Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/18/23
Area Forecast Discussion
National Weather Service La Crosse WI
1055 PM CDT Wed May 17 2023
.DISCUSSION...(This evening through Wednesday)
Issued at 235 PM CDT Wed May 17 2023
Key Messages:
- Showers and storms move into the area Thursday
afternoon/evening. With current forecast conditions, the risk
of severe weather looks to be low.
- Smoke from the Canadian wildfires looks to remain over the area
into Thursday/Thursday night with some potential for this to
get mixed to the surface behind the cold front.
- Generally quiet weather Friday into next week with only a
couple of small chances for rain.
Thursday - Thursday night...
An upper level low over the Canadian Prairies is still expected
to sink southeastward towards the region overnight and through the
day Thursday. At the surface, a cold front looks to push
southeastward across the local area Thursday afternoon-night. CAMs
guidance continues to suggest showers and storms will develop and
move into the local area late Thursday afternoon. With only
modest moisture, model guidance shows a very narrow corridor of
around 500 J/kg of MLCAPE that continues to wane through the
evening. The latest RAP shows sufficient deep layer shear (~40-50
kts), but would hold it just west behind the front. Although there
remains sufficient 0-3 km shear to aid in storm development, the
risk of severe weather would remain low. Although lower confidence
at this time, if sufficient deep layer shear is able to overlap
the instability a bit more, the chance for stronger storms to
develop would increase providing some chances for potential hail
and strong wind gusts.
Data from the RAP suggests the smoke from the Canadians wildfires
will remain over the region into Thursday. With the cold front
coming through the area, there looks to be a good potential for
some of this smoke to get mixed down to the surface. Observations
from eastern Montana and western North Dakota, behind the front,
are showing some restrictions to visibility occurring and will
have to continue to monitor this for our area.
Friday into next week...
Overall, things are looking pretty quiet heading into next week
with only a couple of small chances for some rainfall. The upper
level system that pushes the cold front through the region
Thursday and Thursday night may still be spinning over the
northern Great Lakes Friday. This could place the area in a
cyclonic flow pattern aloft with the potential for some showers to
develop underneath it. However, this does not have support from
all the models with the ECMWF being the most aggressive.
Probabilities for measurable rainfall look to be highest in the
morning when the 17.00Z Grand Ensemble sneaks 30 to 50 percent
probabilities into Clark and Taylor Counties while the latest NBM
is faster to moves things out (similar to the GFS) and only has a
10 to 15 percent probability across Taylor County in the morning.
If it does rain, amounts look to be very light and should mainly
be confined to the morning hours.
Another small chance for rain looks to arrive Sunday afternoon.
An upper level low should be moving across Canada in the vicinity
of Hudsons Bay with the potential for a weak short wave trough
under it to move tracking across the region. Chances for
measurable rain look pretty small with the NBM coming in with
probabilities between 10 and 15 while Grand Ensemble was around
40.
Temperatures through the period look to be on a slow warming
trend. Friday will be the coolest day with highs generally in the
60s. These should then reach the 70s area wide by Tuesday with a
few locations reaching the lower 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1051 PM CDT Wed May 17 2023
Subsiding air upstream of local forecast area within heavier rain
bands are resulting visbys less than 2 statute miles. The higher
concentration of particulate matter is advecting to the surface
within these precipitation bands. Thunder chances return this
evening from northwest to southeast. Have introduced VCSH/SHRA for
this time frame, with future forecasts further specifying exact
timing. While ceiling restrictions are expected farther northeast,
into KMDZ, lower visbys likely within heavier precipitation.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...04/EMS
AVIATION...JAR
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
910 PM CDT Wed May 17 2023
.UPDATE...
Issued at 910 PM CDT Wed May 17 2023
Non-severe thunderstorms have developed this evening over LaMoure
and Dickey counties and should gradually move east out of the
counties over the next few hours. This will clear out
precipitation chances across western and central North Dakota
until an upper low drops through eastern North Dakota Thursday
afternoon. As cold temperatures aloft associated with the center
of the low move in, weak instability should drive some diurnal
showers in central to eastern North Dakota. With this update the
slight and chance PoPs were expanded into central North Dakota
based on the track of the upper low and recent high-res guidance.
UPDATE Issued at 632 PM CDT Wed May 17 2023
23Z surface analysis shows surface front into the James River
Valley, while weak convection is beginning to line the front in
LaMoure and Dickey counties. The fast moving front is outpacing
the progression of convective growth along the line and time is
running out for stronger thunderstorms to impact LaMoure and
Dickey counties this evening. With a south wind and an observed
temperature of 80 degrees, there should still be some modest
instability allowing for a small window of opportunity for a
strong storm to grow before the front pushes east of the counties
completely.
With this update we also extended the mention of smoke through
much of tomorrow as upstream observations and satellite imagery
show smoke in southern Saskatchewan moving in, however the worst
of the density should be along and near the front currently moving
into eastern North Dakota. Light to moderate smoke density can
still be expected for much of western and central North Dakota
tonight, possibly lingering for much of Thursday.
&&
.SHORT TERM...(This Evening through Thursday)
Issued at 208 PM CDT Wed May 17 2023
A cold frontal boundary draped over central North Dakota
continues moving to the southeast bringing scattered showers and
thunderstorms along with it. In addition to showers and
thunderstorms, the cold front is driving areas of smoke to the
surface with visibility as low as 1/2 a mile in some locations.
Visibility has improved some in the far northwest and expectations
are that visibility should continue improve this afternoon and
into the overnight hours from west to east. That said, based on
RAPSmoke guidance, another round of near-surface smoke may impact
the western and southern forecast area Thursday as well. Added
further patchy smoke mentions to account for this.
A severe thunderstorm or two is not out of the question in the
south central this afternoon as there is a narrow window where
moderate instability and shear may be co-located as the frontal
boundary passes through. The RAP suggests around 1000 to 1500 J/kg
of MUCAPE and 25 to 30 kts of 0 to 6 km bulk shear. These are not
the most favorable parameters, but they can still be enough.
Overall, the severe weather threat is expected to remain on the
lower end with quarter sized hail and wind gusts of around 60 mph
being the primary threats.
The front has progressed a little quicker than initially
anticipated, therefore reduced highs for central North Dakota,
including the Bismarck/Mandan area. The reduction in highs still
has not been quite enough in some locations, so will further
adjust. One other small note is that breezy conditions will
continue this afternoon and occur again during the day Thursday.
For Thursday, expect a cooler day with highs in the mid 50s to
lower 60s. Lows tonight will be mostly in the 40s.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 208 PM CDT Wed May 17 2023
The biggest impact at this time for the extended period is in
regards to frost potential late Thursday night and Friday morning.
The expectation remains that surface high pressure will center
somewhere over western North Dakota. This will result in
temperatures tanking down into the lower to mid 30s. At this point
in time, temperatures generally look to remain at least a degree
or two above freezing, but either way, frost development is
likely.
Friday will remain cooler, yet near average for this time of year
before a warming trend this weekend and into next week with highs
generally in the 70s to low 80s. Lows beyond Friday morning are
expected to be in the 40s Friday and Saturday night, then mostly
in the 50s Sunday night and through the remainder of the period.
Dry conditions are expected through the weekend before
precipitation chances return early next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 632 PM CDT Wed May 17 2023
Smoke will continue to impact visibilities tonight, though should
be improving somewhat behind the front that initially brought the
smoke from the northwest. Still, visibilities below 4 miles should
be common overnight. Some more improvement in visibility may
occur tomorrow, but how much it improves in the day is
questionable. Breezy northwesterly winds become lighter this
evening, then increase again during the day Thursday out of the
north to northwest.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...AE
SHORT TERM...Telken
LONG TERM...Telken
AVIATION...AE
Area Forecast Discussion
National Weather Service Buffalo NY
1006 PM EDT Wed May 17 2023
.SYNOPSIS...
High pressure will build across the region overnight, resulting
in a hard freeze inland from the lakes and patchy frost all the
way to the lakeshores. Warmer Thursday and especially Friday.
Dry weather holds until Friday night or Saturday.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
High pressure and very dry air with a more winterlike PWAT of
less than 0.20 inch (less than 25 percent of normal) settles
directly across the region tonight. Outside of some smoke from
distant wildfires, skies will be clear overnight. This along
with light winds will support nearly ideal radiational
conditions with a hard freeze with lows in the mid to upper 20s
well inland from the lakes. Even outlying areas in Buffalo and
Rochester will see widespread frost as temps drop into the lower
30s. Only the nearest few miles within Lake Erie and Lake
Ontario will see temperatures remain in the mid to upper 30s
with just patchy frost. At 10 p.m. Watertown was already down
to 34F so things seem to be on track. No changes to the
frost/freeze headlines in place.
Dry weather continues Thursday and Thursday night as high pressure
moves from the northeast off the southern New England coast. After a
chilly and frosty start, temperatures on Thursday will rebound with
highs into the 60s, except in the mid to upper 50s across the higher
terrain east of Lake Ontario. Winds will be lighter than today.
According to the RAP modeled smoke forecast we`ll see a return of
elevated wildfire smoke from the west through the day which could
make for a colorful sunset Thursday evening. Main weather highlight
for Thursday night is pretty simple, not *near* as cold as tonight.
Lows will mainly be in the 40s to lower 50s though a few spots east
of Lake Ontario could still dip into the mid to upper 30s.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Friday will be mainly dry and warm with a breezy south to south-
southwest wind ahead of a cold front moving east across the central
Lakes. Clouds will be slowly on the increase from west to east
Friday afternoon, with just the slight chance for an isolated shower
or two toward the tail end of the day across far western NY with a
weak pre-frontal trough. Aside from the breezy conditions, it will
be a pleasant day overall with highs ranging through the 70s.
It still looks as though our region will receive some rainfall
during this period, mainly for later Friday night and Saturday.
Challenges continue to be discrepancies amongst various model suites
with regard to exact timing and placement of precipitation, which is
the reason for capping PoPs in the high likely range for now until
these differences are better resolved. One trend noted with the 12Z
guidance package is a slight slowing of the eastward progression of
a surface cold front that will eventually bring the showers to our
area, hence the better chances for rain holding off until the second
half of Friday night for the bulk of the area. The one outlier is
the 12Z GFS, which continues to be faster with the frontal
progression. The other player here is a weak area of low pressure
near the Carolina coast Friday that will slowly advance northward
along the Eastern Seaboard, making it to somewhere near the southern
New England coast on Saturday. At this point, appears the bulk of
the precipitation associated with this system should remain just
east of our area. However, this will likely aid with the slowing
eastward progression of the surface cold front. Lows Friday night
will range from the upper 40s to mid 50s, with highs on Saturday
mainly in the 60s.
Steadier showers will taper off from west to east Saturday night as
the cold front slowly pushes east of the region. Again, exact timing
of when this happens still remains in question. Slightly cooler air
in the wake of the frontal passage will yield overnight lows in the
40s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The main theme for the long range will be persistent high pressure
keeping our weather mainly dry with daytime highs near average for
this time of year. Only exception will be on Monday as some cooler
air briefly invades in the wake of a cold front that moves south
across the region later Sunday and Sunday night. The boundary will
be moisture starved, however may spark a stray light shower across
the North Country Sunday afternoon into the first half of Sunday
night. Otherwise, mainly dry conditions are expected through the
period as mentioned above.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
High pressure with clear skies and light winds through
Thursday. Some high sky cover due to smoke from distant
wildfires at times. VFR flight conditions.
Outlook...
Thursday night and Friday...VFR.
Saturday...MVFR to VFR. Chance of showers.
Sunday...Mainly VFR. Chance of showers.
Monday...VFR.
&&
.MARINE...
High pressure will build across the lake with light winds
overnight. High pressure will gradually shift off the East
Coast Thursday and Friday. Winds will become southerly by Friday
with west-southwest winds becoming established this weekend. At
this time it looks as if speeds will remain generally 15 knots
or less.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Frost Advisory until 8 AM EDT Thursday for NYZ001-002.
Freeze Warning until 8 AM EDT Thursday for NYZ003>008-010>014-
019>021-085.
MARINE...None.
&&
$$
SYNOPSIS...Apffel/JLA
NEAR TERM...Apffel/JLA
SHORT TERM...JM
LONG TERM...JM
AVIATION...Apffel
MARINE...Apffel/JLA/TMA
Area Forecast Discussion
National Weather Service Duluth MN
634 PM CDT Wed May 17 2023
.DISCUSSION...(This evening through Tuesday)
Issued at 252 PM CDT Wed May 17 2023
Summary: A cold front will be entering from the west this evening
bringing showers and storms tonight through Thursday. There is a
marginal risk for severe storms to develop tomorrow afternoon
across Price and southern Iron and Ashland counties. Near surface
smoke may filter in behind the front beginning early tomorrow
morning. There is an Air Quality Alert in place beginning tonight
and running through noon tomorrow. Additional rain chances will
persist into Friday before clearing out this weekend for some
quiet weather.
An upper level low sitting over central Canada combined with our NW
winds aloft continues to pour smoke covered skies into the region
due to the wildfires across Alberta and the NW territory. The
Northland will find itself wedged between an exiting high over
eastern Lake Superior and an incoming low across the southern
Canadian Prairies. The increased pressure gradient between these
two features will surge southerly winds across the region.
A cold front will be marching in from the west this evening
spreading showers and thunderstorms throughout the night and
Thursday. With the system dropping from the NW it will not pack
quite the punch as the lows that swing up from the Central Plains.
PW values are steadily between 1 to 1.3 inches putting it close
to climatological averages for this time of year. MUCAPE does
build up a bit overnight as the LLJ ramps up but overall weak mid
and low level lapse rates will keep damaging storms at bay. We
will see increased chances for thunderstorms Thursday afternoon as
the front moves into NW WI. This is highlighted well in the CAMs
and coincides will with diurnal trends. Price and into southern
Ashland and Iron counties is highlighted in a marginal risk for
severe tomorrow afternoon. There is a very small window for some
upscale growth and linear storm development before surface cooling
quickly diminishes the chances. One last thing of note for this
incoming system would be the chances for some near surface smoke
to develop. Looking far out west over western ND we can see
visibilities rapidly dropping behind the push of rain due to the
sinking nature of the cold air advection. Stations have seen
reductions down to less than 2 miles at times. The RAP model does
highlight this smoke making into the Northland behind the system
by early Thursday morning. We will need to monitor how this
evolves over the west as it approaches as we may need a Special
Weather Statement for the potential travel impacts the smoke could
bring.
As the cold front moves east a compact upper level low will cross
the region for Friday and could promote some additional rain
showers. Satellite trends today would suggest that there will be
a fair amount of smoke mixed in with this upper level low but as
it exits late Friday we should see some clearing skies. However,
with northwest flow continuing over the region upper level smoke
may filter back in later in the forecast.
This weekend is expected to be quiet with Saturday sporting
widespread 70s. A colder air mass rotating across Ontario for Sunday
may bring some cooler temps to the Northland. There still seems to
be some discrepancies with the deterministic guidance on how cold
the air mass will be and the extent of it`s reach. Some frost
advisories may be warranted for Sunday night.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 634 PM CDT Wed May 17 2023
A cold front will sweep through the Northland tonight into
Thursday causing showers and a few thunderstorms behind it.
Ceilings will lower to MVFR overnight into Thursday morning then
increase through the day Thursday. A few thunderstorms will be
possible but we mainly just went with showers tonight. A few
strong thunderstorms will be possible Thursday afternoon over
parts of northern Wisconsin. Low level wind shear will develop at
most locales tonight due to a low level jet.
There remains plenty of smoke from Canadian wildfires across the
region. Some of this smoke is expected to come to the surface
behind the cold front reducing the visibility for a time. We`ve
seen reductions below a mile in parts of North Dakota this
aftenroon/evening. For now, we have reductions from 2-5SM and will
adjust as confident increases with later updates.
&&
.MARINE...
Issued at 252 PM CDT Wed May 17 2023
Enhanced northeasterly flow near the head of western Lake Superior
has brought in waves reaching 4 ft this afternoon. A Small Craft
Advisory remains in effect for these areas into the evening hours. A
cold front marching across the region tonight and tomorrow will
bring some showers and thunderstorms across the Lake. There may be
some brief gusty winds out of the south for Chequamegon Bay into
Saxon Harbor.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 45 63 41 58 / 10 90 60 30
INL 49 60 40 65 / 90 80 40 20
BRD 55 66 42 61 / 50 90 30 10
HYR 50 68 43 59 / 10 90 50 30
ASX 45 67 43 56 / 10 90 60 30
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...Small Craft Advisory until 8 PM CDT this evening for LSZ144-145.
&&
$$
DISCUSSION...Britt
AVIATION...Melde
MARINE...Britt
Area Forecast Discussion
National Weather Service Quad Cities IA IL
625 PM CDT Wed May 17 2023
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 153 PM CDT Wed May 17 2023
Mostly sunny skies with a hint of smoke aloft was seen across all
of eastern Iowa, northwest Illinois and far northeast Missouri
early this afternoon. 18z surface analysis showed a cold front
stretching from the Nebraska/Iowa border southeast into the mid-
Mississippi River Valley and Ohio River Valley, with a large area
of high pressure situated over the Great Lakes. As of 130 PM,
temperatures across our area ranged from 61 in Dubuque to 72 in
Keokuk.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 153 PM CDT Wed May 17 2023
[Key Messages]
1) Quiet weather through daytime Thursday with smoke persisting aloft
[Discussion]
Not expecting any significant weather concerns for the short term
period. Through tomorrow, the high over the Great Lakes is expected
to slowly shift east, allowing a cold front to approach the area
from the west later in the day. Areas in our far north and west in
east central Iowa will have an increased threat of a shower or storm
late in the afternoon and evening, but expecting most to remain dry.
Look for lows tonight to range from the mid 40s (northwest Illinois)
to mid 50s (northeast Missouri), with highs tomorrow climbing into
the upper 70s to low 80s with the return of southerly flow ahead of
the front.
W.R.T. the wildfire smoke, latest RAP analysis shows a rather large
plume of smoke concentration aloft is likely to persist through
tomorrow evening before eventually getting shunted east with the
front. With little in the way of deep vertical mixing occurring, not
expecting much to make it down to the surface to impact air quality.
Like last evening, it will make for a nice sunset!
.LONG TERM...(Thursday night through Wednesday)
Issued at 153 PM CDT Wed May 17 2023
[Key Messages]
1) Showers/storms Thursday night through Friday, some potentially
strong initially
2) More wildfire smoke arrives Friday, may mix down to the surface
3) Dry conditions and warm temperatures favored for the weekend into
next week
[Discussion]
Thursday night and Friday...
Cold core low and cold front will move into the area to start the
period, with enough lift and moisture in place to lead to an
increasing threat of showers and storms. Some storms initially
could be strong, especially along and north of the Hwy 20 corridor
where lapse rates aloft will be steeper. Here, the Storm Prediction
Center has introduced a Level 1 (marginal) risk of severe
thunderstorms. Large hail and damaging winds would be the primary
concern. Elsewhere, showers and non-severe storms are expected with
the front mainly during the overnight hours into early Friday, with
rainfall amounts expected to remain under a quarter of an inch. Some
areas, mainly north of Interstate 80, may see amounts near half an
inch where showers/storms persist longer.
Of additional concern, will have to watch for another round of
Canadian wildfire smoke that will accompany the front. With much
deeper mixing, there is some potential that some smoke could be
briefly brought to the surface, which may lead to minor impacts to
air quality.
Friday night on...
Dry weather will be the rule for this period this weekend into next
week as strong high pressure builds across the Midwest and Great
Lakes. Expect temperatures near normal for the weekend, with a trend
back above normal next week once surface flow shifts back to the
south.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 625 PM CDT Wed May 17 2023
VFR conditions will be seen through 00z/19 as a cold front
approaches from the northern Plains.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Speck
SHORT TERM...Speck
LONG TERM...Speck
AVIATION...08
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
627 PM CDT Wed May 17 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Thursday night)
Issued at 145 PM CDT Wed May 17 2023
Latest surface analysis shows not much of a pressure gradient over
South-Central Texas with a weak low beginning to develop over
southeast New Mexico. With this weak gradient, winds remain light
and variable across most of the area. At the same time some moisture
around 3-5kft is leading to a cumulus field across most of the area
this afternoon with daytime heating. Not seeing any vertical growth
with most of these clouds at the present time. There is one area of
some weakly agitated cu in Gonzales County and the latest run of
the HRRR does show some isolated development there. Can`t rule out
an isolated shower or thunderstorm mainly in the Coastal Plains
later today. Otherwise, temperatures are in the 80s for most
locations and highs later this afternoon should be in the middle to
upper 80s across the region.
Any shower activity will quickly dissipate by sunset. The 12z upper
air analysis shows weak ridging aloft moving through the Rockies and
this expected to affect our region late tonight and most of the day
tomorrow keeping things dry. Lows tomorrow should be cool, in the
lower to middle 60s for most areas. Highs tomorrow will be back in
the upper 80s with some 90s possible mainly out west. As the
shortwave ridging moves east tomorrow, southerly surface winds will
slightly increase out west as the previously mentioned surface low
in eastern New Mexico slowly strengthens. This low should also allow
for a weak dryline to develop west of the Rio Grande. As a weak
shortwave trough approaches the area late tomorrow afternoon on the
heels of the ridge, we should see a fairly decent coverage of shower
and storm activity develop west of the Rio Grande late in the
afternoon. Mid-level flow could be strong enough to bring some of
this activity east of the border into our area around 23-1z, but the
consensus from the hi-res guidance is any activity would be in a
weakened state. The main area to watch for any low probability for a
strong storm is in the western portions of Val Verde County which
will be a bit closer to the dryline and therefore could see some
storms sooner, before they dissipate. The latest Day 2 Outlook from
SPC has that area in a marginal risk. Any activity should be
dissipated by 9 PM and the remainder of tomorrow night should be dry
across the area. With the increased southerly flow, lows Thursday
night will be warmer, in the upper 60s to near 70 degrees.
&&
.LONG TERM...
(Friday through Wednesday)
Issued at 145 PM CDT Wed May 17 2023
Partly cloudy skies are expected across most areas on Friday. By
Friday afternoon, mostly cloudy skies are expected across the Hill
Country in addition to isolated chances for showers and
thunderstorms ahead of a cold front. High temperatures in the low to
mid 90s areawide are expected. Several upper level short waves are
forecast to push across south-central Texas on Friday evening into
Saturday morning. At the surface, a frontal boundary is expected to
push across the area on Friday night closer to the midnight time
frame. Some strong to severe thunderstorms are possible through the
period as the cold front pushes to the south. Large hail and damaging
wind gusts being the main severe weather hazards. Also, locally heavy
rains are possible but not limited to the Hill Country and vicinity.
Periods of heavy rain could lead to flash flooding over poor and low
lying drainage areas.
Cooler conditions are expected for Saturday and Sunday in the wake of
the cold front with showers and storms expected to concentrate across
the Rio Grande and southern Edwards Plateau areas. Saturday`s and
Sunday`s rain episodes over the Rio Grande could impact some
locations if storms do develop with the possibility of getting
isolated of 1 to 3 inches of rainfall amounts.
The wet pattern continues into the middle of next week with slight
to low end chances for showers and storms each afternoon. High
temperatures are likely to stay slightly below or at climate normals
around the low to mid 80s.
&&
.AVIATION...
(00Z TAFS)
Issued at 624 PM CDT Wed May 17 2023
High pressure over the region has brought light and variable winds
and only partly cloudy skies. These conditions will continue this
evening and overnight. All terminals will be VFR. Winds will become
southeasterly Thursday morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 66 92 69 92 / 0 0 0 10
Austin Bergstrom Intl Airport 63 89 66 90 / 0 0 0 10
New Braunfels Muni Airport 65 90 65 92 / 0 0 0 10
Burnet Muni Airport 64 89 67 92 / 0 0 0 20
Del Rio Intl Airport 69 93 71 96 / 0 20 20 10
Georgetown Muni Airport 63 88 67 90 / 0 0 0 10
Hondo Muni Airport 65 90 68 92 / 0 0 0 10
San Marcos Muni Airport 64 89 66 91 / 0 0 0 10
La Grange - Fayette Regional 65 87 67 89 / 0 0 0 0
San Antonio Intl Airport 67 90 68 92 / 0 0 0 10
Stinson Muni Airport 67 91 68 92 / 0 0 0 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...29
Long-Term...17
Aviation...05
Area Forecast Discussion
National Weather Service Grand Forks ND
1019 PM CDT Wed May 17 2023
.UPDATE...
Issued at 1006 PM CDT Wed May 17 2023
Shower band re-intensified a bit over far E ND into far NW MN
between 00z and 02z. Shower band intensified along the 850 mb
front where elevated instability remained in a very narrow zone
from South Dakota into E ND. The activity is weakening a bit now
but showers will continue along the 850 mb front as it moves
gradually east overnight. The most dense smoke seems to be located
btwn the sfc front and the 850 mb front due to a more shallow
mixed layer...as just behind sfc front winds northwest but still
southwest at 900-850 mb. Would expect gradual improvement in sfc
based smoke behind 850 mb front overnight into Thu AM as it
moves east.
UPDATE Issued at 656 PM CDT Wed May 17 2023
Cold front from Baudette to west of Fosston to Hillsboro to near
Lisbon ND moving east. Brief wind gusts earlier with the front
seems to have died down some but still spotty gusts 35 mph in NW
MN. Area of light rain showers just behind front and most
noticeable is 20-25 degree drop in temperature and lowering vsby
in smoke. This surface level smoke likely to be around much of the
night before improving from north late tonight/Thursday. High
level smoke to continue though. This is taken from the RAP smoke
forecast of near surface and vertically integrated smoke. Moisture
for showers is behind the cold front and it quite limited in our
area so only seeing a few showers and light precip. T-storms in
central SD into Nebraska associated with 500 mb short wave moving
east.
&&
.SHORT TERM...(This afternoon through Thursday night)
Issued at 339 PM CDT Wed May 17 2023
-A period of showers and a few thunderstorms are expected this
afternoon through tonight. There is a low probability for a few
strong thunderstorms in southeast ND this afternoon/early evening.
-Smoke will result in reduced visibilities and poor air quality as
the cold front moves through the region this afternoon into Thursday
morning.
-Scattered showers and isolated thunderstorms are expected again
Thursday. Severe weather impacts are not expected, however there is
a low probability for "cold air" funnels to develop during the
afternoon.
A well organized mid/upper low is centered over Manitoba, with
PVA/height falls rotating around this and an associated cold front
responsible shower showers (now over northeast ND). There is a very
narrow warm sector where CAPE has increased to 1000 J/K in central
ND (towards our far southwest), while shear remains very
weak/marginal. Within that warm sector we couldn`t rule out a
brief/strong updraft, but considering the nature of profiles at most
we are probably looking at sub-severe impacts (penny size hail/gusts
around 50 mph). It is more likely that impacts are much less with
only brief heavy rain and lightning activity. This axis of
shower/embedded storms continue to east and southeast through the
evening/overnight with high coverage of light precipitation, but
there is a 30-50% probability for rainfall totals of 0.5" or higher
(combination of ensemble systems). This does include the additional
round of showers/isolated storms expected to develop in the cold
pool as the main mid/upper low transition into our region Thursday.
Due to high vorticity aloft and steep mid level lapse rates we
couldn`t rule out "cold air" funnels Thursday, but with low level
lapse rates much less certain, the chance any of this would be
stretched to the surface/cause impacts is very low (even if it
occurs).
Regarding smoke: NOrtherly flow aloft continues to carry wildfire
smoke into our region from active fires in Alberta and Saskatchewan.
There remains a narrow corridor behind the cold front entering our
CWA where smoke is mixing to the surface and visibilities around 1
mile or less are being reported. Visibilities in smoke are improving
into the 3-6 mile range farther back behind this frontal zone. This
is expected to overspread our CWA this afternoon and evening and as
a result we should see impacts both to travel (brief) and air
quality (MPCA has issued an alter for our MN counties). This will
likely be much worse than we have seen so far. Expect some
improvement late Thursday morning/afternoon (some smoke could still
be lingering though).
.LONG TERM...(Friday through Wednesday)
Issued at 339 PM CDT Wed May 17 2023
Key Messages:
- Smoke from wildfires in Canada may continue to spread over our
area this weekend, although to what extent and whether it will be at
the surface versus aloft remains in question.
- Dry air this weekend may lead to near-critical fire weather this
weekend.
- Precipitation chances increase mid to late next week, although
details remain uncertain on where and how much rainfall will be
received.
Discussion:
Ensembles are in good agreement of northwesterly flow aloft this
weekend to be replaced by upper ridging in the West translating
eastward toward the Northern Plains by early to mid next week. A mid
level shortwave moves through the flow around Sunday, but there is
strong agreement of moisture remaining deficient in allowing a
chance of precipitation. Additionally, the marginal strength of the
wave translates to the surface in the form of a weak backdoor cold
front.
Speaking of moisture deficiency, ensembles show a strong agreement
in a very dry air mass to advect over the region this weekend into
early next week out of western Canada, with over 90% chance of PWATs
less than 0.5 inches, and possibly as low as 0.2 inches Sunday into
Monday, yielding the potential for RH values to dip below 30%. The
driest possible scenario that would achieve these RH values would be
if ridging aloft edges into our area quicker/strong this weekend,
allowing for warmer temperatures and stronger daytime mixing.
This lack of moisture availability as well as current and expected
state of fuels allow the opportunity for elevated fire weather
conditions should winds become sufficient strong enough. At this
time, there isn`t a strong signal for gusty winds over 25 mph,
however there remains a scenario on Monday where the pressure
gradient tightens enough to allow for such a situation, around a 20%
chance of occurring. Ultimately, confidence in reaching elevated
fire weather concerns will increase closer to these days once they
become in the horizon of convective allowing model guidance.
Getting into mid to late next week, guidance brings the upper ridge
east allowing for increasing temperatures and moisture into the area
from either southwesterly or zonal flow aloft. Guidance however
diverges enough on synoptic pattern and associated parameters to
keep details on amount of moisture, location of rainfall, and
potential for organized strong to severe storms unknown at this time.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 656 PM CDT Wed May 17 2023
Winds to turn northwest Fargo by 02z and Bemidji by 06z. Brief
gusts in the winds as well 20-25 kts, though less chance in BJI
than in Fargo. Otherwise NW wind tonight into Thursday with
increase in gusts Thursday aftn. Scattered shower chances appear
Thursday midday and aftn as cold air aloft moves in with upper
low. Ceilings mostly VFR, though some MVFR cigs at times mainly
Thur aftn in the north and east. Vsbys in smoke 1-5SM tonight.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...CJ
AVIATION...Riddle
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1016 PM CDT Wed May 17 2023
.SHORT TERM...(This Evening through Thursday)
Issued at 211 PM CDT Wed May 17 2023
KEY MESSAGES:
1. Band of showers and thunderstorms expected to move into central
South Dakota later today, but will weaken as they move east tonight.
2. Increased smoke aloft will persist into the overnight.
3. Widespread smoke may begin to transport down to the surface
Thursday, and could produce air quality and visibility issues at
times.
4. Prolonged period of quiet weather expected into early next week.
-----------------------------------------------------------------
THIS AFTERNOON: Widespread smoke aloft continues to produce a hazy
appearance in the sky across the Tri-State area. Regional satellite
shows this extensive smoke layer extending well west into central
South Dakota. Even further west, we`re beginning to see a cold
front move into central South Dakota. Currently stretching from
Mobridge to Okaton, this front will reach the western portions of
the CWA by 00z. Minimal instability has developed ahead of the
boundary, likely due to the increased boundary layer dry air and
increased mixing. Behind the boundary, anticipating upwards of
1000- 1500 J/KG to develop by late afternoon. Visibility satellite
also showing extensive smoke behind the boundary with 1/2 to 2
mile visibility in portions of Montana/North Dakota/South Dakota.
THIS EVENING: Convection will begin to increase with the post-
frontal regime late this afternoon and early evening as a mid-lvl
shortwave begins to move into the Dakotas. Some additional
convection along the front itself may be possible from southeast
North Dakota into central South Dakota. Fairly minimal shear and
just modest instability and lapse rates will keep most of this
convection sub-severe as it approaches the western CWA this evening.
The one concern I have is for the potential of some gusty winds
given high cloud base, and dry subcloud layer. Modest cold
developing from decaying activity could push pockets of 40-50
knot winds into areas along and west of a line from Huron to Lake
Andes.
TONIGHT: As lift weakens, and rain runs into a drier airmass the
further east it tracks, precipitation may really struggle to reach
the I-29 corridor prior to daybreak. Temperatures cool into the
middle and upper 50s.
THURSDAY: The aforementioned frontal boundary meanders southeast
through the morning hours of Thursday, with broad mid-lvl
vorticity keeping at least a scattered risk for a few showers
through the morning. More concerning for Thursday will be the
potential for increased wildfire smoke, with the potential that
the smoke layer following the cold front southeast will have a
much easier time transported downward to the surface. Latest RAP
near surface smoke projections suggest the arrival of a lower
smoke plume through the morning, and continuing into the evening
before a stronger cold front drops into the region from the north.
For now, will forecast a 2-5SM visibility drop to mention at
least patchy smoke in the forecast. Air quality levels today are
already in the "moderate" range today, and it`s possible for worse
conditions take place on Thursday.
.LONG TERM...(Thursday Night through Wednesday)
Issued at 211 PM CDT Wed May 17 2023
FRIDAY: High pressure entering the Plains should push most of the
surface smoke south of the area Friday, but with a large upper low
spinning into the Great Lakes, upper smoke may continue to stay in
the region into Friday. Cooler temperatures are likely Friday, with
H850 temperatures falling near 0C. Current projections have high
temperatures remaining in the 60s.
SATURDAY-SUNDAY: Broad ridging over the western CONUS will keep the
central US under the influence of northwesterly flow aloft.
Generally through, despite the arrival of several minor shortwaves
within the flow, the lack of any appreciable moisture will keep
precipitation risks minimal. Temperatures will stay near to
slightly above normal, and with light to occasionally breezy
southwest winds, a fairly nice weekend is expected. Additional
wildfire smoke may return to the Plains this weekend, given the
orientation of the mid- lvl flow to the ongoing fires in Alberta.
MONDAY-WEDNESDAY: Mid-lvl heights rise in the Central US early next
week, and this will spell even warmer low-lvl thermal advection into
the Plains. Temperatures Monday and Tuesday rise back towards the
80s, with temperatures on Tuesday well into the 80s. Convection
risks return by mid-week as a front is pushed eastward.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1015 PM CDT Wed May 17 2023
Isolated to scattered showers and thunderstorms will move from
central SD towards I-29, but the trends continue to hint that it
will be weakening as it moves in this direction. Overall most
activity after about 9z should be fairly isolated. Showers and
storms may try to re-fire over parts of northwest IA and southwest
MN Thursday afternoon. Otherwise, smoke in the mid to upper
levels will continue through the night, but as a front moves
through some of this smoke will likely transport to the surface
and some visibility restrictions will be likely through the day
Thursday.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...Dux
LONG TERM...Dux
AVIATION...08
Area Forecast Discussion
National Weather Service Houston/Galveston TX
620 PM CDT Wed May 17 2023
...New AVIATION...
.SHORT TERM...
(This evening through Thursday Night)
Issued at 307 PM CDT Wed May 17 2023
Isolated showers and storms may develop along the sea breeze late
this afternoon. These storms should remain confined to areas south
of Hobby airport, as HRRR BL heights suggest a very short inland
extent to the afternoons sea breeze.
Clear skies and drier conditions are expected this evening in the
wake of a passing mid to upper level trough. Ridging builds across
the state overnight, allowing for quiet weather to continue into
Thursday. Clearer skies and drier conditions should bring warmer
temperatures on Thursday with highs progged in mid 80s to lower 90.
Onshore flow returns late Thursday afternoon/evening, allowing
moisture to rise across the region. Increased moisture and rising
cloud cover should bring slightly warmer conditions Thursday Night,
with lows in the mid 60s to lower 70s.
03
&&
.LONG TERM...
(Friday through next Tuesday)
Issued at 307 PM CDT Wed May 17 2023
Friday will be the warmest day yet in this period as mid to upper
level ridging strengthens, light southerly flow returns, and sunny
to partly cloudy skies continue. Look for highs in the upper 80s
to low 90s areawide. By late Friday night into Saturday morning, a
cold front will move across Southeast TX...still expecting this
front to make it into the coastal waters near sunrise time. Not
expecting a lot of rain with this front, given that strong ridging
will remain overhead (mid level height at 588-590 dam), but some
isolated activity can occur just ahead and along the front.
However, some showers and thunderstorms could occur after the
FROPA as a surge of moisture along the surface to mid levels and
possibly a weak low level jet moving in Saturday afternoon and/or
evening. We will have to see if the storms are able to develop
again the subsidence aloft. For now, kept low PoPS (25% or less)
and temperatures a few degrees cooler for the day.
On Sunday, the ridge will weaken and with PWs of 1.5 to 1.8
inches, it will not be hard for diurnally driven showers and
thunderstorms to develop in the afternoon. Monday is expected to
have a similar weather pattern, but with slightly less chances
given that it will be a little drier both along the surface and
the mid levels. Highs on Sunday will be in the low to mid 80s,
but will warm back up into the mid to upper 80s by Tuesday.
24
&&
.AVIATION...
(00Z TAF Issuance)
Issued at 620 PM CDT Wed May 17 2023
Variable winds (around 5 knots or less) are expected for a majority
of the upcoming TAF period. Some patchy fog is possible overnight through
early tomorrow morning, mainly in/around the LBX area. VFR with FEW/SCT
clouds anticipated for much of the area.
42
&&
.MARINE...
Issued at 307 PM CDT Wed May 17 2023
Light winds and seas of 1 to 2 feet expected through early next
week. Drier conditions expected through the end of the work week.
Chance of showers and thunderstorms could return this upcoming
weekend.
24
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 64 88 67 90 / 0 0 0 0
Houston (IAH) 66 89 69 90 / 0 0 0 10
Galveston (GLS) 73 85 74 86 / 10 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Indianapolis IN
939 PM EDT Wed May 17 2023
.Forecast Update...
Issued at 939 PM EDT Wed May 17 2023
Smoke continues at high levels across the forecast area as could be
seen by a colorful sunset earlier this evening. Sunset also showed
the texture to the smoke rather than just a haze. Adjusted sky cover
to partly cloudy tonight into Thursday to account for the smoke
layer.
Otherwise forecast is in good shape this evening as temperatures
begin to cool quickly with loss of heating and a dry atmosphere.
Adjusted hourly temperatures to reflect current trends but no
changes were made to forecast low temperatures.
&&
.Short Term...(Through Thursday)
Issued at 115 PM EDT Wed May 17 2023
A slight hazy appearance to the sky may be observed through the
rest of the day into tomorrow. This is due to wildfire smoke from
Canada within northwesterly flow aloft. It is confined to the upper
levels of the atmosphere and won`t be impactful to surface
visibility. Per Canadian and RAP smoke models, this may abate
somewhat temporarily tomorrow with trajectories shifting.
Tomorrow should be as pleasant as today with light winds, low
humidity, and near normal temperatures for mid-May in the low-mid
70s. Perhaps a couple of degrees warmer, but with mean ridging being
weak and low-level flow/advection of any consequence still being
confined to our west, it shouldn`t be more than a couple degrees
difference compared to today. Some cirrus may reach Indiana by late
in the day as deeper moisture plume ahead of the approaching system
starts to move in.
&&
.Long Term...(Thursday night through Wednesday)
Issued at 115 PM EDT Wed May 17 2023
ECMWF/EPS still lags GFS/GEFS slightly with the progression of the
next system that will impact our area, but they are closer that
previous model cycles. Ensemble spread is narrowing some. So, our
confidence in timing of the next rain event is increasing and we
have further narrowed the window of highest probabilities. This
should be Friday evening. Deterministic and ensemble models agree on
the character of this trough being in the form of a closed mid-upper
low with strengthening southwesterly low level flow steady advecting
moisture into Indiana during the day Friday.
One additional detail we may need to refine is some potential for
isolated to scattered showers midday into afternoon ahead of the
main frontal band. But again, we expect most of the precipitation to
fall from a band of convection that should pass through in a few
hours along and just ahead of the DCVA/frontal forcing.
This general pattern can often support just modest instability, as
steepest midlevel lapse rates are confined closer to the
neutral/weakening closed low center to our north. Thus, severe
storms appear to be unlikely at this time in central Indiana.
Ensemble mean QPF has been steady around 0.50" storm total rainfall
for the last few model cycles, confining higher amounts further
south closer to and south of the Ohio River.
Cyclonic flow around eastern U.S./Canada trough will keep us in
northwesterly flow and a dry pattern, although one or more weak
perturbations embedded within may bring a period of mid-high clouds.
Trajectories may also favor wildfire smoke from Canada causing
continued hazy look to the sky and enhancing red colors of sunrises
and sunsets. But, this is generally expected to be a dry and warm
pattern even into the Day 8-14 period per medium-range ensemble
data.
&&
.Aviation...(00Z TAF Issuance)
Issued at 632 PM EDT Wed May 17 2023
Impacts:
* No impacts expected
Discussion:
With a dry atmosphere in place, VFR conditions will continue
through the period. An elevated smoke layer will persist.
Northeast winds will gradually veer to southeast by mid-morning
Thursday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...50
Short Term...BRB
Long Term...BRB
Aviation...50
Area Forecast Discussion
National Weather Service Key West FL
936 PM EDT Wed May 17 2023
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 940 PM EDT Wed May 17 2023
The current meteorological conditions prevailing over the island
chain are characterized by dry,warm, and calm, which can be
attributed to the influx of dry air that entered the area during
the late hours of the previous night and early hours of the
present day. According to the KBYX sounding data, there was a
reduction in precipitable water values from 1.55 inches at 12Z to
1.40 inches at 00Z. While certain boundaries are discernible on
the KBYX radar, the absence of modest low-level moisture in the
atmosphere and surface forcing resulted in a subtle synoptic
pattern. The maximum temperatures recorded today ranged from the
mid to low 90s, with Key West International Airport registering a
high of 85 degrees and Marathon International Airport reaching 91
degrees. Marathon International Airport was the sole location
exhibiting above-average readings today.
The forecast indicates that the remaining period will experience
cloudless conditions and no probability of precipitation. The
overnight temperatures are expected to range from the mid to
upper 70s, except the lower 70s in the inland regions of the
larger islands. Tonight, there is a possibility of showers and
isolated thunderstorms in the outer Straits of Florida waters,
which may be caused by a land breeze from Cuba. According to the
HRRR Caribbean model, there is a possibility that nocturnal
showers develop early tomorrow morning, which may impact the Upper
Keys and the adjacent waters. The HRRR Caribbean model is the
sole source of guidance that presents this particular solution,
albeit noteworthy to acknowledge.
&&
.MARINE...
Issued at 940 PM EDT Wed May 17 2023
A weak pressure gradient across the Florida Keys coastal waters
will promote light to gentle breezes through at least Saturday.
&&
.AVIATION...
(00Z TAFS)
Issued at 940 PM EDT Wed May 17 2023
VFR conditions will prevail at EYW and MTH terminal sites through
18/22Z. Surface winds will be generally light and variable at 5
knots.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...TW
Aviation/Nowcasts....TW
Data Acquisition.....JPR
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest
...UPDATED AVIATION FORECAST DISCUSSION...
.SYNOPSIS...
Issued at 232 PM CDT Wed May 17 2023
Key Messages:
- Isolated to scattered thunderstorms with isolated damaging wind
gusts and marginally severe hail are possible across much of western
and north central Nebraska late this afternoon into the evening.
- Thunderstorm chances continue into Thursday afternoon, however,
the severe threat remains low at this time.
- Behind a cold front, cooler temperatures in the 60s return for a
brief period Thursday and Friday. Overnight lows on Friday fall into
the upper 30s
- Quiet and mostly dry conditions return this weekend with
temperatures warming into the 70s and low 80s.
- Precipitation chances increase across the area toward the middle
and end of next week.
Recent GOES-16 WV and RAP 500-mb analysis showed a broad closed low
centered across the central Pacific Ocean with another area of low
pressure further norther across the Southwest Alaska. Further south
of this feature, a closed trough of low pressure was off the coast of
the Baja Peninsula. Further north of this feature, a closed low
pressure system was noted across Manitoba with a trough extending
south across the far northern Plains. Southwest of this feature, a
shortwave trough was evident across Idaho, extending into central
Oregon. Further north of this shortwave, weak high pressure was
centered across far western British Columbia. A compact low pressure
system was apparent over northern Quebec, with a broad trough
extending southwest across the Great Lakes into the Mississippi
Valley and New England. Closer to home, an upper-level shortwave was
apparent across the Dakotas, bisecting portions of the Panhandle and
northern Nebraska. At the surface, accompanying low pressure was
centered across eastern Manitoba with a trough extending south
from eastern Montana into northern Nebraska. An associated cold
front was noted, extending west-southwest across Montana and North
Dakota. Surface high pressure encompassed much of the central
Plains. At 2 PM CT, temperatures ranged from 74 at Imperial to 80
degrees at Valentine.
Recent GOES-16 RGB imagery shows agitated cumulus fields across the
western and northern Sandhills. KUDX and KCYS, and KLNX radar
imagery has shown robust convective development across the
Panhandle and near the Pine Ridge/Black Hills area into portions
of the northwestern Sandhills. Anticipate diurnal destablization
to continue with additional thunderstorm development expected to
begin within the next few hours impacting western and north
central Nebraska. For further information in regards to these
isolated and scattered thunderstorms, refer to the Short Term
portion of the discussion.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 232 PM CDT Wed May 17 2023
The aforementioned surface trough has been forced further into
the Panhandle and Sandhills within the last few hours. Behind the
pre-frontal trough, the associated weak cold front will push
further south into South Dakota and Wyoming later this evening.
Low-level convergence has already begun to provide synoptic lift
along the pre-frontal surface trough which has promoted the
development of thunderstorms across the western and northwestern
Sandhills. Recent CAMs are seemingly late with the convective
development not beginning until 21Z while thunderstorms are
currently developing across the area. Anticipate these storms to
continue to mature within the next few hours as buoyancy and
diurnal destablization improves further.
A corridor of MLCAPE values nearing 1,000 J/kg will coincide with
mid-level lapse rates near 8-9 C/km and modest deep layer shear
values approaching 30kts. All of these parameters combined will
support an environment capable of developing a strong to isolated
severe thunderstorms across the area. Isolated damaging winds are
main threat within the strongest of storms that do develop. The
secondary threat will be isolated marginally severe hail given the
deep-layer shear and DCAPE (~500 J/kg) that is present. Recent
forecast soundings show an inverted-v profile suggesting that
these thunderstorms will be high-based. As the aforementioned cold
front catches up to the pre-frontal trough, thunderstorm coverage
will increase across southwestern into central Nebraska later
this evening into the night. Closer to sunset the threat for
severe hazards appears to diminish as diurnal heating commences.
Scattered showers and embedded thunderstorms are expected to
continue through the night across the area.
A secondary Canadian cold front will push south across the area
during the day on Thursday, reaching far northern Nebraska by 00Z
Thursday. This will bring another chance for showers and
thunderstorms across the area ahead of the FROPA. The bulk of the
convection appears to remain south of the area, however, meager
instability will be present across portions of southwest, south
central, and north central Nebraska which will be enough to allow
for rumbles or thunder. Any showers and thunderstorms that do
develop should exit south of the area around 21Z. Given the lack
of forcing, shear, and moisture, the severe threat with Thursday`s
activity remains low at this time.
Behind the FROPA, cooler temperatures are anticipated during the day
on Thursday with highs in the upper 60s to low 70s. Subsidence
behind the front will lead to gradually clearly skies Thursday
evening into Thursday night. Hazy skies are anticipated across the
region as some from early season wildfire activity in Canada,
particularly the provinces of British Columbia and Alberta.
Outside of some hazy looking skies the smoke is not expected to
reach the surface, thus no air quality impacts are anticipated
across the local area. Overnight lows will be on the chilly side
in the upper 30s to 40s across the area.
.LONG TERM...(Friday through Wednesday)
Issued at 232 PM CDT Wed May 17 2023
It will be a rather pleasant day on Friday as cool and dry
conditions return with daytime highs remaining in the 60s under
mostly clear skies. Canadian surface high pressure will build into
the area, becoming overhead western and north central Nebraska
around 12Z Saturday. Overnight lows are expected to fall into the
upper 30s to low 40s Saturday morning. Similar thinking to the
previous discussion in regards to the frost potential on Saturday
morning. If model guidance trend lower, we will need to watch for
frost potential. With the current forecast, this potential
continues to appear low. Regardless, will continue to monitor with
subsequent forecasts.
High temperatures rebound into the weekend with highs in the mid
to upper 70s and low 80s. Current forecast and ensemble guidance
suggests a mostly dry forecast this weekend. However, some
solutions suggest a shortwave will track across the area bringing
a slight chance for showers and thunderstorms. Model solutions
diverge in the exact evolution of this brief system, thus
confidence remains low across our area at this time.
Looking further ahead into next week, temperatures remain in the
above normal range through the middle of the week. Precipitation
chances increase again Tuesday afternoon into Wednesday afternoon.
Details remain rather murky as model solutions diverge on
evolution and strength of this system.Will need to continue to
monitor this with subsequent forecasts as models come to a
consistent solution.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 625 PM CDT Wed May 17 2023
VFR conditions are expected to prevail through tomorrow evening
outside of thunderstorms. Scattered to widespread thunderstorms
will continue to push eastward across the area this evening, with
brief MVFR possible in any thunderstorms along with gusty, erratic
winds. Thunderstorms exit tonight, though lingering isolated
showers/storms will remain possible across southwest Nebraska
overnight. Otherwise, winds shift northerly through tomorrow
morning, at around 10 to 15kts in the afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Brown
Area Forecast Discussion
National Weather Service Louisville KY
932 PM EDT Wed May 17 2023
.Forecast Update...
Issued at 930 PM EDT Wed May 17 2023
Calm and clear conditions continue across the Ohio Valley this
evening as temperatures have begun to cool after sunset. A wide
range in readings persists at this hour, from low 70s near the TN
border to mid-to-upper 50s in some of the sheltered valleys of the
KY Bluegrass. Latest nighttime microphysics satellite imagery shows
clear skies for all with the exception of a few residual cu over
Ohio and Butler County. As we head through the overnight hours
tonight, expect temperatures to drop off efficiently as light winds
and mostly clear skies allow for near-optimal radiational cooling.
T/Td spreads should be large enough tomorrow morning for most if not
all to avoid fog; however, will keep patchy fog mention from
previous forecast across Green/Cumberland R. valleys where slightly
greater residual moisture lingers (low confidence).
The previous forecast remains on track at this hour. Have slightly
lowered valley min temps to account for typical ridge-valley splits
on radiational cooling nights. Updated products will be out shortly.
&&
.Short Term...(Tonight through Thursday evening)
Issued at 305 PM EDT Wed May 17 2023
Synopsis...Surface high pressure will keep moving eastward across
the Great Lakes while pushing a dry airmass through the lower Ohio
Valley. At the mid-levels, a shortwave trough will track from the
Ozarks to the Tennessee and lower Ohio Valleys at the same time a
shortwave ridge transitions over the upper Ohio Valley and Great
Lakes.
Tonight...Current surface analysis indicates dry air advection
taking place in the forecast area with dewpoints in the low to mid
50s in southern KY and some upper 40s towards southern Indiana. As a
result, there is some fair weather cumulus development along and
south of the dividing line with sunny conditions in its wake. The
same differential moisture boundary is marked in satellite imagery
by a wildfire smoke plume coming all the way from western Canada.
Aside from the hazy skies, these suspended smoke particles should
provide a vibrant fiery spectacle at sunset. Other than that, quite
weather is expected overnight with fog development indicated just to
the river valley areas along the Lake Cumberland and Green River
basin due to the dewpoint depression elsewhere.
Thursday...The morning will be mostly sunny with lows ranging from
the low 50s in south-central Kentucky to the mid and upper 40s in
southern Indiana under light northeasterly flow. Any instance of fog
will quickly burn off after sunrise. Gradual but limited moisture
advection is expected the rest of the morning and early afternoon as
winds turn to the southeast ahead of the approaching shortwave with
the dry air anchored in the low levels. A low precipitation chance
remains for the afternoon hours, especially for Lake Cumberland and
immediate vicinities. RAP forecast soundings have slightly moderate
instability (1000-1500 J/kg) with weak deep-layer shear and the
aforementioned dry low-level dry air. So, there is a non-zero chance
of pulse storms with strong localized downdrafts as the DCAPE values
are about 800 J/kg. The limited convective activity should dissipate
shortly after sunset following the diurnal heating cycle.
&&
.Long Term...(After midnight Thursday night through Wednesday)
Issued at 300 PM EDT Wed May 17 2023
Main impactful weather for the longer range forecast will be chances
for rain and thunderstorms Friday afternoon into Saturday afternoon
with a few isolated strong thunderstorms may develop.
Thursday night into Friday morning: A weak warm frontal boundary in
between a surface high and low pressure system will funnel moisture
and weak instability into the Ohio Valley in this time frame. This
will lead to some isolated weak showers (probability 20% or less) or
possibly a thunderstorm (probability of lightning 20% or less) or
two heading into Friday morning.
Friday afternoon into Saturday afternoon: The next weather making
disturbance progresses out of the northern plains and will bring
chances for rain (50-70%) and chances for thunderstorms (probability
of lightning 20-30%). Model soundings have a steering flow cap with
a warm layer aloft, which may limit any storms from getting enough
momentum to become severe, however a little bit of surface cape and
effective inflow shear of ~45 kts could lead to some isolated
stronger storms. Limiting factors include the time of day of best
dynamics and a positively tilted trough that passes to the north vs.
over the forecast area.
Saturday evening through Tuesday: A strong upper level ridge of
high pressure builds across the region and brings dry weather and
warming conditions into the Ohio Valley. Afternoon high temperatures
steadily rise into the upper 70s and mid 80s by mid week (60-80%
chance of exceeding 80 by Wednesday), which is on the order of 5-8
degrees above normal for late May. Afternoon pop up showers on
Tuesday is possible, but confidence is low at this point.
&&
.Aviation...(00Z TAF Issuance)
Issued at 710 PM EDT Wed May 17 2023
A ridge of high pressure extending from SW Ontario down into the
Ohio Valley will allow for dry NE flow across the region, with
flight categories expected to remain VFR through the current
forecast period. Winds will relax slightly overnight, but the air
mass should be sufficiently dry to limit any fog development early
tomorrow morning.
As the center of high pressure slides off the northeast U.S. coast
tomorrow, winds will gradually veer easterly and then southeasterly,
which will allow for some low-level moisture to creep northward,
likely manifesting as a 5-7 kft SCT cu field during the late
morning/early afternoon hours tomorrow. There is an outside chance
that LEX/BWG could see a shower/storm tomorrow afternoon/evening;
however, confidence is far too low to warrant mention at this time.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...CSG
Short Term...ALL
Long Term...MCK
Aviation...CSG
Area Forecast Discussion
National Weather Service Marquette MI
659 PM EDT Wed May 17 2023
.SHORT TERM...(This afternoon and tonight)
Issued at 134 PM EDT WED MAY 17 2023
Dry air overhead has supported mostly clear skies expect for high
level indolent haze that more or less, parked itself overhead. This
haze has so far limited how high temps have climbed, but overall
we`ve still observed temps reaching the mid 40s to upper 50s.
Dinural mixing has allowed many sites to tap into drier air aloft,
and these spots have seen RH values dip into the 20s and 30s.
As we progress through the remainder of the afternoon and overnight,
RAP analysis shows the continued presence of haze/smoke overhead.
Again though, not expecting any impacts at the surface. The airmass
will continue to remain dry, and overnight we should decouple from
the warming airmass aloft. With this in mind, expecting the central
and east/south into the mid-upper 30s. The west though, particularly
the far west, should stay in the 40s. With the dry airmass overhead
and not much cooling expected, RH recoveries overnight look to be
poor
.LONG TERM...(Thursday through Wednesday)
Issued at 457 PM EDT WED MAY 17 2023
Overall, not many changes to long-term forecast with borderline red
flag conditions expected across the eastern UP ahead of an
approaching cold front. Several precip chances lead to near-normal
precip amounts across the west-central late this week and lighter,
below-normal precip across the east. Temperatures should average
slightly below-normal through the extended, but there will be
several ups and downs.
Starting with Thursday morning, a few showers or thunderstorms are
possible far west and over the Keweenaw. The 12z 3km NAM has some
localized MUCAPE values around 1000 J/kg on the nose of a ~40kt LLJ,
which could lead to a sunrise surprise scenario with a few stronger
cells possible that may be capable of small hail. This activity -if
it develops- should diminish within a few hours of sunrise as
southerly winds downsloping into the Lake Superior basin get quite
gusty. These gusty southerly winds increase through the day as
mixing depth increases, especially across the east-central where
winds accelerate up the long axis of Lake MI. There is
uncertainty regarding the influence of Lake MI and how deep mixing
gets, but soundings show a very dry layer with strong winds near
the top of the mixed layer so there is potential for stronger
winds, warmer temps, and lower RHs Thursday afternoon. Given the
time of year and recent dryness it seems prudent to err on the
side of caution and hoist a Fire Weather Watch across east-central
Upper Michigan.
Fire weather concerns continue through the evening until a cold
front moves through bringing more widespread precip chances Thursday
evening and overnight. Given how dry we are precip amounts could be
on the high side and seem to have trended down somewhat from the
previous forecast. There could be some locally moderate amounts
>0.5", but think this potential will be confined to the western UP.
There should be a lull in precip Friday morning with renewed precip
chances Friday afternoon, especially if there is enough sunshine to
create sufficient destabilization for diurnal showers. Given the
cold temp profiles as the upper low moves overhead, small hail or
graupel is possible with any stronger showers. Precip chances should
diminish Friday night across most of our area, but there could be a
few lingering showers across the east on Saturday.
A cold front similar to what occurred on Tuesday is expected Sunday
morning with modest CAA through the day on Sunday resulting in
steady or perhaps falling temps through the day. Frost/freeze
potential increases by Monday morning as another cool/dry surface
high pressure settles across the Upper Great Lakes/James Bay region.
Southerly winds and WAA ramp up again Monday night across the west
and Tuesday CWA-wide as the ridge slides southeast across New
England. This ridge also raises fire wx concerns late Sunday through
Tuesday, but light winds on Monday suggest greater concerns for late
Sunday and Tuesday. Precip chances increase toward the middle to end
of next week as south-southwest winds transport richer moisture into
the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 659 PM EDT WED MAY 17 2023
VFR conditions are expected to prevail through this TAF period with
mostly clear skies expected. Expect hazy skies to continue due to
upstream forest fires, but this isn`t expected to mix to the
surface. The next system approaches Thursday, supporting a lowering
trend in clouds and gusty southerly winds of 25 to 35 kts. LLWS will
occur at IWD late tonight into Thu morning.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 457 PM EDT WED MAY 17 2023
Easterly gusts between 15 to 20kt continue into this evening across
western Lake Superior as a meso high pres center develops over the
eastern lake. Low pres and a cold front dropping se into northern
Ontario and MN tonight will lead to increasing E to SE winds
veering S Thursday morning. Expect gusts to 20-25kt, strongest
across central portions of the lake. Winds will increase further
up to 30 kts on Thu, mainly over the east half of Lake Superior
as low-level jet translates across the area. A few gale force
gusts to 35 kt are possible during the late aftn and evening
across the east half, especially at higher elevation observation
platforms. A cold front moves east across Lake Superior Thu aftn
thru Thu night. Post-frontal westerly winds shouldn`t gust above
20kt across western Lake Superior, and the stronger winds across
the east half fall back to under 20kt by sunrise Fri. Expect
winds under 20kt to continue Fri/Fri night. West-southwesterly
winds increase to between 25 and 30 knots across the north-central
lake late Saturday afternoon and evening ahead of the next cold
front dropping s across Lake Superior Sat night. As the front
sweeps across Lake Superior Sat night/early Sun, winds shift n to
nne and there could be a period of gusts to around 30kt for
several hrs after the front passes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Fire Weather Watch from Thursday morning through Thursday
evening for MIZ005>007-012>014-085>088-095-096.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JTP
LONG TERM...EK
AVIATION...07
MARINE...EK
Area Forecast Discussion
National Weather Service Missoula MT
232 PM MDT Wed May 17 2023
.DISCUSSION...The early afternoon GeoColor satellite loop
continues to show smoke moving out of Canada and into the region.
Vertically integrated smoke forecasts from the RAP and PM 2.5 from
Canada’s FireWork system show a combination of haze and smoke
impacting north-central Idaho and western Montana through Friday
morning. A ridge of high pressure is forecast to build into the
region on Friday, which will transition our flow to westerly and
should cutoff the source of smoke and eventually clear the smoke
that is in place.
Smoke is also expected to impact the high temperature forecasts
today and Thursday, so the forecast has been lowered in many
locations across western Montana. While temperatures may not
reach full warming potential in many spots today, the
thunderstorm forecast is a little less certain. There is a bug in
the HRRR modeling system that is not allowing for observed smoke
to be ingested, therefore it may be depicting too much warming and
overproducing shower activity across northwest Montana. The scattered
showers and thunderstorms that remain in the forecast will be of a
slow moving nature. This points to moderate to heavy rainfall
rates being the main concern, with localized minor flooding issues
due to ponding of water and runoff possible through the evening
hours.
Model clusters agree on a ridge of high pressure to continue to
build over the Northern Rockies this weekend. Temperatures are
expected to warm to around 15 to 20 degrees above normal for this
time of the year, translating to mid 80s and low 90s by this
weekend. The high afternoon temperatures and relatively warm
overnights will result in continued mountain snowmelt, keeping
area waterways running high, fast, and cold through the weekend.
While most locations will be dry this weekend, isolated showers
and thunderstorms will be possible each afternoon due to lingering
moisture.
Around 50 percent of model clusters show a trough and strong
surface low pressure system moving into the Pacific Northwest
early next week. There has been a trend toward higher
thunderstorms chances on Sunday ahead of the trough, and the track
of the trough and low pressure system will need to be monitored
for the threat of widespread thunderstorms for early next week.
Some may be wondering what the Memorial Day weekend may end up
turning out to be. Climatology suggests that our average
precipitation towards the end of May increases over the region.
Sometimes cut-off low pressure systems can bring cool and wet
weather. The ensemble model clusters would suggest that the
American GFS system shows a 67 percent probability for a wetter
and cooler system to impact the area, the Canadian shows a 65
percent probability for a drier pattern and the European is almost
split down the middle. One thing we have increasing confidence in
is the fact that models are showing some changes to the upstream
pattern over the Northeast Pacific...they are trending towards
more troughing. This kind of pattern could set the stage for
troughs to be able to track southeastwards towards the Pacific
Northwest, or place our region under southwest flow which is a
milder pattern with a chance for thunderstorms. The Climate
Prediction Center forecast for this period from May 25 through the
31st, shows a 50 percent leaning towards above average
temperatures and equal chances that precipitation could end up
being above or below average.
&&
.AVIATION...Satellite loops show smoke continuing to move
southward out of Canada and into the region today, which is
forecast to continue at least through Thursday. Visibility
reductions from smoke will continue to be observed. Smoke will
keep temperatures from warming to the full potential in many
spots today but thunderstorms are still expected to develop in
central Idaho and west-central and southwest Montana this
afternoon. Moderate to heavy rainfall and frequent lightning can
be expected with the convection. Smoke and fairly high dew points
can lead to very low visibility if fog develops, but an easterly
pressure gradient should keep most of the larger valleys mixed
enough to prevent dense fog.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&
$$
Area Forecast Discussion
National Weather Service Spokane WA
359 PM PDT Wed May 17 2023
.SYNOPSIS...
The Inland Northwest will experience isolated showers and
thunderstorms today and again more so over the mountains of north-
central Washington on Thursday. Some afternoon and evening
thunderstorms will be capable of locally heavy rain, small hail,
and frequent cloud to ground lightning. Temperatures Friday and
Saturday will climb into the upper 80s and 90s, potentially
breaking records. Many rivers will be running swiftly over the
next couple of weeks as above average temperatures cause mountain
snow to melt rapidly. Changes arrive early next week with a cold
front passage Sunday that will bring near normal temperatures and
another chance of afternoon showers early next week.
&&
.DISCUSSION...
Tonight through Friday: Radar this afternoon is showing convection
beginning to blossom around the Spokane/CdA metro areas. Recent SPC
Mesoanalysis shows a rather unstable atmosphere with areas in
northeast Washington and the northern Panhandle under a large
swath of 1500+ J/kg of SBCAPE. This can be attributed to much
warmer temperatures across most locations today despite the smoky
skies with similar available moisture within the atmosphere.
Additionally, there is slightly more shear, quicker storm motions,
and higher DCAPE values, which will be less conducive of flash
flooding, but still supportive of brief heavy downpours. These
ingredients area also more supportive of gusty outflow winds along
with larger- than- pea but smaller-than-quarter sized hail.
Forcing is on the lower side today though, which is why we aren`t
seeing as much coverage with the storms. Storms will wind down
this evening as the sun begins to set. Some high resolution models
are showing a weak impulse to move into northeast WA and the
Idaho Panhandle from the north overnight, which could trigger a
band of showers. Not every model is showing this, but enough for
the forecast to carry a 15-30% chance for it to occur.
Upper level ridging will begin to rebuild over the Pacific Northwest
Thursday with the winds aloft shifting to the southwest. Residual
atmospheric moisture will support afternoon covective showers mainly
over the Cascades and the northeast mountains. The shift of the
upper level flow will push the smoke aloft back into Canada,
although it doesn`t look to fully clear the region until Friday.
Temperatures on Friday will warm under the building ridge with
temperatures climbing into mid 80s to low 90s across the region.
Many places are forecasted to cream their previous record high
temperatures. While it is going to be hot as temperatures will be
around 15 to 20 degrees above climatology, temperatures cooling back
into the 50s and 60s overnight will reduce the risk for accumulation
of heat stress in the body for the general population. Those
sensitive to heat and those without effective cooling during the day
should take precautions to protect themselves during the hottest
times of the day. /vmt
Saturday through Wednesday: As previously mentioned Saturday
continues to look to be the warmest day of the year so far with
temperatures trending 15 to 20 degrees above normal as upper level
ridge axis gets positioned over Northwest Montana. The southwest
flow aloft may allow disturbances to run quickly from southwest to
northeast and fire off convection in the form of showers and
thunderstorms as precipitable water values look to run between 120-
180 percent of normal and prog soundings suggest airmass will be
conditionally unstable. Sunday the upper level ridge gets displaced
further east as a negatively tilted trof runs up the west side of
it. As such Sunday will not only be cooler but could possibly be the
wettest day of the forecast with steering flow moving any resulting
showers and thunderstorms from southwest to northeast at 25-30mph. A
cold pool/trof lingering overhead Monday and Tuesday will provide
continued instability and allow the cool and unsettled weather trend
to continue. The coolest afternoon highs look to be Monday with the
coolest morning lows Tuesday due to this cold pool lingering aloft.
The steering flow should be slower and more complicated Monday and
Tuesday as well. Clusters suggest general trof remains in place as
well for Wednesday but with less intensity in comparison to Tuesday
thus allowing for warmer temperatures and somewhat decreased qpf/pop
numbers but not a totally dry forecast. /Pelatti
&&
.AVIATION...
00Z TAFS: The influx of mid and high level smoke from wildfires
burning in northern portions of British Columbia, Alberta, and
Saskatchewan has inhibited our warming this morning. It seems as
though shower and thunderstorm development has been slow to
develop as a result. While thunderstorms can`t be ruled out for
airports in north Idaho and northeast Washington, probabilities
appear to be 20 percent or less for Spokane, Coeur d`Alene, and
Pullman. The inclusion of thunderstorms this evening and overnight
will be handled through amendments. Smoke has been added to north
Idaho and the eastern third of Washington with visibility
reductions to 5 or 6 miles. Visibility is a low confidence
forecast since the HRRR smoke model is struggling to forecast the
Canadian smoke, so trends have been interpolated from Montana
visibility sensors. /GKoch
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 57 85 58 88 60 90 / 20 0 0 0 0 0
Coeur d`Alene 56 84 57 88 59 90 / 30 0 0 0 0 0
Pullman 54 82 57 85 59 88 / 10 0 10 0 0 0
Lewiston 60 89 63 93 64 94 / 10 0 0 0 0 0
Colville 55 86 56 89 57 92 / 20 10 10 10 0 10
Sandpoint 56 82 55 85 57 88 / 30 10 0 10 0 10
Kellogg 56 81 58 84 60 88 / 20 0 0 10 0 10
Moses Lake 59 90 60 93 63 96 / 10 0 10 0 0 0
Wenatchee 63 88 62 92 65 93 / 10 10 20 0 0 10
Omak 61 88 61 91 62 93 / 10 10 20 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$