Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/27/21
Area Forecast Discussion
National Weather Service La Crosse WI
934 PM CDT Mon Jul 26 2021
.UPDATE...
Issued at 934 PM CDT Mon Jul 26 2021
Concerning tonight...we continue to monitor the severe storms near
Duluth and expect them to continue southeast. MLCAPE values near
1500 and MUCAPEs near 2500 J/Kg are still pooled south and east
of the complex into northeast WI along a stationary front. Wind
shear remains favorable for supercells and upscale storm
potential but does diminish slowly as the complex heads toward
northcentral WI. We are planning strong to severe storms to move
in around midnight in northcentral WI. The low-level flow and
moisture transport convergence into the boundary is forecast to
increase west of Duluth again tonight causing a second round of
storms. This again will be in the CAPE pool on the boundary and
in better deep shear for severe storms. This area of convection,
handled well in the 27.01Z HRRR for the currently observed
instability pool and forecast forcing, then shifts southeast again
and brings a sunrise timed storm chance to western and central
WI. Storms are expected to decay as they move south toward the
I-90 corridor and really only showers are possible. Really nothing
to the south of I-90. A strong to severe storm near and north of
I-94 cannot be ruled out. Slightly bumped up rain chances after
dawn to I-90.
Tuesday is an interesting day that has some potential for severe
storms. Tonights thunderstorms will determine the frontal position
for convergence for later afternoon storm initiation. Right now,
the most likely position appears to be about I-94, with the 26.18Z
Nam 3km on I-90. This seems a bit far southwest for the large
scale pattern. Most concerning is the "fat" CAPE in place across
the area and little cap in place with a 90F/70F T/Td for later
Tuesday. The deep wind shear over the area may be supportive of
supercell-ish modes with very good high level shear /6km+/. The
big question is will the front/boundary be convergent enough to
initiate storms. If storms form, it would pose a larger hail /2"/
and damaging wind threat. The trend in the 27.00Z CAMs is less
initiation...a good thing. But, this boundary and initiation will
depend on how the overnight cold pool evolution. A day to be
weather aware.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 233 PM CDT Mon Jul 26 2021
At 2 PM, skies were partly to mostly cloudy across the Upper
Mississippi River Valley. These were debris clouds from the
convection that was over eastern South Dakota and southwest
Minnesota earlier in the day. A few of these elevated showers at
times have moved into southeast Minnesota and northeast Iowa late
this morning and afternoon. As a result, kept a slight chance of
showers in the forecast for this afternoon. However, as the
moisture transport into this region continues to weaken this
afternoon, thinking that this area should probably dissipate by
26.22z. Temperatures ranged from 82 degree at Medford WI to 92
degrees at La Crosse WI.
For tonight, watching a shortwave trough over central North Dakota.
There has been good drying taking place in the mid levels in that
area this afternoon. As this system, moves out of the thermal ridge
and into an area with slightly cooler 700 mb temperatures expect
that convection will fire along and ahead of it over eastern North
Dakota. The mean 700-400 mb winds would suggest that this
convection should move southeast along the periphery of the thermal
ridge and into our area after 27.02z. The CAMS are differing on far
south this convection will get. The NAM, ARW, and FV3 suggest that
this convection will get as south as least the Interstate 90
corridor. Meanwhile, the HRRR keeps the convection well north of the
area. With the 0-3 km shear in the 30 to 40 knot range, expect to
see line segments which will have the potential of producing
damaging winds. There maybe even 0-6 km shear for even some large
hail. The greatest threat looks to be north of Interstate 94. Low
temperatures will range from the lower 60s to lower 70s.
On Tuesday, there may be some dissipating showers and storms near
Interstate 90 in the morning. As the upper thermal ridge build back
across the area, thinking that much of the rest of the day will be
dry. High temperatures will range from the lower 80s to lower 90s.
.LONG TERM...(Tuesday night through Monday)
Issued at 233 PM CDT Mon Jul 26 2021
Pockets of the forecast area have seen above normal precipitation
over the last two weeks, however 70 to 80 percent of the area is
below normal for the period and could use any rain that falls.
Tuesday through Wednesday night, expect the area to be vulnerable to
showers and thunderstorms as we are on the eastern side of a very
strong ridge with the risk for strong to severe thunderstorms. These
storms will have to work against a very strong cap which lowers
confidence of coverage and timing. Tuesday afternoon, a frontal
boundary is expected to be in the area and there may be convection
ongoing where the cap is weaker. The shear is variable from 25 to
50kts and stronger north of I90. In addition, instability is
moderate. As a result, the storm prediction center has added parts
of our area to the severe weather outlook for Tuesday and Wednesday.
Outside of storms, looking at a very warm and humid period until the
temperatures in the mid 80s to mid 90s, dewpoints in the 60s to mid
70s, and highest heat index values 90 to 105. The very hot air
appears to extend across South Dakota into central Minnesota. We`ll
need to keep an eye on this. 98 to 102 heat index values are
currently forecast for a large area, so will have to consider a heat
advisory should the temperatures remain on track.
The cold front moves through Wednesday night with showers and
thunderstorms. The mid tropospheric ridge becomes flattened with
the north or variable flow Thursday and Friday and a reinforcing
front for Saturday. There may a few showers/thunderstorm with that
frontal passage too. Highs Thursday through Sunday look to be in
the 70s and 80s and dewpoints in the 50s and 60s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 719 PM CDT Mon Jul 26 2021
VFR expected through at least daybreak. Thunderstorms currently
over northern MN will be shifting southeast overnight and it is
expected these will remain northeast of the airfields. There may
be some decaying showers moving in during the morning but the
forecast remains VFR.
Tuesday later afternoon and evening will need to be watched
closely. The thunderstorms tonight will govern where a front is
positioned Tuesday and the front will initiate thunderstorms later
in the afternoon. The higher probability outcome appears to be
that the front will be north of the airfields. However,
thunderstorms could form on the front and move into the airfields
Tuesday evening. The environment looks favorable to produce large
hail and damaging winds with the stronger thunderstorms.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Baumgardt
SHORT TERM...Boyne
LONG TERM...Zapotocny
AVIATION...Baumgardt
Area Forecast Discussion
National Weather Service Boston/Norton MA
1012 PM EDT Mon Jul 26 2021
.SYNOPSIS...
Summer heat returns Tuesday before a cold front slides across
the area Tuesday evening. Unsettled pattern returns with the risk for
showers and a few thunderstorms each afternoon and evening
Tuesday into Friday. Dry and pleasant weather is expected to
start this weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
1010 PM Update...
Previous forecast remains on track. A cluster of scattered
showers & thunderstorms across south central NH should track
east and stay to our north over the next few hours given the mid
level flow. Therefore, maintained a dry/tranquil forecast
overnight with no real forcing in our region for precipitation.
Low temperatures should mainly be in the 60s.
The main issue overnight will contine to be the smoke in the air
and reduced visbility from Wildfires burning in the western
U.S. and western Canada. The HRRR indicates some improvement
overnight from west to east as the core of the smoke plume
pushes east of the region.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday...
High pressure begins to weaken, but clear skies will once again
be muddied by elevated smoke on Tuesday morning as another wave
of wildfire smoke is transported over southern New England.
925mb temps remain quite high during the morning hours, once
again approaching 23-24C. Given good mixing, surface
temperatures will approach 90 degrees, warmest across
Connecticut.
Things become more interesting after 4 pm as a cold front
begins to slide through our area. The greatest threat for
significant thunderstorms is north and west of the MA turnpike,
where some guidance shows surface CAPE exceeding 2000 J/kg.
Additionally, K indicies approach 40 during the same time frame.
One limiting factor tomorrow is that the greatest shear remains
north of our area, across NH. The greatest 0-6 km shear
approaches 40-45 kts, with bulk shear values around 45 kts along
the MA/NH border. Northern MA will find itself in the
crosshairs of favorable shear and high CAPE, suggesting that the
strongest storms will be centered there. Low level lapse rates
approach 8-9 C/km.
CAPE diminishes quickly after sunset, but thunderstorms likely
persist all the way the south coast through midnight. K indicies
will linger in the upper 30s while mid level lapse rates
approach a healthy 6.7-7 C/km. Bulk shear values of 45-50 kts
will also breathe life into some post-sunset storms.
Tuesday Night...
Thunder lingers through the first half of the evening. Behind
the passing cold front, winds will shift from the SW/W to the
North as cooler air rushes in. Lows will once again fall into
the low and mid 60s. Fog is less likely overnight Tuesday as
dewpoint depressions remain between 5-7 degrees.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights...
* Periodic rain and thunderstorm chances through the period,
first on Thursday/Friday morning then again the latter half of
this weekend
* Temperatures trend below normal Wednesday through this weekend
Still a tale of where will the front be, and when will it be
there. expecting a cold front to stall to our south. Lingering
risk for some showers early in the day until this front moves by
our region. Thereafter looking at drier conditions most of
Wednesday. This front should return north as a warm front
Thursday, setting the stage for another round of showers and
thunderstorms Thursday into Thursday night. Another cold front
should move offshore sometime Friday morning, leading to drier
weather Saturday. Yet another warm front and cold front pass by
Sunday into Monday, leading to the chance for more showers and
thunderstorms. None of these days will be a complete washout,
but there will be prolonged periods for a chance of
precipitation.
Still looking like below normal temperatures Wednesday into
early next week.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Mainly VFR conditions persist through Tuesday afternoon before
local MVFR conditions develop in showers and downpours. Smoke
and haze will reduce visibility at times. Patchy fog will be
less widespread overnight, primarily impacting Nantucket and
Martha`s Vineyard.
KBOS TAF...High confidence in TAF. Mainly VFR. Smoke and haze
will reduce visibility at times this evening. Showers develop
late in the day on Tuesday; chance of VCTS.
KBDL TAF...High confidence in TAF. Mainly VFR. Smoke and haze
will reduce visibility at times this evening. Showers develop in
the early evening hours on Tuesday; chance of VCTS.
Outlook /Wednesday through Saturday/...
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Wednesday Night: VFR.
Thursday: Mainly VFR, with local IFR possible. SHRA likely,
slight chance TSRA.
Thursday Night: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA, slight chance TSRA.
Friday: VFR. Breezy. Slight chance SHRA.
Friday Night through Saturday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels.
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Seas have subsided enough to allow any Small Craft Advisories
to expire. Winds will remain below 15 kts with seas below 5 ft
through Tuesday. A cold front will pass over the waters on
Tuesday evening, bringing a chance for scattered showers and
thunderstorms.
/Outlook /Wednesday through Saturday/...
Wednesday: Winds less than 25 kt. Slight chance of rain
showers.
Wednesday Night: Winds less than 25 kt.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.
Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Rain
showers likely, isolated thunderstorms.
Friday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers.
Friday Night: Winds less than 25 kt. Seas up to 5 ft.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft.
&&
.HYDROLOGY...
No active river flood warnings are in effect for rivers and
waterways across southern New England.
However, after having a tremendous amount of rainfall from early
to mid July, many rivers and streams are running much higher
than normal. This is resulting in swift currents that would not
typically be seen in the summer. These swift currents can catch
those swimming or tubing/kayaking on area waterways off guard.
There have been 3 total reports of drownings in the last week on
the Farmington River in CT and Squannacook River in MA given
the higher than usual flows and swift currents.
Those with interests swimming, tubing or kayaking on area
rivers and waterways should be aware that swift currents due to
high flows are occurring. This can result in dangerous
conditions, and it is generally discouraged to swim, inner-tube,
or kayak until flows decrease.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ002>004.
MA...Air Quality Alert until midnight EDT tonight for MAZ002>016-
026.
RI...Air Quality Alert until noon EDT Tuesday for RIZ001>008.
MARINE...None.
&&
$$
SYNOPSIS...Belk/KS
NEAR TERM...Frank
SHORT TERM...KS
LONG TERM...Belk
AVIATION...Belk/KS
MARINE...Belk/KS
HYDROLOGY...Staff
Area Forecast Discussion
National Weather Service Caribou ME
1130 PM EDT Mon Jul 26 2021
.SYNOPSIS...
A cold front will pass through the region overnight and
Tuesday. High pressure builds down from Canada from Wednesday
night, then slides offshore on Thursday. A low pressure system
approaches from the west late Thursday, then crosses the area on
Friday. This low then slowly lifts northeast through the
Canadian Maritimes as high pressure builds in from the west to
close the week.
&&
.NEAR TERM /THROUGH TUESDAY/...
11:30 AM Update...A couple thundershowers have been moving
across the north but now appear to be weakening. Forecast
remains on track with a chance for isolated thundershowers in
the next couple hours. Only change was to lower temps a bit in
the northwest where drier air is moving in.
A cold front is now approaching the FA from Quebec. The front
has a broken line of showers and thunderstorms that stretch
from north of the Saint John Valley back across the Saint
Lawrence River Valley in Quebec.
Elsewhere, there is just one lone thunderstorm that developed
in northern Penobscot County and is now approaching the route 1
corridor between Bridgewater and Monticello. There will be some
cloud to ground lightning and brief heavy downpours with this
storm. Potential for some small hail and a brief gust of wind.
The best chance of showers with embedded isolated convection
late this evening and into the overnight will be across the
northern half of the FA. Loaded the past few hours of observed
data and made some minor tweaks based on the current and
expected conditions for the remainder of tonight.
Previous discussion:
There is a front just arriving at the St Lawrence River in
Quebec. A line of storms can be noted with this front, and have
opted to keep the mention of storms into the evening, with more
emphasis across the north as NAMnest, RAP, HRRR suggest.
Fog is expected to push back into the coastal communities and
Downeast tonight, locally dense.
Decided to remove the chance of rain for Tuesday given the deep
dry layer moving in. There are good lapse rates through the
mid/low levels, so clouds should develop. The good mixing
conditions will also make it a tad breezy, but nothing too
strong.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A shortwave rotates around the base of the cutoff low over SE
Quebec Tuesday night and Wednesday. The shortwave should cause
an area of low pressure to develop along a cold front offshore
late Tuesday night, that then passes just to the S/E of the area
early Wednesday morning. Based on this it should be dry Tuesday
night and Wednesday, except for possibly some light rain or
showers along the Downeast coast late Tuesday night/Wednesday
morning, depending on the exact track and strength of the
coastal low. Lows Tuesday night should be around 5-10 degrees
above normal across the North (mainly mid-upper 40s) and near to
slightly below normal elsewhere (mainly around 50 to mid 50s).
Highs Wednesday should be around 5 degrees below normal, mainly
from around 70 to the mid 70s.
Weak northern stream shortwave ridging builds in Wednesday
night, then passes to the east on Thursday. It should be dry
Wednesday night and at least Thursday morning as a result. An
approaching shortwave could bring some showers and possibly a
rumble of thunder to mainly western zones by late Thursday
afternoon. However, there is quite a bit of uncertainty with
respect to the timing of this shortwave, with some indication
this precipitation could ultimately end of holding off until
Thursday night. Lows Wednesday night should be around 5 degrees
below normal and highs on Thursday slightly below normal.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Noting that the GFS is more aggressive than most other models
with the timing of the shortwave for Thursday night/Friday,
opted for a non-GFS solution during this time frame. As a
result, expect a northern stream shortwave to approach Thursday
night, then lift across Maine on Friday. Have likely pops for
showers everywhere Thursday night and then likely pops mainly
across the North and chance pops elsewhere on Friday. Given the
forecast cool temperatures aloft, also have a slight chance of
thunder in everywhere as well Thursday night and Friday.
The region remains under the influence of a cutoff low over
far SE Quebec Friday night and Saturday. So given the proximity
of the cold pool aloft, have chance pops across the North,
slight chance pops elsewhere, tapering of from S to N during the
day on Saturday.
A northern stream shortwave ridge is progged to cross the region
Saturday night. Still some uncertainty on this so did maintain
slight chance to chance pops across mainly the NW 3/4 of the
CWA.
A northern stream shortwave trough crosses the area on Sunday,
warranting chance pops.
Another closed low tracks into eastern Quebec Sunday night and
Monday (once again model differences on the timing - but given
the blocky nature of the pattern, generally leaned towards
slower solutions), warranting continued chance pops for showers.
It should be noted, that with the two cutoff/closed lows for
late this week/early next week, that in general from Friday
night on, the precipitation will be of a hit and miss nature,
with it more likely to miss than hit at any given location at
any given time.
Lows Thursday night should be near normal, followed by below
normal temperatures Friday-Monday.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: Hazy skies, otherwise VFR for Aroostook terminals.
Isolated showers and thunderstorms through early Tuesday
morning. IFR to LIFR possible with fog developing Downeast,
namely BHB late this evening and overnight. BGR may also see
IFR vis late in BCFG. Light and variable wind, except brief
gusty wind in/near any thunderstorms.
VFR w/ breezy WNW afternoon winds 10 to 15 knots Tuesday as
remaining fog lifts in AM.
SHORT TERM:
Tuesday night...VFR, except MVFR or lower possible at Downeast
terminals.
Wednesday-Thursday morning...VFR.
Thursday afternoon-Friday...Variable conditions with showers
and thunderstorms.
Friday night-Saturday...VFR at southern terminals, with MVFR or
lower possible at northern terminals. NW winds G15-20KT possible
Saturday.
&&
.MARINE...
NEAR TERM: Below SCA conditions. Main item will be dense fog
again over the waters tonight, lifting Tuesday AM. SW winds
Tuesday gusting around 15 kts.
SHORT TERM: Sub-SCA conditions are expected on all waters
Wednesday night-Saturday. Some wind gusts to around 20 kt are
possible on the coastal waters mainly Thursday and Thursday
night.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Cornwell/MCB
Short Term...Maloit
Long Term...Maloit
Aviation...CB/Cornwell/Maloit
Marine...CB/Cornwell/Maloit
Area Forecast Discussion
National Weather Service Charleston SC
957 PM EDT Mon Jul 26 2021
.SYNOPSIS...
Weak low pressure will drift north along the southeast Georgia
and South Carolina coast tonight and Tuesday. A trough will
then bring unsettled weather through midweek. A weak front
could drop into the region late week and stall over the
weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 950 PM: KCLX detected a couple of thunderstorms tracking
NW across the adjacent waters of GA and SC this evening. Another
cluster of thunderstorms was located over the middle Savannah
River valley, drifting slowly east. Conditions favor the
convection over the Atlantic to track onshore later this
evening. The convection to the west should gradually dissipate.
The forecast update will feature slight adjustments to PoP and
Wx. Based on the latest HRRR, the QPF across the region on
Tuesday was increased by a quarter to half inches, primarily
along the coast.
As of 8 PM: Regional radar indicated that the center of low
pressure was pushing onshore south of the Altamaha River. Rounds
of showers and isolated thunderstorms will remain possible as
the low tracks north along the coast. Circulation around the low
is aiding in pushing the sea breeze well inland. KCLX detected
a fine line and a band of showers associated with the sea
breeze over northern Dorchester, across Hampton, to northern
Bulloch Counties. The sea breeze should continue to push inland,
eventually reaching the outflow boundary and convection pushing
east across the Midlands of SC. After the convergence of the
two boundaries, upstream convection should be disrupted and
gradually dissipate.
Previous Discussion:
Tonight: The surface low to our south will move onto land over
southeast Georgia this evening and begin to dissipate, leaving
us within a southeast to south flow around the far western
portion of the sub-tropical Atlantic ridge. Diurnally driven
convection will fade early on, before some nocturnal convection
that forms over the ocean makes a run for the shore overnight.
Coverage will wane from north to south with 40-50% PoPs
decreasing to 15-25% by the evening. Isolated showers and
thunderstorms will continue over the waters and across the
extreme southeast GA counties tonight, given that it`ll remain
unstable offshore. Southerly flow will begin to push convection
onshore once again after midnight when low-level convergence
strengthens. Coverage will increase toward daybreak as land
areas begin to destabilize fairly quickly, which is when we
have slight chance PoPs over the coastal counties.
There will be areas of low stratus and perhaps even some
isolated areas of patchy fog well west of I-95 early morning.
Models are showing the greatest potential just outside our
forecast area, and given that yesterday`s models over-
forecasted fog probabilities for last night, mention of fog has
been left out of the forecast.
Given the southeast synoptic flow and elevated dew points,
it`ll be a relatively warm and humid night. Lows will only
reach the mid to upper 70s, and around 80F in Downtown
Charleston/immediate coastline.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
A surface trough of low pressure will linger over the region through
midweek. Aloft, a broad trough will persist over the Northeast with
a large ridge over the Central U.S. Models indicate PWats will surge
to near or over 2.25 inches Tuesday into Wednesday, before gradually
decreasing Wednesday evening. These values are well above late July
climatology. With aid from weak shortwave energy, scattered to
numerous showers and thunderstorms are expected to develop. Coverage
will peak in the afternoons when instability is greatest, but
activity will be possible just about any time including overnight.
Given the deep moisture and fairly weak storm motions, there will be
a threat for locally heavy rainfall which is backed up by some
probabilistic guidance including the HREF. Slow moving storms could
lead to minor flooding in low-lying and poor drainage areas. The
severe threat looks to be low overall, but a couple stronger to
possibly severe storms can`t be ruled out, with the main hazard
being isolated damaging wind gusts.
Moisture levels will be much lower on Thursday and with lack of
large scale forcing, shower/thunderstorm coverage is expected to be
less than previous days. Perhaps the more interesting forecast note
of the day will be the temperatures. Highs are expected to average
in the low to mid 90s, highest inland, with heat indices around
105.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Surface troughing will linger inland on Friday before a weak front
drops into the region and possibly stalls in the vicinity over the
weekend. Mainly diurnally driven showers and thunderstorms are
possible each day. Hot temperatures and higher relative humidity
values could lead to heat indices of 105-110. Given our heat
advisory criteria of 110, we will need to monitor the potential for
Heat Advisories, especially on Friday.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Prior to the 0Z TAFs, regional radar indicated that the center
of low pressure was pushing onshore south of the Altamaha
River. Rounds of showers and isolated thunderstorms will remain
possible as the low tracks north along the coast. Late tonight,
the combination of deep moisture and weak forcing near the low
center should develop a patch of MVFR ceilings across SE GA. The
low ceilings will have the greatest chance developing over KSAV
after 9Z and could remain through the rest of the TAF period.
Latest HRRR and HREF indicates that SHRA and TSRA will develop
near and to the north of the low center, highlighted with either
VCSH/VCTS for much of the day and TEMPO groups for each site
between 15-19Z for TSRA.
Extended Aviation Outlook: Flight restrictions are possible in
showers and thunderstorms through Wednesday.
&&
.MARINE...
Tonight: The weak surface low that is just to our south will
move onshore southeast Georgia this evening. The marine
community will be situated on the western periphery of the sub-
tropical ridge, producing south to southeast winds of 15 kt or
less. Seas will average 2 to 4 feet, with isolated to scattered
thunderstorms continuing over the waters through the night.
Tuesday through Saturday: Generally south to southwest winds
expected through late week. Winds are expected to remain below Small
Craft Advisory criteria, although speeds on Friday could be in the
15-20 knot range as the pressure gradient tightens. Seas will
average 2-4 feet.
&&
.TIDES/COASTAL FLOODING...
The chances for minor salt water inundation in the Downtown
Charleston area during tonight`s high tide has diminished. As
winds become more unfavorable and astronomical tides continue to
decrease, the recent series of Coastal Flood Advisories has
ended, at least for the near future.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...NED
MARINE...BRM/ETM
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Duluth MN
955 PM CDT Mon Jul 26 2021
.DISCUSSION...(This evening through Sunday)
Issued at 426 PM CDT Mon Jul 26 2021
Summary...The main concern this forecast is this evening`s
convection with the Enhanced risk of severe storms we have. After
that, we have warm weather continuing with chance for more showers
and thunderstorms on Wednesday, and again on Friday.
The convection this evening is an unusual Enhanced risk for this
area, which we do not typically see more than a couple of days a
summer around here. There is a low pressure system over central
North Dakota this afternoon, with a warm front draped east into
our area, generally from the Brainerd Lakes region east into
northwest Wisconsin. Along and south of this boundary the airmass
is strongly unstable, with surface based CAPE values already over
2k j/Kg, with models indicating it may get up over 3k j/Kg at some
point this evening. Sounding from this morning show an Elevated
Mixed Layer that should be over our area this evening that is also
showing as a drier area on satellite imagery. This EML will
produce steep lapse rates in the mid levels, even as it also
produces the capping that we are seeing at the lower levels this
afternoon. Model soundings show that we should have a long
hodograph this evening with moderate to strong winds aloft to help
lengthen it, despite the weaker winds in the boundary layer. This
all shows that if we can get convection to fire, severe storms
are likely, with very large hail and strong winds, as already
depicted in the SPC day one severe outlook. We may have a very
weak shortwave moving along the North Dakota/Manitoba line this
afternoon which has been generating an area of accas and -tsra
over northwest Minnesota this afternoon. This is likely based in
the 700-600mb Warm air advection region, and we do not expect this
area to grow significantly or become rooted in the surface based
instability, at least in part due to its position relative to the
surface boundary. However, ahead of the surface low over eastern
North Dakota we have some decent pressure falls over northwest
Minnesota and would expect some new development in this area
sometime in the next few hours. Models have been wildly
inconsistent in depicting this event, with the NAMNest and FV3SAR
showing development over NW MN and eastern ND by 01Z, then
sliding southeast across the forecast area, but the HRRR not
developing anything until after 03Z, and with much less coverage
than either of the other models. Uncertainty in timing and
evolution is still pretty high, even as of late afternoon.
Unfortunately, we are in the wait and see mode, and we will have
to see how things evolve this evening. There may be some lingering
showers into early Tuesday morning, but otherwise expect the bulk
of the convection to be out of the forecast area shortly after
midnight.
Tuesday should be relatively quiet with the boundary having
shifted south of the forecast area and weak ridging over the area.
Highs to get back into the 80s for the day, though slightly
cooler than today.
We have another chance for showers and thunderstorms on
Wednesday, and while we have a small threat for severe weather, am
not as concerned about it as I am for this evening. Should it
shift a little later in the day and allow instability to build
before the convection moves into the area, that would be a
different story. Highs to creep back up into the low 90s for the
Brainerd Lakes region.
After another quiet day on Thursday, another shortwave should
bring another chance for showers and thunderstorms Friday night
and early Saturday, but it is too soon to determine the severe
weather potential with this. This should usher in a bubble of
cooler temperatures aloft with cooler high temperatures through
the weekend, with highs back in the 70s to low 80s for both days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 653 PM CDT Mon Jul 26 2021
Line of thunderstorms will affect all terminals, except INL,
through the evening. Isold MVFR with the storms, but VFR
elsewhere. Strong gusty winds in the vicinity of the storms, along
with the potential for hail and heavy rain. Will see the storms
diminish/move out of the area through the overnight. Some patchy
BR is also possible with MVFR vsbys after the storms.
&&
.MARINE...
Issued at 955 PM CDT Mon Jul 26 2021
Showers and thunderstorms will affect the nearshore waters
through the night, gradually diminishing toward sunrise. Gusty
winds, heavy rain and frequent lightning will accompany the
storms. Higher waves may also accompany the storms. Quiet weather
Tuesday and Tuesday night as high pressure is nearby. Another
round of showers and storms is forecast for Wednesday. Winds will
be northeast at 5 to 10 knots, with some gusts to 20 knots near
the western arm of the lake, and waves less than 3 feet.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 61 78 60 82 / 90 10 40 60
INL 56 85 62 85 / 20 10 60 70
BRD 63 86 66 92 / 50 10 30 50
HYR 61 84 61 86 / 50 10 30 60
ASX 61 79 59 87 / 70 10 40 60
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&
$$
DISCUSSION...LE
AVIATION...GSF
MARINE...GSF
Area Forecast Discussion
National Weather Service Quad Cities IA IL
604 PM CDT Mon Jul 26 2021
...12Z AVIATION UPDATE...
.SYNOPSIS...
Issued at 118 PM CDT Mon Jul 26 2021
Early afternoon MSAS analysis has large surface high centered over
the CWA, providing mostly sunny skies. GOES-East GeoColor
satellite loops still show some upper level smoke over the
region, although some thinning of that layer has occurred today
across IL and MO. Weak shortwave and clouds across southern MN
this morning has long since dissipated, as it encountered drier
air aloft over northeast IA. Early afternoon temperatures and
dewpoints were similar to Sunday afternoon, with readings in the
upper 80s and middle 60s respectively. Dewpoints should remain in
the 60s this afternoon, as we mix down drier air to the surface.
&&
.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 248 PM CDT Mon Jul 26 2021
Surface high will slide east this evening and overnight, allowing
return flow to setup. This will keep temperatures warmer than
compared to this morning, along with steady or slowly rising
dewpoints. Lows will drop into the middle 60s. All shower and
thunderstorm activity should remain to our north, where better
lift and moisture will reside.
Tuesday...return flow will usher in warmer and more humid air
towards the region. 850mb temps will rise near 23C by the
afternoon and combined with late July sun will boost temperatures
into the low to mid 90s. However, more upper level smoke is
expected to advect into Iowa, which may keep highs slightly lower
than forecast. The next question is how high will the dewpoints
get. Many models have been overdoing the dewpoints lately,
including the NBM. As a result, have kept max dewpoints in the
upper 60s/low 70s on Tuesday. While it will be noticeably more
humid, heat indices are expected to remain in the mid to upper 90s
and below advisory criteria.
.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 248 PM CDT Mon Jul 26 2021
Key Messages:
1. Very warm and humid conditions are expected Wednesday and
Thursday.
2. Precipitation chances return late in the work week, with some
relief from the heat as temperatures return to near seasonable
levels.
Tuesday night-Wednesday...large upper level ridge will be centered
over the central CONUS, with H85 high located over central MO.
Warm and moist air will continue to advect into the area, with
dewpoints reaching the lower to middle 70s by the afternoon. Even
with lowering the NBM initial dewpoints some (have been verifying
too high as of late), I am getting heat index values in the
100-105 degree range across our western counties on Wednesday.
However, since there are still a wide range of solutions regarding
temperatures/dewpoints for Wednesday and after how models
performed with dewpoints yesterday and today, will let the
midnight crew take another look at model trends and make the call
on heat headlines since we are still 2 days out. I am concerned
that any convective debris clouds from the north, mixing depth
Wednesday, and smoke may lessen the heat some. The latest RAP even
brings in some shower chances Wednesday morning. Regardless, it
will be humid Wednesday and anyone working outside should take
frequent breaks and remain hydrated. Highs should reach the low to
mid 90s.
Wednesday night-Thursday...a backdoor cold front and an increasing
LLJ will provide sufficient lift to produce scattered showers and
thunderstorms across northeast IA, southern MN, and southern WI
overnight. Some of these storms may eventually congeal into an
MCS and propagate near our northern border early Thursday. If this
occurs, then damaging winds, heavy rain, and lightning will be
possible. SPC has a Day 3 slight risk for severe weather across
northeast IA and southwest WI for this possibility. Additional
storms may also be possible Thursday afternoon/evening along the
cold front that will be near the IA/MO border at 00z Friday.
Thursday night On...noticeably less humid conditions will be seen
with periodic chances of showers/thunderstorms, as several weak
shortwaves move through the northwest flow. There will be many
hours of dry weather conditions and temperatures will return to
near seasonable readings with highs in the 80s and lows in the
60s. With the large upper level ridge to our west, no significant
rains are forecast through early August.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
ISSUED AT 605 PM CDT Mon Jul 26 2021
High pressure will provide VFR conditions with mostly clear skies
and light surface winds tonight through Tuesday. There is a low
potential for ground fog that could briefly drop visibilities
below 1SM around sunrise.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Gross
SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Sheets
Area Forecast Discussion
National Weather Service Goodland KS
945 PM MDT Mon Jul 26 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 228 PM MDT Mon Jul 26 2021
At the beginning of the short term period, the CWA is under a large
upper air ridge covering the western CONUS with the controlling
upper air high in northeastern CO. The upper air flow varies in a
clockwise fashion across the CWA due to the proximity of the upper
air high on Monday. At the surface, the remainder of Monday
through the night looks to be mostly dry with minimal chances of
precipitation. A brief isolated rain shower or non-severe
thunderstorm cannot be completely ruled out as there is one
currently in northern Gove county. The latest HRRR run does not
predict any precipitation, but the RAP and NAM show brief bouts of
precipitation in the CO counties and the adjacent counties during
the evening. Again, any storms that may pop up should stay below
severe criteria as current convective parameters do not support
severe weather. Surface winds in the CWA expect to be from the
south around 10 to 15 mph for the rest of the day before becoming
lighter and south-southeasterly into the night. The CWA should see
temperatures near the 90 degree mark for the remainder of the
afternoon then see overnight low temperatures in the lower to
upper 60s.
For Tuesday, the upper air pattern looks to stay pretty much the
same as that on Monday as models show the upper air high barely
moving eastward and remaining in northeastern CO throughout the
day. At the surface, current model runs aren`t showing lower
visibilities due to fog in the morning so will not be adding them
into the forecast. The main concern for the day will be the above
normal temperatures with heat indices exceeding the 100 degree
mark in some areas as there looks to be a low chance for
precipitation for the CWA. A Heat Advisory has been issued for
Hitchcock, Red Willow, Decatur, Norton, and Graham counties from
17Z-01Z as the heat indices might have the potential to reach
criteria though it seems marginal at this time. This will be
monitored in case the situation changes to favor higher indices in
the CWA. Daytime high temperatures in the CWA on Tuesday expect
to be in the lower to upper 90s with forecasted heat indices in
the lower 90s to the lower 100s. Tuesday`s overnight lows look to
be between the middle 60s and the lower 70s.
.LONG TERM...(Wednesday through Monday)
Issued at 200 PM MDT Mon Jul 26 2021
Wed-Fri: An expansive upper level ridge, extending eastward from
the Intermountain West into the Central Plains, will persist
through the duration of the work-week. Expect dry conditions and
above normal temperatures.. warmest on Wed and Thu.. when heat
indices may approach 105F.. and a heat advisory may be needed for
eastern portions of the area (mainly east of Hwy 25).
Sat-Mon: Long range guidance suggests that the aforementioned
ridge will amplify over the Intermountain West and extend
northward through western Canada (Alberta/Saskatchewan) -- and
that shortwave energy rotating around a large cyclonic gyre over
Nunavut/Hudson Bay/Quebec may progress southward (along the
eastern periphery of the amplifying ridge) into the Upper Midwest
-- the net effect of which would bring the mid-latitude
westerlies (NNW-NW flow aloft, in this case) in closer vicinity to
the Central/Northern Plains. If this is the case, a somewhat
greater potential for diurnal convection may exist.. though.. with
an increasingly amplified/dynamic synoptic pattern at high-
latitudes.. confidence is below average.. particularly at a range
of 120-168 hours.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 945 PM MDT Mon Jul 26 2021
VFR conditions are expected to prevail through the TAF period at
KGLD and KMCK terminals. Light south winds continue through the
overnight hours, then shift to the southeast by 20z, gusting
around 20 knots or so through 01z.
&&
.CLIMATE...
Issued at 945 PM MDT Sun Jul 25 2021
Record high temperatures for the remainder of the week:
------------------------------------------------------------------
7/27 7/28 7/29 7/30 7/31
------------------------------------------------------------------
Goodland KS 105/1910 106/1943 104/1947 106/1935 105/2002
Burlington CO 103/1960 102/1947 100/2012+ 101/2005 102/2002
Hill City KS 106/1956 110/1940 108/1917 109/1976 113/1934
McCook NE 109/1931 105/2012+ 109/1947 105/2002+ 107/2002
Colby KS 108/1931 109/1943 105/1947 109/1935 108/1935
Yuma CO 104/2011 103/1959 104/1947 104/2005+ 107/2002
Tribune KS 106/1936 105/1943 105/2012 106/2012 107/1934
------------------------------------------------------------------
(+) denotes multiple year records
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory from noon to 8 PM CDT Tuesday for KSZ003-004-016.
CO...NONE.
NE...Heat Advisory from noon to 8 PM CDT Tuesday for NEZ080-081.
&&
$$
SHORT TERM...076
LONG TERM...VINCENT
AVIATION...JBH
CLIMATE...JN/JBH
Area Forecast Discussion
National Weather Service Green Bay WI
813 PM CDT Mon Jul 26 2021
Updated aviation portion for 06Z TAF issuance
.SYNOPSIS...
Issued at 244 PM CDT Mon Jul 26 2021
Very warm and humid with a few rounds of thunderstorms through
mid-week, then turning cooler and drier for the rest of the work
week and into next weekend.
A strong band of westerlies across the northern CONUS and
southern Canada will gradually but substantially amplify during
the period. A longwave ridge position will be in the west, with a
trough in the east. By the weekend, a full-latitude ridge will
extend along the U.S. and Canadian Rockies, with a deep trough
over eastern Canada and the northeast quarter of the CONUS.
The pattern favors very warm temperatures and humid conditions for
a couple more days, with a significant trend toward cooler and
drier conditions thereafter. The precipitation forecast will be
subject to the typical uncertainty related to convective
precipitation during the summer. But the best guess is for AOA
amounts.
&&
.SHORT TERM...Tonight and Tuesday
Issued at 244 PM CDT Mon Jul 26 2021
The latest RAP analysis and satellite/radar imagery show low
pressure over western South Dakota and an associated warm front
stretching east into southern Minnesota. Further north, a
secondary warm front is draped from North Dakota to the
U.P.-Wisconsin border early this afternoon. Most thunderstorm
activity has occurred across South Dakota and southwest Minnesota
so far today. However, dewpoints have been climbing across
northern Wisconsin and northern Minnesota where mixed layer
instability ranges from 600 j/kg over northeast WI to over 1000
j/kg north of Brainard. Some inhibition remains, however, upwards
of 50 j/kg that has limited cu formation over parts of northern
WI. Starting to see pockets of agitated cu from Wood/Portage to
Forest where isolated showers and storms have formed.
Because dewpoints are remaining elevated (not mixing out at some
sites), not out of the question that a few storms could develop
mid to late afternoon north and west of the Fox Valley.
Convergence isn`t particularly impressive near the U.P. border,
but instability and shear will likely be sufficient to develop
strong storms if they initiate. Otherwise, eyes will be watching
trends over northern Minnesota late this afternoon for convective
initiation.
Tonight...Clusters of severe thunderstorms remain expected to
develop over northern Minnesota early this evening. The latest
model guidance indicates a slower arrival time (10pm-12am) as
they move along the warm front (instability gradient) into north-
central WI. Relatively high uncertainty in the details could cause
the arrival time to shift a couple hours either direction. Most
unstable capes of 1500-2000 j/kg and deep layer shear of 35-45 kts
will likely be able to sustain a damaging wind and large hail
threat as storms enter north- central WI. However, instability
should rapidly diminish overnight which should result in a
transition to mainly a damaging wind and heavy rain threat as
storms move southeast. It`s not clear if storms will have enough
instability to work with to propagate into central WI and the Fox
Valley overnight. Fortunately, forward propagation should be
sufficient to negate a high end heavy rainfall threat, but
rainfall rates should be sufficient for at least a low end threat.
Lows ranging from the lower to upper 60s.
Tuesday...Many of the forecast details depend upon how
thunderstorms evolve tonight, where the front and any outflow
boundaries stall out. But generally, guidance points toward the
front stalling from central to northeast WI. The airmass will
remain quite unstable ahead of the front (1000-2000 j/kg of cape),
but convergence (and forcing in general) doesn`t look as robust
as tonight. Models are generally dry for tomorrow afternoon, but
given the uncertainty and forecast instability, didn`t stray far from
the previous forecast. Highs ranging from near 80 over northern WI
to the upper 80s by Wautoma and Wisconsin Rapids.
.LONG TERM...Tuesday Night Through Monday
Issued at 244 PM CDT Mon Jul 26 2021
The overall forecast scenario has held consistent for the past
couple days, and did so again today. Low-end PoPs are warranted
for Tuesday evening due to the presence of a weak boundary in the
area. A lack of large scale forcing suggests any activity will be
isolated. But it could still be strong given the warm/humid
conditions and deep layer shear.
The most significant round of convection is likely to occur
Wednesday afternoon into Wednesday night when mid-level shortwave
crosses the area along with a seasonably strong cold front. SPC
outlooked the southwest half of the forecast area with a slight
risk for severe weather on the early morning day 3 outlook. An
upgrade may be necessary depending once smaller scale details of
the situation become more apparent. PWATs rising to AOA 2 inches
also support a risk of torrential rainfall and possibly flooding.
The very humid air mass across the area will raise the risk of
heat-related issues, especially across central into east-central
Wisconsin Wednesday afternoon/evening.
Much quieter weather is anticipated for the remainder of the
period. Scattered showers and storms will be possible Saturday as
another cold front drops in from the north.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 813 PM CDT Mon Jul 26 2021
VFR flying conditions will persist through much of this evening
as high pressure slowly drifts to the east. A thunderstorm complex
developing over northwest Wisconsin is expected shift into
northern Wisconsin later this evening and into the overnight
hours. Gusty winds and torrential rainfall are possible with
these storms. The strongest storms will likely impact the RHI TAF
site mid to late evening, then impact the AUW/CWA TAF sites around
or shortly after midnight. Cigs may drop down into the IFR
category with any of these storms. Farther south, the storms may
weaken before reaching the GRB/ATW/OSH/MTW TAF sites late tonight;
however, a wind shift will likely occur along with brief gusty
winds. A brief period of LLWS may also develop ahead of the
convection tonight. Improving conditions can be expected at each
TAF site Tuesday morning.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Gray ME
950 PM EDT Mon Jul 26 2021
.SYNOPSIS...
A warm and humid air mass will last through Tuesday before a
cold front moves through late in the day. This front will be
the first in a series that will bring cool and dry air into the
region through the end of the week and the weekend. Showers and
thunderstorms are possible with the front Tuesday night High
pressure will pass through on Wednesday, before another chance
of showers late Thursday with another frontal passage. High
pressure builds in for Saturday, with another front possible by
late Sunday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
945 PM Update... Adjusted PoPs some to better align the area of
higher PoPs to where showers and thunderstorms are currently
located. Although an isolated strong storm will remain a
possibility through around 04Z, the threat for severe weather is
very low and continuing to diminish as CIN continues to
increase over the area. Generally weighted the HRRR pretty
heavily for PoPs through the remainder of tonight as it has done
a decent job with the ongoing convection. Some minor
adjustments to temperatures, winds, and sky cover were also made
but overall the ongoing forecast remains on track.
Previously... 7:00 PM
Update...Have increased pops across Northern NH and Western
Maine as a pre- frontal 500mb shortwave trough begins to
approach the region from Quebec province. Convection is
beginning to fire across VT ahead of a large cluster of storms
in the Saint Lawrence river valley area. WV sat imagery shows
the trough that the CAMs are picking up on with the RAP and HRRR
keeping activity going until at least midnight across the
northern areas. A few strong cells could be possible, and a
isolated SVR can`t be ruled out at this time, but that is a low
prop at this point with a setting sun and decreasing surface
instability.
The classic triple H this afternoon: Hazy, hot and humid as smoke
from wildfires in Manitoba combines with a warm and sticky airmass.
While the Haze is thick enough to reduce visibility to 5 miles and
may be keeping us just slightly cooler most of the region is still
at or above 80F.
A glace to the Northwest shows what`s to come. The thickest portion
of the haze ends at the St. Lawrence valley and just behind it
convection is beginning to fire ahead of another short
wave/cold front just starting to drop into southern Quebec.
Timing out this boundary, we`ve still got most of the afternoon
to go in the hot haze before any of the convection can reach the
US/Canada border, which should occur around sunset. This
morning`s sounding out of Maniwaki shows a region of steep lapse
rates around 700mb which should help to increase instability.
That said, there is also quite a bit of dry air aloft. Overall
it`s a marginal environment for severe storms, but some gusty
winds can`t be ruled out in Northwestern Maine late this
evening.
Well behind the front we have much drier air moving in but we`ll
need it to get here first. While the northern parts of NH and
western Maine may see that benefit tonight the Maine coast will
likely wait out almost until sunrise, and thus continued fog
overnight along the midcoast is expected.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday a second stronger short wave will push through the
region. This will bring scattered showers and thunderstorms to
especially the southern Maine and NH south of the White
mountains. Forecast soundings suggest some marginal severe
storms are possible, with gusty winds being the main threat.
Have kept a mention of gusty winds in for the highest PoP.
Overnight behind the front the drier air will come in allowing
temperatures to drop. Have leaned on the cooler side of the
distribution putting the mountains into the upper 40s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term pattern will continue to be dominated by troughing
across eastern North America, with generally below normal
temperatures and frequent frontal passages through the next week.
The pattern doesn`t look particularly rainy, but the chances for
showers will increase with the frontal passages roughly every other
day.
Breaking it all down, a frontal boundary will be south of the area
by Wednesday morning, but lingering showers may still remain across
southern New Hampshire. These will diminish by the afternoon hours
as high pressure builds into the area. Highs will mainly be in the
low to mid 70s.
The influence of the high pressure will be short lived however, as
low pressure rides northwest of the area on Thursday. Thursday will
start off dry, but a triple point low is likely to develop across
the eastern Great Lakes south of the parent low, bringing widespread
showers and likely a few thunderstorms into the region later
Thursday afternoon through Friday morning. They should move out by
Friday mid-morning, but the trough will be deepening on Friday, with
cooling temperatures aloft likely leading to some pop up afternoon
showers.
The low pressure will strengthen as it moves through the Canadian
Maritimes on Friday and Saturday, becoming anomalously strong for
this time of the year. This will likely lead to some breezy
conditions late Friday afternoon, and then resuming again on
Saturday once daytime heating resumes. A weak ridge will build
in at the surface for Saturday yielding sunshine, but the upper
level trough will reach its maxima on Saturday and Sunday as
cool Canadian air pours into the region.
Another front will likely approach the region late Sunday and into
Monday, bringing another threat of showers and a fresh shot of cool
air for early next week.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Short Term... MVFR visibilities in Haze will continue through
evening before the residual smoke plume moves off shore,
thereafter VFR and clear skies will be the rule, although a few
scattered showers are possible in the north tonight. Valley fog
will drop conditions to LIFR for LEB and HIE, with additional
IFR fog along the coast for RKD. tomorrow sunny skies with just
a chance for scattered afternoon across southern New Hampshire.
Long Term...
Some lingering showers are possible across southern New
Hampshire Wednesday morning. A few pop up showers are possible in
the afternoon, but otherwise VFR conditions are expected
through midday Thursday. A frontal boundary will likely bring
widespread showers late Thursday through early Friday. VFR
conditions return midday Friday outside of a few afternoon pop
up showers and remain through Saturday. Some gusty northwest
winds are possible late Friday and again on Saturday. Scattered
showers likely return late Sunday.
&&
.MARINE...
Short Term...Hazy skies will continue across the waters this evening as
weak southwesterly flow continues. A cold front will cross the
region tomorrow afternoon switching winds to northwesterly.
Long Term...
High pressure will build into the area on Wednesday through
early Thursday, before an area of low pressure moves in from the
west late Thursday through early Friday. A period of SCA
conditions with southerly winds are possible Thursday afternoon
and night ahead of the system. The low will move into the
Canadian Maritimes on Friday and strengthen, possibly bringing
SCA conditions with northwesterly winds late Friday through
early Saturday. High pressure builds across the waters during
the day on Saturday.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
NEAR TERM...Dumont/Tubbs
Area Forecast Discussion
National Weather Service Lake Charles LA
942 PM CDT Mon Jul 26 2021
.UPDATE...
Isolated showers and thunderstorms have continued to develop this
evening well after sunset likely as a result of some outflow
convergence from the stronger clusters of thunderstorms in and
around Jackson, MS. The HRRR is depicting the current storms
relatively well and shows continued isolated development through
the late evening with the isolated convection moving offshore, as
is typical, early tomorrow morning. Adjusted PoPs modestly to
reflect this thinking.
Better cloud cover and convection still expected tomorrow as the
influence of the upper ridge centered over Colorado and Wyoming
becomes less prevalent. This will keep heat indices below
advisory criteria across the area for the first time in three days
although afternoon highs will still climb into the mid 90s where
storms do not develop.
Jones
&&
.PREV DISCUSSION... /issued 655 PM CDT Mon Jul 26 2021/
DISCUSSION...
For 00z TAF issuance.
AVIATION...
No significant changes to previous TAF thinking. Diurnal
convection, although spotty, continues at this time across the
region...this activity should be winding down now that we approach
sunset/loss of heating. Overnight, VFR conditions look to prevail
although we will have to watch for light fog potential later
tonight around areas that got rainfall today. Today looks like a
repeat of today, although with a little more convective coverage
given less capping aloft per forecast soundings as the mid-level
ridge looks to weaken.
25
PREV DISCUSSION... /issued 340 PM CDT Mon Jul 26 2021/
SYNOPSIS...
Latest UA analysis and WV imagery show a broad and sprawling
anticyclonic pattern from the Intermountain West east acrs the
plains into the southeast. A few weak disturbances are noted
within and around the expansive ridge, including a couple of weak
impulses over the western and northeast Gulf of Mexico. At the
sfc, weak high pres acrs the region was resulting in light and
generally vrbl winds, while a weak trough was noted over the cntl
and eastern Gulf.
KLCH radar shows sctd showers and storms developing from NE LA
southward to the lower Atchafalaya Basin, within an axis of 2+
inch PWATs. Activity was drifting west to southwest. Elsewhere,
some very sparse isolated showers have struggled to develop.
Under partly cloudy skies, temperatures have risen into the middle
90s acrs much of the area. Corresponding heat index readings have
been abv 100 degrees, with a few spots around 108.
24
SHORT TERM [Tonight through Wednesday night]...
The aforementioned showers and storms will continue to develop
through late aftn as they propagate into our eastern zones, then
gradually decrease and dissipate through sunset as daytime
heating wanes. Conditions will remain very warm and humid
overnight, with lows in the middle and upper 70s.
Showers and tstms will increase in coverage Tuesday and Wednesday
as the main influence of the ridge stays northwest of the area,
while subtle disturbances move west acrs the Gulf of Mexico.
Convection should remain sctd and diurnal in nature, developing
by early aftn and continuing until around sunset. While a few
storms could produce brief heavy rainfall, amounts are not
expected to be excessive and, for the most part, should stay under
an inch.
High temps the next couple of days will be hot, outside of any
cooling showers. Temperatures will be near normal (lower 90s) acrs
the southern half of the area, while further inland, temps could
top out a few degrees warmer. With temperatures a smidge lower,
apparent temperatures are not expected to be quite as hot, and
heat index values should stay below advisory criteria, although a
few locations in Avoyelles Parish could briefly flirt with heat
index values around 108 Tuesday aftn.
24
LONG TERM [Thursday through Monday]...
Early on the region will be on the southern periphery of ridge
centered over the midwest. Guidance also continues to indicate high
moisture content across the area as well. In addition some weak
waves of energy from the east will cause an enhancement of the
diurnal shower and thunderstorm activity. Little more ridging
builds back into the lat weekend into early next week along with a
drier airmass with rain chances lowering back to more normal
summertime chances.
Temperatures still to remain warm through the period.
27
MARINE...
A generally onshore flow should prevail through the week. Winds
are expected to remain light and seas low through the period.
Shower and tstm chcs are expected to increase by midweek, with
sctd showers and tstms possible through the end of the week.
24
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 77 95 76 95 / 20 70 30 50
LCH 78 93 77 93 / 30 60 30 40
LFT 78 93 76 94 / 30 60 20 50
BPT 76 93 76 94 / 20 50 10 40
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
634 PM CDT Mon Jul 26 2021
.SHORT TERM...
253 PM CDT
Through Tuesday night...
Sunny and very warm conditions will continue the remainder of the
afternoon, especially for inland areas where temperatures will
remain in the upper 80s to low 90s. However, slightly cooler
conditions (lower 80s) will be felt near the lake due to a light
onshore breeze.
Quiet and very warm weather will continue on Tuesday as well,
though the remnants from a developing MCS well to our northwest in
MN tonight may spread some increased early morning mid to high
level cloudiness overhead. I also cannot totally rule out a couple
of early morning light showers or sprinkles from this decaying
MCS making it into far northern IL early Tuesday. However, with
the MCS expected to weaken and decay overnight as it moves
southeastward into a less favorable thermodynamic environment, it
appears this threat locally will be low. I have thus opted to
keep a dry forecast through the day Tuesday. We will also have to
keep an eye on any outflow from this overnight MCS trying to
shift southward down the lake into Tuesday. Confidence is not the
highest with any outflow making it into our area, but if it does,
it could result in a period of onshore flow and cooler conditions
near the lake on Tuesday. Otherwise, it appears capping will be
strong enough during the afternoon to keep the threat of
developing thunderstorms out of the forecast.
Our next small chance for showers and thunderstorms over northern
IL could come as early as late Tuesday night into early Wednesday.
Again confidence is not the highest that we will see much
activity during this period, but with increasing lower-level
moisture, I cannot rule out the possibility. This will especially
be the case if any type of mature MCS is able to develop to our
northwest and track southeastward late Tuesday night.
KJB
&&
.LONG TERM...
320 PM CDT
Wednesday through Monday...
The key messages in the extended remain the warm and humid
conditions Wednesday and Thursday, shower and thunderstorm chances
late Wednesday night through Thursday, as well as dangerous
swimming conditions for Southern Lake Michigan beaches developing
behind a cold front Thursday afternoon through Friday.
The Central Plains ridge remains locked in place midweek with
northwest flow over the Great Lakes region. Surface high pressure
begins to shift to the southeast at the start of the period
allowing southwest flow and associated moisture advection to
return, setting the stage for a warm and muggy Wednesday. Expect
highs in the low 90s and dewpoints in the 70s resulting in heat
indices nearing 100 degrees. As is often the case in the summer
under this northwest flow pattern, the high temperature forecast
will be conditional on any overnight MCS/convection that could
develop and sweep an associated outflow boundary through the area.
Did add some slight chances for lingering precip from overnight
mainly north of I-88. If there is a bit greater coverage of
showers/storms Wednesday AM that could limit some of our warming.
There is also a low chance for a few showers/storms Wednesday
afternoon, but lower confidence on that given strong capping that
looks to be in place. Continues to be a favorable signal for an
MCS to move through the area late Wednesday night into Thursday
morning with a Marginal Risk for severe storms in place for much
of the area to account for this. Locally heavy rainfall will also
be possible with any storms that develop which could create
localized instances of flooding.
12Z Guidance has trended a bit slower shifting the cold front out
of the area on Thursday, with a noted increase in blended PoPs
along and south of I-80 Thursday afternoon and evening. Given the
warm unstable airmass in place ahead of the boundary and decent
shear along the northern edge of the higher CAPE axis could
support strong to severe storms again Thursday that will need to
be monitored if this signal continues.
Expect increasingly gusty north winds off of Lake Michigan behind
the front Thursday afternoon. This will result in noted
temperature drop and an increase in wave action and dangerous
swimming conditions for southern Lake Michigan beaches. So will
continue to advertise a High Swim Risk for late Thursday afternoon
through Friday.
Beyond Thursday, the eastern side of the ridge sags a little in
the wake of the departing wave with temperatures becoming a bit
more comfortable in the 80s and dewpoints in the lower to mid 60s.
A weak disturbance brings additional low precip chances Saturday
night into Sunday.
Petr
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Concerns:
* Light/variable winds early this evening becoming southwest.
Breezier southwest winds expected Tuesday.
* Low probability for a convective outflow boundary to sag into
the region from WI Tuesday which could result in some easterly
wind component for a time.
Early evening surface analysis indicates high pressure ridge
across northern IL. Despite weak gradient and light wind regime,
lake breeze boundary struggled to push west across ORD this
afternoon (essentially bisecting the east side of the field as of
23Z). Wind should trend west/southwest there this evening (as well
as at MDW) as the lake breeze circulation weakens further, with
light southwest winds expected overnight into Tuesday morning.
On Tuesday, the surface ridge axis will continue to drift south of
the terminals, with somewhat breezier southwest winds expected
through the period. Capping inversion aloft noted in forecast
soundings limits the depth of the mixed layer, so have capped
gusts around 15 kts, but could see some gusts in the 15-20 kt
range if we ultimately mix a little more deeply. One potential
low probability complication could be if a convective outflow
boundary (from convection across MN/WI which would likely decay
due to capping farther south before reaching IL) were to make it
into the area. 18Z HRRR indicates such a scenario with a boundary
arriving midday and shifting winds to the northeast/east through
the afternoon. Convection has yet to really develop and grow
upscale across the upper Mississippi Valley this evening however,
and no other guidance depicts such a boundary moving this far
south. Later shifts will continue to monitor, but at this time
southwest winds appear to be the most likely scenario across the
terminals through the TAF period.
Otherwise, only VFR mid-high cloud debris is expected from
convection to our north Tuesday morning.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
631 PM EDT Mon Jul 26 2021
.SHORT TERM...(This evening through Tuesday)
Issued at 401 PM EDT MON JUL 26 2021
WV imagery and RAP analysis indicated a wnw mid/upper level flow
through the northern Great Lakes between a trough through Hudson Bay
into the ne CONUS and a ridge from the Great Basin into the Western
Plains. An upstream shortwave trough located over the Northern
Plains has initiated convection early this afternoon along an
instability gradient north of KINL into the arrowhead of MN southern
Saskatchewan and into ne WI. Otherwise, weak sfc high pressure has
kept conditions dry thus far across Upper Mi with interior temp
readings well into the 80s under partly cloudy skies.
Not great agreement or continuity with the CAMs solutions, although
most solutions maintain generally dry conditions with cap of up to
100 j/kg of CIN into the early evening hours. Consensus of CAMs
solutions shows CIN and weak cap gradually eroding as main shortwave
from the northern Plains moves overhead by late evening/early
overnight with more robust convection initiating in the western cwa
between 9 and 11 pm and then spreading south and east through the
late evening and early overnight hours. MUCAPE values of 1000-1500
j/kg along with deep layer shear of 45-50 kts oriented warm frontal
boundary along or just south of the WI border should result in
organized convection becoming more linear with time late evening
into overnight hours. Given instability and strong shear...SPC
day1 convective outlook has much of the west half of the U.P.
under a slight risk of severe storms and the east half under a
marginal risk. Main threat from severe storms will be large hail
and damaging winds. Would suspect organized convective storms or
any developing bowing segments to turn more south with time later
tonight following the better instability gradient. Any remaining
storms should diminish and move out late tonight as the shortwave
exits to the se.
Tuesday, frontal boundary lingers along south central portions of
the U.P. and a few of the model soundings show building instability
through the day and pooling of higher mid 60s dewpoints along the
boundary. A few of the CAMs try to initiate convection over the
south central U.P. but I have a hard time believing this will happen
as mid-level ridge heights will be building through the day and
drying/subsidence occurring at mid-levels. Soundings also show a
pretty substantial cap that would have to be overcome so expect dry
conditions should be the rule across the cwa. With relatively high
dewpoints still in place, expect there could be diurnal cu over the
interior. With 850mb temps ranging from 12-13c east to around 15c
west, expect max temps ranging from the lower 70s along the Lake
Superior shoreline to the upper 70s to around 80s over interior
locations.
.LONG TERM...(Tuesday night through Monday)
Issued at 328 PM EDT MON JUL 26 2021
The next time period to watch will be Wednesday as another
shortwave rides around the periphery of the upper ridge centered
over the Central Plains. For this next feature, timing has it
coming across portions of Upper Michigan at the height of daytime
heating, which could easily enhance the severity potential if
other parameters come together. Given this consideration, there
are indications that Wednesday`s event could be the bigger one to
watch given that 0-6km bulk shear, instability, moisture content,
and so forth all seem supportive for a severe event. Then the
question becomes track and placement, which is lower confidence as
it is still two days out. Some models have the main convective
complex primarily crossing WI while others, such as the NAM, are
much further north, cutting right through the heart of the U.P.,
which isn`t unreasonable given the expectation of the upper ridge
meandering to the ENE by then. Stay tuned.
Once that convection clears out, expect a brief quiet weather
period on Thursday as surface high pressure stops by. As the
aforementioned upper ridge breaks down late in the week, this will
open the door for an upper trough to sink down across Ontario by
early next weekend, accompanied by another chance for showers and
thunderstorms. Surface high pressure under meridional flow then
looks to build in toward the end of the weekend into early next
week.
As previously discussed, temperatures continue to look on track to
run near to above normal for the long-term period. Highs each day
will generally run in the 70s and 80s, with lows ranging from the
40s in the interior behind a fropa Thursday night into Friday
morning and then again over the weekend, and 50s and 60s
elsewhere/otherwise.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 631 PM EDT MON JUL 26 2021
VFR conditions are expected through most of the period. Showers and
thunderstorms are expected to develop or move into the region this
evening and continue overnight. There is the potential for strong
wind gusts with some of the storms and also some MVFR conditions as
well. However, confidence is limited with the timing/coverage of the
storms.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 401 PM EDT MON JUL 26 2021
Winds are expected to be 20 kts or less through much of the fcst
period. A seasonably strong cold frontal passage Wed night could
generate north to northwesterly gusts up to 20-25 knots behind the
front on Thursday, highest over the east half.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...lg
AVIATION...07
MARINE...Voss
Area Forecast Discussion
National Weather Service San Francisco Bay Area
548 PM PDT Mon Jul 26 2021
.SYNOPSIS...Monsoon moisture has moved into our region with light
shower activity today. Slight chance of showers and isolated
thunderstorms continues into Tuesday morning. Long range trends
remain seasonably warm and dry through the end of the month.
&&
.DISCUSSION...as of 02:55 PM PDT Monday...Many folks have enjoyed
seeing some light rain fall across the region today. It`s been a
long time since we`ve seen actual rain drops instead of just
drizzle drops from marine stratus. The monsoon moisture arrived
earlier today and the first wave of light showers moved across
Monterey County from south to north and has continued to track
northward. Isolated to scattered light showers are now in the
North Bay. We have not had any reports of lightning so far, but
one of our forecasters did report some small hail that briefly hit
his home southeast of Marina, CA this morning. Measurable rain
has generally been just a few hundredths although a few sites
reported as much as 0.08". Current radar shows that the bulk of
shower and lightning activity remains to our south and southeast.
So, how will the rest of today into tomorrow play out? The hi-res
NAM and HRRR models are indicating that we should see a second
wave of shower activity move from south to north later tonight
into Tuesday morning. The difference being that the NAM
illustrates a more organized line of showers while the HRRR has a
more broken, disorganized wave of shower activity. From the hi-
res NAM: estimated timing of that second wave starts around 8 pm
tonight for southern Monterey County. This line of showers will be
oriented SW to NE and should reach South Bay & East Bay after
midnight (approx 2 am) then track across SF soon after. It will
then start to impact the North Bay counties around 3 am and
gradually track north until it exits far northern Sonoma County by
Tuesday afternoon.
We are still seeing the models indicate some instability with
this second wave of showers, so have kept the mention of showers
and thunderstorms in the forecast. There is currently a large
complex of thunderstorms straddling the southern NV and CA
stateline that is producing a lot of lightning
strikes...fortunately, it is also dropping good rain amounts
ranging 0.25-0.75" with a few spots topping out over an inch. The
models do not indicate that that complex will track directly into
the Bay Area, but it does indicate that the instability is
present. It will be interesting to see if the line of showers just
west of that complex will carry some of that instability into our
region and result in a few strikes. However, we`re still viewing
this event as low probability for thunderstorms. NAM is showing
MUCAPE values up to 150 J/kg across our inland areas with this
second wave while the showers over coastal waters might have more
instability with MUCAPE peaking over 400 J/kg. Rain totals from
the second wave are not expected to be super wet, likely staying
under 0.10".
By Tuesday late afternoon/early evening, the excitement should be
over and we will go back to a drier weather pattern. We`ve got a
warm up in the forecast for the second half of the week with
Thursday potentially being the warmest day. Coastal areas should
peak in the mid 60s to mid 70s while inland spots range from the
upper 70s to upper 90s. This is all thanks to a very large and
broad high pressure ridge that will dominate much of the CONUS. By
the weekend, that high pressure will weaken as an upper level low
off the coast of Canada nudges inland and returns our region to a
more marine influenced and seasonable climate.
&&
.AVIATION...as of 5:47 PM PDT Monday...For the 00z TAFs.
Currently VFR across terminals. Satellite imagery reveals stratus
over the coastal waters and SCT mid- and high-level clouds
streaming over the area, in association with a monsoonal push of
moisture from the south. Local radar is picking up on a
disorganized line of convective showers in northern SLO county
near the border with MRY county, but this area of activity should
stay to the south of area terminals. No lightning is being
detected with this activity. Hi- res models are in fairly good
agreement that another push of moisture later this evening and
overnight will allow additional showers to overspread the Central
Coast and later the SF Bay area. These showers may bring brief
periods of light to moderate rainfall, certainly enough to lead to
wet runways. This moisture should exit the region by early
morning around Monterey Bay and mid to late morning around SF Bay.
VCSH have been included in area TAFs for this period. The marine
layer will behave as it has for the last few days, with low-
hanging clouds streaming back in to the coastal terminals starting
this evening (MVFR/IFR) and lifting by mid/late-morning tomorrow.
Vicinity of KSFO...VFR with stratus offshore and SCT high clouds
streaming overhead. Increasing mid/high level clouds into tonight
due to monsoonal moisture, with a moderate sea breeze that will
gradually weaken overnight. Moderate confidence in showers passing
over or near the terminal 09z-16z. These may bring brief periods
of lowered Vis, but should remain primarily VFR. Low confidence
in low CIGs developing over the terminal in the early morning
hours but SCT low clouds may drift into the vicinity along with
likely BKN100 from monsoonal moisture. All cloud layers should
lift and scatter through the morning and afternoon.
KSFO Bridge Approach...Similar to KSFO.
Monterey Bay... VFR with breaks in stratus along the coast and SCT
high clouds passing overhead. Low CIGs will return this evening
close to 03z, with initial MVFR/IFR lowering to IFR/LIFR
overnight. Additionally, a surge of monsoonal moisture is
expected to bring increased mid to high level clouds this evening
and overnight. This will also bring chances for scattered showers
to area terminals from around 07z-15z with lowered Vis due to
mist. Low CIGs, along with higher clouds will clear out by late
morning leading to VFR conditions.
&&
.MARINE...as of 02:37 PM PDT Monday...Winds remain out of the
northwest and are light, yet continue to drive the sea state at
around 7 to 9 seconds despite a weak southerly swell present. Wind
gusts will increase Monday afternoon and into the evening through
the Golden Gate gap and into the San Francisco Bay. Slight chance
of showers and high based thunderstorms remains over the waters
through Tuesday morning. Any developing thunderstorms may be
accompanied with lightning and erratic winds. Chances for
thunderstorms diminish Tuesday afternoon.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...SF Bay until 9 PM
&&
$$
PUBLIC FORECAST: Bingaman
AVIATION: Lorber
MARINE: DK
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Area Forecast Discussion
National Weather Service New York NY
1048 PM EDT Mon Jul 26 2021
.SYNOPSIS...
High pressure builds in from the west overnight. High pressure
will weaken Tuesday with a cold front from the north then
approaching the region. The cold front moves across Tuesday
night. Weak high pressure builds in Wednesday. A cold front
approaches on Thursday and passes through Thursday night into
Friday. High pressure then builds in through Saturday before
another frontal system approaches late on Sunday.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Some residual smoke/haze causing a reduction in visibility
(5-6sm) for northern areas overnight. Otherwise, with high
pressure at the surface building in from the west, expecting
mostly clear sky conditions tonight. Along with decreasing
winds, radiational cooling will be optimized. Some patchy fog
also possible for these far outlying areas overnight with
radiational cooling.
Mid and upper level westerly flow will keep a dry airmass in
place. Dewpoints will stay well down into 60s and even upper
50s overnight. A MAV/MET MOS blend was used for low temperatures
to resolve a more vast range of temperatures between the urban
heat island and outlying rural sections. Lows range from the
upper 50s to near 60 for outlying rural sections to low to mid
70s within NYC.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
High pressure at the surface will gradually weaken on Tuesday. A
cold front will approach from the north and move across Tuesday
night. Drier air at the surface will still be present with
lowering dewpoints going into the morning and early afternoon.
Forecast 850mb temperatures are expected to reach 17 to 18
degrees C. Highs were a blend of NBM and MOS consensus in the
upper 80s to lower 90s. Dewpoints staying mostly in the lower
60s will keep heat indices close to actual temperatures.
Showers and thunderstorms will become probable for interior
areas late in the afternoon, but across the whole region Tuesday
night as the cold front moves closer to the region. Thunder
chances highest for the first half of the night between 8PM
Tuesday and 2AM Wednesday. Instability will be limited and will
decrease more late at night so after 2AM, thunder chances become
slight with a continued chance of showers.
Vertical forcing increases most Tuesday night with positive
vorticity advection in the mid levels. Bulk shear will be
increasing 0-6km to 30-40 kt so some thunderstorms could be
strong with gusty winds. Highest instability at the surface will
be in the southern half of the region with around 1000 to 1500
J/kg of CAPE and less to the north. Most of the upper level
energy seems to be focused to the north of the region where the
height falls will be more and omega will be higher. There is a
marginal risk of severe thunderstorms across parts of the Lower
Hudson Valley and Southern Connecticut.
Lows Tuesday night were taken from a consensus of all guidance
with temperatures ranging from the lower 60s across the interior
to upper 60s and lower 70s along and near the coast as well as
NYC.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
The long term continues to be dominated by a large mid-level trough
that is reinforced by shortwaves in the flow through the weekend
and into next week.
Weak high pressure over the area on Wednesday may result in a few
showers or thunderstorms though coverage should be rather isolated
if they occur at all. The weak high shifts offshore into Wednesday
night providing for an increasing southerly flow advecting moisture
back into the area. An intensifying low pressure system to the north
tightens the pressure gradient over the area ahead of the
approaching cold front. Showers become likely much of the day
Thursday with an isolated thunderstorm possible late in the day.
Though there is some uncertainty in the timing of the frontal
passage, showers looks to continue into Thursday night and
early Friday.
A brisk NW flow behind the front on Friday gradually weakens into
Saturday as a high pressure tries to build in from the southwest,
but Friday and Saturday will be mostly, if not entirely, dry. High
pressure quickly gets pushed offshore by Sunday as another frontal
system brings another cold front into the area for late on Sunday.
The strongest forcing appears to be toward the north of the area,
but the GFS brings in a surge of moisture just ahead of the front
resulting a significant difference in precipitation and rainfall
amounts. Capped the PoPs at a chance for now. Thereafter, models
diverge in the pattern but look to show a generally dry Monday and
Tuesday.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Weak high pressure remains over the region into Tuesday. A cold
front approaches from the north late in the day, and crosses in
the evening.
MVFR in haze for northern terminals through the evening. Some
haze aloft possible tomorrow afternoon, although HRRR model
guidance not indicating vsby impacts to the surface.
Light and variable winds this evening, becoming W/NW less than
7 kt Tuesday morning. S/SE 8-12 kt afternoon seabreeze
development expected at most terminals. Potential for scattered
shra/tsra after 00z.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Light W/NW winds (less than 5 kt) for Tue morning push. S/SE
seabreeze 8-12 kt for evening push. Potential for scattered
shra/tsra btwn 01z and 05z
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
.Tuesday night...Chance of brief MVFR/local IFR cond with any
showers/isolated tstms.
.Wednesday and Wednesday night...VFR. Slight chance of a shower or
tstm.
.Thursday and Thursday night...Chance of MVFR, local IFR, with a
chance of showers and thunderstorms.
.Friday-Saturday...VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
A weak pressure gradient will be in place across the waters
with conditions expected to remain below SCA thresholds through
Wednesday night.
A strengthening southerly flow ahead of an approaching cold
front will likely bring SCA conditions to the ocean waters late
Thursday into Thursday night. Waves will slowly subside on
Friday in a post-frontal NW flow, which may bring marginal SCA gusts
during the afternoon. Elsewhere, conditions are forecast to remain
below SCA criteria. Conditions drop below SCA conditions by Friday
night.
&&
.HYDROLOGY...
Layer PWATS reach almost 1.7 inches Tuesday night. Aside from
the possibility of minor flooding with thunderstorms in low
lying and poor drainage areas with locally higher amounts of
rainfall Tuesday night, no hydrologic issues are expected
through Tuesday night.
Looking ahead, no hydrologic impacts are expected Wednesday
through early next week.
&&
.TIDES/COASTAL FLOODING...
A moderate risk of rip current development is forecast for the
ocean beaches for Tuesday, with a mix of 2 ft S and SE swells.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JM/MW
NEAR TERM...JM/NV/MW
SHORT TERM...JM
LONG TERM...MW
AVIATION...NV
MARINE...JM/MW/NV
HYDROLOGY...JM/MW
TIDES/COASTAL FLOODING...JM/NV
Area Forecast Discussion
National Weather Service Pendleton OR
824 PM PDT Mon Jul 26 2021
.UPDATE...The latest radar was showing a few showers south of
Pendleton moving ne into the blue mountains along with some
showers in and near the Wallowas and the forecast was updated to
reflect this. Further south isolated showers and a thunderstorm is
possible overnight in a plume of moisture streaming into the area.
Otherwise minor changes were done to overnight temps and the
short term forecast appears on track.
A challenge could be with the coverage of showers and
thunderstorms tomorrow. The rap model was generating showers over
central Oregon tomorrow morning that could stretch into portions
of south central Washington by midday and remaining persistent
into the afternoon. Meanwhile the models were moving additional
mid level moisture into central Oregon and into Grant county
Tuesday afternoon. The rap and the hrrr models were developing an
area of convection in this region after 20z with moderate to high
confidence.
&&
.PREV DISCUSSION... /issued 441 PM PDT Mon Jul 26 2021/
SHORT TERM...Tonight through Wednesday...Light showers moving
northeast continues across portions of central OR and the
northeast mountains this afternoon, with only a couple of
lightning strikes being recorded in the last hour or two. Cloud
cover and smoke aloft have helped to limit daytime warming across
the eastern half of the forecast area, with many of these
locations struggling to warm into the low to mid 90s.
A slight chance of showers with thunder possible will continue
into this evening, and linger over portions of the Ochoco-John Day
Highlands and central OR into early tomorrow morning. Overnight,
flow aloft will begin to turn to the south as a sub-tropical low
moves west into the eastern Pacific. This will help to advect more
monsoonal moisture into the region, and help to keep temperatures
in the low to mid 90s in the afternoon. Impulse rounding the upper
level high pressure over central CONUS will help to increase
instability across the mountains in central and northeastern OR
Tuesday, with slight chance to chance of thunderstorms possible
through Tuesday evening. Though thunderstorm chances will be
better tomorrow, fire weather concerns will be below marginal as
any thunderstorm will be capable of producing moderate to heavy
rain. Wednesday, upper high pressure will begin to amplify over
the region while a slot of dry air advects into the region. This
will lead to storm chances diminishing across the central OR and
the northeast mountains by early Wednesday, and for temperatures
to warm into the 90s, though portions of the Basin may hit the
triple digit mark with enough clearing overhead. Winds through the
next couple of days will generally be light to locally breezy in
the afternoons, and become diurnally driven in the nighttime
hours. Lawhorn/82
LONG TERM...Thursday through Sunday...Above average heat into the
triple digits, areas of thunderstorms, and then a cooling trend
are all possible in the extended forecast period.
Ensembles remain in solid agreement that the deep ridging over the
majority of the Western/Central US will continue to extend up into
our region with a deep low offshore of Canada and a trough off of
California. This pattern will continue to increase our
temperatures to end the week and begin the weekend, with upper
90`s likely for much of the forecast region into triple digits for
the Columbia Basin. If current trends follow, some local records
could be threatened by this weekend`s heat wave, along with the
need for some heat advisories to possible excessive heat warnings
later this week.
Divergence between the ensembles then occurs on the strength of
the the ridging, but still agree on the eventual breakdown of the
ridge and subsequent retreat back to the Four Corners.
Temperatures should begin to fall, but are likely to remain above
average for the area. The ECMWF ensembles have better agreement
between the deterministic and the mean based on cluster analysis,
which would favor their solution of a weaker ridge and more
progressive pattern from SW`ly flow from deeper troughing off the
coastline.
Meanwhile, embedded shortwaves within the overall flow and enough
moisture including anomalously high PW values of 1-1.3" are
expected to produce scattered thunderstorm activity from South-
Central through Eastern OR over the majority of the extended
period. Because of the high moisture content, any storms that
form look to be wet and shouldn`t aid in fire weather concerns.
With a daily risk across this region, above average precipitation
values for this time of year are present across the Eastern half
of Oregon, which may be the sign of relief this area has been
looking for. Goatley/87
AVIATION...vfr conditions will persist at all taf sites for the
next 24 hours. Meanwhile some showers and perhaps an isolated
thunderstorm may approach sites krdm and kbdn Tuesday after 22z.
&&
.PRELIMINARY POINT TEMPS/POPS...
PDT 66 91 66 95 / 20 10 20 0
ALW 70 93 70 97 / 10 10 20 0
PSC 71 96 70 98 / 0 0 10 0
YKM 66 96 65 97 / 0 0 0 0
HRI 69 96 69 99 / 10 10 10 0
ELN 64 92 63 95 / 0 0 0 0
RDM 60 87 58 93 / 20 20 30 10
LGD 65 91 64 92 / 20 10 20 10
GCD 66 92 62 94 / 20 20 30 10
DLS 69 93 68 98 / 0 0 0 0
&&
.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&
$$
SHORT TERM...97
LONG TERM....99
AVIATION...97
Area Forecast Discussion
National Weather Service Portland OR
328 PM PDT Mon Jul 26 2021
.SYNOPSIS...Above normal temperatures continue through this
week as high pressure strengthens across the Intermountain West,
with the hottest conditions expected Thursday and Friday, with hot
temperatures continuing through Sunday. A slight chance of showers
and thunderstorms along the central Oregon Cascades tonight and
continuing through at least the middle of the week.
&&
.SHORT TERM...Tonight through Friday...A broad upper level high
pressure anchored across The Great Basin will slowly meander
northward through the middle of the week. This will result in a
gradual warming trend over the next few days, as reflected in the 850
mb temperatures, with the hottest days expected Thursday and Friday.
850 mb temperatures will slowly increase from the low to mid teens
Tuesday and Wednesday, peaking around 20C to 22C Thursday and Friday.
This will mean that temperatures for the week will remain above
normal in the upper 80s to low 90s for Tuesday and Wednesday, and
likely reaching into the mid to upper 90s Thursday and Friday. At
this time models including the NBM, which did an outstanding job at
predicting the record breaking heat in June, are not showing triple
digit temperatures except, in the 90th to 95th percentile runs, which
means that there is a ~10% chance that temperatures of 100 to 105
could happen within the Willamette Valley during this event.
Therefore, while temperatures will be very hot, am not expecting
record breaking temperatures through the weekend. Even though
temperatures will likely not be record breaking, precautions should
be taken during this period of time.
As the high pressure moves northward, expect the southwest upper
level flow to persist, with surface winds remaining primarily onshore
at least through Wednesday. Within this upper level southwest flow
small perturbations within the flow are present. At this time, these
perturbations are currently causing precipitation in central and
northern California. High-resolution models such as the HRRR and the
HRW ARW models are showing these perturbations following the
southwesterly flow. As these perturbations move across the area, they
will bring a slight chance of showers and thunderstorms to the Lane
and Linn County Cascades Tuesday, Wednesday and Thursday. Thursday,
the onshore surface winds will slowly weaken for inland locations
becoming more north/northeast during the daytime Thursday and Friday.
While an easterly wind event is not expected, the slacking winds will
enable the warm 850 mb temperatures to mix down towards the surface.
In addition expect night time cloud cover, which has been aiding in
moderating temperatures, to diminish through Friday. The hottest days
at this time are expected to be Thursday and Friday, the reason that
it could be ether day is due to the very little chances currently
seen in the models. Some locations could see the peak heat on
Thursday while others could see it on Friday and vice versa. While
daytime temperatures will be hot, overnight temperatures will drop
into the lower to mid 60s, which will provide some respite from the
daytime heat. There remains no precipitation chances across the
majority of the CWA through this time period. /42
.LONG TERM...Friday night through Monday...Saturday is expected to be
the last day in this string of hot temperatures as the high pressure
ridge axis anchored across The Great Basin starts to shift eastward
and breakdown into the start of next week. As this breakdown occurs
an upper level low from the Gulf of Alaska looks to push
southeastward along the western Canadian coast line. This will bring
a resurgence of onshore flow to the area and enable a cooling trend
for the area. Given that the NBM, GFS, ECMWF and Canadian models and
their ensembles all show this slight cooling trend, there is little
reason to deviate from the NBM. Unfortunately, there continues to be
no precipitation expected across the CWA through the start of next
week. However, there could be a slight chance of showers and
thunderstorms across the Lane and Linn County Cascades through the
weekend but, overall confidence on the exact timing and coverage
remains low. /42
&&
.AVIATION...Mostly dry southwesterly flow aloft with some high
level cirrus streaming northward through the period. Mainly VFR
expected inland, although some shallow stratus may again push
inland tonight through the lower Columbia River valley. There is
a chance of broken MVFR cigs near KPDX/KTTD early Tue morning
around 14Z to 16Z.
IFR coastal stratus appears to have developed along the Oregon
coast due to upwelling. Expect marine stratus to push back
onshore with lower MVFR to LIFR conditions likely along the coast
by 03Z to 04Z Tuesday. Patchy fog also likely along the coast
mainly south of KTMK. Northerly wind gusts to 25 kt will
continue along the coast through this evening.
For detailed regional Pac NW aviation weather information, go
online to: https://weather.gov/zse
KPDX AND APPROACHES...Mainly VFR conditions expected. Chance for
shallow MVFR stratus to return early Tue morning for a couple
hours around 14Z to 16Z. Northwest wind with gusts up to 20 kt
expected from 00Z to 05Z this evening. /DDH
&&
.MARINE...High pressure remains offshore with low pressure over
SW Oregon and NW California. This will bring the typical
northerly wind pattern over the next several days. Strongest
winds likely through Monday evening. Small Craft Advisories
currently in effect across all waters for wind gusts around 25
kt. The northern waters will see winds 20-25 kts through the
remainder of the afternoon and early evening hours, mainly south
of Tillamook head and inside of 25 nm. Similar conditions across
the central waters through around midnight.
The pressure gradient is expected to weaken Tuesday and Wednesday
with wind gusts generally up to around 20 kt. Northerly winds
likely to increase again Thursday with winds gusting up to 25 kt
again through the end of the week. Seas will be wind wave
dominated and choppy at 4-6 ft on top of a minimal south to
southwest swell of 1. /DDH
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for coastal
waters from Cape Shoalwater WA to Cascade Head OR out 60
NM.
Small Craft Advisory until 11 PM PDT this evening for coastal
waters from Cascade Head OR to Florence OR out 60 NM.
&&
$$
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Area Forecast Discussion
National Weather Service Seattle WA
902 PM PDT Mon Jul 26 2021
.SYNOPSIS...
Continued dry weather with a warming trend is expected the next
several days. A mid level ridge of high pressure will continue to
build north into the area through the week, sending temperatures
to above normal levels for the next several days. Skies will
remain mainly clear in the daylight hours with some clouds
appearing overnight.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Southwesterly flow aloft continues across the area around the
western periphery of the pronounced upper level ridge of high
pressure. This will contribute to some marine stratus overnight in
favored areas. Of additional note is a thin layer of elevated
smoke/haze appears to have drifted across the area but is not
coming from the southwest. It was fairly evident on the last
several visible satellite frames before sunlight disappeared. The
HRRR smoke model this evening hints at some very thin coverage
throughout the next few days as well but the more significant
smoke will remain east and southeast of the area and fortunately
the deep southwesterly flow will keep deeper smoke layers out of
the area through the next few days. Temperatures will steadily
warm through the latter portion of the week as mid level heights
climb with the southwestern ridge building into the area. Temps
will climb quickly above normal Tuesday and then well above normal
by Wednesday and Thursday. Plenty of mid to upper 80s are expected
with low 90s in the warmer spots. LJ
.LONG TERM /FRIDAY THROUGH MONDAY/...
The upper level ridge continues to be the controlling feature
through the weekend. Ensemble guidance continues to highlight a
consistent westward shift of the ridge axis, with some variability
in terms of the amplitude through Saturday. Expect warm
temperatures to continue to trend warmer Friday and Saturday,
solidly into the mid to upper 80s across the interior with some
areas south of Tacoma, and perhaps some locations along the
Cascade foothills east of I-405 reaching into the lower 90s. Low
temperatures will dip into the upper 50s providing some overnight
relief, however some locations through the metro area eastward
into the Cascades could remain in the low 60s overnight which
would be less of a relief. More enhanced onshore flow, and perhaps
slightly cooler temperatures will return by the start of next
week with a strengthening low off the coast of B.C. by late Sunday
or Monday. The warm and dry pattern looks to continue through the
7 day forecast.
&&
.AVIATION...
Generally quiet weather with mainly clear skies to start the
period. Coastal stratus will roll in overnight with onshore flow
and so MVFR/IFR cigs will occur at coastal terminals with just a
brief period of clouds farther inland. This should dissipate all
locales by the 18-20Z timeframe with clear conditions thereafter.
Westerly winds at 5-10 knots will persist.
KSEA...
Light northerly winds at less than 10 knots gradually becoming
westerly overnight and persisting into Tuesday. Mainly clear skies
will give way to some lower clouds 12-15Z Tuesday but not
expecting reduced cigs at this time. Clear skies prevail after
17-19Z.
LJ/Butwin
&&
.MARINE...
Onshore flow will prevail the next few days with nightly pushes of
stronger winds down the Strait of Juan de Fuca. Expecting at least
Small Craft Advisory conditions each evening with some brief
gales. LJ/Butwin
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Tuesday for East Entrance
U.S. Waters Strait Of Juan De Fuca.
Small Craft Advisory from midnight tonight to 5 AM PDT Tuesday
for Central U.S. Waters Strait Of Juan De Fuca.
Gale Warning until midnight PDT tonight for Central U.S. Waters
Strait Of Juan De Fuca.
&&
$$
www.weather.gov/seattle
Area Forecast Discussion
National Weather Service Shreveport LA
925 PM CDT Mon Jul 26 2021
.UPDATE...
A quick update was issued this evening to account for recent
trends in hi-res models with a slight chance of thunderstorms
overnight. Otherwise, there are no major changes to the forecast.
At the mid-levels, a broad ridge is centered across much of the
CONUS with high pressure centered over the central Plains into the
Intermountain West. A few isolated showers and thunderstorms are
lingering over southwestern Arkansas and the ArkLaMiss this
evening with IR satellite imagery indicating clouds spilling off
of earlier convection westward across much of the ArkLaTex.
Tonight, showers and thunderstorms will mostly diminish across the
area with the continued loss of heating. The humid atmospheric
conditions tonight are well-represented by dew points in the
upper 70s to around 80 across much of the area with the exception
being localized drier air in the Shreveport-Bossier metro with
dew points in the lower 70s. It appears that there will be enough
instability maintained overnight across the area for a few
isolated showers and thunderstorms over the ArkLaTex. The 18Z NAM
3km and recent hourly runs of the HRRR are hinting at this. Other
hi-res models indicate showers and thunderstorms completely
diminishing. Did not want to completely discount the HRRR/NAM
given the warm dew points and thus have a slight chance of showers
and thunderstorms to account for this possibility overnight.
For temperatures, a warm and humid night is expected with lows
close to NBM guidance ranging from the mid to upper 70s across
the area. Temp trends continue to favor another hot and humid day
tomorrow with heat indices in to 105 to 110 range. Thus, the Heat
Advisory remains in effect for Tuesday afternoon. /04-Woodrum/
&&
.PREV DISCUSSION... /issued 639 PM CDT Mon Jul 26 2021/
AVIATION...
VFR conditions will mostly prevail overnight as lingering isolated
showers and thunderstorms diminish and skies clear. Some MVFR fog
will develop at El Dorado and Monroe during the pre-dawn hours.
It`s possible that IFR will be needed in the next TAF package at
these locations, but confidence is not high enough to include
this at this time. Afternoon heating will fuel showers and
thunderstorms again tomorrow with VCTS in the terminals in the
late afternoon hours. Outside of any thunderstorms, prevailing
winds will be mostly light and variable through this period.
/04-Woodrum/
PREV DISCUSSION... /issued 316 PM CDT Mon Jul 26 2021/
SHORT TERM.../Tonight through Tuesday night/
Low to mostly mid 90 degree air temps with heat index values in
the lower to mid 100s for most sites. Monroe is by far the hottest
HX with a 112 last hour with a 78 degree dew point from nearby
showers. Most sites are in the lower to mid 70s on the muggy side.
KSHV 88D Radar is showing a scattering of showers and
thunderstorms so far to the east of the I-49 corridor. Movement is
towards the west and southwest at 10-15 mph. El Dorado had some
gusts into the mid 20KT range with a heavy downpour.
Little will change for us over the next 24 to 48 hours with this
weak Tutt upper low on the Gulf coast near Mobile today, slowly
drifting Westward. Another upper low in the W Gulf now will soon
be replaced by this new one arriving, helping to keep a slightly
better than average chance for needed rainfall going in the short
term period. The SPC keeps the threat level at the general and
the WPC QPF dwindles a bit each day from here. /24/
LONG TERM.../Wednesday through Sunday Night/
A strengthening upper ridge over the Central Plains will continue to
be the primary synoptic feature influencing our weather. On
Wednesday, easterly flow or a weak southeasterly flow on the
southern periphery of the ridge will continue to bring deep layer
Gulf moisture into the region. Combined with daytime instability
this should help to focus quite a bit of scattered diurnal
convection along and south of Interstate 30 ahead of a weak surface
front, which will stall across Southwest Arkansas. Afternoon
convection will become more isolated and confined to areas south of
Interstate 20 on Thursday as subsidence increases across the region
with the expansion/migration of the ridge towards the Southern Plains
and Lower Mississippi River Valley. The ridge should retrograde and
amplify late in the weekend. This may allow for a backdoor front and
scattered convection to approach the area late Sunday and into
Monday.
As the ridge approaches and rain chances continue to decrease, a
prolonged period of hot weather will become the primary impact. The
NBM is still running too warm, so daytime high temperatures are
forecast to be a couple of degrees below those values through
Friday. Most locations should remain below the century mark through
Thursday. However, the longer we go without rain, the drier our
soils and vegetation will get. In turn, this will allow temperatures
to warm slightly higher each day. The best chance for air
temperatures above 100 degrees F should be from Friday through
Sunday. Heat index values will likely remain above 105 degrees F for
most of the area. Even with the lower humidity levels for many
locations, I would not be surprised to see portions of the area near
Excessive Heat Warning criteria next weekend. /CN/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 77 97 77 97 / 20 50 20 50
MLU 79 95 76 94 / 40 60 20 50
DEQ 77 95 74 96 / 30 30 10 20
TXK 80 97 77 96 / 20 40 10 20
ELD 76 95 74 94 / 20 40 20 30
TYR 77 96 77 94 / 10 30 10 30
GGG 77 95 75 94 / 20 40 20 40
LFK 77 97 76 96 / 10 50 20 50
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory from noon to 7 PM CDT Tuesday for ARZ050-051-
059>061-070>073.
LA...Heat Advisory from noon to 7 PM CDT Tuesday for LAZ001>006-
010>014-017>022.
OK...Heat Advisory from noon to 7 PM CDT Tuesday for OKZ077.
TX...Heat Advisory from noon to 7 PM CDT Tuesday for TXZ096-097-
108>112-124>126-136>138-149>153-165>167.
&&
$$
04/09/24
Area Forecast Discussion
National Weather Service San Angelo TX
603 PM CDT Mon Jul 26 2021
...New AVIATION...
.SHORT TERM...
(This evening through Tuesday)
Issued at 157 PM CDT Mon Jul 26 2021
Quiet conditions can be expected tonight across the area, with
lows mainly in the 70s. For Tuesday, we will continue to see hot
temperatures with highs in the mid 90s to around 100 degrees.
Also, the upper level ridge is forecast to weaken just slightly
over the area. This, combined with some increased moisture in
easterly flow aloft and at the surface tonight, hints at the
possibility of some isolated showers and thunderstorms Tuesday
afternoon. The HRRR and NAM Nest also indicate this potential, so
have added some low end Slight Chances for showers and
thunderstorms for areas mainly east of a Haskell to San Angelo to
Ozona line for Tuesday afternoon. However, coverage will be
limited, so most areas should not expect to see rainfall.
&&
.LONG TERM...
(Tuesday night through next Monday)
Issued at 139 PM CDT Mon Jul 26 2021
The upper-level ridge will dominate the weather picture for the
next several days. This should result in plentiful sunshine with
high temperatures around 100 degrees and lows in the low to mid
70s. The one exception appears to be Wednesday afternoon and early
evening, when an inverted trough will move westward across south
Texas. This may provide just enough lift and moisture to generate
some showers and thunderstorms. High temperatures were lowered by
a few degrees that day to account for extra cloud cover and
possible precipitation. For the weekend, a broad trough looks to
settle in across the eastern US, which may cause a brief frontal
boundary to intrude into the area by early next week. Other than
that, the ridge looks to remain the dominant weather feature for
Texas into early next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 602 PM CDT Mon Jul 26 2021
VFR conditions will continue through the remainder of the TAF
period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 76 99 74 94 / 5 20 10 20
San Angelo 73 101 74 95 / 0 10 10 20
Junction 71 100 73 94 / 0 20 10 20
Brownwood 75 101 74 94 / 5 20 10 20
Sweetwater 74 99 74 94 / 5 5 5 20
Ozona 71 98 73 92 / 0 10 10 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...20
LONG TERM....SK
AVIATION...41
Area Forecast Discussion
National Weather Service Tallahassee FL
1001 PM EDT Mon Jul 26 2021
.UPDATE...
Not much change needed to the forecast this evening. The last
several runs of the HRRR have maintained convection in SE Alabama
through at least 05z, and this is currently accounted for in the
latest PoP forecast. Don`t see much reason it would continue
longer than that, however the 00z KTAE sounding did have a fair
degree of instability left, and the airmass had moistened from
yesterday. The approach of the weakening tropical low over NE
Florida will also help focus convection on Tuesday, but should
have little impact in our area overnight.
&&
.PREV DISCUSSION [730 PM EDT]...
.NEAR TERM [Through Tuesday]...
Surface low near the Georgia low country will move ashore this
afternoon and weaken as it moves westward. The associated increase
in tropical moisture, as well as a tropical wave moving through the
Gulf, will advect from west to east into our area tonight and
Tuesday. Chances of showers and storms this afternoon and evening
will reside mainly on our eastern border however, the HRRR continues
to advertise development in southeast Alabama early this evening so
have raised rain chances slightly in our western zones. Not much in
the way of convection is expected in the overnight and early morning
hours. Rain chances increase markedly late morning Tuesday through
the afternoon hours with scattered to numerous coverage of storms
and chances around 70% throughout the area. Highs Tuesday will be in
the low to mid 90s with heat indices in the low to mid 100s.
.SHORT TERM [Tuesday Night Through Wednesday Night]...
Across the upper levels, a shortwave vorticity maxima is expected
to move through eastern Georgia and southern South Carolina late
Tuesday night and into Wednesday morning. This is expected to
provide ample upper level support across our SW Georgia regions to
increase PoP chances through this time period. This upper level
support coupled with a lingering weak surface low and high PW
values greater than 2 inches from the current tropical wave moving
into Jacksonville area will create an environment conducive
enough for widespread showers and thunderstorms. This potentially
could cause some nuisance flooding in streams and across drainage
ditches with higher rainfall rates, especially if storms train or
stay over the same areas for extended periods of time. Lows
tomorrow night will be warm with mid 70s expected across the
entire region. Highs will also be warm in the low 90s.
.LONG TERM [Thursday Through Monday]...
As the previously aforementioned shortwave vorticity maxima moves
off the coast of the United States, upper level ridging is
expected to become the prominent synoptic feature through the
remainder of the long term period. As the peak of the ridge axis
is expected to be out west, northwest flow aloft is expected to
return to the region, especially across the southeast. As weak to
moderate troughing develops to our north over the Northeast and
the Mid-Atlantic regions, we can expect a few shortwave impulses
to ride along the periphery of the trough axis to our north and
potentially increase rain chances and severity on any given day
through the long term period. With the trough axis to our north,
and the deep upper level ridge to our west, extremely high PW
values in the 2" range will drop to around 1.5-1.8 through the
long term as some dry air advects into the region through the mid
and upper levels. Overall, seasonable rain chances are expected to
return via diurnal convection that will encompass the area through
the afternoon and evening hours. Currently, the biggest concern
will be heat index values across the region heading into the
weekend, with widespread advisory level heat indices (108+)
possible starting Thursday and continuing through the weekend as
high temperatures in the mid 90s coupled with dewpoints in the mid
70s will lead to these warm conditions. Lows overnight will also
be warm in the mid to upper 70s expected across the region.
.AVIATION...
[Through 00Z Wednesday]
VFR conditions expected this evening. TSRA are possible in
vicinity of DHN through 05z, with a few already within 20 mi of
the airport. Elsewhere, expect quiet conditions overnight with
MVFR conditions at VLD prior to sunrise. VFR conditions after 13z
with sct-nmrs TSRA developing after 19z. Given variability in
model timing for storms Tuesday will only include VCTS groups at
all sites on this TAF issuance.
.MARINE...
Tranquil boating conditions are expected to prevail through the
week as westerly to southwesterly winds will remain around 10
knots or less through Thursday. Seas are also expected to remain
at around 1 foot or less across all waters. Winds will pick up
slightly starting Thursday, with sustained values between 10-15
knots expected. Seas are expected to respond with 1-2 foot swells
more common. Showers and thunderstorms may briefly bring elevated
seas and winds throughout the week.
.FIRE WEATHER...
Aside from low dispersions, there are no fire weather concerns
expected over the next several days.sion here.
.HYDROLOGY...
Localized flooding is possible on Tuesday from the weak low-
pressure system mentioned above that is moving from east to west
into our region today and tomorrow. A marginal risk (level 1/5)
for excessive rainfall exists for the entire region tomorrow in
WPC`s ERO. Overall, expect widespread totals of around 1 inch;
however, isolated higher amounts are possible, especially given
that PW values will be over 2 inches across the region. Any
flooding is expected to remain localized with locations possibly
seeing training storms or getting fast rainfall rates from slow
moving storms. In terms of rivers, there are several in action
stage, mainly in the Suwannee and Ochlockonee basins, but are
forecast to either crest or fall.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 76 94 75 92 74 / 20 70 40 80 30
Panama City 78 92 78 90 77 / 10 60 30 70 40
Dothan 75 93 74 91 74 / 30 70 50 70 20
Albany 77 95 75 93 75 / 30 70 60 70 20
Valdosta 75 94 74 91 74 / 30 70 50 80 30
Cross City 77 91 77 91 76 / 30 50 40 70 40
Apalachicola 79 90 78 89 77 / 20 40 30 60 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...Godsey
NEAR TERM...Scholl
SHORT TERM...Bunker
LONG TERM...Bunker
AVIATION...Godsey
MARINE...Bunker
FIRE WEATHER...Scholl
HYDROLOGY...Bunker