Deep western troughing and the increasing gradient with pressure
falls to the west will result in winds aloft increasing to 30 to 40
kts at 925 hPa, and as much as 45 to 55 kts at 850 hPa, with
strongest gradient between the James River and Buffalo Ridge during
the midday/afternoon hours. The expected gradual increase in the
already established mixed-layer driven mechanically overnight will
introduce winds at the top of the mixed-layer reaching mid 30s to
lower 40s kts by around 17z. The wild card remains in the extent of
lower clouds and impact on mixing depth, with trend in HRRR and the
unavoidable NAM insistence on widespread stratus developing later
tonight/early morning and lingering much of the day over the area.
Have trended just a bit down in temps across southeast SD where
clouds are somewhat more likely to occur. Much regional thought into
the potential for a wind advisory, but finally decided to leave out
of the forecast with overall values nudging up to the lower end of
criteria, and with the uncertainty to mixing depth in the southeast
unidirectional low-level flow.
.LONG TERM...(Tuesday Night through Monday)
Issued at 410 PM CDT Mon Oct 25 2021
Main issue in the forecast lies in the intermediate range - a
dynamic trough moving across the region Tuesday night through
early Thursday. NAM remains the progressive end of the model
ensemble, but trends overall are for a bit slower progression, and
have sided toward ideas in GFS/GEFS/ECMWF/EC Ens Mean. Full
latitude trough is indicated in all solutions moving to the far
western plains by Tuesday evening. Trough has two distinct parts -
a northern stream wave digging through the northern/Canadian
Rockies, and a southern impulse digging thru CO/AZ. System remains
largely two-piece through it`s evolution, with southern wave
eventually closing off low pressure over the southern MS valley,
pulled along by tie to wave in northern stream.
Low-level troughing intensifies in the western plains during the
afternoon, with tightening baroclinicity through the zone heading
into the evening. A bit slower progression to the feature in the
mean, but will still initiate a strong frontal circulation along the
meridionally-oriented boundary. Initial precip development will be
stymied by some capping/very warm temps aloft in the early evening,
but consensus is eventually the cooling aloft by later evening and
early overnight, increasing theta-e advective focus into eastern SD
and the presence of ~500-750 J/kg weakly capped elevated CAPE will
lead toward development of banded precipitation. Environment does
quickly evolve to a more moist neutral status, but a small window
where the strong wind flow aloft and dry layer could lead to perhaps
a gusty storm with small hail into the Missouri River valley later
in evening and early overnight.
With concurrent development of a weak jet streak ahead of the
northern stream trough axis by Wednesday, a good set up for
jet/front interaction with broad neutral lapse rates is established
for Wednesday morning. Shifted blended pops westward to better align
with the deeper frontogenetic forcing and expected near/behind
precipitation distribution with inverted trough. With sluggish
progression of QG dynamics, not looking for much more than a wet day
for most. Another pulse of precip along the frontogenetic axis could
wrap into NW IA on Wednesday evening, leading to another enhancement
of precip. GEFS ensembles indicate that most solutions support the
idea of a longer period of accumulating precip.
Rainfall amounts have also trended somewhat westward, but likely is
room for even more of a westward shift to near/west of I-29 for
maximum axis where frontogenetic axis likely to linger somewhat late
night into the midday on Wednesday. Would not be surprised for a
couple daily precipitation records to fall, given likely efficient
and slow moving precipitation. Locally, a couple inches would not be
out of the question through Wednesday night.
The closing off of the upper low to the south will slow the
departure of the precip a bit, which could linger into Thursday
morning toward Highway 71. Likely will see decrease in the frontal
support further into Thursday, with gradual decrease in deformation
area precip as northerly/northwesterly flow undercuts what remains
from banding. A blustery day with clouds only slowly breaking west
to east, and highs mainly lower 50s east to mid to upper 50s west,
as really don`t have much cold air with this type of system. Kicked
up wind gusts a shade again with decent mixing.
Quiet weather, and mainly seasonably mild heading into the start of
the weekend as ridge aloft rapidly expands into the northern Plains.
Friday and Saturday morning with drier air will likely have some
prospect for patchy frost (west Friday and east Saturday). A strong
wave will punch into this feature on Saturday, driving a distinct
cold front through the area. Some timing differences, and could make
a big deal on highs given the strong thermal gradient. Likely a bit
warmer will be in order from the lower Missouri River valley into
northwest Iowa where a post-18z passage likely to allow some mid to
even upper 60s. Very gusty winds follow later Sat into Sat night,
and noticeably cooler air for Halloween and into Monday. As it
stands, appears temps into the upper 30s to lower 40s at trick-or-
treat time, but winds diminishing to 5 to 10 mph.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1035 PM CDT Mon Oct 25 2021
VFR conditions will prevail along and east of the James River
Valley overnight, including at FSD and SUX. A narrow strip of 1-2
kft stratus remains along the MO River Valley in central SD and
extended into central NE. This is poised to linger well into
Tuesday, expanding eastward to impact HON by 12z. Development of
additional areas of MVFR stratus is possible late tonight,
especially along and west of Interstate 29. This will likely
impact SUX for a few hours around 12z. Big question is whether stratus
will linger during the morning or mix out, so will continue to
monitor model trends. Ceilings will begin to lower heading into
Tuesday evening as showers and isolated thunderstorms begin to
spread east from central SD/NE.
Southeast winds will increase greatly overnight. As the low level
jet ramps up, there may be brief periods of low level wind shear,
but expect winds to continue to mix gusts to the surface
overnight. Gusts exceeding 25 kts are likely to develop by 12z
with windy conditions remaining through the day.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...Chapman
LONG TERM...Chapman
AVIATION...BP
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
959 PM CDT Mon Oct 25 2021
...UPDATE...
.UPDATE...
Issued at 955 PM CDT Mon Oct 25 2021
Have decided to add patchy drizzle for late tonight and Tue AM.
Latest GOES night RGB and sfc obs indicate obvious break in
stratus working its way SE to NW across the area late this eve.
However, stratus is beginning to expand and drift NW across NC/NE
Kan. last 30-90 min, and expect this trend to continue overnight
per latest HRRR/RAP runs. Thus, the break from the stratus should
be fairly short-lived as most areas are once again engulfed in
widespread stratus by 08-10Z. Model forecast soundings and plan
view plots show a gradual deepening of the low level moisture with
time late tonight and into Tue AM, and this will coincide with
persistent weak to moderate lift via low level WAA, beneath a
stout temperature inversion associated with EML. Also, the BL will
remain quite mixed and turbulent, owing to breezy SE winds.
Typically, this is a pretty decent setup for at least patchy
drizzle for our region, and as such, have added patchy drizzle to
the latest forecast update. One potential limiting factor is that
the moisture depth is somewhat marginal, on the order of 1-1.25
km, which is why I limited to "patchy" attm. Increased moisture
depth and/or observational trends could warrant stronger wording
in later forecast updates. Luckily, air temps will remain well
above freezing.
UPDATE Issued at 700 PM CDT Mon Oct 25 2021
Made significant changes earlier in the shift to sky cover
overnight and into Tue AM, and observational data and latest
short term guidance still supports those changes. Status has held
firm for most of the CWA all day, and with continued SE flow and
additional stratus noted upstream over E KS/W MO, see little
evidence to support idea that we`ll get rid of the stratus
overnight. There is a break between the two blocks of stratus
from Beloit/KCNK towards KSLN, which the HRRR depicts quite well.
Agree with the HRRR that this area should fill in as low level
SErly flow incr overnight.
The biggest remaining question I have is potential for fog and/or
drizzle late tonight into Tue AM. Several pieces of model
guidance (both MOS and deterministic) dev some sort of visibility
reduction over various portions of CWA, but agreement on timing
and location is not great, and breezy SE winds and lack of
stronger moisture surge tend to argue against this potential.
However, overall moisture depth should incr with time, and
broad/persistent lift in WAA regime along with turbulent BL
beneath stout inversion could be enough to generate areas of
drizzle...which would undoubtedly come with at least modest
visibility restrictions towards 3-5sm, perhaps lower. Thus, have
added patchy fog wording for much of our Neb. zones as a start,
and will evaluate new 00Z guidance to help make determination on
drizzle later this eve. Regardless of drizzle potential, tend to
favor RAP/HRRR/NAM solutions that keep stratus around for much of
the area through at least midday Tue...and just like today,
there`s a chance it could hang around most of the aftn and again
affect high temps.
&&
.DISCUSSION...(This evening through Monday)
Issued at 329 PM CDT Mon Oct 25 2021
Low stratus continues for nearly the entire forecast area early this
afternoon. A small corner of the northeast has broke out.
Temperatures have struggled to move this afternoon.
There are many concerns for this forecast. Cloud Cover,
temperatures, winds, chances for thunderstorms and severe weather
are just a few.
The first are the clouds for tonight. When we have not cleared out
at this point in the afternoon, there is concern that they will
linger all night long. Have went with a slower clearing during the
evening, but expect that they will return toward sunrise. Will have
to watch to see what the clouds do tonight.
A surface high moves to the east and the pressure gradient tightens
tonight. Winds at 850mb increase to 40 to 50 knots. Expect winds to
start to increase during the night tonight. That should keep any fog
from forming at the edges of the stratus field, but it could also
bring some chances for drizzle to the area. The NAM has an area of
low QPF amounts spreading into the area late tonight and continues
to move through the area during the day Tuesday. Should the stratus
linger, there could be some drizzle out of it. The clouds will also
have an impact on the temperatures during the day Tuesday. Have
lowered highs some and will need to watch them, especially if there
are more clouds.
Tuesday night an upper level low approaches the area and a surface
low and cold front move through the area. In the vicinity of the
front there will be a chance for some thunderstorms. There is a
fairly narrow band of decent CAPE for this time of year that moves
into the area during the evening. The best chance for thunderstorms
will be late in the evening and into the overnight hours. Expect
wind to be the primary threat, but with cooler temperatures and
lower freezing level there could still be some hail potential. Due
to the linear nature of the expected storms, there could be an
isolated tornado or two.
The front finally exits the eastern part of the forecast area on
Wednesday morning. There could be at least a little thunder in the
eastern part of the forecast area during the day on Wednesday. The
precipitation should end from west to east during the afternoon.
Temperatures will be quite a bit cooler on Wednesday with highs only
in the 50s due to cloud cover and behind the front. In addition,
there will be a strong northwest wind. Winds aloft continue to be 40
to 50 knots and with the showers and thunderstorms some of that wind
could mix down toward the surface. By Thursday, when the sun has a
better chance of coming out and there is better mixing, the winds
could be even stronger, especially in the morning. By afternoon
there is a surface high that starts to build in, but winds will be
fairly strong through the afternoon and should die off around
sunset.
Friday and Saturday will have a little warming trend. There is an
upper level ridge that moves through, some warm advection and
sunshine.
A cold front moves through the area Saturday night and temperatures
will be cooler Sunday and Monday. Forecast highs are in the 40s and
lows are below freezing for most areas Sunday night. This could
bring an end to the growing season. Cooler temperatures are expected
Monday night, so if Sunday night is not enough, Monday night will do
it.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday)
Issued at 650 PM CDT Mon Oct 25 2021
Significant weather: Prolonged IFR to LIFR CIGs, perhaps MVFR
VSBYs, strong SE winds.
First 6 Hours: IFR to LIFR. Made significant changes this TAF
cycle as we have been unable to shake these low clds. It now
appears probable both sites will maintain IFR CIGs, and probably
even lower to LIFR within next few hrs. In fact, have already
seen a lowering trend last hr or two and with loss of insolation
expect this trend to continue. Wind will remain breezy out of the
SE around 10-15kt, with gusts around 20kt.
Rest of the Period: LIFR to IFR through Tue AM, possible(?)
improvement Tue aftn. LIFR or barely IFR CIGs are likely after
midnight through much of the morning Tue per latest short term
model guidance/trends. May even approach airport minimums (200ft),
at times, esp. at EAR. VSBYs are more in question as several
models develop MVFR to IFR BR/FG, but breezy SE winds and lack of
more discernable surge of low level moisture argue against it.
Have trended the forecast towards at least some VSBY reduction,
but think this will be more of mist/drizzle and not true FG, so
kept MVFR attm. Given what happened today (Mon), improvement will
probably be very slow/minor Tue AM. Confidence on stratus trends
Tue aftn is low as some models completely mix the stratus out,
whereas others keep us locked in. Will trend towards improvement
19-21Z, but again, this is low confidence. Finally, winds will be
pretty high throughout the day out of the SE...susatained 16-21kt,
with gusts around 30kt, perhaps higher if skies clear out. Removed
LLWS given elevated sfc winds and fact that core of strongest low
level flow looks to remain above 2000ft. Confidence: Medium to
high thru Tue AM, low Tue PM.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...Thies
DISCUSSION...JCB
AVIATION...Thies
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Mon Oct 25 2021
.SHORT TERM...(This evening through Thursday Morning)
Issued at 311 PM MDT Mon Oct 25 2021
The latest RAP analysis has a ridge over the plains as a strong
trough develops over the SW US. This afternoon cloud cover has
been struggling to dissipate over the eastern CWA which has
impacted forecasted highs for the day as Norton and McCook as of
typing this is still in the 40s. The clouds are slowly moving out
of the area from west to east so am still expecting the above
mentioned areas to rebound into the low to mid 50s for their
afternoon highs. Winds have been breezy from the southeast at
15-20 mph and gusts of 30 with a tightened pressure gradient over
the area in part of the developing storm system. For tonight,
clouds return over the northeast part of the area as moisture
return happens over east Central/ Central Kansas, winds will
continue to be breezy at 10-20 mph over the entire area. Overnight
lows are currently forecasted fall into the the 40s to low 50s
across the area.
Tuesday, the trough moves over the area with a triple point setting
up over northern Kansas, southern Nebraska. Locations behind an
eastward moving warm front look to warm into the low to perhaps mid
80s whereas locations in front may struggle to make it into the
upper 70s. Temperatures will need to be watched over the eastern
portion of the area, as another scenario similar to today may set
up where temperatures under perform due to lingering cloud cover,
especially with extra moisture present. The NAM is very cool over
that area so slightly lowered high temperatures to account for
this factor. Winds will be gusty out of the south at 20-25 mph and
gusts up to 40 mph look likely as the top of the mixing layer
looks to range from 40-45 knots. The next hazard for Tuesday will
be near critical to critical fire weather as RH fall into the mid
teens over the western 1/3 of the CWA. A Red Flag Warning has been
issued for that area due to the low RH`s and strong winds and the
already dry fuels being present. The strong winds heightened the
threat as if any fire were to get going it would have the
potential to spread rapidly. The late afternoon into evening sees
a strong cold front move from NW to SW across the area. Wind gusts
of 50-55 mph look possible with the initial passage and behind
the front, as the NAM shows a three hour 12mb pressure change and
the RAP indicates a 7- 8mb pressure change with the passage of the
cold front. The focus then turns to the severe weather threat
with the system as the SPC has eastern portions of the area in a
slight risk. The triple point being in vicinity of the area does
favor severe weather, however forecast soundings show a capped
environment. Clouds will be present over the Palmer Divide and
east Central Kansas leaving the CWA in a narrow corridor for the
heating to occur. If enough heating were to occur then perhaps an
isolated storm or two could get going over Norton/Graham county
with damaging winds looking to be the main threat, and perhaps an
isolated tornado wouldn`t be ruled out as 0-3 SRH values range
from 250-350 and 0-1 SRH are in the 150-200 range. Overall
confidence in severe weather is low at this time as many
ingredients need to come together and with such a small corridor
for diurnal heating to take place.
Tuesday night and through the day Wednesday, will see windy
conditions from the northwest in wake of the storm system with
wind gusts of 40-45 mph possible. Some wrap around showers from
the system may occur but look to be the hit or miss variety.
Wednesday will see cooler temperatures in the 60s and RH values in
the low 20s, which will create elevated fire weather conditions
especially with the strong winds. Lows overnight Wednesday and
into Thursday look to fall into the 30s to low 40s.
.LONG TERM...(Thursday through Monday)
Issued at 225 PM MDT Mon Oct 25 2021
As the strong upper low pressure system continues to move east
across the southern and central plains on Thursday and Thursday
night, a ridge of higher pressure begins stretching across the
Rockies and over the High Plains region. Cooler temperatures are
expected on the back side of the exiting system on Thursday as
surface high pressure moves in along with northwest winds that
remain gusty through the day and relax around sunset as the
pressure gradient begins to slacken. High temperatures will be in
the upper 50s to lower 60s with lows in the 30s.
Dry conditions remain in place through Sunday as the upper ridge
flattens and the flow becomes zonal across the central U.S.
Temperatures warm gradually on Friday and Saturday with highs back
up into the lower 70s on Saturday with southerly near surface flow
ahead of a lee surface trough that deepens along the Front Range in
response to the zonal flow across the Rockies. By late Saturday, a
weak short wave trough moves east of the Rockies in the zonal flow
and cooler air pushes southward across the region from Saturday
night through Sunday and into the beginning of next week as the upper
pattern also sags southward.
Late Sunday, there is a possibility of a light rain and snow mix
developing over some of the favored upslope areas of the forecast
area as easterly return flow moves in around the surface high and
additional weak short wave troughs moves through the westerly flow
aloft. With high temperatures only in the 50s on Sunday with
overnight lows in the upper 20s to lower 30s, there is a
possibility of seeing a mix of light rain and snow Sunday night in
addition to the region seeing a widespread freeze across areas
that have not yet had freezing conditions.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1000 PM MDT Mon Oct 25 2021
KGLD...VFR conditions are expected through the period. South
winds gusting up to 30kts at taf issuance will continue sunrise,
increasing during the afternoon with gusts over 40kts expected.
Winds are then expected to veer to the southwest with gusts to
30kts around 00z, west-northwest with gusts up to 45kts by 02z,
and northwest with gusts up to 45kts after 04z. Wind gusts could
reach 50kts during the early evening hours as a strong cold front
moves through. Blowing dust producing sub VFR cigs and vis cant be
ruled out immediately behind the frontal passage. Rain showers are
possible during the evening as well.
KMCK...sub VFR conditions are expected with stratus and
potentially fog/br from taf issuance through 16z. Winds during
this time period from the east-southeast 11-13kts with some higher
gusts. From 17z-03z VFR conditions are expected. Southeast winds
gusting up to 30kts in the afternoon shift to the north/northwest
around 12kts by 04z. After 05z northwest winds gusting to 30kts,
possibly higher are expected. Rain showers are possible with low
confidence after 04z with sub VFR clouds moving in behind the
front.
&&
.FIRE WEATHER...
Issued at 311 PM MDT Mon Oct 25 2021
A Red Flag Warning has been issued for Tuesday afternoon for Kit
Carson, Cheyenne and Yuma counties in Colorado; Cheyenne, Sherman,
Wallace, Greeley, and Wichita counties in Kansas along with Dundy
county in Nebraska. A strong low pressure system will move towards
the area during the day Tuesday with a warm front moving east over
the area, behind the warm front temperatures look to rise into the
low to mid 80s. The main story looks to be the winds with the
system with southerly winds sustained at 15-25 mph and gusts
potentially exceeding 40 mph. Late afternoon a cold front arrives
from the NW with strong wind gusts of 45-55 mph possible, a few
storms may form along the front over eastern portions of the CWA.
If a fire were to be ongoing at the time of the cold frontal
passage a sudden and dramatic change in fire direction may occur.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Red Flag Warning from noon MDT /1 PM CDT/ to 6 PM MDT /7 PM CDT/
Tuesday for KSZ001-013-027-041-042.
CO...Red Flag Warning from noon to 6 PM MDT Tuesday for COZ252>254.
NE...Red Flag Warning from noon to 6 PM MDT Tuesday for NEZ079.
&&
$$
SHORT TERM...TT
LONG TERM...LOCKHART
AVIATION...99
FIRE WEATHER...TT
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1121 PM EDT Mon Oct 25 2021
.SYNOPSIS...
A strong coastal storm system will enter the southern New
England coastal waters Tuesday, before forming a loop Tuesday
night into Wednesday night. Rain and strong northeast winds
expected through Wednesday. Quieter weather is then expected
for both Thursday and Friday before another storm system
approaches from the south by this weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Update...Timing of PoP into Srn zones look on track so mostly
minor adjustments to temps and dewpoints to keep in line with
latest observational trends.
Previous discussion...A few pockets of rain will continue
tonight, mainly over southern and central sections as a moist
flow continues over the region. Any remaining snow showers
should be limited to the highest peaks this evening. Patchy fog
will continue as well.
Steady rain may make it into southern portions of the forecast
area per latest HRRR and other solutions later tonight. The 12Z
model suite is in general agreement intensifying an area of low
pressure off the Mid Atlantic coastline after 06Z. Forecast
confidence remains relatively low due to the track and
intensification details of the system. However, strong gusty winds
and heavy rainfall will likely impact southern portions of the
forecast area.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Update...Based on initial look at 26.00z guidance...the threat
for greater than 40 kt wind gusts appears a little higher. A
strong Ely coastal LLJ is forecast to develop in the
neighborhood of 60-70 kt at 925 mb. While there will be a stout
inversion aloft...CAA beneath the inversion will keep lapse
rates rather steep and assist in mixing the lower atmosphere.
I blended the HRRR and multi-model consensus with the previous
forecast to increase gusts...especially near the coast and over
the coastal waters...for more discussion there see marine
section below.
Previous discussion...Rapid cyclogenesis will be underway on
Tuesday as the storm unfolds near the 40 degrees north and 70
degrees west benchmark. All models depict a retrograding storm
forming a loop over the southern New England waters Tuesday
afternoon and Tuesday night. Our impacts will be determined by
how far north the system can make it prior to making the left
hand hook. In any case, winds will increase across our region on
Tuesday, especially along the coast where strong winds are
anticipated. Depending on the storm intensity and track, wind
advisories may be needed for the coastline. Currently, wind
probabilities of around 15 percent for wind gusts over 42 kts
are expected in Portland with 35 percent chance in these wind
levels for Rockland. Bufkit profiles continue to pick up on this
low level jet as well.
Rain will continue as well and be heavy at times over southern
sections through Tuesday night along with strong wind gusts.
Have leaned towards the Canadian model in terms of QPF once
again which is a good compromise solution for this forecast
package. A couple river points may have flood issues in southern
New Hampshire and there may be issues with urban flooding due
to clogged drainage areas.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Wet and Windy conditions taper Wednesday evening, for calmer
conditions until the weekend.
As a large and powerful cyclone spins off the east coast, a
mid/upper jet will slide through the Ohio Valley. This takes the
rug from underneath the systems southerly moisture
transport, while high pres to the north hectors the northward
movement of the low as it turns in place. The slow easterly
movement will focus remaining rainfall through Wednesday
afternoon over the waters and coastal communities. There will
also be some upslope enhanced rainfall on eastern higher terrain
faces, in particular southern NH. Otherwise, trended remaining
QPF for Wed down.
Dry air may quickly enter the low levels in the afternoon,
allowing for some sub 900mb mixing. With a relatively close
proximity to a potent NE 50-65kt LLJ just off the coast, Wed
will be windy with inland gusts up to 30 mph possible. These
could stand increasing if short term guidance trends support.
Influence from the storm finally wanes Wed evening and
overnight. Thurs remains dry and breezy, but winds turn north in
wake of the exiting low. The northerly flow will advect cooler
temps in overnight, with a return to widespread 30s.
Dry conditions continue Friday with high pres to the north.
Model guidance came in slower with the onset of another
possible storm this weekend. Rain is forecast to arrive ahead of
low pressure tracking through the Ohio Valley and into New
York. While timing seems in fairly good agreement for a day 7
system, evolution is still uncertain. This revolves around how
progressive the system is on the heels of exiting high pressure,
as well as if it remains a closed sfc low or garners more
influence from a longwave dropping into the Upper Midwest.
Either way, there is decent confidence in a damp weekend for
much of the area, with temperatures again trending above normal
into the mid to upper 50s.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Short Term...IFR with areas of LIFR tonight through Tues night
with low ceilings and rain. Strong NNE winds increase Tues
afternoon, gusting 20-30 kt, at southern and central TAF sites.
Perhaps higher in vicinity of coastal KPWM, KRKD, and KPSM.
Long Term...Windy conditions continue Wed afternoon with some
gusts up to 30 kt mainly across central and southern ME.
Conditions do improve to MVFR/VFR through the afternoon, with
MVFR possibly returning overnight into Thurs AM.
&&
.MARINE...
Short Term...Gale warnings remain in effect for all waters but
based on the early look at 26.00z guidance there is growing
confidence in storm force gusts outside of the bays. NE winds
tend to overperform in the first place...and with
forecasts...especially S of Cape Elizabeth...of 50 kt at 500 ft
there is likely to be frequent gusts in that range. Seas to
build into the 15`+ plus range along the outer waters.
Long Term...Gale conditions to continue through Wednesday night
in NE wind. Conditions trend to SCA Thursday evening with winds
falling below 25 kt Thursday night. Waves will be slower to
decrease from their high point Tuesday night. 4 to 6 ft waves
could linger into Fri afternoon amid swell from exiting low
pressure system.
&&
.HYDROLOGY...
Locally heavy rain expected over southern areas, especially
southeast New Hampshire Tuesday through Wednesday. A couple
rivers may good into flood with some storm drainage issues as
well.
&&
.TIDES/COASTAL FLOODING...
Wave runup models indicate the possibility of splash-over along
the coast beginning Tuesday night and continuing through
Wednesday despite astronomically low tides. Large waves will
combine with storm surge values approaching 3 feet over southern
areas.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Gale Warning from noon Tuesday to 6 PM EDT Wednesday for
ANZ151-153.
Gale Warning from 8 AM Tuesday to 11 AM EDT Thursday for
ANZ150-152-154.
&&
$$
NEAR TERM...Legro
Area Forecast Discussion
National Weather Service Wilmington NC
1107 PM EDT Mon Oct 25 2021
.SYNOPSIS...
A cold front will cross the coast overnight, accompanied by a
few gusty showers. High pressure Tuesday and Wednesday will
bring dry weather, but strong low pressure is forecast to
develop to our west Thursday, bringing increasing winds and rain
through early Friday.
&&
.UPDATE...
Most forecast elements have been updated to account for the area
of showers moving rapidly eastward across the coastal plain.
Upstream observations show convective wind gusts to near 30 mph
have been recorded, and will remain possible in association with
the better developed showers. PoPs have been increased to 70
percent from Bennettsville and Lumberton across Elizabethtown,
with the southern edge of the slight chance (20 percent) line
running from near Lake City to Conway to Myrtle Beach. Precip
should be well off the coast before sunrise. Since dewpoints do
not fall appreciably behind this convective line but wind speeds
do, I`ll watch closely for a 2-3 hour window of fog potential
before the dry air arrives prior to sunrise.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
Synoptic scale moisture now well offshore with rapidly deepening
low pressure. Partly cloudy and increasingly breezy overnight with
temperatures remaining elevated above climatology. Point of
uncertainty regarding rain chances as the upper system`s healthy
vort max swings through. Some low end chance POPs appear warranted
across mainly NC zones, most similar to the WRF depiction. Higher
spatial/temporal models such as the RAP and HRRR seem quite
aggressive in their rain chances and QPF given the lack of deep
moisture as well as the northern path of the main vorticity. Breezy
on Tuesday into Tuesday night with good directional alignment in
wind fields as the gradient remains moderately strong between the
still deepening offshore low and large high building in from the N
and W.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Cool and dry weather on Wed will become very unsettled on Thurs
as frontal system associated with deepening low pressure moving
east toward the Carolinas.
Plenty of cool and dry air will advect into the area in deep
NW-N flow on Wed producing a beautiful fall day. After a very
cool start to the morning temps will rebound into the 60s
topping out near or just below 70 with plenty of sunshine.
Dewpoint temps will be down near 40 or below inland.
This will not last long as a deepening low pressure system
shifts eastward from the Mississippi Valley to the Appalachians
through the day on Thurs. The associated warm front will move
northward on Thurs spreading clouds and rain into the area in
increasing S-SW flow aloft. The latest GFS is showing axis of
heaviest pcp skirting by the east and west, but will have to
see exactly how this system evolves over the next few days,
especially in regards to any severe potential. Pcp water may
reach up near 2 inches in spots over the Carolinas late Thurs.
Overall, expect gusty onshore winds on Thurs becoming more
southerly as warm front lifts north Thurs night. Temps should be
close to 70 on Thurs with increasing clouds and pcp. The
onshore flow at the sfc Wed night will keep low temps back up
between 50 and 55 most places and by Thurs night the temps will
be back up to 55 to 60 in plenty of WAA, although some drier and
cooler air may wrap up around the back end of low toward Fri
morning.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Deep cutoff low should track up the Appalachians toward the Mid
Atlantic coast on Fri. Although some drier air will wrap around
back end of low, there will also be shortwave energy rotating
around low over the Carolinas and good mid level height falls.
Therefore will keep some low end chc of pcp until low lifts off
the northeast over the weekend. Deep W to NW flow will develop
on the back end of the low Sat into Sun leading to clearing and
drying for the latter half of the weekend. Should turn out to be
a cool and dry Halloween night.
Temps on Fri could turn out to be warmer, especially in places
that may see some sunshine with readings in the 70s most
places. The 850 temps will drop out Fri into Sat, about 10C
leaving 60s for highs on Sat with overall seasonable temps into
early next week.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A line of showers will cross I-95 2-3z and about off the coast
by 7z, with drying thereafter, VFR most of if not about all of
TAF cycle. SHRA, or an isolated TSTM could produce a gusty to 29
kt briefly during transit and possibly a short period of MVFR
ceilings at BKN025.
Extended Outlook...Low clouds, showers, and low level wind
shear conditions will develop Thursday as strong low pressure
approaches from the west.
&&
.MARINE...
Through Tuesday night...A rough patch for mariners for the period.
Low pressure off the coast will be both moving to the NE and
deepening. Gradient increases tonight to where advisory level winds,
mainly in gusts will be achieved. They may decrease a bit tomorrow
for a brief time but increase once again in the afternoon as the
flow aligns out of the NW through a deep layer, encouraging vertical
mixing. Conditions may not drop below thresholds until close to
daybreak Wednesday. The offshore wind direction will keep seas just
below thresholds, though wave faces will be quite steep.
Wednesday through Saturday... Gusty offshore NW flow on Wed
behind exiting low pressure lifting off to the northeast will
subside and become more northerly by Wed night. Deep low
pressure system over the lower Mississippi Valley will head
eastward on Thurs with onshore flow developing and then becoming
SE to S once warm front lifts north late Thurs. Expect
increasing winds and unsettled weather into Thurs night before
the winds become more SW on Fri as low heads off to the Mid
Atlantic coast. Overall, expect winds and seas to drop on Wed
down below 3 ft by late Wed but increasing southerly push will
drive seas up above SCA thresholds late Thurs through Fri night
up to 4 to 7 ft possible before slowly subsiding as low pulls
away from the area through the latter half of the weekend.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 3 AM EDT Wednesday for AMZ250-252-
254-256.
&&
$$
SYNOPSIS...ILM
UPDATE...TRA
NEAR TERM...MBB
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...08
MARINE...MBB/RGZ
Area Forecast Discussion
National Weather Service New Orleans LA
619 PM CDT Mon Oct 25 2021
.AVIATION...00z TAF Package...Overall it looks like a rather
impact free night and day tomorrow. Skies are mostly clear with a
few cirrus over the area. VFR conditions are expected to continue
through the next 24 hours. /CAB/
&&
.PREV DISCUSSION... /issued 406 PM CDT Mon Oct 25 2021/
SHORT TERM (This afternoon through Wednesday Night)...
Glancing at the weather maps this afternoon shows a quick moving
shortwave trough digging east into the eastern US, with a
downstream surface low and trailing cold front draped south into
the Tennessee Valley region down across southern MS and LA.
Meanwhile, a very potent storm system continues to deliver
hazardous weather impacts across the western US, with very deep
and high-amplitude troughing pushing east into the Rockies. For
us, the aforementioned cold front will continue to slide south
into the region, eventually undergoing frontolysis and decaying
with time but enough of a push south to allow much drier
continental air to filter into the region. We will continue to see
temperatures and dewpoints to fall all evening and overnight
tonight, bottoming out into the mid to upper 50`s north/mid 60`s
south by daybreak Tuesday. Holding tight on the lower side of NBM
guidance for tomorrow morning given just enough radiational
cooling processes. But overall, Tuesday will start of very nice
with mostly clear skies, only some thin upper-level cirrus
increasing in from the west throughout the day. The increase in
mid to upper-level moisture will be associated with what was
Tropical Storm Rick in the eastern Pacific, with the remnant mid-
level circulation pushing north into southern and central Texas,
out ahead of the aforementioned strong/deep trough pushing into
the central US. Tuesday is looking dry, even with a steady
increase in upper-level clouds with dry air settled in place
behind the front that passed today. Beyond Tuesday is where the
forecast begins to become a bit complicated, so let`s break it
down.
Downstream of the high-amplitude trough, we will begin to see
fast developing surface cyclogenesis over eastern CO/Western KS.
From here, the trough eventually breaks off and dives southeast
while attempting to close off, causing increased steep ridging
over the MS valley region sandwiched between this trough and
another deep upper-low offshore coastal New England. Meanwhile
back here, after the lead post-tropical shortwave passes
spreading north, it leaves behind a general zone of height
weakness with several small-scale pulses of mid-level energy
riding along 40-50kt H5 flow. The result could be an area of
convection developing somewhere from coastal Texas, northeast into
Louisiana late Tuesday night through early Wednesday. This is
where the medium and long-rage guidance differs on resolving this
potential convective feedback, which has everything to do with
downstream destabilization and environmental priming ahead of the
deepening low/strong cold front approaching from the west. For
now, recent trends in the GFS has convection initiating generally
over southwestern LA, but quickly pushing north along a northeast
surging warm front which would place most of our CWA within the
unstable warm sector out ahead of the cold front during the day
on Wednesday. Meanwhile, the 12KM NAM/3KM NAMNEST comes in more
widespread in marine convection, so much so that it spreads a
stratiform precip shield north into our area ahead of the surface
boundary due to isentropic uplift, promoting widespread
subsidence as dry air remains anchored in place from the recent
frontal passage. This could cause some harm in environmental
destabilization/building instability as we never truly get the
long fetch of deep-moist ascent to build into our area out ahead
of this system.
This will be tricky, as the extent and coverage of precipitation
will effect the downstream environment over our area. Noticing
plenty of shear in place, but most of this is typical out ahead of
warm fronts in an elevated environment (ESE surface flow quickly
veering to SW as a LLJ intensifies), with the only surface-based
convection confined to along the front into marine areas, where
severe storms will likely be ongoing during the day on Wednesday.
Late-hour synoptic runs of the HRRR picks up on the development of
this convection, but is a bit too early to catch on trends.
Thoughts from carefully thumbing through model guidance/trends:
The NAM3KM could be too loud on convective feedback initiating
single cells offshore coastal Texas. This typically causes a
domino effect as propagation becomes almost exponentially more
widespread than realistically possible. While the potential for
marine convection looks likely, there is still just too much doubt
on how this will translate downstream into our environment out
ahead of intensifying dynamic shear and impressive pressure/height
falls. Even if coastal convection develops along the warm front,
there very well could be a window wide enough for surface
moisture/some instability to rebuild out ahead of the main cold
front, expected to enter parts of our western CWA Wednesday
evening. There is no question that the shear profile will be more
than enough to support rotating updrafts, but the degree of
rebuilding instability caused by the earlier coastal convection
will determine the extent of linear development along the front as
it races east. Hate to say it, but there are too many "if`s" that
could lead to entirely different scenarios but a system as intense
as this, with a deepening sub-1000mb surface low and attendant
intense surface pressure falls, combined with strong dynamics from
a progressive/transitioning negative-tilt trough. This may very
well become a high shear/low CAPE event as the front swings
through, forcing a squall line or QLCS east through the area. Not
seeing much in the way of mid-level tropospheric modification or
any type of cooler pocket of air aloft to support large hail, as
H5 temperatures generally range in the -7 to -8C range, but can`t
completely rule it out. It is worthy to note, with forcing and
vertical shear being so strong, it will not take much to produce
weak tornadoes and damaging winds regardless of even the tiniest
slither of MLCAPE. Scenarios ranging from potentially two
individual waves of severe weather, to one large and intense QLCS
racing east, to a non-event all together is still in the playing
cards.
Overall, this system will be packed with mesoscale influences
that models are not confidently agreeing on just yet, which makes
sense this far out in advance. Convection allowing models will
begin to attain a handle of these mesoscale processes by this time
tomorrow, hopefully grabbing on to trends a bit more to help
provide a clearer picture. But for now, without getting (too) lost
in the weeds on details, the point of this discussion was to
weight out the wide range of possibilities, which leads to a
lower-confidence forecast. But this is not intended to lessen
concern, as this system has the potential to deliver widespread
severe weather Wednesday night and into Thursday morning, which is
concerning enough given the overnight timing. Expect more details
and higher confidence going into the day tomorrow. Stay tuned.
KLG
LONG TERM (Thursday through Sunday)
While the primary hazards from Wednesday are over, there are still
effects from the front in the CWA. The upper level pattern is
transitioning to a meridional pattern, with the upper level low
moving to the east. However the pressure gradient remains tight
through the upper and SFC levels. With this tightened gradient and
increase cold air advection (CAA) behind the front, temps cool down
significantly. Depending on the model solution, this gradient could
not loosen until Friday or Saturday, which means that Thursday and
Friday are expected to have gusty winds. With the CAA there is an
increased possibility of a low level stratus deck as well. However
this does help decrease PoPs for the weekend as there is dry air
advection behind the front as well. -KO
AVIATION... (18Z Discussion)
Most stations are at VFR conditions and will remain that way for
the TAF period. Stations that are at MVFR conditions will improve
as the cumulus field raises over the day. -KO
MARINE...
A decaying, weak cold front will continue to swing through
coastal waters this evening and into tonight, bringing a steady
increase in northerly offshore winds. At this time, the window for
strongest winds (10-15kts) will be primarily after midnight
tonight through early Tuesday, confined to areas mainly from the
MS sound, south into offshore Gulf zones. Winds will transition
from the north to eventual east-southeast going into late Tuesday
night and into Wednesday morning, with the potential for strong to
severe thunderstorms developing along a warm front surging
northeast through the day on Wednesday. The main threats will be
locally strong wind gusts >=34kts and waterspouts. A cold front is
then expected to swing through coastal waters late Wednesday into
early Thursday, delivering strong westerly winds. At this time,
sustained winds will increase early Thursday, likely reaching Gale
criteria (>=34kt sustained or frequent gusts). Strong winds will
last through Friday and into the upcoming weekend, with winds
steadily lowering with time. Waves/seas will steadily climb as
well, reaching 10-14ft for outer 20-60nm Gulf zones, with some
14-16ft or locally higher wave potential especially Thursday and
Friday, lowering slowly this upcoming weekend. KLG
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 55 79 59 76 / 0 0 10 90
BTR 58 81 63 79 / 0 0 10 90
ASD 57 82 59 81 / 0 0 10 90
MSY 67 81 68 82 / 0 0 10 90
GPT 59 80 60 79 / 0 0 0 70
PQL 56 79 58 79 / 0 0 0 60
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
742 PM EDT Mon Oct 25 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 257 PM EDT MON OCT 25 2021
Water vapor imagery and RAP analysis reveals a rex block over
eastern Canada into the Great Lakes region. Lingering weak cyclonic
flow and instability from the mid-level low or troffiness over the
area continues to result in isolated upslope rain showers/drizzle
into mainly the higher terrain of Baraga and western Marquette
counties this afternoon.
I suspect that the drizzle or isolated showers could linger into
tonight for those same ne upslope flow areas of Baraga and western
Marquette counties as the mid-level trough lingers over the area and
models indicate 850 mb temps are still from -3 to -4C, resulting in
a lake-H85 delta-t of around 14C. By Tuesday afternoon, I anticipate
a transition to drying/subsidence as the rex block breaks down over
the area and shortwave ridging works in from the west. Should also
see a clearing trend by afternoon with the increased subsidence and
low-level anticyclonic flow.
Lows tonight again will generally range from the upper 20s to lower
30s over the interior to the 35 to 40 range closer to the Great
Lakes. Highs Tuesday under a bit more sunshine will mostly be in the
mid to upper 40s, but will likely hit the lower 50s for a few
western interior and south central locations.
.LONG TERM...(Tuesday night through Monday)
Issued at 247 PM EDT MON OCT 25 2021
Beginning Tuesday night, Upper Michigan should find itself under the
influence of a building mid-level ridge. At the surface, high
pressure over eastern Hudson Bay will keep the region under light
easterly to southeasterly flow, so expecting a calm and quiet night.
Overnight lows should largely be in the 30s with some isolated 40s
by the lakeshores and 20s interior west being possible.
From there, attention turns toward split flow progressing eastward
out of the Rockies. A surface low is expected to develop in the lee
of the Rockies Tuesday and slowly track eastward toward the middle
Mississippi River Valley. With the wave expected to reach the
Missouri/Kentucky border late Thursday, inverted trough extending
northward and an approaching shortwave within the northern stream
will help focus precip up into Minnesota Wednesday into Thursday
night. Given the continued slowing trend of this system, the
earliest estimates of when our western counties could see some rain
now appear to be late Wednesday or early Thursday, and even that may
be pushed to the right in subsequent forecasts. Some GEFS members
are also now suggesting the east may stay entirely dry as the
southern upper level low tracks eastward into the Appalachians late
Friday and Mid-Atlantic Saturday.
Ridging and height rises will build into the region beginning late
Friday following the inverted trough/frontal passage. Right now
guidance suggests a dry Saturday is in the works. Upstream on
Saturday though, another shortwave is progged to enter the Northern
Tier and reach the region Saturday night/Sunday. As this wave
progresses eastward and broad troughing looks to establish itself in
response to an amplifying ridge off the west coast, colder air will
pour into the Upper Great Lakes. Early indications suggest 850mb
temps could fall to -5C by Monday morning and to around -10C by
Tuesday night. If this plays out, expecting a chillier and blustery
Halloween with lake effect rain and snow being possible going into
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 742 PM EDT MON OCT 25 2021
Under a cool air mass with NE winds veering E, lake effect stratocu
will continue to stream off Lake Superior thru Tue. With these
clouds, cigs will vary around 3000ft. At IWD, VFR conditions should
prevail thru the fcst period. Stratocu should scatter out for Tue as
sfc high pres ridge passes. At CMX, VFR conditions should mostly
prevail, though there will be some periods of MVFR cigs this evening
and potentially thru the night. At SAW, expect MVFR cigs to prevail
with a more direct NE upsloping wind off Lake Superior. However,
there will probably be some periods where cigs lift to VFR as well.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 257 PM EDT MON OCT 25 2021
The pressure gradient will gradually weaken tonight over the area as
sfc low pressure over the Ohio Valley slides east to merge with a
deepening sfc low over New England. As a result, NE winds 15 to 25
knots this evening should diminish to 20 kts or less late tonight.
These seasonably calmer winds will persist into Wednesday morning
with high pressure moving over the area before increasing again from
the southeast at 15 to 25 knots late Wed afternoon into Wed
night. The wind will then stay below 20 knots Thu into Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JP
AVIATION...Rolfson
MARINE...Voss
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PDT Mon Oct 25 2021
.SYNOPSIS...
Widespread rain will continue spreading southeastward across the
area this afternoon with precipitation ending from the northwest in
the evening. Stronger and gusty south winds will become westerly in
the afternoon, then diminish from north to south tonight. Dry
weather will prevail Tuesday through the weekend, with a warming
trend Tuesday through Thursday. Weak northeasterly winds will occur
Wednesday through Thursday. Onshore flow will return next weekend,
spreading cooling inland and bringing a return of night and morning
coastal low clouds and fog.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Atmospheric river is focused on LA County now, but rain was becoming
widespread in Orange County and northern parts of the Inland Empire
and surrounding mountains. Strong winds were occurring in the
mountains and deserts with numerous gusts over 45 MPH, especially
along and north of I-10.
The timing of the AR and related precip is generally through 5-7 PM
in Orange/San Bernardino County and between 3-7 PM in San
Diego/Riverside County, with most lingering precip ending by 9-10 PM
in southern San Diego County. HRRR and local WRF have been
consistently showing maximum hourly precip rates of around 0.5" in
the El Dorado/Apple burn scars and 0.4" in the Bond burn scar (each
about 0.1" below debris flow thresholds), with local rates of 0.8-
0.9" per hour in the strongest orographic areas in SW San Bernardino
County. ENS QPF has been consistent from the forecast Sunday, with a
very slight downward trend. SAN has mean ENS ensemble member amounts
around 0.15-0.2" though HRRR shows a little more, so likely amounts
around there should be around 0.25" total. SNA is approximately
double that. Saturation/near-saturation will extend to around 10000
feet MSL in San Diego County and 15000 feet MSL in San Bernardino
County, so rainfall will easily occur in the high deserts, up to
around 0.25" total, but rainfall will be sparse in the lower
deserts, generally 0.10" or less even though some moisture is
evident in a shallow low layer coming up from the southeast. Local
mountain rainfall will total over 2" in the San Bernardino Mountains
on the upper south slopes. Widespread flooding is not expected, but
local roadway flooding will be possible in low-lying areas. Little
or no snow fall will occur in the mountains as the snow level will
not fall below 10000 feet MSL until the moisture exits.
Fair weather will prevail starting late tonight as a broad area of
zonal high pressure over the east Pacific gradually shifts east into
the western US. Tuesday will be 5-10 deg F below normal, but
temperatures will recover to near normal Wednesday and 5-10 deg F
above normal Thursday, with some lower 90s possible in warmest
valleys based on some of the ENS contributors to MOS. The
lower deserts will likely be above 90 then as well. The high will
weaken over the weekend as some sort of troughing and/or upper low
moves by to the north, though models are inconsistent with details.
Most likely that will result in a cooling trend then and early next
week, with a return of marine layer stratus near the coast.
&&
.AVIATION...
252030Z...Coasts/Valleys/Mountains...Low clouds with bases 1500-2500
FT MSL. SHRA is occurring across Orange/San Bernardino Counties and
will spread southeastward into Riverside/San Diego Counties through
23z Mon. Vis will be reduced to 2-4 SM and cigs may become locally
under 1000 FT MSL during the heaviest RA. RA will diminish after 02z
Tue across northern areas, and after 04z Tue across southern/eastern
areas. Overnight, stratus covering all areas with bases 2000-3000 FT
MSL.
Breezy S-SW winds, strongest across mtn tops and lee of ridges.
Winds 15-25 kts with gusts 30-40 kt, isolated 50 kt gusts in favored
locations. Winds turning from the S to the NW with frontal passage,
impacting coastal TAF sites 23z Mon-03z Tue. Winds will slowly
diminish after 09z Tue.
Deserts...SCT-BKN with bases 5000-8000 FT MSL with -SHRA 23z Mon-03z
Tue. Gusty NW winds developing after 20z Mon with peak gusts 30-40
kts. STG up/downdrafts along desert slopes.
&&
.MARINE...
A cold front will bring breezy southwest winds today, with a shift
to the northwest as a front moves through coastal waters this
afternoon and early evening. Winds and seas will present hazardous
conditions for small craft. Northwest winds of 10 to 20 kt with
gusts 25 to 30 kt and seas 6 to 11 ft are expected. In addition,
scattered rain showers will accompany this noticeable wind shift,
generally from 2 pm through 7 pm. A Small Craft Advisory is in
effect through early Tuesday morning. Conditions will gradually
improve late tonight and Tuesday.
&&
.BEACHES...
A long period west swell and a long period south swell will combine
to produce high surf and dangerous swimming conditions today through
early Wednesday. Large breaking waves of 5 to 8 feet, with local
sets to 10 feet in southern San Diego County. A High Surf Advisory
is in effect through early Wednesday morning.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 10 AM this morning to 2 AM PDT Tuesday for
Apple and Lucerne Valleys-Riverside County Mountains-San
Bernardino County Mountains-San Diego County Deserts-San
Diego County Mountains-San Gorgonio Pass Near Banning.
High Surf Advisory from 11 AM this morning to 3 AM PDT Wednesday
for Orange County Coastal Areas-San Diego County Coastal
Areas.
PZ...Small Craft Advisory from 11 AM this morning to 5 AM PDT Tuesday
for Coastal Waters from San Mateo Point to the Mexican
Border and out to 30 nm-Waters from San Mateo point to the
Mexican Border Extending 30 to 60 nm out including San
Clemente Island.
&&
$$
PUBLIC...Maxwell
AVIATION/MARINE/BEACHES...Schenk
Area Forecast Discussion
National Weather Service Shreveport LA
1013 PM CDT Mon Oct 25 2021
.SHORT TERM.../Tonight/
The evening sfc analysis indicates that our frontal system has
drifted S into SCntrl LA into Deep E and NCntrl TX, with drier air
evident over N LA and Cntrl MS expected to backdoor SW into much
of S LA through the overnight hours. A portion of this drier air
may backdoor into Deep E TX late tonight, with the Wrn sections of
the sfc front expected to return Nwd across the Srn Plains during
the day Tuesday, while remaining mostly stationary over E TX/S LA.
With some of this dry advection ongoing across Cntrl LA this
evening, already starting to see some patchy FG trying to develop
here as well as portions of extreme SE TX, with vsbys ranging from
5-6SM, and even down to 1/2SM in FG at JAS. The recent runs of the
HRRR have maintained the potential for patchy FG development
mainly from SW LA into portions of SE TX, and advecting NE into
the SW sections of Deep E TX late. Have added patchy FG wording to
the forecast late tonight through mid-morning Tuesday for
Angelina/Srn Cherokee Counties, with the best FG potential
expected farther S of the region before lifting by mid-morning.
Only minor adjustments were needed to the forecast min temps,
mainly to raise temps slightly in the warm sector over the Wrn
sections of E TX, where a sct cu field lingering along the Wrn
edge of the front will help hold temps up overnight. This cu field
is expected to expand back NNE across NE TX/SE OK into portions
of SW AR overnight, but should not affect the temp fall much given
the clear sky and light winds in place attm.
Otherwise, an increasing cu field with the return Srly low level
flow, and cirrus shield from the SW from the remnants of TD Rick
over Cntrl old MX atop the cooler and drier air mass in place
should result in cooler max temps Tuesday, with readings remaining
below record territory for a change in wake of near to record
temps observed the last couple of days over the region.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 643 PM CDT Mon Oct 25 2021/
.AVIATION...
Mostly VFR conditions will continue through the 26/00Z TAF period.
SKC will continue this evening and overnight across much of SW
AR/N LA, although a sct cu field still lingering across the Wrn
and SW sections of E TX near and S of a TYR to OCH/JAS line will
begin to lift back to the NNE by/after 06Z across much of E TX
into SE OK, and enter adjacent sections of SW AR by/just before
daybreak Tuesday. Some patchy FG/LIFR cigs may also develop just
prior to daybreak across portions of SE TX, which may advect into
LFK and linger through mid-morning before lifting. Farther N, some
cu cigs are possible across portions of E TX and extreme SW AR,
possibly affecting the TYR/GGG/TXK terminals between 06Z-09Z,
before a sct cu field develops and expands across much of the
region later in the morning through the afternoon beneath an
expanding cirrus shield increasing from the SW ahead of the
remnants of now TD Rick over Cntrl Old MX. ENE winds 5kts or less
tonight will become SE 6-12kts after 12Z. /15/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 59 82 66 77 / 0 0 20 90
MLU 52 78 61 77 / 0 0 10 90
DEQ 49 75 60 71 / 0 0 40 90
TXK 54 78 64 74 / 0 0 30 90
ELD 49 76 59 71 / 0 0 10 90
TYR 65 86 67 77 / 0 0 50 90
GGG 61 85 65 78 / 0 0 30 90
LFK 65 86 68 82 / 0 0 30 90
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15