Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/03/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
804 PM CDT Wed Sep 2 2020
.UPDATE...
Issued at 802 PM CDT Wed Sep 2 2020
The Red Flag Warning has been allowed to expire. No other changes
made to the forecast at this time.
UPDATE Issued at 716 PM CDT Wed Sep 2 2020
Minor adjustments made to the Wind Advisory, extending the end
time a few hours longer for Brown and Marshall counties.
&&
.SHORT TERM...(This Evening through Thursday Afternoon)
Issued at 259 PM CDT Wed Sep 2 2020
Red Flag to near Red Flag Warning conditions remain over the western
half of the forecast area, with relative humidity values in the 15 to
25 percent range and winds gusting 25kts to around 35kts.
The main concern is the timing of the cold front as it sinks
southeast across the CWA. Will rely heavily on the high
resolution model solutions to get an hourly trend for late this
evening and overnight, particularly the HRRR, RAP13, and GFS1hr,
not only for temperatures and dewpoint trends, but winds. 50kt to
60kt winds are being indicated below 5kft off the HRRR at most
locations, with gust at the surface mainly in the 30kt to near 45kt
range. Will not be out of the question right behind the front to
get a few higher winds to mix down. Will continue the Wind
Advisory, and keep the timing as is, as it tracks well with the
latest thinking.
Will be difficult to rule out a few showers over northeastern SD
after 03Z Thursday. While not completely out of the question for an
isolated lightning strike, have left the potential out for now.
Cooler air and lower dewpoints will move in behind the cold front.
Expect highs in the 70s, and dewpoints in the mid 30s to mid 40s.
This will bring relative humidity values mainly into the 25 to 40
percent range, lowest west of the Missouri River. Northwesterly
gusts of 20kts to around 25kts will be possible again Thursday
afternoon. Lighter winds and a continued cool airmass will help
surface temperatures fall into the upper 40s to low 50s Thursday
night.
.LONG TERM...(Thursday Evening through Wednesday)
Issued at 259 PM CDT Wed Sep 2 2020
A highly amplified mid-level flow pattern is expected to continue
over the CONUS through the long term. The pattern will feature a
western CONUS ridge and central/eastern CONUS trof. The first part
of the period looks mainly dry. However, energy digging southeast
across the Plains Sunday night through Monday night should help
develop fairly widespread overrunning pcpn on the north side of a
front splayed out over the Central Plains. The ECMWF remains more
vigilant in dropping energy south into the Great Basin and develops
a closed low. The ECMWF is therefore less aggressive in pushing the
synoptic cold front as far south and as quickly south as the GEM and
especially the GFS. GEPS guidance does lend some credibility to the
deterministic ECMWF solution, so the forecast may trend more toward
that model in the future. For now the model blend will suffice given
the uncertainty in model solutions. Based on the latest 2m and H850
temp anomalies, temperatures should average near to above normal for
the first half of the period, but will trend to below normal for the
first half of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 625 PM CDT Wed Sep 2 2020
Terminals KABR,KATY,KPIR,KMBG
VFR conditions will prevail across the area tonight and through
the day Thursday. A cold front will track across the area tonight,
with winds shifting around to the northwest and increasing into
the 25kt to 40kt range, with some gusts to 50kts not out of the
question. Winds will diminish, but remain breezy, late tonight
into the day Thursday.
***Construction to improve taxiways at both KABR/KPIR terminals
may cause an occasional temporary visibility reduction due
to blowing dust (bldu), mainly during daytime hours UFN.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until midnight CDT /11 PM MDT/ tonight for
SDZ003>005-009-010-015-016.
Wind Advisory until 3 AM CDT /2 AM MDT/ Thursday for SDZ008-011-
017>023-033>037-045-048-051.
Wind Advisory until 3 AM CDT Thursday for SDZ006-007.
MN...Wind Advisory until 3 AM CDT Thursday for MNZ039-046.
&&
$$
UPDATE...Parkin
SHORT TERM...KF
LONG TERM...TDK
AVIATION...Parkin
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
712 PM CDT Wed Sep 2 2020
.AVIATION...
For the 00Z TAFs, a weak cold front will move across the region
Thursday morning, with winds becoming north at all TAF sites.
Little to no cloud cover is expected. Otherwise, VFR conditions
are anticipated at KGUY, KDHT, and KAMA through late Thursday
afternoon.
02
&&
.PREV DISCUSSION... /Issued 237 PM CDT Wed Sep 2 2020/
SHORT TERM (today through tomorrow)...
Taking a look at water vapor imagery, we can see the upper level
low finally starting to exit the region. As of 1:30 PM, it was
centered roughly over southern parts of the TX Panhandle. Ahead
of the low, there is a jet streak at 300 mb, and the left exit
region is helping produce just enough ageostrophic circulation to
allow divergence aloft and hence lift in the east. Thunderstorms
are ongoing as of writing this across eastern parts of the TX
Panhandle. This area is uncapped with about 1500 J/kg of MLCAPE as
suggest by the RAP analysis. Effective shear is very weak in this
area. In fact, all other thermodynamic/kinematic variables are
weak, so not expecting severe weather, but there is a window until
about 5-6 PM where we could have ordinary thunderstorms across
eastern parts of the forecast area. As the upper low pushes east,
subsidence will be observed on the back side, and we should see
skies generally clearing. Wind speeds will become light and
variable tonight. A cold front will push in from the north
tomorrow, and while the front might not make it completely through
the area, we should see a northerly wind develop for a majority
of the forecast area. With plenty of sunshine tomorrow, highs will
be able to reach the mid 80s to mid 90s; cooler temperatures
anticipated across the northern half of the area.
Guerrero
LONG TERM...
By Friday morning the FA will be under NW flow aloft then quickly
turned to northerly flow in the evening. This will be due to an
upper level high pressure system moving into California and Nevada
by Friday evening. By Sunday the high will spread east over the
Four Corners Region and spread enough to reach the combined
Panhandles. Daytime highs are looking to be well above normal on
Sunday afternoon with highs in the mid to upper 90s.
Clear skies over the weekend will go away at the start of next
week. Cooler temperatures and more cloud cover will moved into the
area Monday night into Tuesday. Confidence in timing is low at the
moment due to model disagreements. However, there looks to be a
very stout upper level trough that will dig down through the
Northern Rockies or the Northern Plains. Again depending on the
timing of the upper level trough and the associated surface front,
the FA will be looking at some daytime and nighttime temperatures
well below normal. Not quite freezing yet, just really cool
compared to an last month that was well above normal. Chances for
showers and thunderstorms will also return to the area with this
system. Have stuck with NBM PoPs and temperatures at this point.
Winds are looking somewhat breezy behind the surface cold front.
Which, by the NBM doesn`t make it here until early Tuesday. It is
still a ways out, but winds could be much higher than what models
are showing at this time, especially the NBM. Neighboring
forecast offices have already started talking to collaborate on
upping the wind speeds in the forecast behind the front on
Tuesday. The general consensus at this time is to use Superblend
for wind speeds at this time.
Hoffeditz
&&
.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.
&&
$$
Area Forecast Discussion
National Weather Service Bismarck ND
1056 PM CDT Wed Sep 2 2020
.UPDATE...
Issued at 1040 PM CDT Wed Sep 2 2020
Cold front has now passed through the entirety of the CWA. Many
areas saw wind gusts over 50 MPH, and a lot of areas experienced
gusts over 60 MPH along the front perhaps enhanced by low topped
convection. Current observations showing winds on a general
diminishing trend behind the front, expect for areas near the
front front where some post frontal showers are perhaps mixing
down the strong 850 mb winds. Given RH values are on the rise,
while winds are generally diminishing have let the Red Flag
Warning expire. Winds for the most part in the Wind Advisory areas
have diminished below criteria and lack any shower activity to mix
down winds. As a result have let mush of the Wind Advisory expire
except across northeastern zones. The High Wind Warning remains
tricky as post frontal winds are still hitting at least advisory
criteria, with scattered showers bringing the potential to mix
down higher gusts. Will leave the High Wind Warning for now and
reevaluate at a later update.
Remainder of the forecast overall remains on track. Adjusted pops
slightly for lingering showers in the south. Min temps tonight
look to be in the 40s with some 50s in areas with lingering cloud
cover. Thursday looks to be cool with perhaps some breezy winds,
although not as high as today.
UPDATE Issued at 709 PM CDT Wed Sep 2 2020
Cold front moving across the state is causing for areas of strong
winds and critical fire danger. Some sites are seeing gusts 60 MPH
or higher, with sustained winds near or over 40 MPH. A few of
these winds gusts have been enhanced by shallow convection
although they are all generally along the synoptic cold front.
Have decided to issue a High Wind Warning for passage of this
front for a brief period of strong winds this evening. Strongest
winds will again come along this front and any weak convective
showers. For the stronger convective storms will continue to
monitor for more short lived convective wind gusts and issue any
needed severe thunderstorm warnings. Either way wind gusts near 70
MPH are possible this evening.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 314 PM CDT Wed Sep 2 2020
Strong winds and critical fire weather conditions through this
evening remain the primary message of our forecast.
As of 20 UTC, a surface warm front is approaching the James River
valley, with deep mixing and increasing low- and midlevel winds in
its wake within the warm sector of an approaching Alberta clipper.
Critical fire weather conditions are ongoing in western and parts
of central ND, and RAP-based Fosberg index values support high-
end values of 60 to 70 in southwestern ND through late afternoon
with wind gusts of 50 mph and minimum RH values around 15 percent.
This is a serious situation and reflects a higher-end Red Flag
Warning.
A strong cold frontal passage is still expected beginning late
this afternoon in northwest ND and through the remainder of the
area this evening. Upstream pressure 3-hour pressure rises on the
order of 6-8 mb are forecast to intensify further with recent RAP
and HRRR cycles forecasting a rather impressive 10 mb/3 hour area
of pressure rises moving through western and south central ND in
the 23 to 03 UTC time frame. Upstream, observed post-frontal gusts
have mainly peaked in the 45 kt range, though a few spots within
north central and northeastern MT have touched the 50 kt speed,
and recent Glasgow radar imagery reveals 70 kt winds within 3000
to 5000 ft AGL. The 17 UTC HRRR cycle was higher with peak winds
in the post-frontal mixed layer than its prior cycles, but the 18
UTC HRRR arrived a bit lower, supporting peak winds at the top of
the boundary layer mainly in the 42 to 47 kt range this evening.
Thus, after much consideration we are holding with a Wind Advisory
instead of upgrading to a High Wind Warning, though we gave it
very serious consideration and later observational trends could
still necessitate such an adjustment. Elsewhere, we added the rest
of east central ND to a Wind Advisory, and kept that eastern
section from Rolla down to Jamestown and Ellendale valid until 09
UTC in collaboration with NWS Grand Forks.
Otherwise, weak instability associated with the frontal passage
may still drive convection and downdraft-enhanced winds,
especially in central ND where CAMs are most aggressive with the
coverage of convection. Given sufficient lightning, we may need to
issue Severe Thunderstorm Warnings to handle this higher-order
wind potential that would be less widespread outside of the newly
issued High Wind Warning.
On Thursday, mixed-layer winds will remain sufficient for breezy
to windy conditions in residual cyclonic flow behind the exiting
shortwave trough. Forecast soundings suggest mean boundary layer
winds on the order of 20-25 kt in central ND, and closer to 20 kt
in western ND. Highs will be cooler, in the mid 60s to lower 70s
F, and it appears the stronger winds will not overlap with the
lowest humidity, the latter of which will be in western ND. The
winds may begin to relax by afternoon in the west, too, when a
surface ridge axis begins to approach the region. That ridge is
forecast to cross the area Thursday night, likely creating a
favorable scenario for radiational cooling, so we relied on the
cooler, MOS-based guidance for lows in that period since it often
verifies well in those scenarios. We`re thus calling for lows in
the 40 to 45 F range over the entire area Thursday night.
.LONG TERM...(Thursday night through Wednesday)
Issued at 314 PM CDT Wed Sep 2 2020
A warming trend is expected through Saturday, but then confidence
remains high in a shift to a colder weather pattern by early next
week, albeit with uncertainty in timing of the transition.
Global ensemble guidance is closely clustered in simulating rising
heights aloft Friday and Saturday with corresponding low- and mid-
level warm air advection beneath broad northwest flow aloft. This
is reflected in NBM-based temperature forecasts which have highs
in the 75 to 85 F range Friday area-wide, and around 90 F in the
southwest on Saturday. Low-level southerly flow may increase on
Saturday, potentially leading to elevated fire weather concerns.
Thereafter, middle- and upper-level ridging in the southwest U.S.
is forecast to retrograde and amplify off the west coast, though
ensemble guidance varies with the degree and position of the 500
mb height anomalies. GEFS-based guidance has remained the most
progressive with corresponding downstream troughing across the
central U.S., and in particular with the lead shortwave which is
expected to herald that pattern change. Ensemble-based cluster
analysis has offered some support for a slower scenario over the
last 24 hours, and indeed the spread in NBM membership for highs
on Sunday -- the most likely period of pattern transition -- has
increased significantly over western and central ND. The mean of
the NBM has shifted warmer with highs on Sunday with the forecast
highs now in the 70s F, though the simple, one standard deviation
of NBM membership ranges from the mid 60s to lower 90s F Sunday.
Thereafter, guidance agrees that a cold front will have arrived by
Labor Day, though the westward extent and amplitude of the middle
and upper-level troughing is uncertain, with the 12 UTC ECMWF the
most aggressive, cutting off a 500 mb by midweek. That particular
model core does have a tendency to be overly aggressive with cut-
off lows, but this exemplifies the uncertainty. Regardless, CIPS
analogs, which are driven by the GEFS, support a high confidence
in well below normal temperatures and high probabilities of the
first widespread frost of the season Monday night and Tuesday
night. NBM-based guidance similarly supports that, as well as a
period of increased precipitation chances centered on Labor Day
as the initial upper-level trough develops across the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 709 PM CDT Wed Sep 2 2020
Strong winds along a cold front will be found through this evening
with many sites seeing gusts over 50 knots. Showers along this
front could also bring brief MVFR conditions through this evening.
Showers and wind then diminish after 05z_Thursday (tonight) with
perhaps some lingering low to mid level clouds producing MVFR
conditions. By Thursday morning widespread VFR conditions look to
return. Winds may be breezy at times in the afternoon, although
not as high as recent days.
&&
.FIRE WEATHER...
Issued at 1055 PM CDT Wed Sep 2 2020
Cooling temperatures behind the cold front has rapidly rebounded
RH values this evening. Much of the area is also seeing winds
diminish. As a result have let the Red Flag Warning expire across
western and central ND.
The pattern of dry northwest flow looks to continue through the
rest of the week and into Saturday. Each day will have RH values
lowering, especially in the west where teens and 20s are possible.
Breezy winds are possible each day, although critical fire danger
criteria may just be shy. Regardless at least elevated fire danger
may continue through Saturday, and those with fire weather
interests should monitor the latest forecast.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until midnight CDT /11 PM MDT/ tonight for
NDZ019>023-033>036-040>047-050.
Wind Advisory until 4 AM CDT Thursday for NDZ005-013.
High Wind Warning until 4 AM CDT Thursday for NDZ025-037-048-051.
&&
$$
UPDATE...Anglin
SHORT TERM...CJS
LONG TERM...CJS
AVIATION...Anglin
Area Forecast Discussion
National Weather Service Caribou ME
1010 PM EDT Wed Sep 2 2020
.SYNOPSIS...
A frontal system will stall across the area overnight into
Thursday. Another cold front will cross the region Friday. High
pressure will build across the region Saturday and move east of
the area Sunday. Another frontal system is expected to slide
across the region during the day on Monday
&&
.NEAR TERM /THROUGH THURSDAY/...
10:10 pm update: We made some adjustments on pops for the
Eastern areas based on the latest radar data and model trends.
Showers continue to track east across eastern Quebec. As these
showers move into the North Woods there may be some embedded
thunderstorms. Otherwise no significant changes were made at
this time.
Previous discussion:
A warm front or warm occlusion is expected to lift into the
region this afternoon w/warming continuing. Dewpoint in the
upper 40s and 50s will rise through the evening into the 60s
throughout the entire CWA. The latest sfc analysis showed this
warming as dewpoints back across the western areas were already
in the upper 50s. Radar showed some showers out ahead of the
occluded front moving across wrn and nwrn areas pushing to the
ne. Rainfall associated w/this first batch of showers is fairly
light. Another batch of showers expected to arrive this evening
as the occlusion arrives into the region. There does look like a
line of enhanced reflectivity shows up right ahead of the
boundary between 03-06z w/some strong wind gusts. The last two
runs of the HRRR picked up on this line. The 12z UA showed a
strong jet max of 50 kts at the 850-700mb layer over Lake Huron
and Ontario, Canada. This feature is shown by the high
resolution guidance such as the NAM12/RAP and NAMNEST to make
its way into the region this evening into overnight hrs. The
NAMNEST was the most aggressive and ominous to say the least
w/showing 50 mph gusts in some sites across western and northern
areas. This could be a tad strong as the soundings show some
crossing of the winds w/SW winds overrunning a SSE winds in the
blyr. Therefore, that jet max will be tempered from mixing down
to the sfc initially. However, this looks like it will change
later in the evening as winds align just ahead of the front
allowing for those stronger winds to mix down. Another factor to
aid this mixing will be the increasing dewpoints and the
potential for some elevated convection. Sounding data does show
elevated CAPE 200-300 joules w/PWS 1.5+ inches, plus 0-6km shear
of 45+ kts. Decided to stay w/the midnight crew`s assessment to
have isolated tstms. Wind gusts were increased to account for
the mixing of those stronger winds aloft.
The Hazardous Weather Outlook was updated to highlight the
strong wind gusts through late evening and the potential for
some snapped tree limbs and power outages. Another item to
mention of the heavy rainfall w/that expected line later this
evening given the high PWS. Activity should wind down during the
morning hrs and the showers move se. Kept the mention of fog
w/the wet ground and slight cooling for tonight.
Last batch of showers to be exiting Washington County Thursday
morning w/the occlusion stalling or washing out across the
Downeast region. The 12z GFS shows some light rain showers
across the Downeast region while the NAM shows some light
activity right along the immediate coast. There is some weak
convergence noted by the NAM along the Downeast coast. There is
a weak upper disturbance that appears to move ne in the broad sw
flow aloft. This would be enough to trigger some to some
showers. The caveat is that the column begins to dry out above
800mbs by late morning. The 12Z NAM and GFS show this setup.
Highest chances for showers is over the coastal waters.
Therefore, carried 20% pops for some showers the interior
Downeast and coast. It will be humid w/temps above normal for
the 1st week of September.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
The CWA will be between two weather systems Thursday night. To
the east, a strengthening LLJ across Nova Scotia and eastern New
Brunswick...to the west, an elongated front from low pressure
north of the Great Lakes. The strengthening LLJ will bring some
moisture onshore across Downeast into Southern Aroostook. This
moisture is located towards the mid-levels and surface, with a
healthy dry layer in between. It will take time for this layer
to saturate, and wont count on it to enhance the chance of
showers before the air mass tracks out of the state. Kept slight
chance of showers in there for the advent some convergence
starts some showers as well as some elevated instability towards
midnight.
Perhaps the more sure item will be fog over the waters and
moving inland overnight. The low level moisture will get trapped
below an inversion as sfc temps cool and onshore flow keeps the
environment moist.
The weak front will pass over much of the CWA during the early
morning hours into early afternoon Downeast. Expect this to wick
away the last of the moisture and fog with the afternoon
becoming mostly sunny in dry NW flow. Winds will be a bit breezy
across the north, but the angle of attack for the front isnt
conducive to stronger gusts of wind. In addition, stronger 850
and 925 winds are placed north of Maine.
Dry weather continues Friday night into Saturday as a longwave
trough slowly tracks north of the region. Some isolated showers
may develop across the far north during the afternoon as lapse
rates steepen with some moisture in the low levels. Elsewhere,
high temps will be cooler with highs around 70 Downeast and mid-
60s in the Central Highlands and north.&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
Saturday night the departing trough flattens and SW flow develops
in the low levels. High pressure that had been over the South,
departs for the Mid-Atlantic, forming some return flow into the
Northeast. The GFS is aggressive with developing low pressure
over the Great Lakes Sunday evening and overnight, tracking it
through the St Lawrence River. ECMWF and Canadian solutions
develop this system over the Upper Midwest. A stronger high
pressure presence over New England keeps the effects of this
system at bay, passing it to the north. There remains too much
uncertainty for much forecaster confidence in this setup, and
continue to keep PoPs on the lower end.
Both of those solutions to support a warming trend however.
Expect this to occur through mid-week as some SW flow helps
advect warmer temps, and S return flow keeps some moisture
around.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: IFR to low end MVFR conditions are expected the
remainder of tonight for all terminals w/some showers. There
will be a period of LIFR especially later this evening into the
overnight hrs ahead of the occluded front. LLWS is expected
overnight w/winds of 45 kt at 2k ft.
Thursday...MVFR early becoming VFR by mid morning for the
northern terminals and KBGR. MVFR looks like it will hang on a
bit longer for KBHB into late afternoon.
SHORT TERM:
Thursday night through Friday...Generally VFR/MVFR with a chance
of showers. However, IFR/LIFR possible during the overnight and
early morning hours both Thursday and Friday with low clouds and
fog at Downeast terminals. West winds light overnight, 10-15 kt
during the afternoon.
Saturday through Sunday...VFR. Slight chance of an afternoon
shower across northern Aroostook county Saturday. West wind
becoming S Sunday night.
Monday...VFR, some afternoon showers across Aroostook terminals
possible.
&&
.MARINE...
NEAR TERM: Winds and seas will remain below small craft advisory
overnight. A few gusts to 25 kts over the outer zones overnight.
Seas will respond w/heights building to 3-4 ft late. Showers
and fog will limit vsby.
For Thu, S winds will drop off to around 10 kt as the llvl jet
lifts to ne by morning. Seas will hold around 4 ft. There will
be showers and fog around which could limit vsby.
SHORT TERM:
Waves 2 to 4 ft will diminish to 2 to 3 Saturday afternoon
through Sunday night. Waves increase again Monday 4 to 5 ft
where a SCA may be needed. S winds will be come WSW through the
weekend increasing towards 20 kt Monday afternoon.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Hewitt/Sinko
Short Term...Cornwell
Long Term...Cornwell
Aviation...CB/Hewitt/Sinko/Cornwell
Marine...CB/Hewitt/Sinko/Cornwell
Area Forecast Discussion
National Weather Service Grand Forks ND
1040 PM CDT Wed Sep 2 2020
.UPDATE...
Issued at 1040 PM CDT Wed Sep 2 2020
Dynamically enhanced convective line continues to move east over
northwest/west central MN with southerly flow ahead of this line
feeding enough instability to continue to maintain strength
despite minimal MLCAPE analyze around 500 J/KG in warm sector.
This is riding along a Warm frontal zone with DCAPE in excess of
1000 J/KG and orthogonal to strongest part of the line is a strong
LLJ/mid level jet continuing to provide ample shear and forcing.
We continue to receive severe wind reports with this line and
with environment holding steady it may continue to be severe until
it exits our CWA to the west.
Regarding Wind Advisories: There is a post frontal lull where low
level inversion is likely inhibiting mixing now, but we are still
seeing observed gusts 40-47 mph in our far west lingering. The
secondary surge of 925-850 mb CAA is less defined in current suite
of RAP/NAM for the overnight period and more towards daybreak
when winds aloft may not be as strong. There is an upstream PV
anomaly and region of subsidence showing up on WV imagery to our
west which could help momentum transfer despite decoupling. HRRR
continues to show consistent run to run signal for 35-40kt winds
late tonight, so I am not inclined to at this stage to change
ongoing Wind Advisories.
UPDATE Issued at 806 PM CDT Wed Sep 2 2020
A strong cold front is starting to move into our west CWA with
showers and thunderstorms along and ahead of this lite, and
additional showers expanding into west central MN. While MLCAPE
is relatively low in eastern ND there is higher DCAPE values
greater than 1000 J/KG and a strong low-mid level jet leading to
effective shear values in the 55-65kt range orientated
orthogonally to the cold front. The strongest winds immediately
along and behind the front are likley enhanced by showers, but
there is a stronger convective enhancement due to those
environmental factors where thunderstorms have developed.
Observations further west of our area vary within these diverse
environments (some locations dominated by synoptic/frontal
momentum transfer and others enhanced by convective processes). As
the sun sets and this DCAPE axis moves southeast the stronger
convective component should drop off, and the initial frontal
burst of winds should drop off.
There is also still a stronger surge of CAA later tonight that is
shown by RAP/NAM to progress eastward before loosing momentum in
northwest MN. Short range models show 40-50 mph gust potential
further north and east than the original advisory. Where it
looses momentum/mixing during the overnight/early morning period
is a tough call. It is possible the strong winds may not make it
as far east, and at the same time some HRRR ensemble members shows
the strong winds making all the way to Lake of the Woods.
Decision was made to bump up the start time for our western
advisory and then add counties to our north and east to cover the
potential of this the late night surge of winds, but did not go
quiet as far east as outlying models indicate. Will monitor
trends this evening to see how it evolves.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 308 PM CDT Wed Sep 2 2020
Winds the primary concern this evening into the overnight as low
pressure traverses the CWA. Strong forcing associated with the SFC
low and along a boundary with strong cold advection will create
showers and possible thunderstorms with ML CAPE 500J/kg. This
activity is expected to move quickly west to east late this
afternoon into the evening with downdraft CAPE values up to
1000J/kg nosing into the warm sector. There in lies the potential
for showers and or thunderstorms to mix down some of the stronger
winds aloft. The HRRR has consistently developed a line of
activity with gusts over 50mph across central ND. The trend in the
CAMS has been a touch slower with the line and subsequently
bringing those strong winds into the Devils Lake area in the 6pm
time frame. With less instability in the valley those winds do
decrease as the line weakens. Mixing does increase in the wake of
the cold front within the CAA regime and the potential to mix
down 850mb winds overnight for the Devils Lake basin down into
the Wahpeton area with gusts to 50mph.
Thursday will see showers end in the east in the morning. Breezy
conditions are in store as NW winds gust to 35 mph and highs
struggle into the mid 60s.
.LONG TERM...(Friday through Wednesday)
Issued at 308 PM CDT Wed Sep 2 2020
The principal opportunity for impactful weather will most likely
present itself early next week, in the form of the potential for
isolated to scattered patches of frost.
At the start on Fri, we would look for temps to trend upward into
the 70s after a cooler Thu and the trend should continue into a
seasonable Sat. A front swinging through early Sun could provide a
RW/TRW chance, but a dearth of moisture/instability would prevent
any impactful precipitation amounts. Behind the front will be colder
air lowering temps during a breezy Sun aftn.
Labor Day will offer high temps that will be most likely shy of 60
degrees for most places. Some guidance presents pcpn chances as a
system swings to the south. Then we head toward the impactful
weather chances. The possibility for areas of frost will present,
more likely Tue night into early Wed. This will largely depend on
cloud cover and wind speed. During this time frame, ensemble 850 mb
temps are projected to "MIN out" with our region in the bullseye of
some sub zero C. temps.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 753 PM CDT Wed Sep 2 2020
Several periods of strong winds will move through the region, with
directions shifting from the south to east to northwest as a cold
front moves across eastern ND and northwest MN. In addition, a
large cluster of showers and embedded strong to severe storms is
moving into eastern ND. While most of this activity should weaken
before it reaching KGFK there will still be enhanced wind gusts
possibility and a period of lighting activity. Expect
showers/storms to end late this evening/early Thursday morning,
with a period of MVFR stratus possible in northwest MN in the
morning period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Wind Advisory until 6 AM CDT Thursday for NDZ008-016-027-030.
Wind Advisory until 5 AM CDT Thursday for NDZ006-007-014-015-024-
026-028-029-038-039-049-052>054.
MN...Wind Advisory until 6 AM CDT Thursday for MNZ001>005-007-008-
013>015-022-027-029-030-040.
$$
UPDATE...DJR
SHORT TERM...JK
LONG TERM...WJB
AVIATION...DJR
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
952 PM CDT Wed Sep 2 2020
.UPDATE...
Issued at 951 PM CDT Wed Sep 2 2020
Strong cold front now through about the northwest third of the
Rushmore state, featuring trailing 7-8hPa/3h pressure rises and
up to around 40 kts flow off-surface, along with a 15-20 degree
temperature drop in the couple hours after passage. Likely will
have a brief period of stronger gusts shortly after the frontal
passage, perhaps locally as high 45 to 50 mph, but much more
likely 40 to 45 mph with some gradual stabilizing this evening
ahead of the front. HRRR has been playing catch-up on winds, and
continues to suggest that the further southeast the boundary
progresses, the lesser the wind gusts should be. Thoughts of
adding a wind advisory for areas from MML-FSD-YKN and west, but
likely will a fairly marginal event. The winds then should drop
off somewhat in the cold advection zone, still quite breezy,
before increasing gustiness again during the morning hours.
Highest sustained winds may occur by mid- to late morning before
dropping back through the afternoon. All in all, should be a
couple periods of marginal advisory conditions (gusts to at least
45 mph/sustained over 30 mph).
Otherwise, will add in a few sprinkles along the northern tier
from around Brookings eastward, but that should be about the best
the mid-level skinny and shallow instability atop the very
dessicated formers surface-based mixed layer is likely to render.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 247 PM CDT Wed Sep 2 2020
Gusty southwest winds developing across the area ahead of a strong
cold front moving through the region tonight. As of 19Z, cold
front had worked into western North Dakota with winds gusting to
35-40 knots. Strong mixing today has lead to elevated fire weather
conditions across the region late this afternoon as RHs have
fallen to 25-30 percent and winds gusting to 20-25 mph. Expect
winds to keep temperatures fairly mild through the evening hours,
but as cold front moves through, strong low level cold air
advection will lead to much cooler conditions by morning. With the
strong cold air advection, atmosphere becomes quasi-mixed, and
could see wind gusts approach 40-45 mph overnight. Considered a
short duration wind advisory for areas behind the front, but with
short term guidance suggesting limited mixing, will hold off for
the time being.
Much cooler conditions expected tomorrow with mixing leading to
gusts around 30 knots for the better part of the day on Thursday.
With 850 hpa temperatures falling into the upper single digits C,
expect high temperatures in the 70s F. Could also see elevated
fire weather conditions again tomorrow with the gusty winds, but
with the cooler conditions, relative humidity values are not
expected to be as critical as today.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 247 PM CDT Wed Sep 2 2020
Looking at a warming trend into the weekend as warmer
temperatures associated with upper ridge in the west expand
eastward. Shortwave is expected to move southeast Saturday night
across the Northern Plains. Models are suggesting steep lapse
rates through the middle levels of the troposphere. If shortwave
is strong enough to lead to saturation, will likely see
thunderstorms. Models are differing on the location of these
storms, with the GFS being a bit farther east than the ECMWF. Have
increased pops in the chance range Saturday night into Sunday
morning east of I-29.
Strong cold front is expected to move south across the region on
Monday. Potential for scattered showers behind the front as a
series of disturbances pass through the region as a cut off low
develops across the intermountain west. This pattern looks to hold
for the better part of next week, leading to highs mainly in the 60s
and the potential for patchy frost Wednesday and Thursday morning.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 658 PM CDT Wed Sep 2 2020
Wind providing the highest concerns for the 00z TAF set this
evening. First will come the prefrontal non-convective low-level
wind shear with winds indicated up to 50-55kts within the
1500-2000ft AGL layer, while likely at least partially decoupling
at the surface. With frontal passage, will then see strong
isallobaric push (8-10hPa/3h rises) with northwest winds aloft
readily mixing with the strong cold advection. Models not
particularly skillful thus far in ongoing stronger wind areas, and
likely are underestimating the potential gusts in the couple
hours following frontal passage, which could easily be in the
upper 30s to lower 40s kts. Mixing will continue through Thursday
with gusts above 25 kts likely to continue much of the day.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...Chapman
SHORT TERM...BT
LONG TERM...BT
AVIATION...Chapman
Area Forecast Discussion
National Weather Service Fort Worth TX
735 PM CDT Wed Sep 2 2020
.SHORT TERM... /NEW/
/Through Thursday Night/
North and Central Texas remains in a fairly complex weather
pattern as an abundance of moisture continues to stream across the
region. Rain chances remain in the forecast this afternoon, with
an uptick in precipitation expected tonight, mainly south of I-20.
Rain chances will slightly decrease tomorrow afternoon as the
strongest forcing for ascent moves farther to the east.
The main upper trough is now located across the Texas Panhandle,
gradually making its way to the east/southeast. With increasing
forcing for ascent as the upper trough approaches, a skeletal line
of showers and storms has developed from the Texas Panhandle
through Central Oklahoma. Although this thin line may be surging
south/southeast quickly, it will be moving into an airmass that is
less favorable for thunderstorm maintenance. Much of North Texas
experienced plenty of cloud cover for much of the morning and
afternoon, reducing the amount of instability available.
Furthermore, the latest RAP analysis suggest the best surface
moisture convergence will keep much of the precipitation just west
of our area. Cant rule out a few storms from impacting areas
northwest of the Dallas/Fort Worth Metroplex this evening, but
overall intensity is expected to be on a downward trend.
The next area that will need to be closely monitored will be a
subtle boundary currently sitting along to just south of the I-20
corridor. Mass convergence seems to be maximized in the region,
with precipitable water values in excess of 2 inches. Confidence
is increasing that another round of widespread rain will develop
as we approach midnight along the boundary. As has been the case
in the past several days, efficient rain producing thunderstorms
will lead to heavy rainfall. Given the multiple rounds of rain the
past few days, the risk for flash flooding will increase if any
one storm lingers for too long. Some areal changes have been made
to the Flash Flood Watch to account for this potential.
By sunrise tomorrow morning, much of the forcing for ascent will
have moved into our southern half, keeping much of the
precipitation confined to areas south of I-20. A decreasing low-
level jet will be reducing the influx of available moisture into
the area, likely reducing the precipitation rates. Rainfall
coverage tomorrow is likely to stay isolated across North Texas
and scattered across Central Texas. At this time, there is no need
to extend the Flash Flood Watch any further than 7AM tomorrow
morning. Highs will remain in the mid to upper 80s throughout much
of the region, with a few 90s possible in the Brazos Valley. Low
rain chances will remain in the forecast tomorrow night as the
main upper level forcing stalls across Central Texas. If storms do
develop tomorrow night, confidence remains too low to pinpoint
exact locations or amounts.
Hernandez
&&
.LONG TERM... /Issued 224 PM CDT Wed Sep 2 2020/
/Thursday night through Wednesday/
The mid level trough responsible for the recent unsettled weather
will weaken as it moves slowly to the east Thursday night through
Friday. Although large scale lift will gradually decrease,
moisture (through about 500 mb) along with a diffuse, stalled
frontal boundary, will linger across the region, keeping at least
some low shower/thunderstorm chances. Since storm coverage will
be limited, the additional rainfall should not result in any major
flooding issues.
Large scale subsidence will increase across the region Saturday
through Monday as an upper ridge temporarily builds in from the
west. Scattered showers and thunderstorms will still be possible
on Saturday, especially during the afternoon hours. Sunday and
Monday will likely be rain-free for most, but we will keep some
slight chances PoPs across the southeast where subsidence will be
the weakest and moisture will be the most abundant.
The building upper ridge will result in decreasing clouds through
the weekend and warming temperatures. Highs Friday and Saturday
will range from the mid 80s to near 90, but most locations will
be back in the low 90s Sunday and Monday. Lows Thursday night
through Monday night will be in the lower 70s, except for some
upper 60s in the north and west.
The focus early next week will be on a large scale pattern shift
with a long wave trough forecast to deepen across the eastern
2/3rds of the country. The ECMWF and GFS solutions still differ on
the fate of the upper trough and timing of the cold front with
the ECMWF being the deeper and slower solution. For now we will
continue to split difference on the timing of the front with
FROPA in North Texas around Tuesday afternoon. Rain and
thunderstorms will likely accompany the cold front followed by
much cooler, breezy and drier conditions for Wednesday. It still
appears that many locations could be in the 50s by sunrise
Wednesday and highs could struggle to make it out of the 70s
Wednesday afternoon.
79
&&
.AVIATION... /NEW/
/00Z TAFs/
Overall, fairly quiet weather conditions are ongoing throughout
much of North and Central Texas compared to earlier today. Weak
reflectivity echoes are being picked up generally along and south
of I-20 this afternoon as scattered showers continue. As the low-
level jet picks up this evening, additional moisture is expected
to lead to the redevelopment of precipitation south of I-20. The
heaviest precipitation is expected to remain south of the
Dallas/Fort Worth Metroplex, with occasional showers impacting the
airports overnight. Thunderstorm activity is expected to be
highest across Central Texas, where moisture content and ascent
will be greater. Thunderstorm chances will be greatest between
10-13Z with the main threat being lightning and heavy rain. IFR
conditions will likely prevail within the same time period given
the combination of low ceilings and poor visibility.
Thunderstorm chances will gradually diminish and ceilings will
improve as we approach daybreak, but the potential for
precipitation cannot be dismissed entirely the rest of the day.
Plenty of moisture and weak forcing for ascent will be in place
tomorrow afternoon, therefore, VCSH will remain in the forecast.
Winds at both Waco and DFW will remain out of the south/southeast,
generally between 05-10 knots. The exception will be during
ongoing precipitation, where higher wind gusts will be possible.
Hernandez
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 74 87 73 87 73 / 60 40 30 40 20
Waco 74 87 73 89 72 / 50 50 50 40 30
Paris 72 84 70 84 69 / 60 50 30 40 10
Denton 73 87 71 87 71 / 40 40 30 30 20
McKinney 73 86 71 87 70 / 50 40 30 40 20
Dallas 74 88 74 88 73 / 60 40 40 40 20
Terrell 74 86 71 88 70 / 70 50 40 50 20
Corsicana 74 85 73 86 72 / 70 50 50 40 30
Temple 73 88 72 89 71 / 70 50 50 40 40
Mineral Wells 72 87 69 86 68 / 50 30 30 40 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT Thursday for TXZ091>095-100>107-
115>120-123-129>133-141>144-156>160-174.
&&
$$
8
Area Forecast Discussion
National Weather Service Lincoln IL
926 PM CDT Wed Sep 2 2020
.SYNOPSIS...
Issued at 248 PM CDT Wed Sep 2 2020
A frontal boundary will stall along the Ohio Valley tonight and
tomorrow with a chance of showers and thunderstorms as far north
as the I-70 corridor. Elsewhere in central Illinois expect dry
weather through at least Saturday.
&&
.UPDATE...
Issued at 920 PM CDT Wed Sep 2 2020
Spotty showers/light rain will continue to affect our far
southeast counties through 3-4 am. No thunder is expected due to
limited elevated instability.
The next concern will be fog formation along and south of I-72.
HRRR, RAP and NAMnest continue to point toward a corridor of dense
fog starting after 09z. High cloud coverage could limit that
potential a bit, but am seeing more signals for fog under the
strong low level inversion, per BUFKIT sounding analysis. Have
added areas of fog in that area earlier this evening, and would
not be surprised if a dense fog advisory is needed at some point
later tonight.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 248 PM CDT Wed Sep 2 2020
This afternoon, a cold front is located near the I-70 corridor and
is slowly pushing south. Occasional showers are expected out ahead
of the front and cannot rule out an isolated thunderstorm, though
the overall threat is low with weak mid level lapse rates and
cloud cover hampering afternoon destabilization. Further north,
expect the rest of the area to be quiet through tonight as weak
high pressure builds in from the southwest.
On Thursday, another cold front is expected to push across the
region. A very dry air mass will be in place with some sunshine
helping to mix down surface dew points. The combination of lower
dew points and continued weak mid level lapse rates will keep
precip chances in check, but cannot rule out an isolated shower
or storm across east central and southeast Illinois during and
just after peak heating near the front. Otherwise, expect breezy
conditions across the region on Thursday. Deep mixing will bring
down stronger winds aloft with gust of 20 to 25 mph expected from
late morning through the remainder of the daytime hours.
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 248 PM CDT Wed Sep 2 2020
Cold front will push across the Ohio Valley Friday while high
pressure builds east from the central Great Plains to the mid
Mississippi Valley. 850 mb thermal trough will be squarely
overhead midday Friday resulting in the coolest day until at
least early next week. After coming off morning lows in the 50s,
highs on Friday will only be in the upper 70s to lower 80s.
Overall a very dry column is expected Friday with steep low level
lapse rates as the cooler air mass settles over the region. Winds
will not be as breezy as Thursday, but still expect some gustiness
to around 20 mph at times during the afternoon. Dew points will
also mix down into the lower 50s and 40 with RH values bottoming
out around or below 30 percent. This combination of drier air and
breezy winds could pose some fire weather concerns Friday
afternoon.
Friday night into Saturday, surface ridge axis will settle along
the Ohio Valley with return flow overspreading Illinois.
Strengthening LLJ over the central Great Plains Friday night will
result in showers and thunderstorms across portions of eastern KS
into northern MO. This activity will be decaying as it moves east
into Illinois Saturday morning, but could see some remnant cloud
cover reach the local area. Dew points will inch back up into the
mid to upper 50s Saturday afternoon while temperatures top out a
few degrees warmer into the lower to mid 80s. LLJ strengthens
again later Saturday, this time focused a little further northeast
across portions of northern MO into IA. Resulting storms could
ride the instability gradient into central Illinois Saturday night
into Sunday.
Early through the middle of next week, large scale pattern change
is in the works, however, models continue to have large
differences in the evolution of the increasingly amplified upper
air pattern. Initial wave moving east across the Canadian Prairies
will help drive a cold front across portions of the Midwest by
Tuesday into Wednesday, though it remains uncertain how far south
and how quickly the front will move. Meanwhile, a second stronger
wave will dig across the PacNW early next week possibly cutting
off over the Desert SW (ECMWF) or remaining open as it digs deep
across the Great Plains (GFS). The GFS remains more progressive
with the front dropping temperatures well below seasonal norms.
Meanwhile, operational GFS does have reasonable support from
ensemble members, although the GEFS mean is a bit slower in the
eastward progression of the deep upper trough and colder air
arriving locally. By Wednesday, differences between the ECMWF and
GFS are around 40 degrees for afternoon highs. GFS indicates highs
will only be in the upper 40s to lower 50s while the much slower
ECMWF still has the area well into the 80s and lower 90s.
Forecast generally takes the middle ground, so anticipate big
changes up or down once better consensus is reached in how next
week evolves. Stay tuned...
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 645 PM CDT Wed Sep 2 2020
A cold front has pushed south of the TAF sites, with primarily SW
winds occurring at the start of the 00z TAF period. Wind will
become light overnight, backing to a more southerly direction or
becoming variable. HRRR, RAP, NAMnest and GFS models are all
pointing toward a band of dense fog forming from just south of SPI
to DEC to CMI and south toward I-70 after 09z tonight. Have
introduced some IFR fog at CMI and DEC for now, but may need to
add SPI if model trends continue. Will monitor closely as the
evening progresses.
Fog should burn off by 14z tomorrow, then winds will become gusty
out of the WSW by late morning.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SYNOPSIS...Deubelbeiss
SHORT TERM...Deubelbeiss
LONG TERM...Deubelbeiss
AVIATION...Shimon
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1154 PM EDT Wed Sep 2 2020
.UPDATE...
Issued at 1153 PM EDT WED SEP 2 2020
First round of widespread rain is making its way across the
region, with the heaviest likely to occur south of the FFA.
Additional activity is expected overnight and on Thursday, with a
somewhat more northerly location favored by models. In light of
that, will leave the FFA as it was issued. However, if later
activity were to occur in the same portion of the area as this
first round, an expansion of the watch further south could be
needed.
UPDATE Issued at 1016 PM EDT WED SEP 2 2020
Convection has developed over central KY this evening, with less
concentrated activity extending into mainly the southwest portion
of the JKL forecast area. The supporting factors for precip
mentioned in the short term section are still applicable, but the
details of exactly where the action happens are still unclear,
with models showing varying solutions. Have updated the POP for
tonight based on evening radar trends and a very smoothed version
of the HRRR blending back into the prior forecast in the morning.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 420 PM EDT WED SEP 2 2020
The afternoon surface analysis shows a frontal boundary is
approaching from the west across the Midwest. Meanwhile in the
Cumberland Valley, we have an area of deeper moisture convergence
and ample PWATs leading to scattered to numerous showers and
isolated thunderstorms in this area. Some of these storms could be
produce isolated heavy rain and even gusty winds at times through
the rest of the afternoon and early evening.
Tonight, we will watch a mid-level wave kick out of the Middle
Mississippi River Valley into the Ohio Valley. This will be
coupled with and increasing low level jet and decent upper level
jet streak providing additional lift from divergence aloft. This
coupled with ample PWATs of 2 plus inches, which are in the 2
standard deviations above normal range for the Lower Ohio Valley,
will lead to periods of heavy rainfall tonight. The HREF shows a
robust swath of precipitation across areas generally along and
north of I-64 and other models such as the GFS and ECMWF seem to
be displaced a little north of this. Given the recent heavy
rainfall across portions of this area and in coordination with
neighboring offices will lean toward a Flash Flood Watch at this
time. The time frame for heavier rainfall would be later tonight
(6z) through Thursday morning (16z).
After this we will still see the potential for showers and storms
through the day Thursday, as a cold front approaches from the
northwest. There is some potential for a few stronger storms under
effective shear around 30 knots Thursday afternoon, but this will
be dependent on the amount of sunshine versus cloud cover for
destabilization. Then by Thursday night the will see the bulk of
showers and storms progress east, as a cold front progresses
across the Ohio Valley and eventually across eastern Kentucky
Friday.
.LONG TERM...(Friday through Wednesday)
Issued at 340 PM EDT WED SEP 2 2020
A cold front will move across the area on Friday, and will bring
isolated to scattered showers and storms to eastern Kentucky. This
round of rain should be out of the area by early Friday evening. A
ridge of high pressure will then push into the region, and will
bring dry and much cooler weather to eastern Kentucky for the
weekend. This ridge should remain in place and keep the weather
dry through next Monday. After that, another frontal boundary is
poised to bring more showers and storms to our area for the middle
of the week.
Temperatures over the weekend will be quite pleasant, with daily
highs in the upper 70s to lower 80s expected(Friday and Saturday).
Things should begin warm up again on Sunday though, as high
pressure strengthens. Highs on Sunday will most likely rise into
the low to mid 80s. This warming trend should continue through the
middle of the week, with highs on Monday and Tuesday forecast to
reach the low to mid 80s on those two days as well, with nightly
lows in the low to mid 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 1016 PM EDT WED SEP 2 2020
A few showers/thunderstorms were affecting the JKL forecast area
at the start of the period, particularly over the Cumberland
drainage basin. There were many more over central KY. The activity
was moving east northeast and will increase in coverage tonight.
The exact timing of precip at any given location is uncertain,
but over the long hall, most places will end up with showers and
thunderstorms tonight and/or Thursday. Because of this, for TAFs,
have mainly used VC (vicinity) for the convection instead of
tempo or a prevailing group. Any thunderstorm could bring IFR or
worse conditions. Outside of this, the area most likely to have
widespread MVFR or IFR conditions late tonight into Thursday is
around KJKL northward, but confidence is not high.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Thursday morning for KYZ044-050>052.
&&
$$
UPDATE...HAL
SHORT TERM...DJ
LONG TERM...AR
AVIATION...HAL
Area Forecast Discussion
National Weather Service Lake Charles LA
Issued by National Weather Service Brownsville TX
1013 PM CDT Wed Sep 2 2020
.DISCUSSION...Satellite and radar images indicate light rain
showers continue to develop across portions of northeast Texas
into northwest Louisiana tonight ahead of the 500mb shortwave
trough across the southern plains. The HRRR progs convection
continuing to develop across portions of northeast Texas into
northwest Louisiana late tonight into early Thurs morning. Outflow
from these showers and thunderstorms may move into the extreme
northwest portions of the CWA early Thurs morning providing a
focus for isolated showers and thunderstorms to develop across
the Texas Lakes Region. Will continue to mention a slight chance
of showers and thunderstorms for that area tonight.
Otherwise...no significant changes are expected for the rest of
tonight into Thursday.
&&
.PREV DISCUSSION.../Issued by National Weather Service Tampa Bay
Ruskin FL/
AVIATION...Southerly flow this evening will become
light and variable overnight, with some patchy fog and low
ceilings possible generally 06-14z. Winds will then increase from
the S/SW in the late morning as skies clear out and lift, with
more southerly flow in the afternoon. VFR conditions prevail,
except MVFR in fog.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 74 93 72 93 / 10 20 10 20
LCH 77 90 76 91 / 10 20 10 30
LFT 75 92 74 94 / 10 10 0 20
BPT 78 90 76 91 / 10 20 10 40
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
PUBLIC...61/Castillo/WFO Brownsville
Area Forecast Discussion
National Weather Service Mobile AL
954 PM CDT Wed Sep 2 2020
.NEAR TERM /Now Through Thursday night/...I have been waiting to
say this all summer but we have a saying for the pattern we are
in. Big bubble, no trouble! An expansive upper level ridge will
continue to dominate the southeast and northern Gulf Coast through
Thursday. This will lead to another day of sunny skies and hot
temperatures. If you thought today was dry, guidance shows even
drier air moving in by Thursday morning and lingering through the
evening. Considering it was difficult for even the normal
summertime cumulus clouds to develop today, Thursday into Friday
will be much of the same.
The only thing that being pesky is the potential for fog over inland
areas Tonight through early Thursday morning. The pattern does
support some development of fog with calm winds, deep but rich low
level moisture (dewpoints in the mid 70) and a low level
subsidence inversion from the upper ridge. However, guidance is a
little wishy washy on producing fog. The NAM and SREF show some
widespread fog, while the high res guidance is pretty void of it.
Given we saw some fog and a brief period of dense fog near
Evergreen last night, it`s safe to say that at least some patchy
to possible areas of fog should develop tonight. Some areas could
get dense but just a little too much uncertainty for a dense fog
advisory.
Temperatures will be hot once again on Thursday with highs likely
approaching the mid 90s across the area. I would honestly not be
shocked if a few places get into the upper 90s over interior south
Central Alabama as the surface mixes out. There might be just enough
moisture to prevent this from happening but cannot rule it out. Heat
indices will be rough but with vertical mixing the dewpoints
should drop enough to keep us in the 100 to 105 range with a few
locations approaching 107 along the coast. BB/03
&&
.PREV DISCUSSION... /issued 638 PM CDT Wed Sep 2 2020/
NEAR TERM UPDATE /Now Through Thursday night/...A deep layer pressure
ridge extends from the southwest Atlantic, westward across the
Gulf through Thursday. Compressional sinking and warming from the
ridge favors very little in the way of precipitation through
Thursday. There are indications that fog will be developing
through the night. Short range ensembles indicate a 40 to 80%
probability of visibility lowering to a mile or less over the
interior. The latest high resolution HRRR is not enthusiastic
about its development but the NAM is. Out of consideration for the
modest SREF probabilities/NAM vsby and that Evergreen Middleton
Field (GZH) saw visibilities lower to a quarter mile in fog during
the early AM hours along with persistence, forecasters will
mention the formation of areas of fog mainly along and north of
I-10 late in the night. A dense fog advisory may be required but
will let the evening shift make the call after monitoring
observational trends/new high resolution guidance. Overnight
lows in the lower half of the 70s interior. 74 to 78 coast. Highs
on Thursday look to range from 93 to 96 interior, 86 to 91 coast.
/10
AVIATION...
00Z issuance...Mainly VFR conditions will continue through the
night with clear skies and light winds. However, after midnight
patchy to areas of fog could develop over inland areas of southern
Alabama and potentially into the northwest Florida Panhandle.
Guidance is mixed on how dense and how widespread the fog could
get but the pattern is supportive of at least some fog and
potentially IFR to LIFR visbys. Coastal areas will likely remain
out of the fog. By the mid- morning, fog should mix out and
conditions will become VFR again. BB/03
PREV DISCUSSION... /issued 352 PM CDT Wed Sep 2 2020/
NEAR TERM UPDATE /Now Through Thursday/...A deep layer pressure
ridge extends from the southwest Atlantic, westward across the
Gulf through Thursday. Compressional sinking and warming from the
ridge favors very little in the way of precipitation through
Thursday. There are indications that fog will be developing
through the night. Short range ensembles indicate a 40 to 80%
probability of visibility lowering to a mile or less over the
interior. The latest high resolution HRRR is not enthusiastic
about its development but the NAM is. Out of consideration for the
modest SREF probabilities/NAM vsby and that Evergreen Middleton
Field (GZH) saw visibilities lower to a quarter mile in fog during
the early AM hours along with persistence, forecasters will
mention the formation of areas of fog mainly along and north of
I-10 late in the night. A dense fog advisory may be required but
will let the evening shift make the call after monitoring
observational trends/new high resolution guidance. Overnight
lows in the lower half of the 70s interior. 74 to 78 coast. Highs
on Thursday look to range from 93 to 96 interior, 86 to 91 coast.
/10
SHORT TERM /Thursday night Through Saturday night/...Ridging
continues across the area Thursday night and Friday, maintaining
the dry to mostly dry forecast across the area. No PoPs on
Thursday and only a few isolated showers or storms on Friday. Weak
surface ridging also generally remains in place across our
forecast area through Thursday night, but a weak surface trough
axis may sag southward into interior portions of southeast MS and
southwest/south central AL during the day Friday. A weak seabreeze
should also develop near the immediate coast by Friday afternoon.
Precipitable water values, which are initially around 1.20 inches
early in the short term period become enhanced between 1.75" and
2" south of the surface trough and along the vicinity of the
seabreeze during the afternoon by Friday and especially into
Saturday. Moisture convergence along these features will be
supportive of at least isolated convective development by Friday
afternoon, and will maintain a slight chance of showers and
thunderstorms from southeast MS into portions of southwest AL and
the western FL panhandle along these boundaries. Any convection
that develops should quickly diminish by early evening so will
follow the trend of keeping a dry forecast into Friday night. We
should also mention that forecast soundings over interior portions
of the region once again indicate another favorable setup for
patchy fog development (a very shallow saturated airmass near the
surface with much drier air extending from just above the surface
to around 500 mb), so will carry patchy fog over locations along
and north of the I-10 corridor late Thursday night. Little change
was otherwise made to the overall temperature forecast. Lows
Thursday night range from around 70 to the lower 70s inland and in
the mid to upper 70s near the immediate coast. Highs on Friday
will warm into the mid 90s over most interior locations and around
90 to the lower 90s near the coast. Maximum heat indices mostly
range between 100-105 degrees on Friday. /12
EXTENDED TERM /Sunday Through Wednesday/...The ECMWF and GFS
models remain in good agreement through Monday afternoon, with
some discrepancies Monday night and Tuesday with the development
of a highly amplified upper trough. The surface boundary over the
deep south may move south along the coast Monday through
Wednesday with deeper moisture pooling up along and south of the
boundary, brining an increase in PoPs (especially to the southern
half of the forecast area). This convection will primarily occur
in the afternoon and early evening hours. Prior to the upper ridge
breaking down, look for afternoon temperatures Saturday to be in
the low to mid 90s over interior and upper 80s at the beaches.
Wouldn`t be surprised through to see a few readings in the upper
90s across south central Alabama. Heat indices will likely range
from 100 to 107 degrees on Saturday and Sunday. High temperatures
should then lower several degrees Monday through Wednesday, into
the mid 80s to lower 90s. Low temperatures will continue to be in
the low to mid 70s. /12
MARINE...No impacts forecast this week. Winds and waves will be
higher near scattered thunderstorms late in the weekend through
early next week. /10
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Spokane WA
444 PM PDT Wed Sep 2 2020
.SYNOPSIS...
Temperatures will surge well above average Friday and Saturday
with afternoon readings climbing into the 90s. The passage of a
dry front on Saturday will produce the combination of hot, dry
and breezy conditions during the afternoon. Monday also has the
potential to be dry and windy as temperatures return closer to
average early next week.
&&
.DISCUSSION...
Tonight: Breezy west winds will subside this evening. The dry
front that passed early this morning will continue to push east
allowing our pressure gradient to relax. Patchy blowing dust has
been observed today over the Waterville Plateau and portions of
the Upper Columbia Basin including the Ritzville area. Our dust
threat will diminish quickly by early evening as winds drop below
20 mph. July and August were very dry with much of our dryland
wheat country receiving very little rain. With increased winter
wheat planting activity, fields will be prone to producing dust
until we can get some much needed rain.
Smoke from the Evans Canyon fire between Yakima and Ellensburg has
pushed across south central Washington into the L-C Valley. So far
today, the smoke has not gotten as thick as it was a week or two
ago in the Lewiston area, but it will have the potential to become
worse tonight into Thursday morning. The wind trajectory and the
HRRR Smoke Model suggest the potential for more smoke from the
Evans Canyon fire to be pushed toward southeast WA.
Thursday and Friday: Temperatures will trend warmer THU and FRI.
Look for widespread upper 80s to low 90s on THU afternoon. The
majority of our lowlands will climb into the 90s on FRI with
Lewiston, Moses Lake, and Grand Coulee flirting with triple
digits. Keep in mind average highs for the first week of September
are upper 70s for Spokane, Colville, and Kellogg while low 80s are
average for Wenatchee, Moses Lake, Omak and Lewiston. Our late
season "heat wave" will be nice for folks looking to enjoy a few
days at the lake, but is not good news for our wildfire situation.
Fuels continue to be very dry. Folks with plans to enjoy outdoor
recreation this weekend should be mindful of burn bans that are in
effect. /GKoch
Saturday through Wednesday: The dry and warm temperatures will
continue into the holiday weekend, and possibly into next week.
Certainty, due to little model agreement, decreases moving into
Monday. The high pressure system over the western CONUS will keep
the ridge over the Pacific NW through Saturday. Following a long
lasting ridge, the region will begin to see fluctuations in the
weather due to passing shortwaves. On Sunday night and early Monday,
some models continue to show precipitation dropping into MT.
However, there are some indicating a westerly push, bringing
precipitation into far northern WA and Idaho Panhandle. Models will
continue to be monitored.
Winds will be breezy through the weekend into early next week, with
the peak gusts on Saturday and Monday. There will be a wind shift,
beginning the period from the W-SW, to a northerly flow early next
week. On Saturday, the Kittitas Valley and Palouse may have gusts
up to 20-25 mph, with many active fires in the area. Sunday will
have a decline in winds, but will pick up again on Monday. The
winds may reach gusts to 25-30 mph in locations such as the
Okanogan Valley, central Panhandle, and Columbia Basin. These
stronger winds will be a more widespread concern, especially with
dry conditions and regional fires. Additionally, any smoke from
British Columbia fires may funnel into the region with these new
northerly winds.
After peaking on Friday and Saturday, temperatures will begin a
moderate decline on Sunday, with highs remaining at, or just above,
seasonal normals. Highs will remain in the 80s and 90s throughout
the weekend. However, the models are not in agreement with how cool
we will get by early-to-mid next week. JS
&&
.AVIATION...
00Z TAFS: Gusty winds will subside around 2Z for all TAF sites
except KEAT which will stay gusty until around 10z. Smoke from
wildfires will continue to impact southern WA mostly around KLWS.
Otherwise, VFR condtions are expected through the TAF period.
VMT/SB
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 53 89 56 94 60 94 / 0 0 0 0 0 0
Coeur d`Alene 53 87 54 93 58 91 / 0 0 0 0 0 0
Pullman 51 87 53 94 57 90 / 0 0 0 0 0 0
Lewiston 62 94 61 101 67 98 / 0 0 0 0 0 0
Colville 46 91 49 96 52 96 / 0 0 0 0 0 0
Sandpoint 48 84 51 90 55 90 / 0 0 0 0 0 0
Kellogg 57 84 58 92 63 89 / 0 0 0 0 0 0
Moses Lake 54 93 57 99 59 97 / 0 0 0 0 0 0
Wenatchee 63 93 66 97 67 96 / 0 0 0 0 0 0
Omak 56 93 60 97 62 97 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Shreveport LA
1003 PM CDT Wed Sep 2 2020
.UPDATE...
Latest radar loops show some very weak echoes and some isolated
showers per surface observations. Latest NAM and HRRR still
suggest a band of convection will develop across East Texas south
of Interstate 20 northeast into Louisiana during the early morning
hours. This band of showers and thunderstorms should drift
north into the Flash Flood Watch area. With the possibility for
more rain, the watch was left intact for now.
The majority of the forecast appears on track. PoPs were lowered
areawide through 06z, and some minor updates were made to the
hourly temperature and winds grids.
CN
&&
.PREV DISCUSSION... /issued 732 PM CDT Wed Sep 2 2020/
UPDATE...
See below for 03/00z Aviation Discussion.
Updated ZFP issued for the expiration of the Heat Advisory.
AVIATION...
For the 03/00z TAFs, convection has ended across the area for the
time being, but more showers and thunderstorms are expected to
develop and move into the area after 03/07z. This activity will
likely begin south of the Interstate 20 corridor and gradually
move northward before exiting the area or dissipating very late in
the TAF period. MVFR/IFR ceilings are also expected areawide
after midnight with a slow improvement back into the VFR range at
most terminals by the afternoon hours. MVFR/IFR flight conditions
may persist at some East Texas locations through the end of the
period.
CN
PREV DISCUSSION... /issued 240 PM CDT Wed Sep 2 2020/
SHORT TERM.../Tonight through Thursday Night/
Outflow boundary across north Louisiana into Southern Arkansas has
been the source for convection this afternoon. Moisture ahead of
the boundary combined with an upper-trough overhead to allow for
sufficient instability to generate some descent convection later
this afternoon. Strong winds, heavy rainfall, and small hail may
be possible with some storms.
Lingering upper-level trough to remain west of the region through
at least Friday night. Instability associated with the trough to
continue to maintain periods of convection through the end of the
work week. Thus a Flash Flood Watch remains in effect through the
overnight hours. Based on some of the hires models, convection to
set up across the southern end of the watch area, mainly just
north of I-20, and lift north during the pre-dawn hours. Flash
Flood guidance suggests that the watch area is a pretty good
representation of those vulnerable areas that may struggle to
handle much in the way of heavy rainfall and thus no adjustments
will be made at this time.
A Heat Advisory is also in effect through 7 PM this evening across
portions of deep east Texas and north Louisiana. With, current
heat index values of 102 in Natchitoches and 105 in Monroe, will
hold off on making any adjustments. /05/
LONG TERM.../Friday through Wednesday night/
The long term continues with better than average rain chances to
start, but still looks to trend dryer over the weekend as high
pressure arrives a little better in the back door than the front
this time of year. A 1025mb high will remain in the OH valley into
Saturday and early on Sunday with the lingering frontal boundary
over our South and soon washing out with NE winds running out of
gas.
As we begin the new work week the light and variable winds early
will become S/SW with a slight chance for showers sea breeze style.
Then into Tuesday look for much better rain odds again a strong cold
front moves across the plains states. A 1032mb high will be over the
Dakotas and continue to drive southward into midweek, that is, if
you like the GFS. The Euro is very different with a closed low over
Utah and still sea breeze mode for us.
The GFS sweeps the front Eastward as the long wave become pronounced
over the mid MS valley with our heights aloft falling to below
average. Meanwhile, the high pressure on the sfc and aloft hangs
tough on the eastern seaboard with the latest ECMWF with a deep
closed low back building a bit in NV. Suffice it to say temperatures
will vary greatly with each solution and we are running middle of
the road more or less between the two. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 73 87 70 88 / 50 40 30 50
MLU 73 93 73 93 / 20 20 20 40
DEQ 71 83 69 85 / 60 60 30 40
TXK 71 81 71 83 / 70 60 30 50
ELD 72 86 70 87 / 50 40 30 50
TYR 73 85 72 86 / 70 70 50 50
GGG 73 86 71 87 / 60 70 40 50
LFK 73 93 74 92 / 30 40 40 50
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Flash Flood Watch until 7 AM CDT Thursday for ARZ050-051-059>061-
070.
LA...None.
OK...Flash Flood Watch until 7 AM CDT Thursday for OKZ077.
TX...Flash Flood Watch until 7 AM CDT Thursday for TXZ096-097-108>112-
124-125.
&&
$$
09/20