Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/04/23
Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
239 PM AKDT Thu Aug 3 2023
.SHORT TERM.../through Friday night/...Main Takeaways:
-Quiet and calm weather conditions continue.
-Light wind speeds with variable directions at times likely.
-If the low clouds from today are able to clear out, the extra
sunshine tomorrow (Friday) will lead to much warmer temps - in
the upper 60s to 70s, for those in the northern panhandle.
Watching the satellite imagery and webcams today has shown low,
stubborn clouds in the northern panhandle while the southern
panhandle is seeing clear skies. A few thunderstorms can also been
seen in western Canada.
Going forward, isolated t-storms are possible in the extreme
northern panhandle (mainly near White Pass) early in the evening.
But as temperatures cool and atmospheric stability returns, any
storms that are in the area should fade out quickly. The rest of
the panhandle should have quiet skies, just lingering clouds in
the north and clear skies in the south.
Fog developed last night, so that has been included in this
forecast for the southern areas. Latest HRRR and NAMnest hinted at
some reduced visibility where skies are expected to be clear.
Temperatures tomorrow will depend on if you have clouds lingering
or clear skies. Similar to today, temperatures will reach the
upper 60s to 70s in the sunny regions. But if clouds are stubborn
and don`t fade out, then expect more normal values in the low to
mid 60s.
.LONG TERM.../Saturday through Friday/...Weather pattern trend in
the upper levels remains on track, with the ridge in western
Canada expected to gradually break down through the middle of next
week. During this time, a broad upper level trough will extend
into the central Gulf of Alaska. This will lead to a transition to
overall onshore flow over the panhandle for early to mid next
week.
As a result of this shift, the seasonably warm and dry weather will
be limited to this weekend, with the potential for some areas to
see record high temperatures. Overall afternoon high temperatures
are expected to reach the mid to upper 70s or low 80s for
Saturday and Sunday, with warmest temperatures expected Saturday.
Light showers and cooler temperatures return to the panhandle
Sunday evening into Monday. While precipitation is expected to be
primarily light and showery early in the week, model guidance is
continuing to suggest a more organized system with a strong front
approaching the panhandle sometime Tuesday into Wednesday.
Inherited wind forecast in the gulf was kept, with winds trending
towards 20kt or greater approaching the outer coast for that
timeframe. Overall for next week the pattern will remain cooler
and wet as multiple systems are expected to transit the gulf
bringing showers and increased winds with associated frontal
passages.
&&
.AVIATION.../Until 00Z Saturday/...CIG and VIS conditions have
improved into the VFR flight category for the majority of SE Alaska
and will generally remain that way through most of the 24-hour
TAF period. One exception is Yakutat, which will remain within the
IFR/MVFR range for the entire period due to a marine layer that
will remain in place or relatively nearby. Scattered fog with the
potential of being locally dense may occur over other portions of
the Panhandle for tonight and into tomorrow morning. Both LLWS
magnitudes and SFC winds will be on the lighter side and generally
non-impactful for the entire SE Alaska region through the whole
24-hour TAF period. Some SFC wind variations due to afternoon sea
breezes will occur, especially over areas that receive any
appreciable sunshine.
&&
.HYDROLOGY...Suicide Basin began to show water levels dropping
Sunday evening but has now since slowed. Preliminary analysis
indicate initial lowering of water level was due to further
melting of the side drainage channel allowing water to flow into
Mendenhall Lake. Based on latest webcam image and current water
levels, best estimates indicate that Suicide Basin has reached a
state of equilibrium and Mendenhall Lake water levels continue to
fall.
A release of Suicide Basin is still expected to occur and we will
continue to monitor conditions moving forward. Please continue to
monitor weather.gov/ajk/suicidebasin as well as social media for
any additional updates.
&&
.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...None.
&&
$$
SHORT TERM...GJS
LONG TERM....STJ
AVIATION...JLC
HYDROLOGY...GJS
Visit us at http://www.weather.gov/Juneau
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1100 PM EDT Thu Aug 3 2023
.SYNOPSIS...
As low pressure gradually tracks eastward across
southern Quebec, a cold front will approach overnight and move
across our region Friday afternoon into Friday evening. Multiple
rounds of showers and thunderstorms are expected, especially on
Friday. Some storms may become severe, with locally heavy rain also
possible. Fair and dry weather returns Saturday as high pressure
builds in.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
.UPDATE 1059 PM EDT...A weak warm front or thermal sfc trough
continues to lift north/northeast of the forecast area. The
strongest thunderstorms are over the Tug Hill Plateau moving
into the southern Adirondacks and Lake George Region. Small hail
(0.5-0.75") is possible along or north of the Mohawk River
Valley and possibly gusty winds 40 mph or so. Latest SPC
Mesoanalysis has MLCAPEs 500-1000 J/kg with 0-6 km effective
bulk shear 25-35 KT or so. PWATS have risen into the 1.2-1.4"
range. Some organized cells with marginally large hail or wind
gusts are possible over the northern most zones. The
thunderstorms/showers to the south of Albany continue to weaken.
Some adjustments to PoPs, cloud cover and weather with this
update. Some of the CAMs (3-km HRRR and ARW-WRF) continue to
have a line of showers and thunderstorms come through overnight,
and other do not with the prefrontal sfc trough. We kept small
hail and gusty winds in the forecast up to 06Z. Some flood
advisories may be needed for quick bursts of rain in the 1"/hr
or so time frame due to slow movement ahead of the disturbance.
Lows will be milder with mid 50s to lower to mid 60s.
.PREV DISCUSSION [335 PM EDT]...
Friday expected to be an active day. A stronger upper level
short wave is expected to approach from the north/west along
with an associated surface cold front. There will be ample
moisture with dewpoints in the 60s and PWATs between 1.25-1.50",
which are slightly above normal for early August. There should
be sufficient breaks in the clouds late morning/early afternoon
to result in moderate levels of instability by mid/late
afternoon. HREF mean SBCAPE forecast to be 1200-2000 J/Kg, with
0-6 km shear of 25-35 kt. So the CAPE/shear balance looks good
to sustain organized convection. Even pockets of 700-500 mb
lapse rates of 6.5-7.0 degC/Km forecast in the afternoon, so
large hail will be a threat along with damaging wind gusts.
There remains a Slight Risk (level 2 of 5) from the Storm
Predication Center for most of the area.
Localized flash flooding is a secondary threat with possible
multiple rounds of storms with downpours in some locations. The
Weather Prediction Center has a Marginal Risk of excessive
rainfall for the entire area. Greatest concern will be where
repeated downpours move across the same areas, but should be
rather isolated. High temperatures should reach in the upper 70s
for valleys, although it will feel more humid compared to the
previous several days.
Showers and storms should end from NW to SE early to mid
evening Friday, as the disturbance and cold front move east well
into New England. Winds will shift to the northwest behind the
system, with drier air filtering in overnight. Lows look to be
in the 50s to lower 60s.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Northwest flow continues on Saturday, although it will be much
drier and more neutral than cyclonic flow. Also, surface high
pressure will be building E/SE from the Great Lakes. So
subsidence will lead to pleasant mid-summer conditions with high
temperatures near normal (lower 80s in valleys) with
comfortable humidity levels (dewpoints in the 50s to lower 60s)
and a NW breeze around 10 mph. Dry and cool conditions expected
Sat night, as high pressure settles in. Lows will be in the
upper 40s to upper 50s.
Sunday should be another dry and mostly sunny day, with high
pressure gradually moving east across the area. The flow aloft
turns more westerly, with humidity levels remaining comfortable
and high temperatures near normal.
Sunday night looks to be milder, as a southerly flow develops
around high pressure departing off the New England coast. Most
of the area should remain dry, although a warm front approaching
from the south/west could bring a few showers to western areas
prior to daybreak Monday.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
The aforementioned warm front is expected to push north/east
across our area on Monday, as an unusually strong surface
cyclone (MSLP anomalies of -3 to -4 STDEV) tracks eastward
across SE Canada into the lower Great Lakes. The warm front will
bring a chance of showers/T-storms into the day, but timing
differences in the guidance make it difficult to determine when
the system`s cold front will pass through. At this time, the
best potential for strong to severe storms in the warm sector
look to be across western/central NY through Mon. This is still
four days out, so will continue to monitor. Due to the unusual
strength of the cyclone severe storms are possible. Locally
heavy rainfall will be another threat, with PWAT anomalies
increasing to +1 to +2 STDEV.
The system might be east of our area by Tuesday, but will
mention lingering chance PoPs due to some slower guidance
indicating the cold front passing through early in the day.
Wednesday looks dry as high pressure builds in from the
south/west. Forecast confidence decreases by Thursday, as it
depends on the timing for when a potential system approaching
from the west moves in. For now will only mention slight/low
chance PoPs until guidance becomes more clear. Temperatures
expected to be near normal through much of next week.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00z Saturday...VFR conditions currently prevail at all
terminals and likely will for the next several hours. Most
recent radar scans show a few thunderstorms that may threaten to
disturb the unrestricted flight conditions at KGFL, though
trends are pointing to storms remaining south of the terminal
boundaries. Will monitor trends and amend where necessary to
account for worsening conditions.
A good deal of uncertainty exists with this forecast,
specifically as it pertains to the possibility of additional
showers during the overnight period. Models are not portraying
a consistent solution which has made it difficult to form a
confident conclusion surrounding changes to flight categories.
At present, radar trends and more HiRes guidance points to a
chance that KGFL/KALB/KPSF experience brief periods of light
showers later tonight that could worsen conditions enough to
meet MVFR thresholds. Included TEMPO groups into the TAFs where
appropriate.
Confidence is also a bit on the low side surrounding mist/fog
formation. Though some models indicate the consistency of a
light breeze overnight that could inhibit mist/fog formation,
others indicate a decrease in wind speeds that could allow its
formation. Indicated the possibility at KGFL and KPSF where
climatology suggests conditions could be favorable to meet IFR
thresholds as a result.
Tomorrow, the chance for more widespread showers and
thunderstorms increases. PROB30 groups were added to the TAFs to
account for thunderstorm chances in the afternoon and early
evening. Stronger storms could yield as low as LIFR conditions,
but maintained IFR for now until lead time decreases and
influence of storms becomes more clear.
Throughout the 00z TAF period, winds will be mainly out of the
southwest, spanning a range of sustained speeds of 5-10 kt.
Stronger gusts are likely with thunderstorms that pass over
terminals tomorrow afternoon and evening.
Outlook...
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Moderate Operational Impact. Breezy. Chance of SHRA...TSRA.
Monday Night: High Operational Impact. Breezy. Likely SHRA...TSRA.
Tuesday: Moderate Operational Impact. Breezy. Chance of
SHRA...TSRA.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...JPV/Wasula
NEAR TERM...JPV/Wasula
SHORT TERM...JPV
LONG TERM...JPV
AVIATION...Gant
Area Forecast Discussion
National Weather Service Boston/Norton MA
929 PM EDT Thu Aug 3 2023
.SYNOPSIS...
A few showers moves across the region overnight, mainly
northwest of the I95 corridor. Otherwise mostly dry tonight.
Cold frontal passage brings more widespread showers and
thunderstorms Friday afternoon and evening. Mainly quiet this
weekend before more rain chances develop sometime early next
week.
&&
.NEAR TERM /UNTIL 5 AM FRIDAY MORNING/...
930 PM update...
Very pleasant evening with southerly winds and increasing clouds
yielding milder conditions than previous nights. Temps mainly
65-70 at 9 PM and given the parameters mentioned above, not much
more of a temp drop overnight. Mainly dry across MA/RI/CT this
evening. Lots of upstream convection across NY state into VT,
with most of this activity remaining north of our region
overnight. A new area of light showers just north of NYC is
moving NE and this will enter CT shortly. This area of showers
is likely to expand overnight in response to a modest low/mid
level SSW jet developing. This conveyor belt of moisture will
advect NE and yield scattered showers overnight, mainly NW of
I95. Previous forecast captures this well, so no major changes
with this forecast update. Earlier discussion below.
---------------------------------------------------------------
Previous Discussion...
Generally dry weather is expected for much of the area this
evening though some showers are likely to stray into western and
central MA as the leading edge of our next shortwave trough
rotates in from the west. HREF ensemble members, such as the
HRRR and the NSSL WRF, are all over the place regarding shower
coverage into the daylight hours of tomorrow, ranging from
mostly dry to widespread light shower activity into the I-95
corridor. 925mb jet developing overnight will preclude winds
from decoupling in most locations, with breezy conditions
overnight, though increasing clouds and dewpoints in the upper
50s will limit radiational cooling like we`ve seen the past few
nights regardless of if winds are able to slacken.
With the "supermoon" still near full, coastal flooding will
again be a risk this evening with the overnight high tide around
1:30 am. Thus, we have hoisted a coastal flood statement for
the eastern Massachusetts coast from Essex County to Cape Cod.
&&
.SHORT TERM /5 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
A few rounds of rain are possible tomorrow, though the threat for
flooding rain in training storms, especially during the first half
of the day, has weakened considerably with the latest suite of
guidance. While there will be healthy LLJ in place, of 25-30kt at
925mb, interacting with an approaching cold front, PWATs are less
than impressive, maxing out at ~1.5" or ~120% of normal, on the
leading edge of the shortwave. Hi-Res guidance has taken several
steps back in both coverage and intensity of showers through early
afternoon, with some guidance trending completely dry through almost
22Z (the HRRR). While we of course can`t use one model run to deduce
the threat for downpours, the 24 hour prob match mean QPF is also
lackluster, with hardly any "bullseyes" of greater than 1" present
anywhere near our CWA. It appears that the greatest threat for more
significant precipitation will be to our north across central NH,
where the LLJ runs up against the White Mountains ahead of the
front. Additionally, the anomolously dry stretch of weather we had
this week has allowed FFG to recover considerably, with 1-HR FFG
approaching or exceeding 2" in many areas; except for portions of
central and western MA where it remains 1.5". Still, given we are
anticipating widespread QPF totals of only 0.5-1.0", we will be
hard pressed to find opportunities for flash flooding outside
of urban areas that happen to be hard hit by a downpour. It is
for these reasons that we collaborated with both neighboring
WFOs and WPC to drop the slight ERO for our area, favoring a
more marginal risk for flooding. Given the deescalating risk
for heavy rains, we also elected to forgo a flood watch. Should
guidance swing wildly in a wetter direction this evening, the
overnight shift may consider additional headlines.
The second, and likely more robust, chance for rain comes late
tomorrow evening into the early overnight hours along a mainly
linear line of convection developing along the cold front;
though, a few discrete showers are possible ahead of the line.
Like most convective events we experience, the potency of this
line will be impacted greatly by time of arrival, with much of
instability waning after sunset. Additionally, rather robust
cloud cover tomorrow will limit the convective potential, but we
should be able to muster up MUCAPE values of 1000-1500 j/kg.
This instability combined with ~100- 120 m2/s2 of 0-1km SRH and
mid level lapse rates of 6-6.5 degrees should be enough to allow
a few strong to severe storms to develop along the convective
line. Gusty, damaging winds will be the greatest risk tomorrow,
though we cant rule out some small hail.
While most instability wanes after sunset, there is a brief pulse of
MUCAPE back to ~1000 j/kg across SE MA and the Cape, indicating that
we may see a resurgence of thunderstorms after ~09Z, resulting in
some strong storms over the previously mentioned area as well of the
waters to kick of Saturday. Otherwise, a drying, clearing trend will
develop for much of the CWA prior to sunrise.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Highlights...
* Dry Saturday and Sunday. Temperatures near/slightly below normal
low humidity.
* Early next week temperatures trend near/slightly above normal with
higher humidity.
* Shower and storm chances return late Monday/Tuesday.
Details...
Saturday and Sunday...
Lovely weekend on tap thanks to building high pressure at the
surface and rising mid level heights. Dry northwest post frontal
flow will be in full swing by sunrise Saturday and continues through
most of the weekend. This as the mid level ridge axis moves from the
Great Lakes Saturday to New England late Sunday. This will provide
dry weather each day and plenty of sun, especially on Saturday. By
Sunday we`ll see more diurnal clouds given a surge of moisture at
850mb. Temperatures at that level will be around +12 to +13C which
will translate to highs in the mid 80s; right around normal for
early August. Dewpoints in the 50s and low 60s will make it feel
comfortable for most.
Monday through Thursday...
By the first half of the week we`ll see the mid level ridging
replaced by a trough which swings through SNE around Tuesday. Ahead
of this system we`ll see southerly return flow as early as Monday
morning advecting warm and moist air back into the region with
dewpoints once again climbing into the upper 60s/low 70s by late
Monday/Tuesday. Thus, expect much more cloudcover starting Monday
with warm frontal rain showers and thunderstorms late followed by a
cold front late Tuesday which will eventually usher in a drier
airmass. Given PWATs as high as 2+ inches and a 30-35kt LLJ, showers
late Mon/Tue have the potential to contain some very heavy
downpours. Wednesday and Thursday confidence is lower but things
once again look to dry out as ridging takes hold once again. No
signs of abnormal heat on the horizon.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update...
Tonight...High Confidence this evening with moderate confidence
after midnight.
Generally VFR, though areas of MVFR ceilings developing by
sunrise across the interior. Most terminals will remain dry at
any given hour, but isolated to scattered light showers may wet
runways, especially across the interior. S/SW winds will
maintain around 10kt overnight.
Friday and Friday night...Moderate Confidence.
Widespread MVFR with IFR developing, especially across western
Terminals. Rain will become more widespread ahead of an
approaching cold front, with showers and isolated thunderstorms
most likely across eastern terminals through about 18Z. A more
linear line of storms will develop across our western zones
between 17Z-19Z, traversing from northwest to southeast,
bringing showers and thunderstorms to most terminals through
04Z. S/SW winds gusting to 20 kt ahead of the front before
slackening and shifting to the NW behind the frontal passage.
This transition will again occur through ~04Z.
KBOS TAF...Moderate confidence in TAF.
Mainly VFR tonight before MVFR develops during the daylight
hours of Friday morning. Scattered showers and isolated
thunderstorms through 18Z. A more robust convective line
develops and approaches the terminal between 00-02Z. Utilized a
PROB30 group to account for uncertainty in the location of
convective cells.
KBDL TAF...High confidence in TAF.
Mainly VFR this evening, MVFR likely to develop before 12Z.
Generally dry Friday though a few showers possible before cold
frontal passage brings a linear line of showers and
thunderstorms through the terminal between 22-01Z. SW winds
gusting to 20 kt shifting to the NW behind the frontal passage.
Outlook /Saturday through Tuesday/...
Saturday through Sunday Night: VFR.
Monday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance SHRA.
Monday Night: Mainly VFR, with areas IFR possible. Breezy.
Chance SHRA, isolated TSRA.
Tuesday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, isolated TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Friday night...High Confidence.
S/SW gusting to 20 kt through Friday night; a few gusts to 25kt
possible across the extreme northeastern waters, though will be
intermittent and did not warrant a SCA extension. Seas
generally 2-4 ft though winds of up to 5 ft possible across the
outer waters.
Winds will shift abruptly to the NW and slacken considerably
behind a frontal passage between 02-06Z Saturday.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers.
Saturday Night through Monday: Winds less than 25 kt.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers, isolated thunderstorms.
Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Chance of rain showers, isolated
thunderstorms.
&&
.TIDES/COASTAL FLOODING...
Coastal flood statement in place across the eastern MA coastline
for tonight`s high tide. Given the full moon peaked last night,
we anticipate that this will be the last coastal flood statement
needed in association with the "Supermoon"
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ250.
&&
$$
SYNOPSIS...BW/KS
NEAR TERM...Nocera/BW/KS
SHORT TERM...KS
LONG TERM...BW
AVIATION...Nocera/BW/KS
MARINE...BW/JWD
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Dodge City KS
934 PM CDT Thu Aug 3 2023
...Updated Mesoscale...
.MESOSCALE DISCUSSION...
Issued at 934 PM CDT Thu Aug 3 2023
Infrared satellite imagery and lightning detection networks
indicated thunderstorms intensifying rapidly over east central
Colorado at 930 pm CDT, as combining outflows interact with
increasing instability with eastward extent. Severe thunderstorm
watch has been issued for all of SW KS, but per coordination with
SPC, confidence with convective coverage and wind damage is higher
along and north of K-96 through the overnight hours. While
instability is clearly stronger with southward extent toward
Oklahoma, nocturnally increasing capping may limit the southern
extent of activity. At any rate, strong outflow winds of 50-70 mph
are expected from the strongest storms, especially in proximity
to WFO Goodland`s CWA.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 202 PM CDT Thu Aug 3 2023
Main focus this afternoon will be overnight convection.
At 18z today a surface boundary/cold front was located south of
the Oklahoma border and extended from the Panhandle of Texas into
South Central Kansas. Several of the CAMs along with nearly 50%
of the HREF ensembles develop convection near this boundary across
southeast Colorado late today given the afternoon instability, a
moist easterly upslope flow and low level 0-1km moisture
convergence as an upper level trough exits the Rockies and moves
out into the West Central High Plains. Key item of interest is
that afternoon convection near this boundary and ahead of an upper
level trough was already developing over the Raton Mesa at 18z.
Given this verification, location of the surface boundary and high
theta-e ridge axis being located north of the boundary and in
extreme southwest Kansas will be expanding the higher probability
for storms tonight (50-70%) southward all the way to the Oklahoma
border and favor the HRRR trends for convection moving into
southwest Kansas between 01z and 03z. Although the northern storms
that will be crossing west central and north central Kansas will
have a higher probability of producing heavy rainfall given
current precipitable water values 1.5 or higher… any storm this
evening across western Kansas will be capable of producing wind
gusts in excess of 60 mph. Hail may also be possible prior to
sunset and given the current timing it appears that the better
chances for this large hail will be near or west of the Colorado
border.
These thunderstorms will increase in coverage as they cross
western Kansas, especially near and north of the mid level
baroclinic zone that will be located north and east of the Dodge
City area. This would be an area later shifts may wish to monitor
for possible water issues if widespread convection does occur and
lingers for several hours after midnight.
This overnight convection will taper off early Friday morning
east of Dodge City. Confidence is low (<30%) on when the exact
timing of when this precipitation will end but based on the latest
CAMS this precipitation should end by 15z Friday at the latest.
As the convection ends the skies will clear. Given the potential
cloud cover on Friday, early morning convection and where the
clusters of the SREF temperature plumes are forecast to be am
currently leaning towards to cooler 25th to 50th percentile NBM
guidance for highs.
For Friday night will be monitoring another upper wave moving out
of the Rockies and into the West Central High Plains which will
once again bring with it another round of thunderstorms to
southwest Kansas. At this time am unsure just how quickly the
atmosphere will recover from the previous nights convection but
the potential does exist that a few of these storms could be
strong or even marginally severe in the evening as they move into
west central Kansas.
.LONG TERM...(Saturday through Thursday)
Issued at 202 PM CDT Thu Aug 3 2023
Main items of interest in the later periods will be that the wet
weather pattern will continue through early next week and
temperatures will be unseasonably cool.
For the start of the weekend period the ensemble trends remain
similar to the past several runs with an upper ridge building over
the Western United States. This will allow a northwest flow aloft
across Western Kansas to develop while at the surface a
southeasterly upslope flow will be establishing itself across
southwest Kansas and eastern Colorado. Both the ECMWF and GFS
ensembles continue to indicate a decent upper level trough exiting
the Rockies and moving out into the Plains Saturday night and
given the environmental setup conditions will be favorable for
widespread rainfall along with strong damaging winds and hail. At
this time, it is still a little early to pinpoint the exact track
of these storms as they cross western Kansas but based on the
general location of the 700mb temperature gradient and 850mb winds
from ensembles and the latest deterministic runs it looks like
most of western Kansas will have the best opportunity (60% to 70%)
for precipitation. Strong to severe thunderstorms along with
widespread rainfall can also be expected with these storms
Saturday night.
From Sunday through early next week the only big changes in the
weather pattern will the location of the mid level baroclinic
zone. Typically, what happens is that with each cluster of
overnight thunderstorms the mid levels cool and then when our next
in a series of upper level waves move out into the plains the
track of the next cluster of strong to severe thunderstorms will
end up being further south. This is not always the case but does
happen often. The latest guidance now appears to be picking up on
this trend with the highest chances for precipitation Saturday
night (>50%) northeast of the Dodge City area decreasing to less
than 30 percent by Monday. Southwest of Dodge City the chances
will increase from <30% Saturday night to >50% for Sunday night
and Monday night. This wet weather pattern should be coming to an
end by the middle of next week as the upper level trough over the
Western United States moves east towards the Rockies.
As for temperatures...a cold front will drop south into the
panhandle of Texas and western Kansas Friday night with a
reinforcement of cooler air invading southwest Kansas late this
weekend following our Saturday night widespread rain event. This
cooler air will then remain in place as several more opportunities
for convection crosses southwest Kansas through early next week.
Cloud cover combined with the reinforcement of cooler air late
this weekend into early next week will favor unseasonably cool
temperatures (highs on Monday only in the upper 70s to mid 80s)
for all of western Kansas. Warmer temperatures will start to
return towards mid week as the precipitation chances end and an
upper ridge starts to build into the Rockies.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 515 PM CDT Thu Aug 3 2023
VFR will prevail through this TAF cycle, with varying amounts of
midlevel clouds. Scattered thunderstorm potential is expected
overnight during the 00-12z Fri time range. Convection is expected
to propogate eastward out of eastern Colorado. Using the 12z ARW
as a guide, included VCTS/CB mention in this TAF update. Highest
confidence of convective impacts is at HYS where a convective
TEMPO group was included during the 06-10z Fri time range. Primary
impact from convection will be outflow winds of 45-55 kts. Outside
of convective outflows, light northeast winds will prevail through
much of this TAF cycle.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 67 94 68 95 / 70 10 20 20
GCK 66 90 67 93 / 70 10 20 20
EHA 64 95 66 95 / 60 0 10 10
LBL 67 94 68 97 / 50 10 20 10
HYS 68 92 68 93 / 70 20 30 20
P28 72 97 72 98 / 20 20 20 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...Turner
SHORT TERM...Burgert
LONG TERM...Burgert
AVIATION...Turner
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
636 PM CDT Thu Aug 3 2023
.Discussion...
Issued at 411 PM CDT THU AUG 3 2023
Key Messages:
- Scattered Thunderstorm Activity Late This Afternoon
- Hot and Humid Conditions; Heat Advisory Southwest Forecast Area
Friday
- Overnight Convection Possible; Marginal Severe Threat
- Active Storms Saturday Evening; Severe Storms Possible
Discussion:
The western two-thirds of the CONUS is dominated by an H5 ridge
that has allowed this hot and humid airmass to remain in place
across the region. The current 594dam contour is analyzed from
Central Texas to the lower Mississippi River Valley. There are a few
short-wave troughs that have been traversing across the Canadian
Prairie Provinces and these have been just strong enough to attempt
to deamplify the H5 ridge across the area. As this has been
happening, multiple localized vorticity maxes have been ejecting
from the Rockies across the Plains and into the Great Lakes. The
first wave is starting to move into Iowa, with a remnant MCV
currently in northeastern Kansas from the convection last night that
has dissipated. Expect scattered activity to develop this afternoon
in response to pockets of diurnal heating where the lingering cloud
cover was able to break apart. Would not expect convection this
afternoon to amount to any appreciable severe threat, as the lapse
rates are very weak and at the moment deep layer shear is not overly
impressive. At the surface, there is a stalled thermal boundary over
the lower third of the CWA and can be noted on GOES 16 visible
satellite imagery rather easily. Areas in southern and far
southwestern MO and southeastern Kansas have been mostly clear
through the afternoon. The remnant convection from this morning has
been on the cool side of the boundary, and outflow from this has
helped to reinforce the boundary and prevent further northward
movement. The weak surface cyclone over Kansas has also stalled as
there is not much in the way of available steering flow.
Differential heating has helped to strengthen convergence along this
boundary throughout the afternoon and there has been some
insentropic ascent that supported weak showers. However, a strong
cap remains in place along with these weak lapse rates that has kept
showers short-lived and relatively weak. Currently watching another
short-wave trough coming off the Front Range that is expected to
provide strong thunderstorms across portions of the High Plains and
Central Plains late this afternoon and evening. This short-wave is
progged to reach our area late this evening and overnight. Mid-level
CVA has been increasing through this afternoon, and the notable H5
height falls should start after 00z this evening for our counties in
eastern Kansas and west-central Missouri. Favorable kinematics are
expected along this short-wave, with 0-6km bulk shear increasing to
around 35 kts in the vicinity of the surface boundary. However, the
thermodynamics are not looking overly impressive. The lack of any
mid-level cooling will keep lapse rates throughout much of the
troposphere weak. MUCAPE values as progged by the RAP have been in
the ballpark of 1000-1500 J/kg, and HREF mean values have been
similar. South of the thermal boundary, MUCAPE values may reach 2500
J/kg, but the supportive mid-level forcing may not dig far enough
south for that to be realized. The potential for storms late this
evening will be dependent on either the surface boundary`s ability
to break the cap, or the LLJ to organize Central Plains activity and
maintain an MCS system eastward into the forecast area. If storms
either break the cap or an MCS holds together, mainly looking at
wind gusts of 60-70 MPH and perhaps hail up to quarter size. CAMs
continue to struggle to handle storms well, thus leading to lower
confidence in timing and intensity of storms. With respect to QPF,
HREF mean values are holding around 0.25 inches, and local
probability matched-mean values up to 0.75 inches. Most of this QPF
should be west of the heavy axis of rainfall from earlier in the
week. Although the CAMs have been struggling with convection, feel
that based on the current setup these rainfall amounts are a
reasonable estimate.
Friday morning and afternoon, would expect convection to dissipate
as it moves eastward along with the short-wave. If a stronger MCS
remains organized, it may still pose a threat for low-end severe
wind gusts past 12z. Once the first wave passes, a brief period of
subsidence is likely during the early afternoon with H5 height rises.
However another short-wave will be in the works over the Central
Plains again and will provide diffluent flow by the middle of the
afternoon. If the surface boundary remains in place, this may
provide forcing for additional storm develop Friday afternoon and
into the evening. The 18z HRRR attempts to develop strong convection
around 22z Friday afternoon, but has been bouncing around in its
solutions. This is mainly tied to thermodynamic recovery with the
morning MCS (or lack there of). If there is clearing Friday
afternoon, would expect more potential for stronger storms to
produce strong wind and some hail. The threat for severe storms
remains conditional on being able to destabilize, and is very
difficult to try and depict mesoscale details Friday afternoon into
evening.
More H5 short-wave pulses move across the region on Saturday. As
these kinematic features move across a high theta-e airmass, shower
and thunderstorm potential will continue. The deterministic GFS and
NAM are attempting to lock onto a stronger vort max Saturday late in
the evening across the area. Deep layer shear increases as this
short-wave moves through, which could support robust updrafts and
lapse rates improve. As with the previous two days, this will be
very conditional on the preceding activity and ability of the
boundary layer to recover. If the surface thermal boundary remains
in place, this may help provide a source of lift for stronger
storms. GEFS and other ensembles have probabilities above 80 percent
for at least 0.1 inch of QPF across most of the area, which
increases confidence in at least seeing precipitation activity on
Saturday. Current probabilities for exceeding 0.50 inches are less
than 20 percent, which should limit flooding threat across eastern
portions of the forecast that saw flooding earlier this week.
However if stronger thunderstorms become efficient rain producers,
this may alter the hydro threat heading into Saturday.
For the remainder of the week, the 594 dam high retrogrades toward
the Four Corners Region as more short-waves moves across the
Canadian Prairie Provinces. This eventually takes away the ridge
over our region and provides mainly zonal flow. However, a few more
short-waves and vort maxes are likely to sneak through the zonal
flow which will introduce periodic chances for rain showers and
thunderstorms.
&&
.Aviation...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 635 PM CDT THU AUG 3 2023
Scattered showers continue around the KC metro, so have continued
VCSH through 3z this evening. Another round of showers and
possibly thunderstorms will be possible Friday morning. Brief
periods of MVFR CIGs may be possible early Friday morning, but
have kept the KC metro terminals VFR (went with BKN025 at STJ).
Light winds out of the northeast are expected through the period.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory until 8 PM CDT this evening for KSZ057-060.
Heat Advisory from noon to 8 PM CDT Friday for KSZ057-060.
MO...Heat Advisory until 8 PM CDT this evening for MOZ053.
Heat Advisory from noon to 8 PM CDT Friday for MOZ053.
&&
$$
Discussion...Krull
Aviation...BMW
Area Forecast Discussion
National Weather Service Green Bay WI
1032 PM CDT Thu Aug 3 2023
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Friday
Issued at 231 PM CDT Thu Aug 3 2023
As was expected, isolated to scattered thunderstorms will be the
initial focus to begin the short term portion of the forecast for
late this afternoon into the early evening.
A shortwave impulse is currently dropping southeast over southwest
Quebec Province with an associated upper-level jet maximum
currently moving southeast across eastern Upper Michigan and
northern Lake Michigan. The RRQ of this feature is helping to
provide some weak synoptic scale upward motion in concert with
some focused boundary layer lift associated with a cold dropping
southward across the forecast area. Along and ahead of the
frontal boundary SBCAPES were pushing 2500 J/Kg (RAP) with 0-6
shear of 25-30 kts over northeast/eastcentral Wisconsin. Local
RAP soundings indicated inverted-V profiles which would favor a
greater strong wind gust potential. Near storm environment is
certainly favorable for a few isolated storms to get close to
severe limits for the next couple of hours in this area. PWs are
still holding in the 1.25" range with winds in the lower half of
the troposphere somewhat weak, so precipitation efficiency will be
favorable for some brief torrential downpours. West of the Fox
Valley, overall forcing is weaker in general, thus storms will be
weaker and be more isolated in nature.
CAM guidance suggests surface frontal boundary should drop south
of the forecast area by around 02-03Z so anticipate isolated to
scattered convection to end with skies gradually clearing
overnight.
Some patchy fog still seems plausible, especially over parts of
northcentral Wisconsin as residual boundary layer moisture will
likely linger and winds become light after midnight.
To end the work week, Friday should be a decent day with daytime
highs mostly in the low to middle 80s with more comfortable
dewpoints falling into the upper 50s by later in the afternoon.
.LONG TERM...Friday Night Through Thursday
Issued at 231 PM CDT Thu Aug 3 2023
The main focus of the extended period will be the active weather
potential over the weekend. Behind this quiet weather will start
off the upcoming work week before the next chance for rain crosses
by the midweek.
Surface high pressure will still be in the region Friday night
into Saturday morning, making for a dry start to the extended
period. Skies will likely be cloudy through the day as a
strengthening low pressure system brings in warm air aloft, which
will limit daytime highs to the lower to middle 80s for most of
the region. Warm air advection will likely bring a few showers
into the region by Saturday evening as the warm front lifts into
the region. Precipitation coverage then increases through the
overnight hours but will mostly remain light as convective potential
will be fairly limited during this period. By Sunday morning, the
low pressure system will begin to occlude and slow down,
prolonging precipitation through much of Sunday. Dynamics will
improve over the day Sunday as the low passes over Wisconsin,
bringing in fairly strong vorticity advection as the colder air on
the backside of this system begins to filter in behind this
system. As a result, there could be some potential for severe
weather, especially if we can develop any better instability
during the day. Another concern will be the potential for very
high rainfall totals. This system will have access to Gulf
moisture for much of Sunday as additional convection develops,
and with PWATs pushing 1.75-2.25 inches, heavy rainfall will be
possible much of the day Sunday. Much of central to east-central
WI is in the Day 4 Slight Risk for excessive rainfall. There is
still some time for the axis of the heaviest rain to shift with
the warm front in the next few days, but confidence is growing
that widespread heavy rainfall will be something to watch for this
weekend.
Behind this system, quieter weather will be in place to start off
the work week. Temperatures will remain a few degrees below normal
early next week, ranging from the lower to upper 70s by the middle
of the week. Models do bring another shortwave through the region
by the middle of the week, but the timing on this is still fairly
uncertain.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1032 PM CDT Thu Aug 3 2023
VFR conditions are expected during the TAF period as showers and
thunderstorms have pushed south of the area. Some patchy fog may
again be possible after midnight, especially at RHI. Mostly sunny
skies and VFR conditions should prevail on Friday as high
pressure builds in across the area.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM.....ESB
LONG TERM......Uhlmann
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Gray ME
1031 PM EDT Thu Aug 3 2023
.SYNOPSIS...
A warm front will pass north of the region today bringing warmer
temperatures...more humidity and the chance for a evening
showers and thunderstorms. A cold front will approach the
region tomorrow and push through tomorrow night with more
widespread showers and thunderstorms. Drier air will move back
into the region behind this front for the weekend with high
pressure and comfortable temperatures expected.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
1030 PM Update...
Have raised pops again across portions of the forecast area.
Latest radar imagery showslight precipitation continuing along
and near the coast with heavier precipitation in thunderstorms
in the Connecticut River Valley north of Lebanon and moving
east. An SPS has been issued for gusty winds with this system.
The latest HRRR does have this area of storms gradually
weakening during the overnight hours.
Update...
Have updated the forecast to increase pops for this evening and
the overnight hours across the region. Latest radar imagery
continues to show showers crossing portions of Maine and New
Hampshire, with convection lingering to the west over Vermont.
This convection should weaken this evening, however have
increased the chances for thunder over portions of the Granite
State as this precipitation heads east. Made minor adjustments
to the near term portion of the forecast in terms of
temperatures, dew points and winds.
Prev Disc...
Front draping across the CWA tonight will be fairly underwhelming,
but play a big role in events on Friday. Not a lot of
instability to work with for additional shower or thunderstorm
development tonight, but can’t rule out a stronger shower that
drops a fair bit of rain in a short period. Lows tonight should
fall into the lower 60s or upper 50s as additional cloud cover
and breeze helps to insulate from much radiational cooling.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
How far east this boundary makes it tonight will play a role in
how Friday’s rain event takes place. Still remains much
uncertainty on positioning of heavier rainfall, but confidence
is high that a isolated flash flooding may result where stronger
showers or storms track over the same place for a period of
time. While PWATs and dewpoint temps will be lower than previous
events, some kinematics support slower cell movement.
Backbuilding will be possible should instability prove to
develop into the afternoon despite the chance for abundant cloud
cover in the AM.
NBM and some members of the HREF outline a region of southern
NH into coastal ME as locations that could see some of these
training showers or storms. CAPE wants to develop most over this
portion of southern NH, with a gradient tapering into the Lakes
Region of ME. Thus included heavy rain wording with
thunderstorms here for tomorrow afternoon and early evening.
Should be noted that 12z HREF guidance backed off on its 3hr FFG
exceeding probs, and flash flooding threat looks to be more
isolated than widely scattered. With stiff LLJ sitting just off
the coast tomorrow afternoon, any sea breeze or coastal front
that develops could very well be the forcing line to zipper or
maintain some of these heavier showers along. Additionally,
terrain such as the Whites can act as lift amid an otherwise
messy frontal passage. Definitely not counting out flash
flooding potential, so attention should be paid to any warnings
or advisories that are issued.
As far as stronger to severe storm potential, the best overlap
of ingredients appears to be mainly the southern half of NH.
Deep shear is marginal, but low level shear approaches 30 kts.
With tall skinny CAPE profiles and mid/low level lapse rates
cooperating, some wet microburst potential is there should a
stronger core develop. Just how much instability develops is in
question as cloud cover may be broken to overcast come sunrise
due to nearby precipitation along the front.
Deeper moisture will be moved away as upper trough transits
into New England. This should have much of the precip tapering
off into midnight or shortly after. Upper jet will assist in
moving drier air into the region. Overnight lows appear close to
those that are expected tonight.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Overview: Relatively progressive flow expected with
across the Northeast with multiple shortwave troughs passing
through the region. Temperatures will general be near seasonal
normals through this period with cool comfortable conditions
this weekend transitioning to more muggy conditions by the
beginning of next week.
Impacts: No weather impacts expected through the weekend with
high pressure firmly in control. Next chance for impactful
weather will be Monday night into Tuesday as the next trough and
cold front approaches the region. A moist unstable airmass will
move into the region on strong southerly flow, which could bring
the chance for strong thunderstorms and locally heavy rain.
Quieter weather is expected for Wednesday into Thursday.
Forecast Details:
Saturday looks like a nice day as the cold front pushes off the
coast with all rain shower activity coming to an end. The upper
level will still be in vicinity across Quebec province, so
daytime instability clouds are expected to develop over most of
the area with a stray shower or sprinkle possible, but overall
looks to be a nice day. 500mb ridge axis moves overhead on
Sunday along with surface high pressure bringing a fantastic
Sunday, will be a great day to enjoy the outdoors with low
humidity. Return flow becomes established on Monday ahead of the
next 500mb shortwave trough in the Ohio River Valley.
Temperatures and dewpoints will quickly surge upward on Monday
with strong WAA at all levels. Looks like PWATS could surge up
to 1.5" by Monday night with dewpoints reaching back into the
upper 60s and maybe even 70 degrees in Southern New Hampshire.
Confidence on timing of next cold front and how progressive the
wave is still relatively low. But looks like Tuesday will have
the best chance for thunderstorm activity. Looks like broad
cyclonic trough in the mid-levels becomes established Wednesday
through Thursday with the potential for afternoon showers across
the interior with temperatures trending cooler.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term...VFR tonight with some VCSH or -SHRA. Can`t rule out
some VCFG for areas that receive rain this evening and cool
overnight, mainly valley locations such as HIE, LEB, CON.
Ceilings trend towards MVFR early Friday morning, some IFR
possible at AUG/LEB/HIE as day progresses. Additionally, RA may
be heavy at times with low vis Fri afternoon with TS.
Long Term...No significant aviation impacts are expected over the
weekend with northwest flow bringing dry air to the region. Next
chance for impactful aviation weather will most likely be Monday
night next week as a possible marine push brings low ceilings and
visibility to coastal TAF sites.
&&
.MARINE...
Short Term...Front will approach the waters this evening,
remaining in vicinity through Friday. It will finally clear the
waters Friday evening. Onshore flow will allow waves to build
through tonight and Friday, leading to waves 4 to 5 ft on the
outer waters. Have extended SCA through tomorrow afternoon.
Long Term...A cold front will push through the coastal waters early
Saturday morning, with a general offshore flow over the weekend.
Seas and winds will stay below SCA conditions. Next weather maker
will approach the region late Monday night with strong onshore flow
and the potential for fog formation and strong SCA level southerly
winds.
&&
.TIDES/COASTAL FLOODING...
Expect a very similar situation for the high tide cycle tonight
given water levels a few inches above astronomical tide
forecasts. Onshore flow continues tonight, and have leaned
towards ETSS output as it fits closer to current obs.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 8 PM EDT Friday for ANZ150-152>154.
&&
$$
NEAR/SHORT TERM...Cannon
LONG TERM...Dumont
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
625 PM CDT Thu Aug 3 2023
...Aviation Update...
.SYNOPSIS...
Issued at 324 PM CDT Thu Aug 3 2023
Key Messages:
- Severe storms possible tonight with damaging winds, large hail and
heavy rain possible.
- Marginal risk for severe storms Friday afternoon/evening.
- Another threat for severe storms Saturday afternoon/evening
mainly over eastern and and southeastern portions of the
forecast area.
H5 analysis this morning had high pressure anchored over the
Arklatex with a ridge extending north into the Ozarks and
southeastern Kansas. Further west, a closed area of low pressure was
located over eastern Idaho. Downstream of this feature, a weaker
shortwave trough extended from central Nebraska into northern
Kansas. Both of these features were south of a northern stream ridge
which extended from south central Canada, north into eastern
portions of the NW Territories of Canada. Another feature of note
this morning was a weak shortwave off the coast of northern
California. At the surface, a quasi-stationary front extended from
the northern Texas Panhandle, east-northeast into far southern
Kansas and the central Ozarks. This afternoon, a weak surface trough
extended from the western Panhandle into far southwestern Nebraska.
Skies were partly to mostly cloudy across western and north central
Nebraska this afternoon. Temperatures as of 2 AM CDT, ranged from 79
degrees at Gordon to 85 degrees at Imperial.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 324 PM CDT Thu Aug 3 2023
The threat for severe storms and possibly heavy rain tonight are
the main forecast concerns. Late this afternoon, a lead shortwave,
associated with the closed low over eastern Idaho, will cross
northern Colorado and southern Wyoming. Thunderstorms are expected
to initiate along the I25 corridor from eastern Wyoming to Denver
around 20z this afternoon. Activity will approach the western
border of the forecast area around 23z this evening, hitting the
highway 83 corridor in the 02z to 04z time frame. The latest HRRR
runs this morning along with support from the 4KM NAM and NAM12
solns have slowed down the onset of thunderstorms tonight. Taking
these solns into account, keeps storms out of the forecast area
through 23z this evening. Activity crosses into the eastern
panhandle around 00z, then hits the highway 83 corridor around 03z
this evening. With the later expected timing, went ahead and made
adjustments to this afternoon`s forecast and slowed down the
progression of storms tonight. With respect to the threat for
severe storms tonight, two main modes/hazards are expected. First,
there will be a threat for large hail, mainly west of highway 61
early this evening as there is a threat for more discrete storms
in these areas. Mid level lapse rates along with SB CAPE of
1500+J/KG, straight hodographs and effective bulk shear of 30 KTS
will be enough to support this threat. Second, as the evening
progresses, these storms are expected to congeal into a line as
they approach the highway 83 corridor. The latest NAM12 soln this
morning is indicating a nice area of downdraft CAPE in excess of
1000j/kg across southwestern Nebraska and northwestern KS this
evening which would facilitate strong winds. The HRRR runs this
morning, along with the 12z-4km NAM soln is also indicating some
bowing structures with their forecast reflectivity products later
this evening. These signatures are most prolific from far SW
Nebraska into northern Kansas. Another concern for tonight`s
forecast is the threat for flood potential across portions of
southwestern Nebraska. Locations across Frontier, Hayes and
portions of Lincoln county, saw rainfall amounts of 2 to as much
as 5 inches of rainfall last night. The heaviest rainfall was from
eastern Hayes, into Frontier county. This was on top of heavy
rain which also occurred Tuesday night from far eastern Hayes into
Frontier county. With the heavy rain in these areas over the past
couple of nights, am concerned with flash flooding potential
tonight. Forecast PWAT`s are between 1.25 and 1.5 inches early
this evening in SW Nebraska, so plenty of moisture is available
for heavy rain. With this in mind and after conversing with
emergency management, will hoist a flood watch for Hayes and
Frontier counties for tonight through Friday morning. There still
is the potential for 1 to 2 inches of rainfall in these areas,
although storm motion should be faster tonight compared to last
night. On Friday the upper level low will track into northwestern
South Dakota. Showers and thunderstorms from the overnight will
gradually lift east of the forecast area by mid morning in the
eastern forecast area. Slightly drier air aloft will try to push
into the area Friday, however, southerly low level winds will
allow boundary layer air to remain in place across the area. PWATS
Friday afternoon will be around 1.25 inches. Slightly less than
tonight`s but still enough moisture to support precipitation and
thunderstorm development Friday afternoon/night. With afternoon
heating and destabilization ahead of a shortwave rotating around
the southern periphery of the upper level low, thunderstorms will
develop Friday afternoon over the higher terrain of eastern
Wyoming, western Nebraska and northeastern Colorado. Aided by a
weak frontal passage, storms will track east into the evening and
nighttime hours. Storm coverage Friday night is expected to be
less than tonight`s as low level moisture is not as robust. Severe
storms will remain in play Friday night as surface to 6 KM shear
remains in the 30 to 35 KT range.
.LONG TERM...(Saturday through Thursday)
Issued at 324 PM CDT Thu Aug 3 2023
A second, stronger cold front will be forced through the forecast
area Saturday. Showers and thunderstorms will fire INVOF this
feature Saturday afternoon and evening. As was the case overnight,
this feature is faster compared to yesterdays model runs. That
being said the severe threat appears to be south and east of the
forecast area. Northwesterly flow aloft will develop early next
week and persist through midweek. The pattern will amplify
somewhat with a trough developing across the upper midwest into
the Ohio Valley. High pressure, currently over the Arklatex, will
drift west into northern Mexico and the southwestern CONUS midweek
amplifying a ridge across the western third of the CONUS. The
northwesterly flow will be fairly active with periodic
disturbances bringing daily precipitation chances to the Central
Plains. Temperatures will be below normal in the extended periods
with highs in the 70s Sunday and Monday, transitioning to 70s to
lower 80s Tuesday, Wednesday and Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 624 PM CDT Thu Aug 3 2023
Thunderstorms on the CO/WY high Plains this evening are expected
to move east through wrn and ncntl Nebraska overnight. Storm
activity is expected to become more numerous across wrn Nebraska
as it develops into a north-south line of storms. This process
should be underway by 02z-03z this evening. It is worth noting
this forecast may not verify. Storms could remain mostly isolated
as they move east overnight. Whatever develops should exit ncntl
Nebraska by 12z-15z Friday morning.
An area of MVFR/IFR ceilings are expected to develop across wrn
and ncntl Nebraska 09z-15z Friday morning affecting areas south of
highway 20. VFR/local MVFR should be widespread by 18z.
Isolated thunderstorms are possible west of highway 61 Friday
afternoon; from about 21z onward.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday morning for NEZ070-071.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1052 PM CDT Thu Aug 3 2023
.UPDATE...
Issued at 724 PM CDT Thu Aug 3 2023
...Increasing heavy rain and flash flood threat tonight, as well
as increasing severe weather potential...
A flash flood watch has been issued from portions of central MO
across all of southeast MO into southern IL from 03-14z. The
latest surface analysis shows a well-defined quasi-stationary
front draped from southern KS across southern MO. The air mass
along and south of this front is very unstable at this time with
SBCAPE of 5000+ J/KG. Thunderstorms are expected to develop across
portions of central MO later this evening as an increasing west-
southwesterly LLJ provides strong lift of this unstable air mass
to the north of the frontal zone, and lift associated with a
migratory MCV in NW MO impacts the area. While the overall set- up
is not as prolific as the previous few nights, widespread
thunderstorms are expected to evolve from central into southeast
MO resulting in an elongated MCS with regions of training storms.
High rainfall rates with the stronger storms are expected due to
deep warm cloud depths of 4+ km and PWs of 2.2 inches or greater.
The latest LPPM guidance from the 12z HREF supports localized
rainfall totals of 4+ inches. The heavy rain last night and early
this morning has produced a broad region of saturated soils in
swath from central into southeast MO with MRMS CREST Soil moisture
of 60-80+ percent, which has suppressed the FFG values to 1.5
inches or less in 3 hours. As a result, locally heavy rainfall
resulting in flash flooding will be easier to develop, and given
this threat, the flash flood watch has been issued. There is also
a greater severe weather threat tonight than previously
anticipated. The very unstable air along with deep layer shear of
around 30 kts will support potential for organized severe storms,
possibly a short-lived supercell or two, but more likely multicell
storms possibly evolving into short bowing clusters capable of
damaging winds and large hail.
Glass
&&
.SHORT TERM... (Through Late Friday Night)
Issued at 327 PM CDT Thu Aug 3 2023
1) A few showers, perhaps an isolated thunderstorm, are possible
this afternoon. Thunderstorm potential will increase later this
evening into the overnight period. A few of these thunderstorms may
be strong to severe with large hail, damaging wind and locally heavy
rainfall.
2) Active weather continues into Friday with yet another round of
thunderstorms possible with a few strong thunderstorms possible.
Clouds have lingered across the region longer than expected, helping
to temper any surface destablization this afternoon with SPC
mesoanalysis showing 25-50 J/kg of CIN extending from central MO
through southeast MO. A notable separation extists between thicker
cloud cover in these areas and much greater surface instability over
south-central and southwest MO, where 3000+ J/kg of SBCAPE exists.
Fortunately, the remnant MCV tracking over southwest sections of the
CWA hasn`t had much to work with, producing scattered showers from
central MO to east-central and southeast MO. Thought much of the
actitity have remained lightning-free, a rumble of thunder cannot be
ruled out over far southwest sections of the forecast area.
Another MCV is expected to push out of Kansas and into northwest MO
late this afternoon. CAMs have varied on their handling of this
feature, ranging from next to nothing to loosely clustered
thunderstorms. The latest 18z run of the HRRR has truly backed off
development over northwest MO with development favored over central
sections of the state. This make better sense given the remnant
surface boundary extending across central sections of MO. South of
the boundary and within the warm sector, a corridor of MUCAPE values
are expected to range from 2000-3000 J/kg along a wind of 30-35
knots of 0-6km shear. However, the LLJ is more compact and focused
over southwest MO late tonight with the nose of the jet directed at
south-central and southeast MO. Furthermore, mid-level lapse rates
of 7-7.5C decrease to 6C from southwest MO through east-central MO.
A loosely clustered area of thunderstorms may produce a few strong
to severe thunderstorms with large hail and damaging winds with the
window likely limited to the 04z-08z. Despite PWATs of 2-2.5 inches,
thunderstorms will have movement and a bit less training potential
as the boundary is shifted slightly further southwest. Flood
potential looks localized, largely to areas that have seen rounds of
heavy rain in recent days. PMM/LPMM show localized striations of
2-4 inch amounts are possible where this system tracks, so we will
need to monitor this should it shift over areas that were
impacted last night.
The boundary continues to linger over the region in the same manner
it has today, though a bit further southwest. A few showers and an
isolated thunderstorm linger into early Friday. Yet another MCV
ejects out of eastern Kansas with additional chances for showers and
thunderstorms Friday evening over central MO, pushing southeast
through the late evening. CAMs have a variety of scenarios once
again, but the general theme is for the system to take a similar
track around the mid-level ridge Friday evening into Friday night
with a few strong thunderstorms possible once again.
Maples
.LONG TERM... (Saturday through Next Thursday)
Issued at 327 PM CDT Thu Aug 3 2023
(Saturday - Next Thursday)
A broad upper ridge continues to encompass the southern U.S. with
quasi-zonal flow through the central portions of the country. Near
normal temperatures extend into the weekend with episodic chances
for showers and thunderstorms. The brunt of the activity looks to
arrive late Sunday into early Monday along a cold front the will
push from north to south
Ensembles show a fairly limited spread through the long range period
with a general trend toward cooler and drier conditions. Monday
afternoon through early Wednesday. However, I am hesitant to call it
a completely dry forecast. There are some indications that the
southward progress of the boundary may slow a bit as an upper level
shortwave moves across the region. Some semblance of shower
potential may linger through the day Monday. If there is a
completely dry day next week, it would favor Tuesday with surface
high pressure building into the mid-Mississippi Valley from the
Plains.
The active pattern returns by midweek as the boundary begins to
shift back northward as a warm front and additional disturbance
track through the Midwest late Wednesday into Thursday.
Maples
&&
.AVIATION... (For the 06z TAFs through 06z Friday Night)
Issued at 1046 PM CDT Thu Aug 3 2023
Patchy light rain showers and patchy MVFR stratus was located from
central MO into the St. Louis area at 0330z. Some of this patchy
stratus may persist a bit after 06z, otherwise we are still
anticipating a big uptick in showers and storms during the
overnight hours. Things look like they will get started a little
later than earlier thinking. Sometime between 06-07z a complex of
thunderstorms is expected to develop across central MO, elongate
and shift southeastward through the overnight hours. KJEF and KCOU
have the highest potential for thunderstorm impacts, while
thunderstorms may stay just southwest of the St. Louis terminals
and they will just have showers. In the wake of this activity,
around 10z, MVFR flight conditions due to stratus/fog will develop
and persist into mid-late morning with conditions improving to
VFR by 18z.
Glass
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch until 9 AM CDT Friday for Boone MO-Callaway MO-Cole
MO-Crawford MO-Franklin MO-Gasconade MO-Iron MO-Jefferson
MO-Madison MO-Moniteau MO-Osage MO-Reynolds MO-Saint
Francois MO-Sainte Genevieve MO-Washington MO.
IL...Flood Watch until 9 AM CDT Friday for Monroe IL-Randolph IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
749 PM EDT Thu Aug 3 2023
.SHORT TERM...(Today and Tonight)
Issued at 132 PM EDT THU AUG 3 2023
This morning, some showers made landfall on the UP shores of Lake
Superior and overperformed the majority of model guidance, with only
one of the 00Z CAM runs showing convection over the north-central
UP: the WRF FV3. The hazards for this round of thunderstorms were
lightning and sub severe hail and wind gusts.
Skies have mostly cleared for this afternoon save for a cu field
from Marquette southwest to the state line. CAM guidance has backed
off on the thunderstorm potential, with the vast majority of
models showing no CI this afternoon. The most notable exceptions
are the 15Z HRRR and the 12Z WRF FV3 which have some cells in the
Menominee vicinity around 20Z. As a cold front sags south this
afternoon into the evening, SBCAPE is expected to drop
significantly across much of the UP, except for a pocket of up to
2,500 J/kg lingering in the Menominee vicinity late this afternoon
per SPC Mesoanalysis. Effective bulk shear remains in the 30- 40
kt range, so any storms that do initiate will be able to maintain
strong updrafts for a while. However, the strongest instability,
forcing, and shear do not quite line up, and with little model
support for convection, expecting a mostly quiet evening across
the UP.
As pressure rises overnight, clearing skies will allow temperatures
to fall to the dew point by the early morning hours, but post-
frontal winds appear to be too high for widespread fog development.
However, some pockets of patchy fog may develop in areas of lower
winds in the interior west.
.LONG TERM...(Friday night through Thursday)
Issued at 403 PM EDT THU AUG 3 2023
Confluent northwesterly flow Friday followed by a midlevel ridge
axis moving overhead will lead to tranquil weather through Saturday.
The main feature of interest in the long term is a strong positively
tilted shortwave trough moving eastward through the northern Plains
on Sunday. This wave may eventually phase with a northern stream
wave orbiting around the Hudson Bay low on Monday, resulting in the
shortwave becoming neutral or negatively tilted. Medium-range
deterministic models and ensembles continue to indicate the
potential for an unseasonably strong surface low tied to the
shortwave to track across the Upper Midwest/lower Great Lakes Sunday
into Monday, which could bring a soaking rain and breezy conditions
to the UP during this timeframe. Midlevel troughing is forecast to
continue into the middle of next week, likely leading to a
continuation of seasonably cool temps.
Friday, high pressure nosing in from southern Ontario should promote
a cool northerly flow through the day, keeping temps near normal to
a bit below normal in the northern half. Some lower stratus is
indicated by some models along the Superior shoreline east of the
Keweenaw, but that does not appear to be the most likely outcome at
this time. Weak return flow develops on Saturday which will boost
temps a bit closer to normal areawide. For Sunday, moisture and lift
will increase from west to east as the shortwave approaches. There
is still a decent amount of model spread with the timing and track
of the system. It is likely that the central/eastern UP will remain
dry in the morning, with rain becoming likely for most of the
forecast area by the afternoon and evening. If a more northerly
track with the low verifies, some thunderstorm activity cannot be
ruled out Sunday. However, model consensus supports the low tracking
south of the region, which would lead to the local area being more
in the stratiform rain area late Sunday into Sunday night (assuming
a more southerly track doesn`t verify, which could keep the area on
the northern fringes of the rainfall). Rain chances trend downward
through the day Monday, but it should remain breezy, as many
ensemble members have the low pressure center at sub-1000 mb. This
is rather impressive for this time of year, and in fact, both the
NAEFS and EPS show the ensemble mean low at -3 to -4 standard
deviations from normal. Temps should be on the cool side Sunday
through midweek in the wake of this system. A few diurnal showers
could linger Tuesday/Wednesday with the midlevel troughing remaining
in the vicinity.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 748 PM EDT THU AUG 3 2023
VFR conditions will prevail at all sites through the period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 403 PM EDT THU AUG 3 2023
High pressure building in from the north may result in some
northeasterly 20 kt wind gusts over far eastern portions of the lake
Friday and Saturday. Otherwise, winds should be less than 20 kt
through Saturday. Sunday into Tuesday, an unseasonably strong low
pressure system is likely to track from the Upper Midwest across
southern Lake Michigan and Lake Huron into Quebec. Rain is likely
Sunday into Sunday night with some embedded thunderstorms possible.
Easterly winds may gust to near 20 kt on Sunday, with northwesterly
winds increasing on the back side of the low Monday into Tuesday. If
the storm track is far enough north, potential exists for wind gusts
of 20 to perhaps 30 kt Monday into Tuesday, strongest over the
eastern half of the lake.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...GS
LONG TERM...Thompson
AVIATION...Voss
MARINE...Thompson
Area Forecast Discussion
National Weather Service Nashville TN
813 PM CDT Thu Aug 3 2023
...New UPDATE...
.UPDATE...
Issued at 752 PM CDT Thu Aug 3 2023
Latest radar shows showers have ended across Middle Tennessee,
and expecting dry conditions the rest of the evening. Already
seeing some patchy fog development in our eastern counties where
dewpoint depressions are near zero, and some locally dense fog is
possible overnight east of I-65.
However, main impact tonight will be the next round of storms
in our western half. The OHX 00Z sounding is very moist with a
PWAT of 2.05 inches, and surface observations show a boundary in
place from today`s rainfall stretching from just east of Paducah
to west of Lawrenceburg. Models are unanimous that another
shortwave trough axis in the prevailing northwest flow aloft will
move southeastward across the region tomorrow, sparking another
round of numerous showers and thunderstorms along the boundary
around 07-09Z. This activity will then spread southeastward while
expanding a few counties east/west of the boundary Friday morning
before ending Friday afternoon. Several CAMs such as the HRRR and
NAMnest show repeated thunderstorms moving across our southwest
counties dumping as much as 4 or more inches of rainfall late
tonight into Friday, which is concerning after today`s 1 to 3
inches of rain in that area. Therefore, I went ahead and issued a
Flood Watch for our west/southwest counties in coordination with
surrounding offices. Higher flood threat is in the southwest part
of the watch, whereas some of the eastern counties are more of a
buffer due to uncertainty on where the exact location of the
heaviest rain axis will set up. Went ahead and updated precip
chances accordingly and raised pops above guidance to near 100
percent in our southwest, decreasing to slight/no chance in our
northeast. Rest of the forecast remains on track.
&&
.SHORT TERM...
(This afternoon through Saturday Night)
Issued at 218 PM CDT Thu Aug 3 2023
Mainstream model data is not very useful for the upcoming short term
period which runs through Saturday night. That said, will be
adhering more to the short term cams and nearer term trajectory
trends. Will lean more toward major model support as reach
toward the extended.
Widespread shower activity covers a good portion of the mid state
this afternoon. Rainfall amounts thus far are as high as 1 1/2 to 2
inches across west central portions of the cwa. Looking upstream we
see the back edge on approach and we can look for precip termination
by late this afternoon, from northwest to southeast.
Moving forward, looks like 2 smaller mcs systems for tonight and
into Friday. Trajectory based progs indicate the heavier rain will
occur across our southwest third or so. As mentioned prior, 6 hr FFG
values are just north of 4" so not expecting to issue any flood
watch unless an ISC box-in dilemma presents itself. Moreover, WPC is
not just showing a 47 hr accum of 2 inches across our southwest as
opposed to the 3" earlier. So, will lean toward localized flood
potential for our southwest. Latest f-builder data supports 1 to 2
inches of additional rainfall for our southwest for tonight, with an
additional inch Friday morning.
On Saturday, a little bit more in the way of mid level ridging is
noted. Deeper moisture is not in place and some midday capping and
late day subsidence looks to be the rule. Thus, lower pops.
For the near term temps, should be noticeably warmer with upper 80s
on Friday and lower 90s Saturday with the lower pops. Overnight lows
look like lower 70s.
&&
.LONG TERM...
(Sunday through next Thursday)
Issued at 218 PM CDT Thu Aug 3 2023
In the extended forecast, we will see the upper high shift a little
bit westward across northern Mexico, while strengthening a touch.
The generally active west northwesterly flow will continue with
shower and tstm chances persisting. Having sad that, in an effort to
pinpoint any enhanced chances, I see the following. On Monday a
frontal boundary will be on approach and will increase convective
coverage at that time. Then toward the end of the work week, a more
pronounced trough/shortwave will reach our area on Thursday.
With all of this activity, additional qpf totals for the extended
period only look like up to 1 inch for our eastern areas with lesser
amounts west. Periphery model examinations show a few 2-3 inch areas
but nothing really organized or carrying any higher confidence based
continuity levels. Otw, tropics across the Atlantic sector are
looking clean.
For the extended temps, the period will start out rather hot as we
await that aforementioned frontal boundary. Highs on Sunday look like
lower to perhaps mid 90s. Then, upper 80s to near 90 for the
remainder with dewpoints back down into the 60s.
&&
.AVIATION...
(00Z TAFS)
Issued at 605 PM CDT Thu Aug 3 2023
Conditions will be poor across the entire area through much of
the TAF period. Low ceilings and areas of fog will develop between
03Z and 06Z, reducing visibilities and likely resulting in MVFR to IFR
conditions. Beginning around 10Z, another round of rain showers
will then stream into the area, favoring the western half of
Middle TN. Rain will be heavy at times, keeping IFR visibilities
and low ceilings in the area until it clears out around 18Z.
Conditions should improve back to VFR at all TAF sites thereafter.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 73 87 71 92 / 40 60 10 20
Clarksville 73 88 71 91 / 60 70 20 30
Crossville 66 81 63 85 / 20 40 10 10
Columbia 71 87 70 91 / 70 80 20 30
Cookeville 68 83 66 87 / 20 30 10 10
Jamestown 67 81 64 86 / 10 20 10 10
Lawrenceburg 71 85 69 90 / 60 80 20 30
Murfreesboro 71 88 69 92 / 30 60 10 20
Waverly 71 86 69 89 / 80 90 20 40
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 3 AM CDT Friday through Friday afternoon for
Dickson-Giles-Hickman-Houston-Humphreys-Lawrence-Lewis-Marshall-
Maury-Montgomery-Perry-Stewart-Wayne.
&&
$$
UPDATE.......Shamburger
SHORT TERM...21
LONG TERM....21
AVIATION.....Clements
Area Forecast Discussion
National Weather Service New York NY
1112 PM EDT Thu Aug 3 2023
.SYNOPSIS...
A frontal system approaches tonight into Friday and will move
across the region Friday night. High pressure returns for the
weekend. Another frontal system is expected to impact the area
from late Monday into Tuesday. Weak high pressure builds in
briefly Wednesday. Another frontal system approaches Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Increased POPs to slight chance for the entire forecast area
over the next few hours as a trough approaches from the west.
Otherwise, forecast is on track.
High pressure continues moving offshore this evening. Despite
SE flow increasing this afternoon, dew points have lowered as
drier air has mixed down to the surface. A weak surface trough
has set up mainly across the interior on NW. SPC mesoanalysis
indicated CAPE has started to increase inland. However, model
soundings are still depicting a cap around 15kft. This will
likely inhibit any stronger updrafts from developing early this
evening. A few showers are possible this evening across the
interior of NE NJ and the Lower Hudson Valley, and have expanded
slight chance probabilities into NYC and into southern
Westchester county, as HRRR showing scattered showers remaining
possible. Not mentioning any thunder for tonight, think the
lingering capping is going to inhibit any parcels from reaching
high enough to support lightning development. The cap does start
to weaken this evening, but loss of heating will lower
instability levels.
Otherwise, a frontal system will continue approaching tonight.
Warm advection will begin to increase overnight and could
generate a few showers, especially early Friday morning.
Instability is limited and will continue with just a chance of
showers towards day break. There could be pockets of moderate
rain, but not anticipating any heavy downpours out of this
activity. Lows will be in the middle to upper 60s except around
70 in the NYC metro. Dew points should start rising into the
60s, making it feel a bit more humid.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
Closed upper low over Quebec will help amplify troughing and
lower heights over the northeast on Friday. A frontal system
will approach during the day with a pre-frontal trough ahead of
it. Warm advection showers are possible in the morning. There is
also a period in the morning when portions of the area lie in
the left exit of a 70-90 kt 250 mb jet streak.
CAMs are coming into better agreement on the evolution of
convection in the afternoon and evening. There is good
agreement that a line of showers and thunderstorms will develop
well to our north and west along the pre-frontal trough in the
afternoon. The approaching cold front will help push this
activity towards the south and east late in the afternoon and
evening. There is still a decent amount of spread in the timing
of when this activity will make it into the area, but favoring
evening from northwest to southeast. The environment should be
see some destabilization in the afternoon with dew points also
increasing into the upper 60s. Bulk shear may average around 30
kt in the evening, coinciding with when the potential convective
line enters the interior. SPC has placed interior Lower Hudson
Valley and interior NE NJ in a marginal risk with an isolated
damaging wind gust possible. The line is progged to weaken as it
moves south and east through the rest of the evening as it
encounters a more stable environment. If the line ends up
several hours faster, the threat for an isolated severe storm
is possible further south as instability would be higher.
However, showers with some thunder are still expected down to
the coast. Locally heavy rainfall is possible with minor poor
drainage flooding the main concern. The line will be progressive
and currently not expecting training storms to produce more
significant rainfall and flash flooding.
Any lingering showers/storms push off the coast 02-04z with the
cold front making its way offshore early Saturday morning. A
brief shower cannot be ruled out as the front passes offshore,
but overall clouds will begin to diminish and some drier air
begins to filter in from the north towards day break Saturday.
Lows will range from the lower 60s inland to the middle and
upper 60s near the coast.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Near zonal, to low amplitude, upper flow will keep systems
progressive Saturday through the middle of next week. Initially
a low amplitude ridge builds slowly toward the region Saturday
through Sunday morning, with the ridge axis passing to the east
Sunday afternoon. Then a shortwave across the upper plains
Saturday will be digging into the upper midwest Sunday, and then
into the region Monday into Tuesday as the upper flow flattens.
At the surface weak high pressure builds in behind a cold front
Saturday morning, and moves offshore Sunday. A warm front
approaches early Monday and lifts north during the day.
Thunderstorms will be possible in the warm sector Monday, with
little CAPE and surface based instability. Weak high pressure
builds in to the southwest Wednesday into Thursday.
Temperatures will remain near seasonal normal levels Saturday
through Thursday, with moderate humidity with dew points mainly
in the 60s, slightly higher Monday in the warm sector ahead of
a cold front.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A weak warm front will move across tonight into Friday morning,
followed by the approach of a cold front late Friday into Friday
night.
Winds diminish tonight and then shift more to the SW around 10
to 15 kt after the Fri AM push. Winds increase somewhat in the
afternoon with gust 20 to 25 kt.
Low end VFR/high end MVFR cigs and a few showers with the warm
front Friday morning. There is a chance for thunderstorms by
late afternoon in association with the approach of the cold
front. Better chances for MVFR and lower conditions in any
thunderstorms. There is uncertainty in exactly where and when
any thunderstorms will develop at this time.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled AMD expected. Low end VFR/high end MVFR
conditions possible Friday. Uncertainty in where and when
thunderstorms may move through Friday afternoon and evening.
OUTLOOK FOR 00Z SATURDAY THROUGH MONDAY...
Late Friday night: Chance of showers, ending late. MVFR cond
possible.
Saturday and Sunday: VFR.
Monday: Chance of late day showers and thunderstorms from NYC
north/west with MVFR or lower cond.
Monday night and Tuesday: Chance of showers/tstms with MVFR or
lower cond.
Tuesday night: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Increased wind speeds and gusts, mainly across the western ocean
waters and western Long Island Sound, as winds have been
stronger in these areas this evening as high pressure departs to
the east. An occasional gust to 25 kt is possible near the NY
Harbor and ocean west of Fire Island Inlet. Seas here may also
briefly build to 4 ft. Winds and seas will weaken overnight and
remain below SCA levels into Friday morning. Winds increase and
seas build Friday afternoon and evening ahead of a cold front.
Winds should largely stay below 25 kt, but an occasional gust to
25 kt cannot be ruled out. Ocean seas should also build to 4
ft, but should stay below 5 ft. Winds and seas subside behind
the cold front passage late Friday night into Saturday morning.
Winds and seas will remain below SCA levels across the forecast
waters from Saturday morning through Monday evening. With an
increasing southerly flow ahead of a frontal system Monday ocean
seas will likely build to SCA levels by late Monday night and
remain elevated into Tuesday morning. Occasional gusts on the
ocean waters may also be near SCA levels during the same time
period.
&&
.HYDROLOGY...
Showers and thunderstorms late Friday afternoon into Friday
evening may produce locally heavy rainfall. Minor urban and poor
drainage flooding is in the main threat.
There are no hydrologic concerns from Saturday through the middle
of next week.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip current development at the
ocean Friday and Saturday with a 2 foot, 9 to 10 second,
southerly swell.
Astronomical tides remain high with the full moon from Tuesday
evening. Minor flooding is again possible during tonight`s high
tide cycles. A coastal flood advisory remains in effect for
southern Queens and Nassau Counties. Coastal flood statements
remain in effect for Staten Island, Southern Brooklyn, and
Southern Fairfield. A statement may also be needed for the south
shore back bays with Friday night`s high tide, but water levels
will continue to lower.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Coastal Flood Advisory until midnight EDT tonight for NYZ178-
179.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...DS/MET
NEAR TERM...DS/MET
SHORT TERM...DS
LONG TERM...MET
AVIATION...JP
MARINE...DS/MET
HYDROLOGY...DS/MET
TIDES/COASTAL FLOODING...
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
522 PM MDT Thu Aug 3 2023
.DISCUSSION...(This Evening Through Thursday)
Issued at 220 PM MDT Thu Aug 3 2023
Water vapor imagery shows a shortwave trough lifting northward
through northern WY into southern MT with broad ascent
overspreading much of the Northern Plains and Northern Rockies.
Scattered showers and thunderstorms have formed across the CWA
this afternoon, with greater coverage westward where the best
ascent is centered. RAP analysis denotes strong moisture transport
from the surface to 700 mb, where deep southeasterly, upslope
flow prevails. Given the weak shear (effective bulk shear < 25
knots) coupled with nearly moist adiabatic mid-level lapse rates,
widespread severe weather is not expected; although a few strong
to severe storms are possible through this evening. The area with
the highest severe potential stretches from the central Black
Hills into SW SD, where the stronger shear exists.
The primary concern tonight through Saturday will be heavy rainfall
and potential flash flooding (the Flash Flood Watch remains in
effect through 00z Sunday). Anomalously high precipitable water
values were observed across the region via 12z RAOBS (e.g., KUNR
PW was at 1.42", 161% of normal/93rd percentile; KRIW at 181% of
normal/95th percentile). Broad, large-scale ascent coupled with an
increasingly moist air mass will support heavy rainfall rates
through Saturday. Given the convective nature of the rainfall,
amounts will be highly variable across the forecast area. However,
conditions are favorable for efficient rainfall production and
flash flooding given slower storm motion (cloud bearing winds < 20
knots) and with any training storms. Already (as of 145pm MT this
afternoon), radar estimates of 3-5" of rain have fallen across
portions of eastern MT (Fallon County).
In terms of forecast trends, the heaviest axis of forecast QPF has
shifted slightly northward this afternoon, from the northern half of
the CWA into SE MT/SW ND. Drier air is expected to filter into the
far southern counties through the weekend, which may limit the
precipitation potential from southern Campbell County (WY) eastward
into Tripp County (SD). Despite this shift, the far southern counties
still have potential of 0.5-1.5"+ with any thunderstorms through the
weekend.
Looking beyond the weekend, active northwest flow will persist with
cooler than average temperatures and daily chances of showers and
thunderstorms through the end of next week.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 519 PM MDT Thu Aug 3 2023
Scattered to widespread showers/storms will continue to cross the
area through this evening, with a slow decrease in coverage
overnight. IFR conditions expected within stronger storms due to
very heavy rainfall. Local MVFR cigs may develop overnight across
northeastern WY and portions of western SD, continuing into Friday
morning. More widespread showers/storms will redevelop Friday
afternoon.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Flood Watch through Saturday afternoon for SDZ001-002-012>014-
024>032-041>044-046-047-049-072>074.
WY...Flood Watch through Saturday afternoon for WYZ054>058-071.
&&
$$
DISCUSSION...Eagan
AVIATION...Johnson