Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/04/24
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1012 PM EDT Sat Aug 3 2024
.SYNOPSIS...
A slow moving cold front will gradually move east across the
region through Sunday. This system will bring a few more rounds
of showers and thunderstorms, which will be most prevalent
across areas south and east of Albany. Some storms will likely
produce locally heavy rainfall. A stronger cold front approaches
from the northwest on Monday, potentially resulting in some
strong to severe thunderstorms.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
.UPDATE...A few light, patchy showers still exist mainly south
and east of Albany as the upper trough continues to push farther
east. Latest guidance continues to trend down the already
scattered coverage of showers overnight, so adjusted PoPs
accordingly. Otherwise, all else remains on track with
additional details in the previous discussion below.
.PREV DISCUSSION[0347]...Radar showing several clusters of
showers and thunderstorms have developed across SE NY, with most
of the activity still upstream of our forecast area. Will have
to see how this evolves, as the convection is occurring where it
is more unstable (MLCAPE > 2000 J/Kg) vs. in Ulster, Dutchess
and Litchfield counties where MLCAPE is 1000-2000 J/Kg.
Effective shear is ~30 kt so will still need to monitor for some
strong to severe storms in these 3 counties. Locally heavy
rainfall is the other threat, although the Slight Risk(level 2
of 4) outlook was trimmed southward to just include the far
southern part of the forecast area, with a Marginal Risk(level 1
of 4) across most of the rest of the area. Mainly isolated
instances of flash flooding are anticipated.
Showers/T-storms (mainly southeast of Albany) will linger into
this evening as the upper trough axis and weak cold front start
to gradually move eastward across the area. Locally heavy
downpours may occur, especially through midnight with PWAT
anomalies still running high (+1 to +2 STDEV). The coverage and
intensity of convection should gradually wane with loss of
daytime heating. Isolated to scattered activity is expected
after midnight, although increased PoPs to 30-40% overnight from
around Albany northward as several runs of the HRRR indicating
a possible flare up of convective showers and a few storms. It
will remain warm and humid with lows in the 60s to around 70F.
The upper trough axis and surface cold front will continue to
slowly push eastward across the area on Sun. Guidance in good
agreement the trough will weaken as is moves through. The
surface front also should lose its definition and become
somewhat diffuse. So the result is expected less coverage of
showers/T-storms compared to prior days. Despite expectation of
mostly cloudy skies, with a relatively moist air mass still in
place and a few breaks of sun from time to time, SBCAPE values
may reach 1000-1500 J/Kg. The deep layer shear looks fairly weak
< 25 kt, so organized/severe storms are not anticipated.
Brief/isolated gusty winds and locally heavy rainfall may occur
in some of the taller storms. High temperatures look to be in
the mid to upper 80s in lower elevations with continued humid
conditions. Dewpoints will still be in the lower 70s in lower
elevations, with max heat indices in the lower 90s.
A few showers/T-storms may linger into Sun evening, although
should then dissipate through the rest of the night as a small
area of surface high pressure builds in from the west. Lows will
still be slightly above normal mainly in the 60s.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
On Mon, an upper level trough will be digging across SE Canada,
the Great Lakes and into the Northeast. A short wave
disturbance embedded in the mean trough will drive a cold front
southeast across the area. Timing looks to be during the
afternoon to evening hours. The Storm Prediction Center has a
Marginal Risk (level 1 of 5) for severe storms, as the deep
layer wind shear is forecast to increase to substantial levels
for this time of year > 40 kt. There are some discrepancies in
the magnitude of instability, however if there ends of being
overlap of instability/shear ahead of the front the threat for
severe storms could increase. Will monitor for possible upgrade
in subsequent outlooks. High temperatures could get quite warm
ahead of the cold front, with upper 80s to lower 90s in lower
elevations. With dewpoints in the mid/upper 60s, max heat
indices could reach the lower/mid 90s. A Heat Advisory may
eventually be needed south of Albany.
Showers/T-storms could linger into Mon night depending on the
cold front timing, although the severe threat should diminish by
later in the evening. The cold front should clear the entire
area by early Tue morning. Low temperatures Mon night look
slightly cooler than recent nights, ranging from the mid 50s in
the Adirondacks to upper 60s in the Hudson Valley.
Despite the cold front being positioned south of the region on
Tue, it could still be unsettled with showers developing on the
cool side of the boundary as a weak wave of low pressure moves
along it. The southward progress of the front is expected to
stall across the northern mid Atlantic region. The environment
will be much more stable north of the front, so no severe
weather is anticipated. High temperatures will be much cooler
with mid to upper 70s in most lower elevations, except lower 80s
near Poughkeepsie.
The front over the mid Atlantic is forecast to drift slightly
southward Tue night, so chances for showers will decrease
through the night from north to south. Lows will be cooler than
we have seen in a while with lower 50s to lower 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Temperatures are expected to remain cool (slightly below
normal) through much of the long term period, which will be a
big change from the persistent hot/humid conditions we`ve seen
since early July.
In terms of rain chances, Wed looks mainly dry at this time
with a stalled front positioned over the mid Atlantic region. If
the front shifts slightly north, there would be an increasing
chances for some showers, mainly for areas south of Albany. Will
continue to mention 20-40% PoPs to account for this
possibility. Thu into Fri looks mainly dry with surface high
pressure positioned over the region, although some guidance
showing a possible northward shift in the front over the mid
Atlantic approaching so will mention 30-50% PoPs.
Will continue to closely monitor the progress/evolution of the
tropical system near the southeast and coastal Carolinas, as
moisture from it may interact with the old front positioned to
our south. This may evolve into a heavy rain set up for part of
the area towards next weekend, although the forecast is very low
confidence at this time. For the official track of the tropical
system visit the National Hurricane Center website:
hurricanes.gov.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Through 00z Monday...VFR conditions currently prevail across all
terminals this evening with this afternoon`s showers having
dissipated and/or moved out of the forecast area. Throughout the
overnight period, some additional showers are possible as an
upper-level disturbance moves across the area. TEMPO groups were
added to account for this possibility at KALB/KGFL/KPSF where
probabilities of conditions being impacted are higher. With
these showers, MVFR ceilings are possible with brief reductions
to MVFR visibility, but VFR visibility is more likely outside of
a heavier shower.
Once showers move out of terminal bounds or dissipate, VFR
conditions will be resumed again into tomorrow morning and
afternoon. Another round of showers and thunderstorms is
possible tomorrow afternoon with an approaching cold front but
plenty of model discrepancy lowered confidence enough to keep
this convection out of the TAFs for now. Will provide additional
details in future updates when confidence increases.
Winds throughout the 00z period will prevail primarily out of
the south to southeast through the overnight, becoming variable
throughout the day tomorrow. Sustained speeds will range from
about 2-6 kt throughout this cycle.
Outlook...
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Moderate Operational Impact. Chance of SHRA.
Wednesday Night: Low Operational Impact. Slight Chance of SHRA.
Thursday: Low Operational Impact. Slight Chance of SHRA.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...JPV
NEAR TERM...Gant/JPV
SHORT TERM...JPV
LONG TERM...JPV
AVIATION...Webb
Area Forecast Discussion
National Weather Service Bismarck ND
940 PM CDT Sat Aug 3 2024
.KEY MESSAGES...
- Chances (30% to 60% north and 20% southwest) for showers move
into western and north central North Dakota after midnight.
- Much cooler over the coming days with highs mainly in the 70s
through Friday, the exception to that being Tuesday with some
lower to mid 80s. At least some chance for showers and
thunderstorms each day. The risk of severe thunderstorms is
very low.
&&
.UPDATE...
Issued at 920 PM CDT Sat Aug 3 2024
Overall only minimal changes to the forecast overnight.
Initially thought pops might be moving in too quick. Latest HRRR
and RAP 00Z 08/04 guidance is even quicker to bring mainly light
precip into the northwest and north central overnight. A couple
of impulses can be seen just north of the International Border
moving from Alberta into western portions of Saskatchewan.
Bufkit soundings indicate initially dry mid levels quickly
moisten overnight in response to the approaching waves. In the
end, we kept pops pretty close our given pops, but we did blend
in a bit of the quicker RAP/HRRR guidance. There is some slower
guidance and didn`t want to completely buy into the quicker
guidance given the initially dry mid levels over western and
central ND. Updated text products will be transmitted shortly.
UPDATE
Issued at 549 PM CDT Sat Aug 3 2024
Cold front has now pushed through the James River Valley with
chance for strong to severe storms this evening diminishing
quickly. There is some elevated instability and strong shear
behind the front so will monitor for the next hour or so before
completely pulling precipitation chances here. Otherwise a quiet
evening looks to be in store with north to northeast surface
flow turning more northeast to east. Clouds will also be on the
increase this evening with precipitation chances moving into
the northwest after midnight. Will take a closer look at timing
of precipitation here with the next update.
&&
.DISCUSSION...
Issued at 214 PM CDT Sat Aug 3 2024
Surface low pressure is located over southeastern ND. Thus,
associated cold frontal boundary has moved through all but the
southernmost portions of the forecast area. As a result, highs
have mostly peaked and are expected to remain in the upper 70s
to low 90s, with most 90 degree readings either along or near
the ND/SD border. Breezy northerly to northeasterly winds are
prevalent behind the cold front.
Thunderstorm chances for this afternoon remain low overall with
a 20 percent chance in the southern James River Valley of ND. A
strong cap that was in place earlier today is beginning to
erode with a combination of daytime heating and more importantly
the aforementioned frontal passage. Should the cap break before
the frontal boundary passes into South Dakota, then with plenty
of instability (4000 J/kg or more) and adequate shear (30 to 40
kts 0 to 6 km bulk shear), the ingredients are there for any
thunderstorm to rapidly become strong to severe. Golf ball size
hail and winds up to 60 mph are the primary threats. The
residency time for any thunderstorms in North Dakota will be
relatively brief before moving off into South Dakota.
For tonight, Canadian low pressure will continue to flatten the
west CONUS ridge that has been talked about over the past many
days. Weak shortwave energy will slide through the area
resulting in the potential for showers tonight in the west and
especially northwest. Instability is very limited, so while a
rogue lightning strike isn`t completely out of the question in
areas of 100 to 200 J/kg of CAPE, a rumble or two of thunder
wouldn`t be completely surprising.
Other than on Tuesday when the ridge attempts to briefly
recover and reamplify, moderately below average temperatures
mostly in the 70s are expected for most locations, most days.
And even on Tuesday, most locations progged to reach the 80s are
those along and south/west of the Missouri River. Periodic
showers, along with a few thunderstorms, are possible through
most of next week. The threat for severe weather is very low.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 549 PM CDT Sat Aug 3 2024
VFR conditions are expected through the 00Z TAF period.
A cold front has moved through western and central ND this
afternoon. Expect a north to northeast surface flow this evening
shifting more northeast to east through the TAF period. Winds
generally 8 to 15 mph tonight and Sunday morning, although there
may be gusts to around 25 mph early this evening. Winds will
pick up later Sunday morning and Sunday afternoon 15 to 25 mph
generally from the east. Shower chances increase late tonight
and slowly through the day Sunday with better chances occurring
after the TAF period, but will include a VCSH at KXWA and KMOT
Sunday morning.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...TWH
DISCUSSION...Telken
AVIATION...TWH
Area Forecast Discussion...Updated
National Weather Service Billings MT
826 PM MDT Sat Aug 3 2024
.UPDATE...
High-based showers and a couple isolated thunderstorms were found
over the southwest mountains and adjacent foothills this evening.
The convection will continue to lift north and east through the
rest of the evening, with additional isolated showers and
thunderstorms possible over central and eastern areas overnight as
a low level jet sets up with easterly flow. Temperatures are
gradually dropping into the 80s and have cancelled the Heat
Advisory for the area. PoPs and weather have been updated through
tonight. The previous discussion is below. STP
&&
.DISCUSSION...
Through Sunday Night...
The backdooring easterly winds have slowed today`s warming, and
as of 1pm, temps are in the 80s to lower 90s (5-12F cooler than
Friday at this time). Lofted smoke has also thickened a bit.
Today`s temp forecast may end up underachieving a little, but we
will still see highs well into the 90s, and near 100F in spots,
per 700mb temps near an anomalous +16C. Satellite imagery shows
cumulus beginning to develop over the Beartooth-Absarokas. As mid
and high level monsoon moisture continues to increase, we should
see isolated high-based weak thunderstorms in the late afternoon
and evening over the west half of our cwa. Later tonight, w/ a
southeasterly low level jet, rising pwats and modest elevated
instability, some showers and thunderstorms should affect our east
overnight. High res models show fair confidence with regard to
nocturnal activity.
Going back to satellite imagery, note the subtropical wave lifting
through the Sierras today. This energy will lift to the northeast
and supply ascent in our region tomorrow at a diurnally favorable
time. In addition to the tap of monsoon moisture, easterly winds
will increase low level moisture, and we expect pwats to increase
to 1-1.25" tomorrow. In fact, the latest HREF shows pwats near
1.5" east of Billings by late afternoon. A very healthy value for
our region regardless of the time of year. All ingredients point
toward showers/thunderstorms being likely tomorrow afternoon &
night, with activity exiting our east late Sunday night per the
track of the shortwave. Storms will produce brief heavy rain and
perhaps hail (freezing levels fall sufficiently for hail). HREF
also suggests a few notable updraft helicity tracks over our east
in the evening, with seems plausible given a pre-frontal easterly
low level jet. SPC has highlighted our cwa for a marginal risk of
severe storms tomorrow. Wind is the highest risk but hail is also
possible, in addition to heavy rain. Please keep all of this in
mind if you have outdoor plans.
Wetting rain (0.10" or more) is likely (50-70% chance) for all but
the far south/southeast (20-40% in this area). The probability of
0.25" or more is 30-50% over our western mountains and along/
north of a line from Billings to Ekalaka. This will be a welcomed
drink of water for many.
After a warm night tonight, temps Sunday will again be above
normal but not quite as hot as today. Look for highs in the 90s,
with near 100F in our southeast at places like Sheridan & Broadus.
That said, a Heat Advisory remains in effect today, but do not see
a need to extend it into tomorrow. Sunday night will be post-
frontal and cooler. It is possible that the cold front/subsidence
allows some smoke from the west to surface in our region, but the
HRRR currently does not show this happening.
JKL
Monday through Saturday...
An active weather pattern will bring cooler temperatures,
especially to midweek, and a daily chance of precipitation.
Monday into Tuesday morning will be one of the drier days of the
weak, with PWATs briefly falling under 1 inch, however, a weak
shortwave moving through will still bring a 30-50% chance of
showers and thunderstorms over the western mountains and a 15-30%
chance over the rest of the region. Then, Tuesday afternoon
through Wednesday, PWATs are expected to increase to 1-1.25
inches. Coupled with more energy moving into the region, there is
a 60-80% of showers and thunderstorms over the mountains and a
50-70% chance over the plains. The pattern then looks to remain
open to additional energy moving through for Thursday into the
weekend, bringing a daily 40-60% chance of precipitation over the
mountains and a 20-40% chance over the plains.
Highs on Monday and Tuesday will be in the upper 80s to low 90s.
Then, a push of cooler air will drop highs into the mid 70s
Wednesday and into the upper 60s to low 70s by Thursday. Thursday
continues to look like the coolest day with temperatures starting
to increase again into the weekend, reaching the upper 70s to low
80s by Saturday. Archer
&&
.AVIATION...
Increasing lofted smoke from the west will continue to reduce
slant range visibility. Look for isolated high-based thunderstorms
along the western foothills late this afternoon (i.e. near KLVM &
KHWQ). A few showers and weak thunderstorms will spread eastward
across the lower elevations tonight. Storms may produce brief/
erratic wind gusts late this afternoon and evening. All TAF sites
have a <10% chance of seeing a TS. Otherwise, VFR will prevail
over the next 24 hours. There is a much higher probability of
showers & thunderstorms Sunday afternoon/evening. JKL
&&
.PRELIMINARY POINT TEMP/POPS...
Sun Mon Tue Wed Thu Fri Sat
-----------------------------------------------------------
BIL 069/094 061/089 063/092 060/074 056/071 054/077 056/082
24/T 61/U 23/T 56/T 44/W 32/W 23/W
LVM 059/092 054/092 056/092 054/078 049/072 047/077 049/082
28/T 51/U 35/T 55/T 34/T 23/T 35/T
HDN 067/097 060/089 060/092 058/075 053/072 052/078 053/083
22/T 61/U 22/T 65/T 44/T 32/W 23/W
MLS 071/095 060/081 062/090 060/074 053/071 053/076 057/082
22/T 71/B 12/T 55/W 33/T 23/W 33/T
4BQ 070/099 062/084 061/095 062/076 055/070 055/076 057/083
22/T 61/B 12/T 55/T 44/T 23/T 33/T
BHK 064/090 055/071 054/087 057/077 051/073 050/078 053/082
22/T 72/T 12/T 55/T 23/T 22/W 33/W
SHR 062/098 058/089 059/094 057/076 051/071 050/079 052/082
22/T 41/U 12/T 55/T 55/T 33/T 24/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Forecast Discussion at weather.gov/mqt.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...None.
&&
$$
DISCUSSION...Huyck
AVIATION...Rothstein
MARINE...Huyck
Area Forecast Discussion
National Weather Service Des Moines IA
1051 PM CDT Sat Aug 3 2024
...Updated for the 06z Aviation Discussion...
.KEY MESSAGES...
- Showers and thunderstorms north tonight and again Sunday
night, a few severe possible.
- Hot through Monday with temperatures in the 90s.
- Two back to back waves Monday into Tuesday and Wednesday into
Thursday will reinforce cooler air into the area, sending
highs back to the 70s.
&&
.DISCUSSION...
Issued at 251 PM CDT Sat Aug 3 2024
Warm and dry today as high pressure has suppressed any cloud
development this afternoon. Meanwhile, low pressure is off to the
northwest, across the Dakotas and Minnesota. Convection associated
with the low will develop later this afternoon and evening, slipping
into northern Iowa late this evening and overnight. A few
stronger storms are possible as ML CAPE exceeds 1000 J/kg. RAP
soundings show modest lapse rates under 7 C/km which may
support small hail and Dcape around 1000 J/kg supporting a few
stronger gusts. Overall the environment is borderline for severe
potential overnight, however a few stronger storms may be
possible. CAMs struggle with the evolution into the overnight as
some solutions squash convection through the overnight while
others continue sparse activity Sunday morning into central
Iowa. Given the recent poor performance of CAMs, there is low
certainty in any one solution.
Sunday will be another hot one in the 90s as thermal ridging
continues to dominate the central US. The only uncertainty here is
whether those sowers and storms persist into the late morning as a
few CAMs suggest. If so, that may put a damper on temperatures which
occurred a few times this past week. As the northern extent of
the thermal ridge just touches northern Iowa, the area is primed
for passing perturbations across the area. Yet another weak
impulse is expected on Sunday evening passing across northern
Iowa. The parameter space improves here with better lapse rates,
more instability, and a more focused area of forcing as the
baroclinic zone shifts south. This will allow for more
widespread convective activity late Sunday evening and into the
overnight.
Temperatures peak Monday across central and southern Iowa in the mid
to upper 90s , however the northward extent of the heat is less
certain due to the potenitial lingering convection and cloud
cover from the overnight convection. By Monday afternoon
overnight into Tuesday a more compact shortwave will pass
across the area, however models indicate a little less
instability to work with which my inhibit more robust
convection. Much cooler air filters in behind the system as
highs Tuesday remain in the upper 70s to near 80. A reinforcing
shot of cooler air accompanies another shortwave across the area
Wednesday into Thursday, bringing another round of showers and
thunderstorms to the area.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 1050 PM CDT Sat Aug 3 2024
Scattered storms in central MN expected to diminish, but may
brush the IA MN border near MCW. For now, low confidence on
arrival and have left out. Otherwise, light winds with next
potential for any showers mainly late in the period aft 00z
Monday. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Hagenhoff
AVIATION...REV
Area Forecast Discussion
National Weather Service Gray ME
1019 PM EDT Sat Aug 3 2024
.SYNOPSIS...
A series of frontal systems will track through the region late
tonight, Sunday and again on Monday, bringing chances for
showers and thunderstorms, some of which could produce locally
heavy rainfall. A weak area of low pressure will track off the
southern New England coastline on Tuesday and Wednesday,
bringing scattered showers to southern Maine and New Hampshire
while high pressure allows for dry conditions for northern areas.
Another frontal system will bring scattered showers to the
region late in the week as tropical activity remains across the
Southeastern US.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
1015 PM Update...Dry but very muggy conditions exist for the
most part late this Saturday evening. Height falls will occur
later tonight and that may allow for renewed shower and
thunderstorm development. Will keep chance PoPs going.
Thunderstorms will be capable of torrential rainfall rates.
Otherwise, fog is likely in valley locations once again late.
650 PM Update...Not much going on at the moment as lack of
forcing has limited precipitation to isolated showers. The
question is whether or not subtle height falls near an
approaching boundary in the mountains allows for a redevelopment
of showers and thunderstorms much like last night. CAMs are at
odds with the HRRR continuing to be most robust. Will continue
to monitor.
Previously...
Not expecting much in the way of showers thru this evening.
There is some sort of boundary that sit across the NH and W ME
mtns and this setting some small and short-lived convective
showers, but this too should weaken before sunset, as we head
into an area of relative ridging at different levels. This has
also help clear out a lot of the CWA. However, there is another
wave in the 500 MB and mid level floe that approaches after
midnight and should be the focus for another late night into
early morning round of showers. I have followed much closer to
the CAMs than the global models, and this would lead to
something to similar to what happened Sat morning, with the
central and srn half of the CWA seeing the more potent
convection, mainly in terms of rain and lightning, and less to
the N, which would linger across E zones into the mid-morning.
Overnight lows are not expected to change from previous nights
and will mostly be in the upper 60s to low 70s with patch fog
developing.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
While any showers will end by mid morning, there is a much
better chance of a secondary round of convection, especially S
of the mtns Sunday afternoon into early evening. This is the
result of that boundary we see in the mtns today slowly drifting
S during the day on Sunday. Given the air mass and water
content, any convection could produce torrential downpours. It
wound be as warm on Sunday, with highs probably staying in the
80-85 range in many spots, but may be upper 80s in SE NH and far
SW ME. Tds will not change much though, and itll still be very
humid.
That boundary moves offshore Sunday evening, but also
deteriorates, and there is little change in the air mass behind
it. Maybe dew points drop off by 2-3 degrees, which we could see
in lows ranging from the low 60s in the mtns to the upper 60s in
the S, but thats about it. This will probably lead to fog in
more places given the rain and the very saturated air mass
trying to squeeze out some water as temps fall a slightly lower
than previous nights. However, it should stay mainly dry with
some clearing overnight.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The last in a multiple, series of frontal systems will finally
cross the forecast area on Monday from northwest to southeast.
Ahead of this front, hot and humid conditions will continue with
air temperatures reaching the lower 90s and surface dew points
topping out near 70 degrees. This will bring heat indices as
high as the mid 90s over southern portions of Maine and New
Hampshire. Showers and storms will form in proximity to the
front as instability increases during the day as an abnormally
high PWAT scenario continues. Some of the storms may have
locally very heavy rainfall and gusty winds.
On Tuesday we can expect much lower dew points as the front
settles south of our region with high temperatures mainly in the
70s which will be a significant cool down for the region. The
challenging portion of the forecast is how far south the front
settles over southern New England before a weak wave travel
along it on Tuesday and Wednesday. This weak area of low
pressure will bring clouds to southern areas as well as a chance
for showers. Northern areas are expected to remain dry.
Operational models and ensemble solutions differ in agreement
as to whether tropical moisture will interact with a trough late
in the week well ahead of any potential tropical activity. Jet
dynamics may very well play a role in the formation of heavy
rainfall, however that axis may end of falling south of our
region. In the meantime, with low confidence in late next weeks
forecast, will continue with scattered showers in the grids.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Short Term...Tonight looks very much like previous nights, with
fog and low cigs developing in the usual spots, and like early
Sat morning, expecting another cluster of TSRA to move through
just before and after sunrise. It may end up slightly further N
than Sat, but they will include another found of very heavy rain
and frequent lightning. Then after a brief improvement to VFR
another line of TSRA develops across central NH into coastal ME
Sunday afternoon into early evening. Fog may be prevalent and
hit all the terminals on Sunday night.
Long Term...Mainly afternoon and evening scattered showers and
thunderstorms expected tonight, Sunday and into Monday.
Localized IFR conditions with LIFR conditions possible in late
night fog as well. Conditions will be variable on Tuesday with
showers possibly developing along the exiting cold frontal
boundary. Drier air follows midweek before more showers enter
the region late in the week.
&&
.MARINE...
Short Term...Any fog that was over the eater is now gone, but
should develop, at least around and S of Pen Bay later tonight,
but it may dissipate again Sunday morning, only to return Sunday
night. Otherwise winds/seas remain below SCA levels.
Long Term...Winds and seas stay below SCA levels into next week.
We may see patchy fog into next week limiting visibilities.
&&
.HYDROLOGY...
A series of front will cross the region tonight, Sunday and
Monday. Multiple rounds of showers and thunderstorms with
locally heavy rainfall are possible during this period as PWATs
remain around 2" and renew the threat for flash flooding. An important
takeaway remains is that the airmass is anomalously moist and
any organization could support rain rates over 2"/hr and a
threat for flash flooding, particularly in areas that have
recently seen heavy rainfall.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...Cempa
LONG TERM...Cannon
AVIATION...
MARINE...
HYDROLOGY...
Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Sat Aug 3 2024
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Extreme heat will be the main story this weekend and into Monday as
high temperatures soar upwards of 110 to 116 degrees and overnight
temperatures only cool into the middle 80s to lower 90s across the
lower deserts. Daily thunderstorm chances will continue over the
next few days, but storm coverage will be primarily focused over
Arizona high terrain. An upper level disturbance arriving early next
week will bring better potential for more robust storms and greater
coverage of storms, as well as a cooler temperatures.
&&
.DISCUSSION...
An unseasonably strong ridge of high pressure has become established
over the 4-Corners region with 500 mb hghts now approaching 598 dam.
Hghts aloft have also increase over south-central AZ and are now up
to 595-596 dam according to the latest RAP 500mb analysis. This
expansive area of high pressure is expected to persist into early
next week, resulting in excessively hot temperatures across the
Desert Southwest through Monday.
Today, we will see highs approaching 115 degrees in some locations
such as Phoenix, Yuma, Blythe, and El Centro. There is currently a
75% chance that Sky Harbor will exceed the record high of 114 this
afternoon (see climate section for more information on records). Low
temperatures tonight will be very uncomfortable, with many locations
not falling below 90 degrees. As far as rain chances go today,
instability will be much more limited today (SBCAPE largely below
1000 J/kg) and therefore storms are expected to remain isolated
across our region. The highest rain chances will be around 30-40%
across S Gila County and 20% or less in the lower elevations of
south-central AZ. The only caveat will be a complex of storms
expected across Pima County which could send an outflow boundary
into Pinal and Maricopa Counties this evening, which may result in
patchy blowing dust along I-8. It is not out of the question that a
storm or two could form along said boundary as it progresses towards
the Phoenix Metro area tonight.
On Sunday, the subtropical high over the 4-Corners region is not
expected to move much at all which will allow temperatures to yet
again climb well above normal. Lower desert highs will be similar to
today in the 108-115 range which will result in areas of major to
extreme HeatRisk. Therefore, it is important to continue to practice
heat safety measures to keep yourself safe during this stretch of
very hot temperatures. Latest hi-res guidance including the HREF
does indicate slightly better instability tomorrow afternoon across
south-central AZ up to 1000 J/kg. Forecast soundings also show very
high DCAPEs approaching 2000 J/kg. Thus, convection may be more
robust with slightly higher coverage across the central deserts
Sunday afternoon and evening with the main threats being strong,
gusty outflow winds.
&&
.PREVIOUS DISCUSSION...
Signs still point toward a more active monsoonal pattern, with
greater storm intensity and coverage during the early to middle
portions of next week as an inverted trough (IT) moves in from the
east and undercuts the subtropical ridge. Global ensembles have the
IT reaching the Sonoran Desert as early as Monday afternoon or
evening next week. Global ensemble means have the core vorticity
passing mostly through northern Mexico, but regardless of whether a
track staying just to the south limits the full potential of
thunderstorm activity, there is strong agreement that the wave will
help push moisture levels back up, and thus instability, as well as
bring increased mid-level easterly winds. Global ensembles have PWAT
values climbing back into the 1.6-1.7" range and mixing ratios to
around 11-12 g/kg by Tuesday. GEFS probability for >1000 J/kg of
CAPE respectively goes up to around 40-50% for most of southern AZ
with this moisture increase. NBM PoPs remain highest on Tuesday,
with widespread 30-40% across southern AZ.
This shortwave during the first half of the week should help
moderate and lower high temperatures slightly, but based on the
current NBM forecast not enough to fall below normal. Then by the
end of the week, as the influence of the wave wanes and moisture
levels drop slightly again, temperatures may go right back up with
the persistent strong high still in place over the region.
&&
.AVIATION...Updated at 2310Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Distant outflows causing potentially more than one abrupt wind shift
this evening will be the primary weather issue through Sunday
afternoon. While storms with SCT mid/high cloud decks will be common
around the periphery of the Phoenix airspace, odds of any direct TS
impact is well under 20% and not considered in this TAF package.
Instead, weakening northerly outflow would be most likely to impact
KDVT/KSDL early evening with a separate long traveling southerly
outflow potentially sweeping into KPHX/KIWA mid/late evening.
Confidence in exact directions and timing still remains low with the
possibility of outflows dying before reaching any given terminal. An
eventual shift to easterly should be established after midnight with
a return to a westerly component near/shortly after noon Sunday.
Probabilities for more direct outflow and TSRA impacts appear much
higher Sunday evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Sunday afternoon under a
few occasional midlevel cloud decks. Wind directions will vary
between a daytime SE component and a general veering towards an
overnight SW component. TS well east of KBLH may result in a period
of evening easterly winds, however confidence is too low to include
in this TAF package.
&&
.FIRE WEATHER...
Scattered thunderstorms will be possible this weekend across the AZ
high terrain. Although storm chances will remain low (20% or less)
in most lower desert locations, there will still be the risk for
strong outflow boundaries which could result in a sudden wind shift
and gusty winds at active burn areas. Much better chances for
widespread wetting rains will arrive early next week, with
possibility for isolated flash flooding across the new burn scar
locations. Aside from thunderstorm outflows, winds will should
remain light and diurnal with afternoon gusts into the teens.
Minimum RH values will mostly reside in the 10-20% range through
this weekend with overnight recovery to 30-50% most areas.
Temperatures this weekend will be several degrees above normal,
with lower desert highs reaching the 110-116F range. Temperatures
will cool down closer to normal by Tuesday with the arrival of
better moisture and cloud cover.
&&
.CLIMATE...
Phoenix Daily Record Temperatures
High Warm Low
---------- ----------
8/3 114 (2020) 92 (2023)
8/4 116 (1975) 91 (2018)
8/5 116 (2023) 95 (2009)
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Monday for AZZ530>555-559-
560.
CA...Excessive Heat Warning until 8 PM PDT Monday for CAZ560>570.
&&
$$
DISCUSSION...Salerno
PREVIOUS DISCUSSION...Benedict
AVIATION...18
FIRE WEATHER...Salerno
CLIMATE...Benedict
Area Forecast Discussion
National Weather Service Reno NV
129 PM PDT Sat Aug 3 2024
.SYNOPSIS...
* Showers and thunderstorms will continue through this evening. A
few storms are possible again Sunday, then mainly dry conditions
prevail for next week.
* Smoke from ongoing wildfires will impact areas mainly north of
I-80 at times through this weekend.
* Above average temperatures return Sunday and continue through
next week, with moderate HeatRisk in most lower elevations.
&&
.DISCUSSION...
THUNDERSTORMS THROUGH THE WEEKEND, THEN DRY:
* Showers and thunderstorms began developing around 11 AM south
of US-50 in western NV and in Mono County, with a general
northward movement of 15-20 mph. Most cells were pulse type with
shorter life spans, but additional activity developing upstream
has produced some training cells.
* Storm activity will continue pushing northward across western NV
and eastern CA through this afternoon, then the high resolution
guidance favors additional development over northeast CA-
northwest NV from late afternoon into the evening. While
moisture is relatively plentiful with PW values around 1 inch,
the risk of a few lightning fire ignitions outside the rain
cores exists, especially for northeast CA/northwest NV where
faster cell motions of 25-30 mph are anticipated. Other hazards
with today`s stronger storms include periods of heavy rainfall
with potential for isolated flash flooding if cells train or
anchor to a terrain feature for sufficient duration, small hail,
and outflow gusts near 50 mph.
* The upper level shortwave supporting today`s convection will
lift northward into southern Oregon this evening, taking the
best forcing out of CA/NV. Some outflow interactions could
linger across northwest and west central NV until around sunset,
with clearing expected overnight.
* Residual moisture and a weaker upper disturbance may bring
isolated short-lived showers and thunderstorms Sunday afternoon
to parts of Mono, Mineral and southern Lyon counties. Otherwise,
a drier pattern is expected to prevail for the upcoming week
with less than 10% chance of thunder each afternoon.
SMOKE AND HAZE:
* Smoke and haze from the Park Fire will continue to affect
northeast CA and parts of western NV this weekend. Southerly
flow should bring some relief and improved air quality later
today to Lassen and northern Washoe counties, although smoke
could return tonight as winds shift to westerly over northern
CA. HRRR smoke trajectory models showed less smoke coverage
compared to yesterday, but the thick cloud cover over the fire
area could be underestimating the smoke output captured by the
model. Keep an eye on fire.airnow.gov for the latest air quality
measurements.
TEMPERATURES/WINDS THIS WEEK:
* Temperatures for the upcoming week will run about 3-6 degrees
above average due to a prevailing ridge over the southwest US,
with highs in the upper 90s-near 100 for lower elevations and
mid-upper 80s for Sierra communities. HeatRisk will generally
reach the Moderate category each afternoon.
* A slight cooling may arrive by late week as a bit more
troughing over the northwest US could flatten/weaken the ridge`s
western extent over CA/NV. Most afternoons should see typical
SW-W breezes with gusts to 25 mph, with a potential slight
increase by late week if the flatter ridge scenario occurs. MJD
&&
.AVIATION...
* For the main terminals around Tahoe and far western NV, the best
chances for thunderstorms will continue until around 23-00Z,
while for KMMH the threat for storms has already diminished.
Storm activity then shifts farther north and east for the late
afternoon and evening, ending by midnight. Plan on short periods
of MVFR/IFR conditions from brief heavy rain and/or small hail,
lightning, and gusty winds to 30-35 kts with today`s storms.
* VFR conditions then return overnight and continue through the
upcoming week, with more typical SW-W breezes around 20 kt for
most afternoons between 21-04Z. Haze from the Park Fire may
produce minor reductions in slantwise visibility, especially for
areas north of I-80. MJD
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
Area Forecast Discussion
National Weather Service Salt Lake City UT
216 PM MDT Sat Aug 3 2024
.SYNOPSIS...A monsoonal surge will expand the potential of
showers and thunderstorms throughout the area on Saturday.
Temperatures will cool slightly before becoming hot again early
next week. Daily shower and thunderstorm chances will continue
across southern and eastern areas through next week while northern
areas dry back out early next week.
&&
.SHORT TERM (Through 12Z/6AM Tuesday)...
Satellite imagery shows an area of mid and high level cloud cover
that continues pushing northward through northern Utah this
afternoon. This band of cloud roughly marks the northern periphery
of the monsoonal moisture working northward across the state
today. Mesoanalysis shows a sharp gradient in PW values from
around 0.5 inches in southwest Wyoming to around 1 inch over
central Utah (with values continuing to increase to around 1.25
inches in Washington County). Surface-based CAPE also increased
along this same axis to 1000 J/kg along and south of Millard to
Emery Counties. Deep southerly flow across the region resulting
minimal shear values, largely less than 20 knots, and supportive
of northward storm motions around 10-15 knots. At 700 mb to the
surface there is evidence of a convergent boundary along the
central spine of mountains into central Utah, which should help to
further increase the forcing for ascent over the terrain in
central Utah this afternoon. Thunderstorms developing over the
central mountain terrain will quickly upscale via colliding cold
pools as it move northward in the mean flow. However, with the
drier environment in place across northern Utah, storms will start
to collapse moving off the terrain, with the drier sub-cloud
layer will favor strong, gusty outflow winds advancing northward
along the Wasatch Front into this evening. Largely expect wind
gusts in the 30-50 mph range, however, a few isolated wind gusts
to 60 mph cannot be ruled out, especially in terrain favored
locations.
Farther south, for much of central Utah, the slowish storm
motions, deeper moisture, and potential for training/backbuilding
will setup a marginal risk for flash flooding. The most prone
areas through central Utah would be area burn scars, so long as a
storm can train or backbuild over the scar. Meanwhile, into
southern Utah, the southerly flow will primarily carry the storms
initiating in Utah away from the more sensitive basins and slot
canyon areas. However, the wild card remains how well storms can
maintain moving off of the higher terrain in Arizona. Many
members of the HREF have little in the way of thunderstorms making
it into far southern Utah this afternoon. However, recent runs of
the HRRR have supported the idea of some heavier rain producing
storms moving out of Arizona into southern Utah later this
afternoon and early evening. Surface dew points are in the mid 50s
largely from the Paria River basin westward through Zion and
Washington County. This corner of southern Utah would have the
best chance of realizing any heavy rain and thunderstorms, while
points east from the Escalante basin through Capitol Reef to the
Swell have dew points in the mid 40s limiting the potential today.
On Sunday, the ridge flattens slightly as it shifts almost due
south of us, allowing a drying westerly flow to develop across
Utah. While the column will start to dry, low-level moisture will
still be in place, supporting developing instability in the
afternoon. Showers and thunderstorms developing over the higher
terrain will largely track off to the east, which will favor
locally heavy rainfall into eastern basins such as Capitol Reef NP
and the Swell. Elsewhere across Utah, isolated to widely scattered
showers and thunderstorms are expected through the afternoon, and
in the Salt Lake Valley, there will probably be a storm moving off
the Oquirrhs mountains by early to mid afternoon. This flattening
of the ridge with lower-level moisture still in place will give us
a one day "reprieve" from the hotter temperatures, allowing the
HeatRisk to back off to moderate (orange level) on Sunday,
although daytime highs will only be a few degrees cooler.
.LONG TERM (After 12Z/6AM Monday), Issued 355 AM MDT...
High pressure will continue its hold over our region early next
week, allowing for hot triple-digit temperatures for many valleys.
Monsoonal moisture also remains in our forecast, bringing a daily
chance for showers and thunderstorms across southern Utah and
portions of central/eastern Utah. Each afternoon/evening will
bring an enhanced risk for heavy rains/flash flooding of sensitive
areas such as slot canyons, normally dry washes and recent burn
scars or areas of very steep terrain.
Toward the latter half of the week, we continue to see trends toward
a weaker area of high pressure. This would allow temperatures to
cool off ever so slightly. Monsoonal moisture looks to remain toward
the end of the week though amounts and locations continue to be
fuzzy and range from similar trends from earlier in the week to more
widespread across the state.
&&
.AVIATION...KSLC...Scattered showers and thunderstorms capable of
gusty, erratic outflow winds and lightning are likely from 00-06Z.
Winds will prevail from the south, but directions and speeds will be
altered through 06Z by showers and thunderstorms. Conditions will
clear after 06Z with light southeast winds overnight. Dry conditions
are likely for the end of the weekend, with isolated showers and
thunderstorms likely around terrain to the east. Winds will
transition from southeast to northwest around 19Z.
.REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and
thunderstorms through roughly 03Z in southern Utah and 06Z elsewhere
will be capable of gusty, erratic outflow winds, lightning, and
locally heavy rain. Clearing conditions are likely overnight with
light winds. Showers and thunderstorms are likely after 18Z for
locations east of a line from roughly KEVW to KCDC.
&&
.FIRE WEATHER...
Monsoon moisture continues to move in from south to north across
the state today as a ridge of high pressure is in place just to
our east. The moisture will maximize across Utah later today and
tonight. This will lead to numerous to widespread showers and
thunderstorms developing over central Utah this afternoon and
forming a strong cold pool which will push northward through
northern Utah as strong/gusty outflow winds. Gusts largely in the
30-50 mph range, but isolated gusts to 60 mph are possible mainly
for Juab, Utah, Tooele, Salt Lake counties. For central and
southern Utah, deeper moisture in place will promote locally heavy
rainfall which could lead to isolated flash flooding and areas of
wetting rains
A drier westerly flow will start on Sunday, reducing moisture
levels early in the week. As the ridge builds over the area along
with drier air, temperatures will become quite hot again, surging
5-10 degrees above normal. The ridge shifts a bit more eastward
later in the week opening the door for a return of monsoon
moisture into southern Utah.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory until 9 PM MDT this evening for UTZ101>107-114-116-
118>120.
Excessive Heat Warning from 10 AM Monday to 11 PM MDT Tuesday
for UTZ101-103>106-116-123-124-131.
Heat Advisory from 10 AM Monday to 11 PM MDT Tuesday for UTZ102-
107-114-115-118>122-128>130.
WY...None.
&&
$$
SHORT TERM...Church
LONG TERM...NDeSmet
AVIATION...Wilson
FIRE WEATHER...Church
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity