Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/28/24
Area Forecast Discussion
National Weather Service Binghamton NY
919 PM EDT Tue Aug 27 2024
.SYNOPSIS...
There will be multiple rounds for showers and thunderstorms tonight
through Wednesday. While some showers cannot be ruled out Thursday,
the next best chance will be late Friday into Saturday. Temperatures
become more seasonable after Wednesday.
&&
.NEAR TERM /THROUGH THURSDAY/...
900 PM Update...
Water vapor imagery shows a small short wave riding over the top of
the upper level ridge toward PA and NY. This feature was providing
some lifting and forming some showers and isolated storms in western
NY. SPC mesoanalysis shows that instability in western NY with a
sharp gradient to virtual no instability east of I-81. There was
also CIN developing as the days heating radiates off to space.
Dewpoints were near or above 70F in western NY and mainly in the low
to mid 60s east of I-81. Even with moisture advection aloft, the
lack of mixing should keep dewpoints lower near the ground and lead
to some elevated instability as this wave moves east. CAMs are
struggling with the details in this marginal environment. So our
forecast is to combine the previous forecast with some of the latest
HRRR data w/ current radar data. Hence we have some slight chance to
chance POPs for this first minor batch of showers. Then later
tonight, another wave presses south from southeast Canada and pushes
a front toward northern NY. Moisture and instability was limited so
we keep slight chance POPs later tonight. Otherwise, much of
previous forecast looks on track with just some tweaks.
330 PM Update...
A shortwave moves in from the west this evening. This shortwave will
kickoff isolated to scattered showers and thunderstorms. Short range
guidance is showing 500 to 1000 J/kg of MLCAPE but 0-6 km bulk shear
is weak at 20 to 25 kts. Strong storms cannot be ruled out with
strong gusts being the main hazard.
Overnight, a frontal system will drop south and support a line of
showers and thunderstorms. This line will extend from Ohio up
through northern New England. However, the line becomes broken as it
moves into New York so PoPs are low over the region. The best
chances will be west of I-81 prior to sunrise Wednesday morning.
Elevated instability will lead to frequent lighting and heavy
downpours. While there will be some instability and shear will be
higher than this evening, the environment will be capped, so severe
storms are not anticipated. Still, storms with gusty winds will be
possible.
The broken line of convection continues to dip south through the
morning. Some lingering showers and thunderstorms will be possible,
but most guidance dries conditions out by midday. Some CAMs show
afternoon thunderstorms over Central PA that drift eastward. Most
keep these to the south but the HRRR brings those into NEPA.
Isolated stronger storms cannot be ruled out but again, confidence
is low. The risk for severe weather Wednesday evening and night
continues to trend more southward. SPC has put NEPA and Catskills in
a marginal risk, down from a slight risk. A band of 1500-2000 J/kg
of CAPE extends east into far southern areas of NEPA. Shear will be
25 to 30 kts. The severe potential would be for damaging wind gusts.
If the trend continues southward with where the front sets up, then
there is a chance that the overnight hours will be quiet.
Tonight, temperatures will be quite mild, only falling into the 60s
and low 70s. There will be a wide range of temperatures across the
region Wednesday. Temperatures will be in the mid 70s over north-
central NY and upper 80s/low 90s in NEPA. Heat indices will be close
to advisory criteria, but it was decided to hold off as the forecast
as trended cooler and just a few locations within the Wyoming Valley
would meet criteria. Wednesday night, temperatures will be in the
50s and 60s across most of the region.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
235 PM Update...
Surface high pressure over Canada expands into our region Thursday
behind the front. How far south it expands depends on the position
of the stalled front south of the Mason Dixon line. This results in
mostly calm and dry conditions over central NY while northeast PA
and the twin tiers could see some lingering showers Thursday
afternoon and overnight. Otherwise northerly flow is in place at the
upper levels with temperatures expected to range in the 70s by mid
afternoon. Overnight lows fall into the mid 50s to low 60s across
the area.
Pattern aloft transitions into an brief upper level ridge with
Southerly flow returning to the region. High pressure shifts
east on Friday with mostly dry conditions expected in the
morning ahead of the next system. Upper level trough located
over the Great Lakes pulls moisture back into our region Friday
afternoon and evening kicking off rain showers over the western
portion of our area. Rain showers and thunderstorms are expected
overnight as the trough begins to dig into our region along
with a warm sector. Highs in the afternoon will range in the 70s
with overnight lows in the mid 50s to mid 60s.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
235 PM Update...
Upper level trough holds for the entire period with a relatively
active pattern continuing during the weekend. Upper trough axis
moves through on Saturday along with a surface cold front. This
brings showers and thunderstorms to the region most of the day.
System moves out Saturday night with temperatures remaining
relatively mild despite the frontal passage. A secondary cold front
moves through Sunday afternoon as another shortwave dips into the
region. This front advects cooler air into the region but with
limited moisture. Cannot rule out shower development as
northwest flow may induce weak lake response. Drier air moves in
early next week with surface high building in over north
central US.
Temperatures over the weekend will range in the 70s to low 80s with
overnight lows in the mid 50s to low 60s. Cooler temperatures settle
in early next week behind the front with highs in the mid 60s to low
70s and lows in the mid 40s to low 50s.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions are expected until late tonight/early Wednesday
morning. A brief shower or storm will move in from the west
this evening to ELM and ITH. Then overnight, a frontal system
will bring a line of showers and potentially thunderstorms to
the region. There is uncertainty if this line holds together
when it moves into the region, but even with this uncertainty,
showers and reduced visibilities were added to RME and SYR, with
a lot less certainty with the other terminals. With this
system, ceilings will fall over NY. Guidance is hinting at IFR
late in this period, but for now, conditions were capped at Fuel
Alt. AVP will be far enough south and should not see showers or
restrictions.
Southerly, light winds will remain calm throughout the
overnight and early morning hours. Then during the afternoon on
Wednesday, winds become northwesterly and breezy with peak
gusts up to 15 kts at some terminals.
.Outlook...
Wednesday Afternoon through Overnight...Improving to VFR; low
chances for showers at KAVP.
Thursday...Mostly VFR but a small chance of a shower or storm
generally from KELM-KBGM southward; best chance KAVP.
Friday through Sunday...Chances of showers and
thunder/associated restrictions, especially Friday Evening
through Saturday.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...BTL
NEAR TERM...BTL
SHORT TERM...ES
LONG TERM...ES
AVIATION...BTL/KL
Area Forecast Discussion
National Weather Service Bismarck ND
837 PM CDT Tue Aug 27 2024
.KEY MESSAGES...
- Isolated to scattered severe thunderstorms are possible
Wednesday late afternoon through the evening across central
and parts of western North Dakota. The main hazards expected
are damaging wind gusts up to 70 mph and large hail up to the
size of golf balls.
- Breezy conditions are expected Wednesday as a cold front moves
through the area, with strong westerly winds on Thursday.
- Seasonably cool to near normal temperatures are forecast
through the holiday weekend, with a warming trend next week.
&&
.UPDATE...
Issued at 837 PM CDT Tue Aug 27 2024
The forecast remains on track.
UPDATE
Issued at 658 PM CDT Tue Aug 27 2024
Quiet weather is expected this evening. Remaining diurnal cu
will continue to dissipate over the next couple hours resulting
in clear skies tonight. Added patchy fog to far southwestern and
most of central ND late tonight into early Wednesday morning.
Confidence is lower in the southwest as winds become breezy
tonight. However, with light southeasterly winds further east,
confidence is higher in fog development.
&&
.DISCUSSION...
Issued at 327 PM CDT Tue Aug 27 2024
This afternoon, a closed low was moving through eastern North
Dakota, with two main areas of scattered showers around the
center of the low: one in northern Minnesota, and one in
southeast North Dakota. These will slowly drift east and
diminish through the remainder of the afternoon. Skies will
continue clearing from west to east as the low exits, with
mostly sunny skies across the west and central, except for some
shallow fair weather cu that has developed. A deep surface low
has already developed in central Alberta, with a tightening
pressure gradient leading to breezy southeasterly surface winds
in western North Dakota that will persist through the night
tonight, with otherwise quiet weather.
Our focus then turns to the potential for severe thunderstorms
on Wednesday, as a stout upper low is progged to approach from
the west, skirting the International Border. The previously
mentioned surface low and attendant cold front will move
through, with southwest flow aloft overspreading the front and
leading to the development of scattered showers and
thunderstorms, including potential for isolated to scattered
severe thunderstorms. Deterministic guidance is coming into a
stronger consensus on the timing of the cold front, with the
expectation it will be oriented north-south and placed somewhere
in central North Dakota around 00 UTC Wednesday evening. The 12
UTC HREF paints some modest max UH tracks across central North
Dakota, with the probability of severe thunderstorms much lower
across the west.
The expectation is that there will be a plume of strong
instability on the order of 2000-3000 J/kg ahead of the cold
front as moist, southerly low- level flow advects in dew points
in the 60s F. Bulk shear will be increasing as the afternoon
and evening progresses due to strengthening flow aloft, with
around 30 knots in the afternoon quickly becoming 40 to 50 knots
through the evening hours. Our current thought is that the
largest hail potential will be with any initial storms that
should be discrete due to upper flow being nearly perpendicular
to the frontal boundary. However, there is a relatively narrow
window of time before winds aloft become more southwesterly and
subsequently less perpendicular to the front, which would
promote a multicell/cluster storm mode, growing upscale along
the boundary. This would then shift the primary threat to wind,
with forecast DCAPE over 1000 J/kg and HRRR soundings
advertising 0-3km shear quickly increasing to 30-35 knots after
00 UTC as the upper low approaches.
With the increasing confidence in the overall setup as well as
a higher-end environment, we have bumped up our hazards to be
damaging winds up to 70 mph and large hail up to the size of
golf balls. There is certainly potential for hail to be larger
than golf ball size with any initial discrete storms, but we did
not want to widely message that threat since spatially it is
likely only a possibility for a relatively small area. We also
cannot rule out a tornado threat, with increasing low- level SRH
as well as the knowledge that a boundary will be around.
Forecast soundings are advertising modest curvature in the
bottom half of hodographs, so this will be something to keep an
eye on, especially in the short term once we see storms
developing. One other area of interest is a potent low-level
jet progged to develop over the James River Valley after 03
UTC, shifting east through the night. This will likely aid in
keeping shear elevated and convection going through the night,
with blended POPs at 60 to 80% for areas generally along Highway
83 and east Wednesday night.
In the post-frontal regime on Thursday, expecting strong
westerly winds, although the thought right now is that they will
stay just below advisory. Cooler air will also filter in,
leading to highs in the upper 60s to upper 70s. There could be a
few showers and non-severe thunderstorms under the cyclonic flow
aloft, with blended guidance advertising chances (30%) in the
northwest.
Broad ridging begins to expand across much of the western and
central CONUS for the holiday weekend, with another front moving
through late Saturday to bring cooler temperatures on Sunday.
Carrying a dry forecast for now although can`t rule out some hit
or miss showers at some point through the weekend. The trend is
for up and down but overall seasonable temperatures through
Labor Day, with warmer temperatures favored next work week.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 658 PM CDT Tue Aug 27 2024
VFR ceilings and visibility are generally expected through the
period with two exceptions. First, patchy fog may develop in the
far southwest into central and eastern ND tonight, with the best
chances in the James River Valley through the Turtle Mountains.
Though confidence isn`t high enough to include in any TAFs at
this time. Second, towards the end of the period, there is the
potential that a few thunderstorms will develop along a cold
frontal boundary with better chances after 00Z Thursday. Severe
storms are possible with large hail, erratic winds, and
significantly reduced visibility. Exactly where any storms
develop is always in question, though the best chances are along
and east of Highway 83. In addition to potential reductions in
visibility and thunderstorm activity, breezy southeasterly winds
are expected to expand from west to east across the state
tonight and into the day Wednesday, before becoming westerly as
the cold front moves through.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Telken
DISCUSSION...Jones
AVIATION...Telken
Area Forecast Discussion...UPDATED
National Weather Service El Paso Tx/Santa Teresa NM
540 PM MDT Tue Aug 27 2024
...New AVIATION...
.SYNOPSIS...
Issued at 130 PM MDT Tue Aug 27 2024
Daily shower and thunderstorm chances will continue with a
decrease in chances for next week. Temperatures will be near or
just below normal.
&&
.DISCUSSION...
Issued at 130 PM MDT Tue Aug 27 2024
The main monsoonal flow is centered across NM and far West Texas
with the subtropical ridge centered well to our east. There is
also a closed low over central TX, but other than helping steer
the monsoonal plume, it is not much of a player for our weather.
Convection is already underway across our mountains and eastern
lowland locations. Rich moisture is in place at the surface with
RAP analysis showing widespread 500-1500 J/kg of CAPE. The only
question is whether last night and this morning`s rains will limit
thunderstorm potential. The HRRR insists it will be a limiting
factor, largely keeping convection where it is now until later
this evening and tonight, and so far the cu field and radar agree.
Nevertheless, just about any where has at least a low chance for
additional rain in the next 12 hours or so.
Our pattern changes little for tomorrow except with modest height
falls at H500, suggesting some further mid-level cooling. The
ridge will begin to build to our north with a weakness trailing
across the Plains, back toward southern NM. This will keep
moisture in place along with subsequent rain and storm chances
through at least Friday. By this weekend, a weak cold front along
with some continental air will sweep through, but the Euro and GFS
show about 24 hour difference in timing with the GFS coming
through first Saturday morning. NBM still shows decent pops for
Saturday, but there is a steady decrease as we go into next week.
Drier air will continue to funnel in from the north and
northeast, slowly killing POPs. With that said, the GFS and Euro
disagree on how far south moisture will be suppressed. The Euro
has a stronger high, pushing the moisture well into Mexico. The
GFS keeps the moisture near the international border.
Temperatures will decrease through the weekend and into early next
week. NBM has temperatures below normal by Monday thanks to a cool
front. Temperatures begin to climb again for next week with a
faster climb expected if the high is as strong as the Euro
suggests.
&&
.AVIATION...
(00Z TAFS)
Issued at 533 PM MDT Tue Aug 27 2024
Widespread shwrs/tstms will persist through the early portion of
the TAF period, with the majority of activity favoring areas along
the Rio Grande Valley and wwd. Any direct hits to terminals may
create brief MVFR/IFR conditions due to reductions in cigs/vsbys.
Storms will be capable of sudden outflows, which will result in
wind shifts and gusts btwn 20 and 30 kts, as well as brief and lcl
heavy rainfall. Shwrs and isold tstms will diminish aft 28/06Z
but will return tomorrow aftn.
&&
.FIRE WEATHER...
Issued at 130 PM MDT Tue Aug 27 2024
Monsoon moisture is in place keeping rain and storm chances in the
picture. Min RH values will only drop to the upper 20s and lower
30s. Thunderstorm coverage will be greatest in the mountains with
scattered coverage in the lowlands. The cooler temperatures and
weak winds will result in poor to fair venting.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 73 94 73 95 / 30 40 40 20
Sierra Blanca 65 86 66 88 / 20 30 30 50
Las Cruces 68 90 67 93 / 40 50 50 20
Alamogordo 65 88 64 90 / 30 50 40 40
Cloudcroft 48 64 48 66 / 30 70 40 70
Truth or Consequences 65 85 64 89 / 40 70 40 30
Silver City 59 78 58 84 / 70 80 50 50
Deming 66 89 65 92 / 60 60 50 20
Lordsburg 65 87 64 90 / 70 80 50 20
West El Paso Metro 72 90 72 93 / 30 40 50 20
Dell City 67 92 68 93 / 10 30 20 40
Fort Hancock 70 93 69 95 / 20 40 40 40
Loma Linda 66 84 66 85 / 30 40 40 30
Fabens 70 92 69 93 / 30 40 40 20
Santa Teresa 69 89 69 91 / 40 40 50 20
White Sands HQ 70 89 70 91 / 40 50 40 30
Jornada Range 67 88 66 90 / 40 60 50 30
Hatch 66 89 65 93 / 50 60 50 30
Columbus 68 88 67 91 / 60 50 40 10
Orogrande 66 88 66 89 / 30 50 40 30
Mayhill 52 76 52 78 / 30 70 30 70
Mescalero 52 75 51 78 / 40 70 40 70
Timberon 52 75 51 77 / 30 60 40 60
Winston 54 75 51 82 / 50 80 40 40
Hillsboro 60 84 59 88 / 60 70 50 40
Spaceport 64 87 62 90 / 40 60 40 30
Lake Roberts 54 78 52 83 / 60 90 50 60
Hurley 60 83 59 87 / 60 80 40 30
Cliff 59 88 58 93 / 60 80 40 40
Mule Creek 61 82 59 86 / 60 90 40 30
Faywood 62 82 61 86 / 60 80 50 30
Animas 65 88 64 92 / 70 70 50 20
Hachita 64 86 63 90 / 70 60 50 20
Antelope Wells 64 87 64 90 / 70 60 40 20
Cloverdale 61 83 61 85 / 80 70 40 20
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...Flood Watch until 9 PM MDT this evening for NMZ414>416.
&&
$$
FORECASTER...40-Breitreiter
Area Forecast Discussion
National Weather Service Flagstaff AZ
804 PM MST Tue Aug 27 2024
.SYNOPSIS...Isolated to scattered showers and thunderstorms each
afternoon, mainly over the higher terrain. Near-normal
temperatures and mainly light winds are otherwise expected.
&&
.UPDATE...Showers and storms have largely diminished over the
region, with only a few isolated storms remaining over southern
Apache County. Some overnight activity may linger as outflows
from storm activity over southeastern Arizona help to sustain
some overnight activity. Anything that does develop overnight
should be minimal, but is still enough to maintain PoPs overnight.
Minor updates this evening for latest trends and guidance,
otherwise the previous forecast remains in good shape.
&&
.PREV DISCUSSION /414 PM MST/...Showers and thunderstorms have
progressed further north and westward today over Northern Gila
County, Eastern Mogollon Rim, and White Mountains. The trend of
increasing moisture north and westward will continue this week.
This will bring low to moderate grade monsoon activity over
northern Arizona.
The HRRR is showing some convection developing late tonight and
early Wednesday morning over western parts of our CWA. Have
included low PoPs over parts of Yavapai and Coconino counties for
those time periods. The increase in moisture looks to last
through around Saturday before decreasing again Sunday as the high
becomes centered over the Great Basin. A low grade monsoon then
continues into next week.
&&
.AVIATION...Wednesday 28/00Z through Thursday 29/00Z...Mainly VFR
conditions with daytime winds W 5-10 kts. Slight chance for MVFR
conditions and some gusty winds near ISO -SHRA/-TSRA after 19Z.
OUTLOOK...Thursday 29/00Z through Saturday 31/00Z...Mainly VFR
conditions, with W/NW winds 5-10 kts on Thursday, becoming VRB on
Friday. Slight chance for MVFR conditions and some gusty winds
near ISO -SHRA/-TSRA each afternoon.
&&
.FIRE WEATHER...Wednesday and Thursday...Chance for isolated showers
and thunderstorms each afternoon, mainly in the higher terrain along
and south of the Mogollon Rim. Gusty, erratic winds and brief heavy
downpours expected around storms. Otherwise, generally light westerly
winds each afternoon with near-normal temperatures.
Friday through Sunday...Chances for isolated showers and thunderstorms
each afternoon, with the greatest chances over the higher terrain.
Near-normal temperatures with mainly light and variable winds.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
PUBLIC...Humphreys/MAS
AVIATION...Humphreys
FIRE WEATHER...Humphreys
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Green Bay WI
1100 PM CDT Tue Aug 27 2024
Updated aviation portion for 06Z TAF issuance
.UPDATE...
Issued at 930 PM CDT Tue Aug 27 2024
Cold front has cleared the area and the threat for strong storms
has ended. Just have a slight chance for storms next few hours.
Otherwise, there may be a few showers into the overnight in wake
of the front and the going forecast had this covered well. May
even see some patchy drizzle over the north with upslope flow. At
the least, expect low clouds and fog to expand overnight behind
the front. At this time, any fog is not expected to become dense.
Expect winds to shift northerly the rest of tonight. These winds
will become a bit breezy late tonight through Wednesday, especially
on the Bay and Lake Michigan. A Small Craft Advisory was issued
earlier for the lake for stronger winds and higher waves, while
small craft should exercise caution on the bay due to the elevated
winds and choppy conditions.
&&
.KEY MESSAGES...
- Threat for strong thunderstorms has ended. A few showers into
the overnight as cold front exits to the southeast.
- Cooler and less humid air arrives tonight into Wednesday.
- A round of showers and thunderstorms is expected late Thursday
into Friday. Locally heavy rainfall, over an inch, will be
possible, especially across central WI.
&&
.DISCUSSION...
Issued at 419 PM CDT Tue Aug 27 2024
Short Term...Tonight and Wednesday
Focus concerns revolve around precipitation trends for the rest of
the afternoon and overnight. Current radar imagery show showers
have developed in parts of southwest Wisconsin, and a few pixels
of reflectivity are starting to show up in north-central
Wisconsin. CAMs have not been great at handling the evolution of
rain/storms today, with the HRRR probably the most responsive to
the current situation. Will loosely follow the HRRR through today,
while also taking into account other models and the environment.
Instability briefly waned following the morning convection, but
sunshine has helped warm the boundary layer and boost instability
this afternoon, with both SBCAPE and MUCAPEs up to 1600 J/kg in
central WI as of 21Z. As the activity currently in SW WI
continues tracking northeast there is potential for some storms to
develop. However, soundings show a decent cap around 900mb which
may be too much to overcome. Additionally, the HRRR/other CAMs
don`t make much out of this. Continue to carry low-end PoPs (~20%)
in central and east- central WI through this evening, but
confidence of anything more than some showers is low. If a storm
does manage to break through the cap, strong or severe storms will
be possible with strong winds the main threat.
Farther north, instability is lower, in the 200-1000 J/kg range,
but the atmosphere has not been worked over here and there is not
a hindering cap. There is also more broad lift due to the
proximity to the RRQ of an upper jet and 500 mb shortwave. CAMs
are in some agreement showing scattered shower/thunderstorm
develop here in the late afternoon and evening, and then winding
down overnight. Slightly more confident in something developing in
the north this evening, by less confident on the extent of the
coverage. Given the parameters, severe storms are not as likely
across the north.
Tonight, patchy fog development is likely given today`s precip and
lingering humidity, especially from central into east-central
Wisconsin. Lows will range from the mid 50s to mid 60s.
Wednesday, a few showers may linger across Door County in the
early morning, otherwise, mostly cloudy skies are expected.
Temperatures will be cooler ranging from the upper 60s in the
Northwoods and northern Door County, to the middle 70s in central
Wisconsin and the Fox Valley. Humidity will be lower as well.
Long Term...Wednesday Night Through Tuesday
Main focus will be on the next round of showers and storms late
Thursday into Friday. Temps look to remain at or a little above
normal Thursday through Saturday, then cooler air is forecast to
spread into the region.
Models in decent agreement bringing an upper low across southern
Canada late in the week, with a shortwave trough and frontal
boundary swinging across the western Great Lakes late Thursday
into Friday morning. This will produce a widespread area of
showers and storms, most likely in the 7pm Thursday to 7am Friday
timeframe. With the current timing, instability would be held in
check across the area, plus a forecasted capping inversion in
place, keeping severe chances on the low side. But we will need
to monitor if any upstream convection can remain organized enough
to sneak into our area. Heavy rain will be a threat as PWATs climb
to 1.5 to 2.0". Rain totals of 0.50-1.50" are looking likely for
most spots, with some locally higher amounts possible.
Dry weather returns behind the front Friday afternoon into most of
Saturday, then another shortwave is forecast to drop down from
Canada, bringing a chance for showers and storms late in the
weekend. Sprawling high pressure is then forecast to spread
across the Great Lakes early next week, bringing dry and quiet
conditions.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1055 PM CDT Tue Aug 27 2024
Cold front has worked southeast of WI. There could still be a few
showers or even some patchy drizzle over northern WI, but the
threat for storms has ended. Expect VFR cigs to deteriorate to
LIFR/IFR at all TAF sites the rest of the night with visibility
more in the MVFR or perhaps IFR range.
A murky morning is then expected on Wednesday as a brief airmass
change takes place. Plan on mainly IFR cigs to grudgingly lift to
lower MVFR by early afternoon as visibility improves to VFR. Cigs
will improve to high-end MVFR or low-end VFR, but it will take
until late in the day. Even with as winds shift to the north-
northeast behind the cold front, they are not expected to be much
higher than 10 kts. However, some gusts of 15-20 kts are possible
at times on Wednesday, especially at GRB due to stronger channeling
flow downstream of Bay of Green Bay.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.........JLA
DISCUSSION.....KLJ/Bersch
AVIATION.......JLA
Area Forecast Discussion
National Weather Service Grand Rapids MI
951 PM EDT Tue Aug 27 2024
.KEY MESSAGES...
- Strong to Severe Storms into this Evening
- More Storms on Friday
- Dry and Cool Labor Day Weekend
&&
.UPDATE...
Issued at 951 PM EDT Tue Aug 27 2024
As noted in the AVIATION section of this discussion, we have
spotty chances for precipitation the rest of the night. The 23Z
and 00Z runs of the HRRR seem to have a good handle on the evolution
of storms that formed near Chicago and then took a right turn
into the far SE Lake Michigan lakeshore. Extending southwest from
these storms is a nearly continuous line of additional
thunderstorms reaching all the way into northern Missouri. HRRR
guidance suggests gradual weakening of this upstream convection as
it eases northeast towards far SW Lower Michigan overnight. Some
storms would therefore still be possible from around the I-94
corridor southward in the early morning hours. It should be noted
however that model predictability with thunderstorm timing and
placement as of late has been extremely poor; hence, we should not
necessarily expect any sudden forecast clarity in the overnight
hours.
As also noted in the AVIATION section, we will have to watch for
areas of dense fog, particularly farther north towards US-10.
&&
.DISCUSSION...
Issued at 256 PM EDT Tue Aug 27 2024
- Strong to Severe Storms into this Evening
Strong theta-e advection today is adding to the very moist air
mass already in place across Lower Michigan. The capping inversion
has eroded across the northern half of the forecast area with
strong to severe storms now moving through. The main threat
through this evening remains along and north of I-96, while severe
threat continues to be limited near I-94 corridor by the capping
inversion/warm mid-level temperatures.
Lack of shear should limit tornado threat but D-CAPE is sufficient
for strong downburst winds, which are the main threat along with
large hail in the isolated strong, persistent updrafts. The
storms move east and out of the forecast area early this evening
with scattered storms still possible along various outflow
boundaries.
- More Storms on Friday
The convective action shifts south on Wednesday and Thursday with
the outflow boundary-reinforced cold front stalling south of
Lower Michigan, then gradually moving north as a warm front
Thursday night into Friday. The cold front advances east into
Lower Michigan by Friday afternoon with a final round of strong
to severe storms possible.
- Dry and Cool Labor Day Weekend
The frontal passage on Friday will usher in a much cooler and
drier airmass with dew points plunging into the 40s by early next
week. High pressure building over the central Great Lakes Sunday
into Monday will mean fair weather with comfortable temperatures.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 744 PM EDT Tue Aug 27 2024
Thunderstorms this afternoon and evening have provided a temporary
break from additional precipitation in the short term. We do see
storms in the Chicago vicinity but those appear to be rooted to a
surface boundary and are moving little. Model guidance suggests a
smattering of thunderstorms possible overnight, possibly
associated with activity noted even farther upstream in the IL/IA
vicinity. However, given marginal probability and large
positional uncertainty with any such activity, am reluctant to
introduce even VCTS at this time.
What appears more certain is growing MVFR/IFR fog potential after
midnight given light winds and a wet ground coupled with a very
humid airmass. Dense fog is not out of the question farther north
towards US-10 whereas the terminals to the south (from I-96
southward) have a good shot at at least IFR ceiling restrictions
towards sunrise Wednesday.
&&
.MARINE...
Issued at 256 PM EDT Tue Aug 27 2024
Strong thunderstorms moving across the Lake this afternoon with
winds gusting over 40 knots then scattered showers overnight. More
thunderstorms with strong gusty winds are expected on Friday.
Otherwise, winds and waves should be generally light with winds
below 20 knots and waves 3 feet or less into the weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ050-056-057-
064-071.
MARINE...None.
&&
$$
UPDATE...TJT
DISCUSSION...Ostuno
AVIATION...TJT
MARINE...Ostuno/Ceru
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
819 PM CDT Tue Aug 27 2024
.KEY MESSAGES...
- Scattered thunderstorms will remain a threat into the night,
most widespread this evening west of the Illinois River. Intense
lightning, scattered large hail, and localized heavy rain are
all expected.
- While the heat headlines have been allowed to expire, potential
will exist for another advisory on Wednesday, depending on where
the outflow from the overnight storms ends up.
&&
.MESOSCALE...
Issued at 819 PM CDT Tue Aug 27 2024
Heat headlines were allowed to expire on schedule. As of 8 pm, a
few areas west of I-55 still have a heat index near 100 degrees,
though oppressive dew points in the 80 degree vicinity continue.
Despite CAPE values topping out over 7,000 J/kg, a large part of
the forecast area has escaped the storms thus far. An MCS has
developed near and west of the Mississippi River, with an isolated
supercell riding across the Chicago metro. However, over the last
couple hours, storms have been expanding in an area from west of
Macomb to near La Salle. Radar estimates of rainfall are around
1.5 inches in parts of Knox and Stark Counties, due to storm
movement less than 10 mph. High-res models continue to struggle
somewhat with the storm evolution, though the HRRR is doing a
little better as of late, with the greatest storm concentration
north of a Macomb-Danville line through midnight. Storms have been
a profuse lightning producer, with current rates around 300
strikes per 15 minutes in Knox and Stark Counties. The recent SPC
Day1 update has pushed the level 2 risk south to Springfield,
where there remains a subtle boundary from earlier today. RAP
guidance keeps the instability quite robust past midnight (MLCAPE
values still over 4000 J/kg at 2 am north of I-72), so storms that
do manage to form and linger will still have some oomph.
Geelhart
&&
.SHORT TERM...(Tonight through Wednesday)
Issued at 255 PM CDT Tue Aug 27 2024
19z/2pm surface analysis shows high pressure anchored over the
Southeast U.S. while a cold front extends from western Wisconsin
southwestward into Nebraska. Very hot and humid conditions are in
place across central Illinois as evidenced by heat index readings
at or above 110 degrees along/north of a Jacksonville to Lincoln
line. The oppressive heat will continue through early evening
before the heat index gradually drops below 90 degrees by 10pm.
CAMs continue to show at least widely scattered convection
developing ahead of the slowly approaching cold front: however,
areal coverage varies greatly among the different models. The HRRR
has been consistently on the dry side...while other models such as
the Fv3 and HRW NSSL are much more bullish with thunderstorm
development. Latest visible satellite is largely clear across
eastern Missouri/Iowa: however, a couple of towering Cu are
percolating south of KUIN/KIRK as well as south of the Saint Louis
metro. Think this trend will continue over the next few hours,
with widely scattered thunderstorms spreading into the Illinois
River Valley after 8pm. Think areal coverage will be greatest
along/north of I-72 where 30-40 PoPs are warranted. While
instability parameters are initially extreme with SBCAPEs in
excess of 4000J/kg, deep-layer shear remains less than 20kt.
Greater shear will focus further N/NW across central/northern Iowa
into far northern Illinois and southern Wisconsin tonight where
severe weather probabilities are considerably greater. Further
south across the KILX CWA, think a few of the stronger cells may
produce scattered damaging wind gusts north of the I-72 corridor
after 8pm.
The exact extent of convection tonight will set the stage for what
happens Wednesday afternoon/evening. Most solutions are suggesting
that outflow from storms either across central Illinois or just
off to the N/NW tonight will drop southward into the area on
Wednesday. How far S/SE this effective boundary settles remains
somewhat in question: however, several CAMs suggest it may be
between I-72 and I-70. While the most favorable instability/shear
parameters overlap further downstream across northern/central
Ohio, a lesser severe weather risk will develop across the E/SE
CWA along the boundary...with scattered damaging wind gusts and
large hail possible by late afternoon and evening. Given the
expected position of the outflow boundary and the likely presence
of SCT-BKN cloud cover, temperatures will be held down considerably.
In fact, am expecting highs mostly in the upper 80s and lower
90s...with middle 90s confined to locations along/south of I-70
where a Heat Advisory may be needed if current trends continue.
Barnes
.LONG TERM...(Thursday through Next Tuesday)
Issued at 255 PM CDT Tue Aug 27 2024
Low chance PoPs will continue on Thursday as the boundary becomes
stationary across central Illinois: however, the strongest forcing
and deepest shear will be focused further northwest across
Minnesota/Iowa ahead of the next approaching cold front. That
particular front will push through central Illinois on Friday,
setting the stage for another round of potentially strong to
severe convection across the E/SE CWA during the afternoon and
evening. Once the front passes, a major pattern change will bring
much cooler air into the region this weekend into early next week.
High temperatures will drop into the lower to middle 80s on
Saturday...then even further into the middle 70s by Monday.
Overnight lows will initially be in the upper 50s/lower 60s, but
will dip into the lower 50s by Monday night as Canadian high
pressure builds into the Midwest.
Barnes
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 615 PM CDT Tue Aug 27 2024
Challenging aviation forecast due to potential for thunderstorms,
but timing remains somewhat uncertain. In the short term, KPIA
appears most likely to see activity early this evening, but have
included about a 4-hour window for VCTS at the remaining sites mid
to late evening and past 06Z. Can`t rule out thunder lingering as
late as about 10Z, though there is more uncertainty in this time
frame. Depending on where various boundaries settle, scattered
convection will be possible again later in the day Wednesday.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
745 PM EDT Tue Aug 27 2024
.KEY MESSAGES...
- Showers and some thunderstorms tonight, mainly during the
evening. Severe storm risk continues to diminish.
- High swim risk for the Lake Superior beaches of Marquette
County on Wednesday.
- Another round of showers and storms Thursday night and Friday
morning. For now, severe storms are not expected.
- Cooler, less humid conditions settling into Upper MI tonight
and Wednesday. Temperatures then seasonable through early next
week, though a breezy, cool day is expected on Sunday.
&&
.DISCUSSION...
Issued at 451 PM EDT Tue Aug 27 2024
Medium range models are in good agreement on the large scale flow
changes that will occur thru early next week. Mid-level trof that
has moved onshore over BC/Pacific NW will lead the development of an
eastern N America trof over the Labor Day holiday weekend. As that
western trof reaches Hudson Bay to the Upper Great Lakes Fri/Sat,
building ridge upstream over western N America will force another
shortwave to dive se thru s central Canada, leading to the initial
trof amplifying over eastern N America during Sun and Labor Day. The
eastern N America trof then quickly lifts out to the ne by midweek
as mid-level height rises/positive height anomalies rapidly spread e
across the southern half of Canada, setting up low amplitude/nearly
zonal flow across the southern half of Canada for the last half of
the week. For Upper MI, this evolution of the flow will support a
cool day on Wed in the wake of passing cold front today, then
warming to above normal Thu ahead of the aforementioned approaching
trof. Cooling will initially be limited Fri/Sat in the wake of the
associated passing cold front. Passage of second shortwave and
amplification of mid-level troffing will support much sharper
cooling on Sun. Warming will return by midweek as low
amplitude/nearly zonal flow quickly spreads across southern Canada.
Temps for the last half of next week should run at least 5F above
normal. As for pcpn, passage of cold front and transition to cooler
conditions for Wed will bring drier weather that lingers into Thu.
Approach of the aforementioned trof and passage of its associated
cold front will bring shra/tsra back to Upper MI from w to e Thu
night/Fri morning. Dry weather returns w to e on Fri with dry
weather lingering into Sat. Cold front associated with second
shortwave that amplifies eastern troffing will then bring another
bout of shra Sat night, but there are some timing issues as would be
expected at that time range. Shot of cool air may support some lake
effect -shra on Sun under cool nw low-level flow. Next week then
overall looks on the dry side under low amplitude flow across
southern Canada, or at least no significant or widespread rains
appear in the offing. Onset of waa early next week as eastern trof
lifts out may offer a schc, less than 20pct chc, of some shra
sometime in the Tue/Wed time frame.
Tonight/Wed, shortwave is currently over the eastern Dakotas per
water vapor imagery and RAP analysis. Due to height rises being
forced downstream by the much stronger shortwave trof progressing
eastward from the Pacific NW/sw Canada, this wave will rapidly
deamplify/weaken as it continues eastward. Although the wave is
weakening and although cold front will be settling s of the area in
the next few hrs, the wave will provide forcing for additional shra
and some tsra to develop as instability lingers above
cooling/increasingly stable sfc-based layer. Any storms that develop
will become elevated, posing less of a svr risk. A few -shra may
linger Wed morning over the se fcst area. Otherwise,
elongating/weakening wave will progress over Upper MI on Wed, but
under a now stable air mass over the area, will opt for a dry day
after any early -shra se. It will be notably cooler in the wake of
the cold front. Expect min temps tonight mostly in the 50s to lwr
60s F. Under low-level ne flow on Wed, highs will range thru the 60s
F. A few spots may top 70F farther away from flow off of the Lakes.
The ne winds and resulting waves on Lake Superior will support a
high swim risk for the beaches of Marquette County on Wed.
With sfc high pres centered to the ne of Lake Superior, it won`t be
an ideal radiational cooling night Wed night. In addition,
precipitable water only falls back to about 80-100pct of normal, so
not a really dry air mass either to aid cooling. Favored a middle
ground approach for mins, ranging mostly from the mid 40s to mid 50s
F. As becomes typical at this time of year, there is some concern
for stratus to develop off of the Great Lakes as higher dwpt marine
layer air advects into radiational cooled interior where temps are
lower than the dwpt of the marine layer air. With winds becoming se,
late night/morning stratus may develop into central Upper MI.
On Thu, vigorous shortwave trof now over the Pacific NW/sw Canada
will move out across the Canadian Prairies and the Dakotas.
Associated cold front will approach Lake Superior by evening. Front
should be far enough to the w to allow dry weather to prevail across
w and central Upper MI on Thu. Fcst will hold off any pcpn mention
over far western Upper MI until near 00z. Shra and some tsra will
then progress w to e across the area Thu night/Fri morning. Fcst
soundings and time of day suggests that we`re probably looking at
elevated convection. With estimated effective deep layer shear under
30kt, svr storm risk appears minimal for now. Shra/tsra will depart
w to e late Thu night thru Fri morning. Pcpn should exit Luce county
around noon on Fri. Sharp post-frontal column drying will support a
quick trend to mostly sunny skies on Fri, and with limited initial
caa, temps will rise thru the 70s, topping out at around 80F where
westerly winds downslope.
A similarly warm day is anticipated on Sat ahead of the next cold
front dropping se toward the area. Sct -shra associated with that
front should occur Sat night. A breezy, cool day will follow on Sun.
With median 850mb temps from the ensembles falling into the 4-6C
range, isold/sct lake effect -shra off of Lake Superior are a
possibility under the cool nw flow. Expect highs in the 60s F.
Dry weather is currently expected on Mon/Tue. If the high pres
dropping se out of Canada behind the Sun shortwave ends up over
Upper MI Sun night or Mon night, would expect a chilly night with
some frost potential in the interior.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 744 PM EDT Tue Aug 27 2024
Moist northeasterly flow will keep low cigs around for most if not
all of the night tonight. Latest model consensus suggests that SAW
will hold at IFR, with MVFR favored at CMX/IWD. At SAW, LAMP/HREF
guidance suggests there is about a 25% probability of LIFR cigs and
perhaps IFR or lower vsby with lake-induced fog/drizzle blowing in
through about 12Z. Included a TEMPO through 02Z for conditions below
airport mins as the first bout of fog/drizzle appears to be blowing
in. Also, nonzero probabilities of brief IFR cigs at IWD and MVFR at
CMX in roughly the 09-15Z range. Cigs will gradually rise during the
daylight hours on Wednesday as drier air and diurnal heating take
effect.
&&
.MARINE...
Issued at 451 PM EDT Tue Aug 27 2024
In the wake of passing cold front and ahead of high pres centered
just sw of Hudson Bay, ne winds have kicked up, gusting to as high
as 25-30kt across w and central Lake Superior. As the high settles
into northern Ontario tonight, ne winds will continue to gust into
the 20-30kt range across much of the lake. While gusts will settle
back to under 20kt across the e half of Lake Superior on Wed, gusts
up to around 25kt will continue across the w. With a little closer
approach of the high Wed night, expect winds to fall under 20kt
lakewide as they veer to the se. A cold front tied to deepening low
pres heading ne toward Hudson Bay will approach by Thu evening. This
front will then pass across Lake Superior Thu night/Fri morning.
Expect se to s winds to increase Thu aftn/evening with gusts to 25-
30kt. Winds will swing around to the wsw behind the front for Fri.
These wsw winds will be strongest, gusting to around 30kt, across
western Lake Superior. Winds diminish slightly Fri night/Sat, but
still gusting to around 25kt over western Lake Superior and to
around 20kt over eastern Lake Superior. Another cold front will
sweep se across Lake Superior Sat night. A cool air mass following
the front will lead to better mixing of higher winds down to the
lake sfc for Sun. Early indications point to a 30-50pct chance of nw
gale gusts across central and eastern Lake Superior on Sun,
especially during the morning.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 10 PM EDT this evening for
MIZ005-006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
DISCUSSION...Rolfson
AVIATION...Thompson
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Omaha/Valley NE
1101 PM CDT Tue Aug 27 2024
.KEY MESSAGES...
- There is a 20-40% chance of storms and a 5% chance of a severe
storm along and south of I-80 into this evening. Hail and
damaging winds are the primary threats.
- There is another chance (60-80%) for thunderstorms on
Thursday, with potential for a few stronger storms.
- Following the storms Thursday, expect cooler temperatures
heading into the weekend into early next week (70s and 80s).
&&
.DISCUSSION...
Issued at 355 PM CDT Tue Aug 27 2024
Mid-afternoon analysis showed a surface boundary draped west to
east across the area with ongoing spotty showers and a few
isolated storms perking up at times throughout the day. Farther
south into KS, some stronger storms were starting to fire and
should continue to expand in coverage, possibly into far
southeast NE as we go through the evening. There remains quite a
bit of spread in short term guidance as to just how far north
they expand, with guidance such as the 27.19Z HRRR suggesting
they largely remain in KS and MO, while the 27.18Z NAMNest
brings storms as far north as Lincoln. As far as environment
goes, shear remains rather weak, though instability is decent,
with latest SPC objective mesoanalysis showing 2000-3000 J/kg of
MUCAPE across southeast NE. So should storms move into that
area, a few could produce severe hail. In addition, model
soundings show an inverted V in the low levels, indicating at
least some potential for downbursts/damaging winds. All in all,
there`s about a 20-40% chance that storms get into that area and
a 5% chance of severe storms.
A few spotty storms could linger into the early morning on
Wednesday on the nose of some weak low level moisture transport.
Also can`t rule out some patchy fog in areas that are able to
clear out overnight. Otherwise, the rest of Wednesday should be
fairly quiet and seasonably warm and muggy with highs in the
upper 80s to mid 90s and perhaps a few locations touching 100
heat indices.
By Wednesday night into Thursday morning, guidance is in good
agreement that a cutoff low will be moving along the US/Canada
border with an attendant cold front pushing into western/central
NE. In addition, low level moisture transport will be pointing
toward northeast NE, which could lead to some additional shower
and storm development Thursday morning. Southerly flow ahead of
the front will continue to usher in warm, moist air during the
day, but a more southwesterly component in our area will
somewhat limit things (as will persistent cloud cover/showers)
and keep the greatest instability to our east. Shear will once
again be weak, which should limit our severe weather threat, but
still can`t rule out a few stronger to isolated severe storms
Thursday afternoon and evening, with some precip lingering into
Friday.
Once that front and precip exit, we`ll remain under northwest
flow aloft and while guidance suggests some weak shortwave
energy sliding through, we should largely remain dry (and
cooler) heading into the weekend, especially by Sunday as
surface high pressure starts to push in. Expect highs Friday and
Saturday mostly in the lower to mid 80s, followed by widespread
70s (and maybe even upper 60s) Sunday into early next week.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1056 PM CDT Tue Aug 27 2024
Shower and storm activity has shifted from near KLNK to east of
KOMA, with the expectation that these storms stay outside of its
vicinity before dissipating by 07z. Signals for overnight low
clouds have weakened somewhat, with the best chances for lower
status and areas of mist being east of KOFK and north of KOMA,
though other locations may set FEW to SCT at FL010 from 11-15z.
Winds will become southeasterly through the morning and
increase in speed to over 10 kts through most of the
afternoon/early evening at KOFK while weaker winds stay in place
at KOMA/KLNK.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
DISCUSSION...CA
AVIATION...Petersen
Area Forecast Discussion
National Weather Service New York NY
1049 PM EDT Tue Aug 27 2024
.SYNOPSIS...
High pressure moves offshore tonight with a cold front sliding
through on Wednesday. High pressure will then build down from the
north Thursday into Friday. A frontal system will affect the area
for the weekend, with Canadian high pressure building in for
early next week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
The forecast is on track with only minor changes needed.
After a clear start, clouds are predicted via NWP to move into
the region later at night, especially for the western half of
the area. The night is expected to be primarily dry, although a
vort induced shortwave (associated with convection across
Central NY/PA could fire up a few showers later at night into
early Wednesday morning across the area. It will be humid and
seasonably warm with not much of a temperature spread across the
region with dew point readings in the upper half of the 60s on
a light S to SW synoptic flow. Night time lows are expected to
range from the upper half of the 60s to the lower 70s.
For Wednesday things have changed from previous forecast
cycles. The CAMs do not look nearly as impressive with respect
to shower and convective activity. After looking at various
forecast cycles there is a warm layer at 5 to 12 kft which
assists in capping things some. It will take more effort to get
parcels to the level of free convection (LFC). Thus the CAMS are
hinting at reflectivity but have difficulty in getting any
meaningful convection to fire across the CWA. One could argue
that the NSSL, and NAM make the best attempt, and perhaps the
HRRR as well. The HRRR on most of its recent runs has suggested
that convection gets going just south of the CWA. After
collaboration with SPC, the region is now in mainly a marginal
risk of severe weather on Wednesday, with is a downgrade
previously from a slight risk. If a couple of storms do form,
they will be capable of some strong gusty winds, but this looks
like a low likelihood relatively speaking from earlier.
Regarding temperatures on Wednesday the cold front appears to
be getting a bit more of a quicker push to the SE. The upper
level disturbance also appears to get sheared in the guidance.
Thus there appears to be more of a westerly component to the
flow towards later morning into the early afternoon. This would
serve to mix out things a bit more and lead to slightly lower
dew point readings. Heat indices will likely range from the mid
to upper 90s, and technically this is a tad below heat advisory
criteria (the one day criteria). But it appears to be close
enough to at least leave the heat advisory up for now and
continue it for the same zones that were issued previously. In
any event, it is going to be hot and humid so keeping with the
same messaging in products.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
For Wednesday night the flow quickly goes northerly during the
late evening, and then northeast after 6z. Dew point readings
drop into the middle and upper 50s up north, and the lower and
middle 60s elsewhere, thus it begins to feel more comfortable
going into Thursday morning with low temperatures primarily
getting through the 60s.
A few showers post frontal may attempt to get into western
sections periodically late Wednesday night and during Thursday.
The lower levels dry out quite a lot, but cannot rule out a few
sprinkles of a quick shower mainly for western sections during
this timeframe. Otherwise expect partly to variably cloudy skies
and much more comfortable conditions with temperatures likely
getting to about 5 degrees below average for the day Thursday.
Daytime highs will be in the middle and upper 70s for the most
part.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Good model agreement in weak shortwave troughing over the
northeast US moving east Thu Night into Friday, with shortwave
upper ridging briefly building in Friday into Fri Night. Rest of
forecast period will be influenced by an expanding central
Canadian trough, centered around closed upper low spinning
through northern Ontario/Quebec Friday thru Monday. Troughing
will amplify across the NE Sat thru Mon as a couple of shortwave
troughs slide through the region. Model spread in shortwave
timing increases a bit towards the end of the period, but
overall fairly good agreement.
At the surface, Canadian high pressure centered over northern
New England Thu Night, gradually slides east through Friday
Night. The result will be a maritime Canadian airmass advecting
into the region on persistent ENE flow. Onshore flow under
subsidence/waa inversion aloft may result in stratus development
and a few showers particularly across western areas into Friday
morning, before deep layered ridging strengthens. Temps will
run slightly below seasonable.
Weak lead shortwave approaches Sat and crosses Sat night with
associated pre-frontal trough approaching Sat aft/eve, and crossing
Sat Night. Good moisture advection and warm rain process ahead of
the trough (PWATS +2 std), with weak/elevated instability. Combined
with strengthening synoptic lift, this should present the potential
for scattered to numerous showers and isolated tstm threat late
Sat/Sat eve, translating east Sat night. Temps moderating to near
seasonable on Saturday with increase humidity levels.
Main upper trough axis approaches Sun/Sun Night, with pre-frontal
trough sliding east and cold front approaching. Potential for
isolated to scattered showers/thunderstorm activity, but
considerable cloud cover and best moisture/llj axis potentially
moving east, could mute activity. Temps slightly above seasonable
with Tds in upper 60s/lower 70s.
Trough axis slides overhead Monday and east Monday Night, with cold
front passing east Sunday Night into Monday morning. Drying
conditions Monday on NW flow as Canadian high pressure builds from
the NW. Sct-bkn instability cu and a few showers possible,
particularly across interior Mon aft. Temps nears seasonable.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
VFR with high pressure in control through this evening. A cold front
begins approaching tonight and moves across the area on Wednesday.
S-SE winds less than 10 kt this evening and first half of tonight.
Some terminals in the city may see gusts of around 15 kt
through 01Z, but winds should generally diminish this evening
before gradually increasing and becoming SW towards day break
Wednesday. SW winds around 10 kt are expected in the morning,
but will shift to the W and then NW into the afternoon. NW winds
10-15 kt with gusts up to 20 kt expected in the afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected overnight.
A shower is possible Wednesday morning. There is also a low
probability of a shower/thunderstorm Wednesday evening, but
confidence is too low to include in TAF at this time.
OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
Wednesday night: VFR.
Thursday: Mainly VFR. Slight chance of an afternoon/evening
showers/thunderstorm north and west of the NYC terminals.
Friday: VFR.
Saturday: Chance of showers, possible thunderstorms and MVFR or
lower.
Sunday: Mainly VFR. Chance of a shower/thunderstorm, mainly in the
afternoon and evening.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
A SW flow prevails through tonight with ocean seas up to 3 ft.
Ocean seas nudge up a bit closer to 4 ft for the eastern ocean
by Wednesday afternoon with a cold front approaching and moving
through the waters later in the day. There may be a brief period
of small craft gusts Wednesday afternoon for the eastern most
ocean water s. The winds do switch to the W on Wednesday, then
quickly to the NW, N, and NE through Wednesday night.
By early Thursday morning a period of marginal small craft wind
gusts are possible for the southern near shore and ocean waters
via a tightening NE flow. Small craft, or at least marginal
small craft conditions will remain possible for the ocean waters
through much of the day Thursday with gusts 20-25 kt and
easterly wind waves of 4-6 ft seas. Have leaned towards WNA
guidance over NWPS guidance based on historical performance
during warm season E/NE flow events.
Marginal SCA seas likely on the ocean Thursday night with 15g20kt
E/NE winds flow. Winds and seas gradually subside on Friday, with a
weak pressure gradient keeping all waters below SCA criteria Friday
night this weekend.
&&
.HYDROLOGY...
No hydrological impacts are anticipated during Wednesday with any
storms that do form being widely scattered to isolated, and will
also move along quickly. Any hydro impacts towards the weekend
towards Saturday appear minimal at this time.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip currents on Wednesday as southerly
winds wave build to 3 ft, combined with a lingering 1 ft se swell.
Moderate to high rip/longshore current risk (rip current risk will
be enhanced especially along jetties and groins) Thursday with a
strong e to w sweep of 2 to 4 ft surf.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NYZ069>075-
176>178.
NJ...Heat Advisory from 11 AM to 8 PM EDT Wednesday for NJZ004-006-
103>108.
MARINE...None.
&&
$$
SYNOPSIS...JE/NV
NEAR TERM...JE/JP/NV
SHORT TERM...JE
LONG TERM...NV
AVIATION...JP
MARINE...JE/NV
HYDROLOGY...JE/NV
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Tucson AZ
200 PM MST Tue Aug 27 2024
.SYNOPSIS...Scattered mainly afternoon and evening showers and
thunderstorms will continue through Wednesday. Thereafter, a
decrease in coverage will take place late in the week and over
the weekend with isolated to scattered showers and thunderstorms
mainly south and east of Tucson. High temperatures will be within
a couple of degrees of normal through the weekend.
&&
.DISCUSSION...Weak southerly to southeasterly mid to upper level
flow this afternoon between broad eastern Pacific troughiness and a
weak high over New Mexico. Adequate moisture across much of our
forecast area with PWAT values around 1 inch to 1.2 inch to result
in scattered showers and thunderstorms. We`re already seeing that
early this afternoon mainly from the Tucson area and points
eastward. The storms haven`t been too strong today but with SBCAPE
values around 500 to 1000 J/KG and DCAPE values around 1000 J/KG,
we can still manage a strong thunderstorm or two this afternoon.
Main concerns will be locally heavy rainfall due to the slow moving
nature of the thunderstorms along with gusty winds. Some of the CAMs
including the latest HRRR are depicting that the storms over the
White Mountains will push outflow towards the southwest later this
afternoon, which combined with the local storms already forming to
the east of Tucson may result in more clustering of thunderstorms
this evening across Graham/Greenlee/Cochise Counties. Confidence on
this is a bit low but certainly a possibility that some thunderstorm
activity will persist later into the evening hours than usual,
especially out east.
Wednesday will have similar moisture levels to what we are seeing
today which is certainly enough to support scattered showers and
thunderstorms once again mainly from the Tucson area south and
eastward. We`ll have to wait and see just how much cloud cover from
any complexes tonight persist into Wednesday before having a better
handle on specifics.
Starting Thursday and heading into the weekend, the atmosphere dries
out slightly with just some recycling moisture. With PWAT values
down around 1 inch, the best chances for isolated to scattered
showers and thunderstorms will be to the south and east of Tucson.
Ensembles are showing a broad high rebuilding aloft early next week
across Arizona. Still some uncertainty in the details of where
that will be and the resulting mid level flow pattern. For now, it
does look like the bulk of the moisture will still be bottled up to
our south in Sonora with isolated showers and thunderstorms mainly
south and east of Tucson.
Temperatures will be near to slightly above normal through the
forecast period.
&&
.AVIATION...Valid through 29/00Z.
SCT-BKN clouds at 6k-9k ft AGL and SCT-NMRS SHRA/TSRA from Sells
eastward thru 28/07Z. Slowly decreasing clouds and precipitation aft
28/07Z thru 28/19Z. SCT-BKN clouds at 6-9k ft AGL again aft 29/18Z
with SCT SHRA/TSRA developing mainly from Sells eastward.
Visibility restrictions, wind gusts up to 45 kts, heavy rain, small
hail and mountain obscurations possible with the stronger TSRA.
Outside of thunderstorm wind gusts SFC wind 12 kts or less, favoring
a SLY/SWLY direction during the afternoon hours and variable in
direction at other times. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Expect scattered to numerous showers and and
thunderstorms through Wednesday, then a gradual decrease in
storms late in the week and weekend. Min RH values will be 20-30
percent in most valley locations, with minimum`s of 15-20 percent
west of Tucson across central/western Pima County. Outside of any
thunderstorm outflow winds, 20-foot winds will generally be 15 mph
or less, with afternoon/early evening gusts to 20-25 mph and light
winds overnight.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
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