Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/21/23
Area Forecast Discussion
National Weather Service Aberdeen SD
545 PM CDT Thu Jul 20 2023
.SHORT TERM...(This Evening through Friday Night)
Issued at 200 PM CDT Thu Jul 20 2023
Overall quiet weather for the short term with high temperatures
around average for this time of year. Overall flow per EC/GFS
ensembles, along with deterministic models, continue to indicate the
ongoing low pressure system over northeast Canada and a ridge over
the western CONUS (and a strong mid level high over the Southwest)
at 500mb by 00Z Friday. Due to this, northwest flow remains over the
Northern Plains through the short term period. Within this flow, a
shortwave will swing down from the northwest Friday afternoon into
the evening, brushing our northeast/eastern CWA per Rap model. At
the surface, a high pressure system remains over the area with a
system to our southwest. With the northwest flow, HRRR vertically
integrated smoke model indicates the return of some smoke aloft this
evening through Friday. Although very subtle, I went ahead and added
this to the sky grids.
With the incoming shortwave pulse, several soundings over the
northeast/east CWA show a classic "inverted V sounding" with quite
the dry air near the surface-~800mb (due to the high pressure
system) Friday afternoon and evening. Few of the CAMs show at most
some isolated cells forming in this area. To cover this, I added 15%
pops (as surrounding offices collaborated), mainly around and east
of the James River Friday afternoon through the evening as NBM kept
the area dry. EC meteograms indicates less than 10% chance of rain
across northeastern/eastern SD and right around 10% across western
MN. With the dry air at the surface, rain would be light, if
any/virga. MUCape values will be max around 1000 J/KG with the 30kt
bulk shear staying over Sioux Falls area per HREF. That shear does
move northeastward after 00Z Saturday, but the pops should be done
by then or out of the area. HREF DBZ>40 shows about 40-50% chance in
this area with the storms staying elevated. No organized severe is
expected but cannot rule out some gusty winds and small hail
possible if some become stronger.
.LONG TERM...(Saturday through Thursday)
Issued at 200 PM CDT Thu Jul 20 2023
A western CONUS upper ridge and eastern CONUS upper trof remain in
the forecast to start the long term. The western ridge will continue
to expand/amplify as it slowly advects to the east through the
middle of next week. As that weather feature moves east, it will
spread a pretty healthy capping EML east into the Northern Plains.
This should effectively shut off most chances for convection early
next week. However, prior to that time period, a ridge riding s/w or
two could produce isolated activity over the eastern Dakotas and
Minnesota this weekend. More energy aloft may lead to a bump up in
convective activity come mid to late next week as temperatures aloft
cool some across the region. Temperatures will be climbing
throughout the long term. Near normal readings this weekend will
jump to above normal for the early and middle part of next week as
H7 temps sour above +12C and H850 temps push north of +20C. Some
hundred degree sfc temps look possible.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 545 PM CDT Thu Jul 20 2023
Terminals KABR,KATY,KPIR,KMBG
Dry weather and VFR conditons will continue over the next 24
hours. Expect winds at or below 10kts as high pressure remains
overhead.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
SHORT TERM...MMM
LONG TERM...TDK
AVIATION...KF
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1109 PM EDT Thu Jul 20 2023
.SYNOPSIS...
Low pressure moving from the upper Great lakes to Quebec will
bring rounds of showers, thunderstorms and the potential for
heavy downpours late tonight into Friday. The highest potential
for heavy downpours that may result in areas of flooding is
tomorrow afternoon into the evening. Isolated showers may
linger into Saturday before dry weather returns for Sunday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 1030pm, thicker cirrus clouds continue to spill eastward
into the Mohawk Valley and the southern Adirondacks ahead of the
convection that is tracking through western and central NY.
Further east, mostly clear skies continue but cirrus clouds will
spread eastward as we approach Midnight. The organized bowing
segment that resulted in numerous downed trees and wind damage
in western NY is losing steam as seen via the latest IR
satellite imagery which shows cloud tops warming and the radar
imagery that indicates the cold pool is out running the
updraft/downdraft convergence zone. The instability remains
mainly elevated so there is still potential for thunderstorms
overnight (and heavy downpours) into early Friday but unlikely
for storms to become severe. Latest MCD focus on PA and southern
NY where the better ingredients and tighter instability
gradient are in place.
The HRRR and the RAP continue to capture the timing the best of
the CAM guidance with showers and storms reaching the southern
Adirondacks and the Mohawk Valley by 05 - 09 UTC before heading
into the Hudson Valley and Capital District by 09 - 11 UTC. It
should then head into western New England by 11 - 13 UTC. POPs
still look good so left the POP forecast as is.
Previous discussion...Otherwise, strong thunderstorm cluster
currently developing over lower MI is expected to continue
tracking east/southeast through this evening into
western/central NYS and northern PA. As it shifts farther east,
this should gradually weaken, however will have to watch western
areas (Mohawk Valley/SW Adirondacks and eastern Catskills) as
there could be enough momentum to bring some thunderstorms with
strong wind gusts into these areas after midnight. Instability
looks mainly elevated across our region, with boundary layer
stability increasing, especially from the Hudson River and
points east. So although thunderstorms with brief heavy
downpours and frequent lightning may occur closer to the Hudson
River Valley after 3 AM, the potential for mixing down strong
wind gusts should decrease significantly.
Since these showers/storms should be moving through fairly
quickly, any heavy downpours should be brief through daybreak.
Lows mainly in the lower/mid 60s.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Flood Watch for Flash Flooding remains in effect for the Lake
George Saratoga Region, Capital Region and southern VT from noon
Friday through 2 AM Saturday...
Initial band of showers/thunderstorms should continue tracking
eastward across the region and into western New England through
8 AM Friday. There should be a break after this through at least
late morning, with perhaps some breaks of sunshine developing.
As the cold front approaches from the west, several lines/bands
of showers/thunderstorms should develop and track eastward
during the afternoon/early evening hours. These bands should be
slower moving, with some potential for backbuilding, resulting
in locally heavy downpours. The Capital Region and points north
and east are located within the best potential for over 1+
inch/3 hours, with some possibility for even higher amounts
(rainfall rates reaching/exceeding 1 inch/hour). This area is
also coincident with previous heavy rain/flooding within recent
weeks, and therefore the flood watch for flash flooding remains
in effect for this area.
Outside the watch area, heavy downpours and some
backbuilding/training downpours will still be possible, however
coverage may be more isolated/scattered, so isolated flash
flooding can not be ruled out, especially areas south/southeast
of the Capital Region.
In addition to flash flood potential, isolated severe
thunderstorms will be possible given the potential for MU CAPES
reaching 1000-1500 J/kg and 0-6 km shear of 25-30 KT. SPC has
placed the entire region within a Marginal Risk for severe
thunderstorms, a couple of instances of strong/damaging winds
and large hail.
Showers/thunderstorms should taper off from west to east Friday
evening, with just isolated showers possible later at night,
mainly across the southern Adirondacks and southern VT. Areas of
fog may form late at night as well.
Upper level trough will be closer to the region Saturday,
however main upper level energy should lift north of the region.
Some breaks of sun may develop in the morning, however enough
cold air aloft may promote isolated/scattered showers and
isolated thunderstorms Saturday afternoon for areas mainly north
of I-90. Highs in the mid 70s to lower 80s.
Clearing and cooler for Saturday night with patchy fog
developing. Lows mainly in the mid 50s to lower 60s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Weak upper level troughing and some upper level impulses may
trigger scattered showers/thunderstorms Monday-Tuesday, mainly
during the afternoon hours. Thereafter, chances for
showers/thunderstorms may decrease by mid to late next week,
depending on how quickly the upper level trough weakens.
Temperatures should be above normal through the extended, with
daytime highs reaching the upper 70s to lower/mid 80s Sunday,
with mainly 80s for Monday-Thursday, with some valley areas
possibly reaching around 90 by Thursday. Overnight lows in the
50s to around 60 through Wednesday morning, warming into the 60s
for most areas by Thursday morning.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...VFR conditions this evening will degrade to
MVFR/IFR during two waves of showers and thunderstorms during the
period, the first overnight and the second on Friday afternoon.
Current conditions are largely clear skies with unrestricted vsbys
and light and variable winds across the region. Low cloud cover at 4-
6 kft will steadily increase through the evening and early overnight
ahead of an approaching band of heavy showers and thunderstorms
currently located in westernmost New York. While these storms are
expected to gradually weaken, the band will likely affect all local
terminals between 08-11Z, with the confidence in thunder highest at
ALB/GFL and somewhat lower at POU/PSF as high-resolution models
consistently show a weakening trend not only as storms track
eastward, but also toward southeast New York state. As such, have
excluded any TS mention overnight at POU/PSF, but left TEMPO groups
for heavier showers at the times when thunder is most likely to
occur. MVFR vsbys appear most likely for general showers, with IFR
vsbys possible in heavier elements. Strong gusty winds are possible
within any thunderstorm. Additionally, low-level wind shear nearing
30 kt out of the south to southwest are possible across the region
in the morning between 10-15Z.
A return to VFR vsbys behind the line of storms from roughly 12-18Z
Saturday morning may still see persistent MVFR cigs with low-end VFR
possible at all terminals and increasing southerly winds at 8-12 kt
with gusts of 15-20 kt most likely at ALB. Afternoon diurnal storms
will develop across the region after 17-18Z, again resulting in MVFR
vsbys during general showers and IFR vsbys possible in
thunderstorms. Convection is expected to exhibit more of a scattered
distribution rather than the organized linear form from the
overnight period. Storms will persist through the remainder of the
TAF period to 00Z Saturday.
Outlook...
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: Low Operational Impact. Isolated SHRA...TSRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. Isolated SHRA...TSRA.
Monday Night: Low Operational Impact. Isolated SHRA.
Tuesday: Moderate Operational Impact. Scattered SHRA...TSRA.
&&
.HYDROLOGY...
Showers and thunderstorms return late tonight and continue
through Friday evening. Some areas could see heavy rainfall,
between 1 and 3 inches with locally higher amounts. Minor
flooding problems and isolated scattered flash flooding will be
possible Friday and Friday night. A Flood Watch for Flash
Flooding as been issued for the Lake George Saratoga Region,
Capital Region and southern VT. The Weather Prediction Center
has a Slight Risk for excessive rainfall in place for most of
our region for Friday-Friday evening.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Flood Watch from Friday afternoon through late Friday night
for NYZ041>043-048>054-083-084.
MA...None.
VT...Flood Watch from Friday afternoon through late Friday night
for VTZ013>015.
&&
$$
SYNOPSIS...KL/NAS/Speciale
NEAR TERM...KL/Speciale
SHORT TERM...KL
LONG TERM...KL
AVIATION...Picard
HYDROLOGY...
Area Forecast Discussion
National Weather Service Amarillo TX
657 PM CDT Thu Jul 20 2023
...New AVIATION...
.SHORT TERM ...
(This evening through Friday night)
Issued at 234 PM CDT Thu Jul 20 2023
Severe thunderstorms across the northern Panhandles this evening
through tonight is the main headline with the short term forecast.
The main hazards with these storms will be damaging wind gusts (up
to 80 mph) large hail (up to ping pong ball size), and very heavy
rainfall could lead to flash flooding. A cold front will move
across the Panhandles tonight and temperatures will cool down into
the 70s and 80s tomorrow.
The latest 20/18z H500 RAP analysis shows a shortwave trough
currently moving over the Rocky Mountains in Colorado as of the
time of this writing. Scattered convection is developing on the
leeside of the Rockies and across the Plains of CO/KS. A few
storms are even developing as far south as the higher terrain of
NM. Across the Panhandles, temperatures have been increasing into
the mid to upper 80s across the area with a few locations in the
mid 90s. Dew points continue to remain above most model guidance
with widespread dew points in the 60s with areas in the low 70s
across the east and north.
The above mentioned shortwave trough will propagate southeast
across the High Plains this evening. At the same time, a surface
cold front will propel southward across this same area. Both of
these features will provide plenty of lift to generate
thunderstorms in the high moisture environment of the High Plains.
Cannot rule out a storm making it to the far western Panhandles
from convection forming in NM, but the current thinking is that
these storms will struggle to make it this far east. The main show
will be with the storms near the cold front as it surges south
tonight. Strong to severe storms are likely along this front as it
moves across SE CO, southern KS, and the northeastern Panhandles.
The latest mesoscale models indicate that MLCAPE values could be
in the 2500-3000 J/kg range along with bulk shear values of 35 to
40 kts. Current thinking is that the storms will be linear by the
time they make it this far south, so damaging winds would be the
primary hazard. Very strong wind gusts will be possible with any
bowing segments in the line. Cannot rule out large hail given the
above parameters, especially if an embedded supercell can form
along the line. Even though the tornado threat is low, cannot
completely rule out a quick spin-up along the line given the low
forecast LCL heights.
The other main hazard with the storms tonight will be the very
heavy rainfall associated with the thunderstorms this evening
through the overnight hours. Forecast soundings indicate plenty of
moisture throughout the column, especially across the northeastern
portions of the forecast area. PWAT values could be in the
1.5 to 1.75 inch range as the thunderstorms move into the
Panhandles this evening. Very heavy rainfall is expected with the
storms, with rainfall rates potentially upwards of 3 inches per
hour. Thunderstorms may continue behind the cold front across the
northern zones through early tomorrow morning. These storms may
train over the same areas and heavy rainfall will continue to be
possible through sunrise on Friday morning. The 20/12z HREF
continues to have a 20 to 40 percent chance for 2 inches of
rainfall across the northeastern Panhandles from this system.
Given this potential, have issued a Flood Watch for the Oklahoma
Panhandle as well as the north central and northeastern Texas
Panhandle.
The cold front will move across the Panhandles tonight and breezy
to gusty winds are possible along and behind the front. Winds will
generally remain out of the north to northeast during the daytime
hours on Friday. Cooler air aloft will be in place over the High
Plains and temperatures will be much cooler than they were earlier
this week, with highs in the 70s and 80s. Another weaker shortwave
looks to traverse across eastern NM and the western Panhandles on
Friday afternoon and evening. Thunderstorms may form across the
higher terrain to the west and move across the western and
southern TX Panhandle during the evening hours. Severe weather is
not expected with these storms as the atmosphere should be mostly
stable across the area.
Muscha
&&
.LONG TERM ...
(Saturday through next Wednesday)
Issued at 234 PM CDT Thu Jul 20 2023
An upper level ridge will be centered over the 4-corners Saturday
morning. This will put the Panhandles under a northwest flow aloft
which will help to pull some thunderstorms off of the mountains
toward the western Panhandles Saturday night.
Thunderstorm chances will then be close to zero from Sunday through
Wednesday. The upper level high will move slowly to the east and
will end up over the Panhandles by Wednesday evening. As the high
builds eastward it will put the Panhandles under a more increasing
north to northeast flow which will not be as favorable to bring
thunderstorms into the area.
Highs are expected to be above normal from Sunday through Wednesday
with readings generally 5 degrees either side of 100.
&&
.AVIATION...
(00Z TAFS)
Issued at 646 PM CDT Thu Jul 20 2023
For the 00Z TAFs, showers and thunderstorms will likely impact KGUY
later this evening, with some potential for KDHT to be affected as
well. Have composed the terminal forecasts for those 2 sites
accordingly. It appears KAMA will not be impacted by the storms so
have omitted from that site. A cold front will move across the
region tonight with gusty northeast winds in its wake. In addition,
MVFR cigs will likely develop at the TAF sites late tonight and
persist into the morning hours on Friday, followed by improvement
at KDHT and KAMA during the afternoon. There is some potential for
IFR cigs to develop at KGUY late tonight into Friday morning.
Confidence is low in this development so have kept cigs at MVFR
levels at that site for this forecast cycle.
02
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 67 83 63 89 / 10 10 30 0
Beaver OK 64 77 61 88 / 80 20 0 0
Boise City OK 62 76 58 87 / 80 10 20 10
Borger TX 68 84 64 92 / 30 10 20 10
Boys Ranch TX 67 83 64 91 / 20 10 30 10
Canyon TX 67 85 63 89 / 10 10 30 10
Clarendon TX 70 85 65 87 / 10 10 30 0
Dalhart TX 63 79 59 88 / 50 10 30 10
Guymon OK 63 77 59 89 / 80 10 10 0
Hereford TX 67 85 64 90 / 10 10 30 10
Lipscomb TX 66 79 61 88 / 60 20 10 0
Pampa TX 67 80 62 88 / 20 10 20 10
Shamrock TX 69 84 63 87 / 20 10 20 0
Wellington TX 71 88 64 89 / 10 10 20 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch through Friday morning for TXZ002>005.
OK...Flood Watch through Friday morning for OKZ001>003.
&&
$$
SHORT TERM...05
LONG TERM....15
AVIATION...02
Area Forecast Discussion
National Weather Service Denver/Boulder CO
954 PM MDT Thu Jul 20 2023
.UPDATE...
Issued at 954 PM MDT Thu Jul 20 2023
The forecast is performing well with only minor updates this
evening.
We had widespread strong thunderstorms this afternoon and evening
which produced large hail and damaging gusts, mostly northwest to
southeast across the forecast area. There is a bit of lightning
up around the Divide but it hasn`t been surviving to the plains.
On the plains, this afternoon`s convection is slowly exiting
southeast and there is stratus in its wake. There will be more
light to moderate rainfall under those showers early tonight.
There is mist and fog under the stratus, which is reducing
visibility around the urban corridor. So far, it has not been
persistent nor widespread enough to warrant a highlight, and we
will continue to monitor it.
Our partners at CDPHE have issued another Air Quality Alert for
the Front Range Urban Corridor valid until 4 PM MDT tomorrow, as
hot temperatures and light winds will allow ozone concentrations
to reach unhealthy levels. More information is available in our
AQABOU.
&&
.SHORT TERM...(This evening through Friday)
Issued at 231 PM MDT Thu Jul 20 2023
Strong thunderstorms have already developed over the mountains,
foothills and adjacent plains early this afternoon. These will
continue to develop and spread eastward over the plains through
the evening hours. Severe thunderstorm watch has just been issued
for much of the eastern plains of Colorado with the exception of
Phillips and Sedgwick county until 03z. Instability is improving
with ML CAPE at Denver at 1200j/kg of latest ACARS sounding with
just a small inversion left at 750mb. The scarcity of storms over
the Denver area maybe due to the morning cloudiness and showers
that occurred early this morning. Current precipitable water
values closing in on 1.20" of water with continued threat of very
heavy rain with storms. Expect the deepest moisture farther east
with pw values close to 1.50". Rainfall rates up to an inch in 30
minutes or less is expected with strongest storms.
The features responsible for the severe weather today is an upper
wave now entering northwest Colorado with noted drying occurring
behind the wave across Utah and Nevada. RAP Analysis showing 60kt
speed max slicing across central Colorado. Given latest HRRR showing
a second round storms early this evening from the back edge of the
upper wave this looks like a reasonable solution. Substantial dry
and subsidence kicks in behind the wave with drying and storms
ending from northwest to southeast through the night. Drier airmass
along with warmer temperatures expected for Friday. Looks like
enough moisture for isolated showers/thunderstorms over the
mountains and adjacent plains.
.LONG TERM...(Friday night through Thursday)
Issued at 231 PM MDT Thu Jul 20 2023
An upper level high amplifies while sitting over the Four Corners
this weekend. This pattern will keep northwest flow bringing drier
air into the region. Low levels will have enough moisture Saturday
due to shortwave in the southern Rockies. This could lead to
isolated weak high based showers mainly in the foothills and South
Park Saturday afternoon. These high based showers will likely
produce strong wind gusts and light rain until Saturday evening.
Additionally, without much cloud cover, temperatures will begin to
warm. Parts of the foothills, urban corridor and plains increase
near mid 80s to lower 90s. Mountains and valleys trend near the low
to upper 70s Saturday afternoon. Clear skies continue through Sunday
morning.
Relative humidity across the region decreases near 15-20 percent
for the higher elevations. Northwest winds remain weak near 10-12
mph thus fire weather conditions should remain low. With MLCAPE
near 100 J/kg for the foothills and mountains, decided to decrease
NBM PoPs Sunday keeping less than 20-25 percent for the foothills
and majority of Park County. Additionally, without much cloud
cover, temperatures will begin to warm. Parts of the foothills,
urban corridor and plains increase near mid 80s to lower 90s.
Mountains and valleys trend near the low to upper 70s Saturday
afternoon.
Moisture continues to wrap around the upper level system which
increases our chances for diurnal showers and storms next week. Most
guidance favors the higher elevations for scattered showers and
storms but a stray shower or storm cannot be ruled out for the
Palmer Divide. ECMWF ensembles display increasing temperatures
Monday through Wednesday all areas. Both GFS and ECMWF ensembles
present KDEN reaching 98-99 for a high temperature both Monday and
Tuesday. With increasing cloud cover
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 538 PM MDT Thu Jul 20 2023
Expect generally VFR conditions through the period, intermittent
MVFR conditions are possible with passing storms, and cloud bases
below 6000 feet. Much of the threat has cleared our around the
terminals for the moment, with a little development near APA and
just a few more storms upstream. Those could bring impacts in the
next few hours but should not be as significant as the activity
from this afternoon. Following the convection, expect a stratus
deck for the night which should diminish by mid morning. Winds are
highly variable with outflow and do not look to turn to typical
drainage tonight. Winds should come around southeasterly and
easterly tomorrow, isolated thunder in the vicinity is possible in
the afternoon, then winds should come around to drainage in
evening.
&&
.HYDROLOGY...
Issued at 231 PM MDT Thu Jul 20 2023
Deeper moisture today will enhance the risk of flooding in the
burn scars. Rainfall rates up to an inch in 30 minutes or less
may occur with the stronger storms. Storm motions will be moving
at a decent clip which may help to minimize flash flooding as long
as training storms don`t develop. Flash flood watch has been
extended until midnight tonight for the Palmer Divide region,
including Washington county.
The flash flood threat remains little to none over the burn areas
this weekend.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Flood Watch until midnight MDT tonight for COZ046-047-049.
&&
$$
UPDATE...EJD
SHORT TERM...Entrekin
LONG TERM...AD
AVIATION...EJD
HYDROLOGY...Entrekin/AD
Area Forecast Discussion
National Weather Service Boston/Norton MA
1027 PM EDT Thu Jul 20 2023
.SYNOPSIS...
Dry weather is expected to continue this evening, then showers
and thunderstorms return Friday. Some thunderstorms across
western Massachusetts and Connecticut may have strong wind
gusts and heavy rain associated with them. Though we can`t rule
out a pop-up shower or thunderstorms across interior southern
New England on Saturday, mainly dry weather prevails. Gorgeous
midsummer weather for Sunday with mostly sunny skies, low
humidity levels and seasonably warm temperatures. Humidity then
returns for early to mid next week, with an increasing chance
for showers and thunderstorms around Tuesday into Wednesday.
&&
.NEAR TERM /UNTIL 8 AM FRIDAY MORNING/...
Adjusted rainfall chances and timing overnight. Largely relied
on the 00Z HRRR and NationalBlend. Thought the 00Z HRRR had the
best handle on the convection and it possible timing into
the Berkshires, but was looking for a slightly less
deterministic timing, hence the incorporation of the
NationalBlend data. At this time, thinking rainfall chances
start to increase about 2 AM, but really ramp up towards 5 AM.
Will be monitoring this timing through the overnight, and making
further adjustments as needed.
Given the time of day, also thinking that while there may be a
few thunderstorms nearby, their intensity should be decreasing.
This is in part to the humidity minimum presently across the
western half of southern New England, where dewpoints ranged
around 60 degrees. Minor tweaks to temperatures and winds, also.
755 PM Update:
Did have a pop-up heavy shower develop in southern Bristol
County MA (near the Rehoboth to Swansea area) on the sea-breeze
but that has since dissipated. Light sea-level pressure pattern
with modest E flow for eastern New England with light SE flow in
the interior.
Couple things to contend with for tonight. First is the
development and landward expansion of coastal stratus and
possible mist/fog. Only some hints/wisps of stratus well
offshore Nantucket now, though RAP/HRRR BUFKIT profiles are
steadfast in advancing a stratus deck back landward between
05-11z (after midnight to the pre-dawn/early Fri AM hrs),
probably not expanding much further north than the I-95 corridor
in MA/RI. Secondly - taking a wider lens, well to our west in
the lee of the Gt Lakes is a severe mesoscale convective system
tied to a potent shortwave trough moving out of Lower Michigan.
Model consensus is that this MCS thunderstorm complex weakens as
it moves into central NY later tonight, although we may see a
portion of this in the form of increasing mid clouds and perhaps
some remnant showers sneak into the Berkshires and interior CT
towards daybreak. So while current weather situation is
tranquil, increasing clouds from the SE and moving in from the W
are anticipated for the second half of the overnight.
Previous discussion:
Upper level trough currently over the western Great Lakes moves
east overnight along with its associated surface low. This will
begin to shift winds south overnight allowing for moisture to
begin streaming into the region. Most of the region will remain
cloud free this evening before midnight, then high clouds begin
to filter in from the west. Overnight lows should be in the low
to mid 60s, with a low chance for our typical radiators to drop
below 60F.
&&
.SHORT TERM /8 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
The 500 mb short wave begins to exit the Great Lakes region and
swing NE across New England. Expecting scattered to numerous
showers and thunderstorms ahead of the the trough and associated
cold front with modest destabilization and bulk shear. The main
threat for severe weather looks to be across western MA and CT
with MLCAPE ranging from 500-1000 J/kg and 0-6km bulk shear
around 30 knots. The main hazard looks to be a strong to severe
wind gusts with steep low level lapse rates. HREF indicates that
sig tor parameter will be nearing 1.0 along with curved low
level hodographs means there is low tornado chance tomorrow. As
per usual, mid level lapse rates are not good only 5-6C/km.
Heavy rain fall will be a threat tomorrow with PWATS rising back
to 1.5 inches, but storms will be rather progressive so flash
flooding is not expected to be widespread. As storms move east
in the late afternoon, they will begin to weaken with
instability and shear dropping quickly east of Worcester. Highs
tomorrow will be in the upper 70s to low 80s with cloud cover
spreading across much of the region. Dew points will be on the
rise again getting back into the upper 60s to low 70s with SSE
winds bringing in tropical moisture from the ocean.
Thunderstorms begin to dissipate around sunset tomorrow evening.
A cold front begins to enter the region overnight, but showers
and thunderstorms are not expected with subsidence aloft and
very dry mid level air. Low level cloud cover will likely stick
around ahead of the cold front with continued southerly flow in
the low levels. Lows should drop into the mid 60s with dew
points remaining in the mid 60s as well.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Highlights:
* Other than hit-or-miss pop-up shower or t-storms in the
interior, mainly dry Sat with drier air and decreasing
humidity levels for the evening.
* Pick of the weekend is Sunday with sunny and seasonably warm
weather but much lower humidity levels.
* Trends warmer, more humid early to mid next week with
shower/storm chances more focused with a cold front around
Tue or Wed.
Details:
Saturday:
Cool front seems more likely to be positioned just offshore by
early Sat morning, with shortwave trough aloft over interior
northern New England. May still have enough remnant, if weak,
instability to pop a shower or rogue t-storm Sat aftn in the
interior but we anticipate the coverage of these pop-ups to be
more isolated/hit-or-miss with most staying dry. Opted for a 20%
PoP to reflect this, with dissipating trends to pop-up
showers/storms with sundown. Looking at a noticeably drier air
mass filtering in for Sat evening, particularly north of the
Cape Cod Canal. Highs Sat in the low to mid 80s, while under
clearing skies and lowering dewpoints, lows Sat night in the
lower to mid 60s, with mid/upper 60s for the coastlines.
Sunday:
Really nice Sunday in store for Southern New England with mostly
sunny, dry weather and warm temperatures, but especially much
lower humidity levels (e.g. dewpoints in the low to mid 60s,
with mid to upper 50s dewpoints in the interior). Clear skies
and light winds will set the stage for a cooler and more
comfortable mid- summer night than we`ve experienced essentially
for much of July. Highs are seasonably warm in the middle/upper
80s with lows in the lower 60s.
Early to Mid Next Week:
SW flow resumes with a return to elevated humidity and at least
daily chances for showers and t-storms. Shower and t-storm risk
appears more focused with higher coverage with a frontal system
around Tue or Wed, though models vary on the eastward
progression of the initiating cool front. Have kept NBM-based
PoP around the later Tue/Tue night timeframe but as
deterministic guidance varies on the arrival (e.g. Canadian is
into Wed, ECMWF and GFS are into the Tue/Tue night period), the
timing is still subject to further adjustment in later
forecasts.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence
Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight: Moderate confidence.
VFR through at least 05z. Thereafter, developing and expanding
stratus at IFR-LIFR levels moves NW into ACK and then spreading
into the South Coast and PVD. Possible some stratus may lurk
nearby at OWD and BOS, but think BOS stays out of stratus. Left
at a SCT015 to indicate there may be a layer of stratus around.
Farther west, should see increasing, if VFR clouds, from a
weakening complex of showers and storms now over western NY.
Light SE winds.
Note that due to a phone line outage at ACK, AMD NOT SKED
included for the 00z ACK TAF. No ETR currently known.
Friday...Moderate confidence.
VFR for interior terminals with IFR possible for Boston between
12-15Z. Visibility will increase in the morning for Cape Cod
and Nantucket but low clouds will keep it IFR for most of
the day. Thunderstorms are possible mainly across western
terminals in the late afternoon. Light and variable winds mainly
out of the SSE.
KBOS TAF...Moderate confidence in TAF. VFR tonight. Confidence
decreases after 12z tomorrow as easterly onshore flow may bring
in some MVFR/IFR ceilings. Returning to VFR/MVFR for tomorrow
afternoon.
KBDL TAF...Moderate confidence in TAF. VFR through the TAF
period. Thunderstorms are possible tomorrow late afternoon
mainly between 20z-00Z.
Outlook /Saturday through Tuesday/...
Saturday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Saturday Night through Monday Night: VFR.
Tuesday: VFR. Slight chance SHRA, isolated TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight... High Confidence
Mainly light winds out of the SSE tonight with seas less then 3
feet. Fog looks likely to develop across the southern waters
after sunset, spreading north into the eastern waters
overnight.
Tomorrow... High Confidence
Winds remains light out of the SSE with wave heights less then
3 feet. Fog should begin to rise by mid to late morning, but low
clouds will likely prevail tomorrow.
Tomorrow night... High Confidence
Winds still out of the SSE with waves heights less then 3 feet.
Outlook /Saturday through Tuesday/...
Saturday: Winds less than 25 kt. Slight chance of rain showers.
Saturday Night through Tuesday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...Loconto/KP
NEAR TERM...Belk/Loconto/KP
SHORT TERM...KP
LONG TERM...Loconto
AVIATION...Belk/Loconto/KP
MARINE...Belk/Loconto/KP
Area Forecast Discussion
National Weather Service Cheyenne WY
538 PM MDT Thu Jul 20 2023
.UPDATE...
Issued at 215 PM MDT Thu Jul 20 2023
The second round of showers and thunderstorms has commenced early
this afternoon with the strongest storm currently over central
Albany Co in WY. Widespread stratiform precipitation has developed
over east-central WY where little instability is present, but
there is plenty of lift associated with the upper level shortwave
passing through. The aforementioned outflow boundary propagating
west from this morning showers and thunderstorms appears to have
cleared the Laramie Range leading to CI farther west.
Additionally, the latest RAP shows the instability axis has also
shifted farther west with MLCAPE around 1000-1200 J/kg. Still
looking at heavy rainfall and large hail as the main threats
through early this evening as storms propagate farther east, but
have noted a slightly southward shift in the CAMs with stronger
storms and UH tracks mainly into CO compared to runs earlier this
morning. These recent environmental changes may lead to a
transition of main thunderstorm hazards to flash flooding earlier
for southeast WY and the southern NE Panhandle. Will continue to
monitor satellite and radar trends, but currently seeing the
beginnings of a line of storms developing in southern WY that
could lead to heavy rainfall with the moist profiles and high PW
values. Will need to pay particular attention to training storms
and areas that already received notable rainfall earlier today.
UPDATE Issued at 1055 AM MDT Thu Jul 20 2023
Latest GOES WV imagery shows a compact progressive shortwave
moving across southern WY that led to initial showers and
thunderstorms early this morning as light stratiform rainfall
continues across the NE Panhandle at this hour. Had some pretty
high rain rates with these storms as KCYS ASOS reported nearly a
half inch in a quick 30 minutes just before 6 AM MDT. MRMS QPE has
been pretty consistent with observations and also had areas of
1-1.5 inches between observation sites with earlier storms in
southern Goshen Co and western Kimball Co. This precipitation has
preconditioned the ground for more heavy rainfall and potential
flash flooding with this afternoon`s storms. GOES visible imagery
shows an outflow boundary propagating west towards the Laramie
Range which will be the focal point for additional CI in the
11 AM to 1 PM MDT time frame. CAMs continue to support widespread
strong to severe thunderstorms across much of Laramie Co and
portions of Platte and Goshen Co in WY early this afternoon with
large hail (possibly significant over 2 inches) possible,
especially with clearing skies across southeast WY currently. The
latest SPC outlook has stretched the slight risk area into
southern portions of the CWA from Cheyenne to Kimball for this
afternoon.
&&
.SHORT TERM...(Today - Friday Night)
Issued at 305 AM MDT Thu Jul 20 2023
An active 24-36 hours ahead across southeast Wyoming & the western
Nebraska Panhandle w/ multiple chances for strong to severe storms
in addition to localized flash flooding. A challenging scenario as
both global & high-resolution models have recently had a very hard
time resolving the abnormally moist boundary layer in place due to
the extremely wet antecedent conditions over much of the CWA. This
was seen yesterday with models being much too dry and stable which
created an illusion of a limited severe weather threat. Instead, a
more substantial severe weather episode evolved w/ reports of very
large (baseball size) hail near Torrington. Today is different, as
virtually all guidance appears to have a strong grasp on potential
moisture availability. PWATs today are progged to peak between 1.2
and 1.5 inches for all areas along & east of the Laramie Range at/
around 18z, maximized along the Platte River Valley. This is close
to climatological maximums & 2+ standard deviations above expected
values for mid to late July, per the latest NAEFS analysis. At the
surface, multiple high-resolution models are progging surface dew-
points in the lower 60s from Cheyenne to Wheatland, and then along
and south of the Platte River Valley at mid-day. All CAMs are very
aggressive w/ convection today, but still differ greatly w/ regard
to the overall timing and evolution. HRRR is doing a bit better w/
capturing the surface moisture compared to yesterday, but is still
initializing very poorly with limited convection over the CWA thru
at least late morning. Numerous showers and embedded thunderstorms
have already plagued much of our western areas through much of the
night, occasionally producing wind gusts up to 45 MPH. The concern
is certainly there for another overperforming severe weather event
today.
That said, the first round of convection is already underway, with
a few stronger updrafts currently developing across central Albany
county just north of Laramie with trailing light stratiform to the
west over much of Carbon County. This activity is developing ahead
of the first of two distinct short waves that are poised to impact
the region today, this one tracking very slowly along the Wyoming/
Colorado border. Latest RAP/SPC Mesoanalysis suggests the presence
of moderate elevated instability w/ MUCAPEs of 1000-1500 J/kg over
areas roughly along & south of the Platte River Valley, juxtaposed
with 30-40 knots of effective bulk shear. The 00z NAMNest was very
aggressive with showing the rapid intensification of this activity
after 12z, and the environment would certainly support that. While
the NAMNest has backed off slightly from this idea, believe we may
have a few severe storms capable of producing large hail & perhaps
strong winds in the 12z-18z time frame especially as this activity
quickly moves into an increasingly moist & unstable environment to
the east over the high plains. Hail will most likely be the bigger
hazard w/ early morning convection given the fact that this should
be elevated above a stable boundary layer.
A second vigorous short wave will move in from the northwest later
this morning into the early afternoon, likely merging w/ the first
wave and transitioning the mid-level (H5) flow to northwesterly at
35-45 knots. Meanwhile, moist and deep low-level upslope flow will
persist beneath. CAMs are in excellent agreement that this will be
the trigger for the rapid development of numerous showers & storms
along the Laramie Range, moving rapidly southeast through the late
afternoon and early evening. Given the anomalously moist air mass,
as discussed earlier, efficient rainfall production is likely with
enhanced potential for flash flooding. 1-hour FFG around 1.5 to 2"
should be easily achievable in such an environment, and CAMs still
suggest multiple swaths of such amounts in 1-2 hours, as mentioned
in the afternoon discussion yesterday. WPC has placed a large part
of the area in at least a MRGL Risk for Excessive Rainfall, with a
SLGT Risk over Laramie & Kimball Counties, even a MDT Risk just to
the southeast over northeastern Colorado. Previous expectation was
for heavy rain to dominate the hazard discussion as model guidance
has generally shown less than 1000 J/kg of MLCAPE. Overall thermal
profiles would support potential MLCAPEs around 1500-2000 J/kg, if
clearing can occur behind morning convection, helping push surface
highs into the 70s amidst very cold temperatures aloft & resulting
steep mid-level lapse rates exceeding 8 deg C/km. Further, general
flow will be more than sufficient for organized storms with a deep
layer of 35 to 40 knot flow & substantial low-level veering likely
supporting 45 to 55 knots of effective shear. Supercell structures
are likely with any storms that remain discrete. Flow becomes more
unidirectional/westerly above 10k feet, likely supporting possible
organized/bowing line segments as well. As such, a threat for very
large hail (possibly golf ball or larger w/ discrete storms) along
with damaging winds should accompany the flooding threat. This may
be conditional based on late morning/early afternoon clearing, but
still expect at least a marginal hail/wind threat as well.
Northwesterly flow aloft and near-surface upslope continues Friday
with isolated to widely scattered showers and thunderstorms likely
once again during the afternoon, particularly along & just east of
the Laramie Range. Once again, CAPEs of 1000-2000 J/kg and 30+ kts
of 500-mb flow will support supercell structures with large hail &
damaging winds with any storms that develop. However, would expect
to see some capping issues given the onset of 700-mb WAA as larger
scale ridging begins to translate eastward toward the Rockies.
.LONG TERM...(Saturday - Wednesday)
Issued at 305 AM MDT Thu Jul 20 2023
A few changes from yesterday`s forecast... Long range models now
hold onto northwest flow across southeast Wyoming and the Nebraska
panhandle until Monday night. Therefore, dropped temperatures a few
degrees Saturday and Sunday from what they were previously, but kept
overall warmest temperatures Monday as flow transitions to weaker
westerly flow. Tuesday will still be quite hot with temperatures
potentially reaching 100 degrees in the High Plains. The ridge
begins to flatten out Tuesday into the end of the week, cooling
temperatures and increasing precipitation chances, mainly over the
higher terrain.
Opted to increase precipitation chances over the higher terrain
Saturday due to the widespread precipitation likely Thursday into
Friday, which would keep increased moisture at the surface. Saturday
into Sunday, as long as southeast Wyoming and the Nebraska panhandle
maintain northwest flow, there will be at least low end
precipitation chances in the higher terrain. Monday as the flow
transitions to westerly, downsloping, precipitation chances.
However, some long range models are showing a few
shortwave passages Thursday into Friday, potentially weakening the
ridge allowing monsoonal moisture to make its way up to southeast
Wyoming and the Nebraska panhandle. As this is still in days 7+
uncertainty remains high and the pattern will undoubtedly change,
but it is something to watch.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 537 PM MDT Thu Jul 20 2023
Storms will continue throughout the evening at most terminals, with
light to moderate rain expected. These storms will bring low CIGs
and poor visibility at times. Storms will clear out before 06Z, but
BR/FG and low stratus will develop in its place early Friday morning
for most terminals east of the Laramie Range. MVFR to IFR conditions
will be expected during this time. FG and low stratus will clear out
by mid Friday morning.
&&
.FIRE WEATHER...
Issued at 305 AM MDT Thu Jul 20 2023
No near-term fire weather concerns w/ widespread measurable rain &
potential severe storms today, along with a cooler weather pattern
expected to persist through the end of the week. Fire concerns may
increase late in the weekend through next week w/ a building upper
level ridge forcing daytime highs into the 90s for much of the CWA
with generally lower chances for precipitation.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...MB
SHORT TERM...CLH
LONG TERM...LK
AVIATION...SF
FIRE WEATHER...CLH
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
235 PM PDT Thu Jul 20 2023
.SYNOPSIS...Hot interior temperatures will continue through
Saturday, with the hottest temperatures expected on Friday.
Temperatures will then gradually cool through early next week, but
interior temperatures will remain near to above normal through
the rest of the period. Temperatures along the coast will remain
near normal. No rain is forecast to occur during the next seven
days.
&&
.DISCUSSION...The day started out with a thick blanket of stratus
covering most of the coastal waters, with some drying downwind
from Cape Blanco and Cape Mendocino. Over the course of the day,
stratus has thinned and eroded significantly. Stratus remains over
areas from the Eel River Delta to Humboldt Bay, but there are even
breaks there. Nevertheless, the marine layer remains around 2000
feet deep, and stratus is expected to expand across the coastal
waters and adjacent land areas later this evening. Across the
interior, sunny skies prevail. Temperatures this afternoon range
from some lingering upper 50s along portions of the immediate
coast to the mid to upper 90s across portions of Trinity,
Mendocino, and Lake counties. Smoke from the Flat Fire of SW OR
continues to billow, with some spreading S into our County Warning
Area. Have continued to populate HRRR smoke guidance to account
for visibility reductions.
A large upper low continues to spin near 50N/146W. A sprawling
upper ridge persists across the S from S CA to the lower MS
Valley. Through the end of the week, the upper low will meander
near where it is currently situated. However, the S ridge will
nose farther to the N over the Desert SW. This pattern will allow
temperatures to continue to warm across the interior, with the
hottest temperatures in our area expected over Lake and extreme E
Mendocino counties. The hottest day is expected to be on Friday.
The latest NBM guidance has trended down a bit with temperatures,
but deterministic MOS guidance remains just as hot over the next
48 hours. As a result, have left the Heat Advisory for Lake County
unchanged. Temperatures will start a slow decline beginning
Saturday, the interior temperatures closer to normal by the early
to middle portion of next week.
Along the coast, stratus will continue through most of the period,
although at least partial clearing is expected in many locales
each day. Patchy drizzle is possible again tonight from Cape
Mendocino N to Humboldt Bay. Local tools suggest that this will
continue to be possibility most nights and mornings into the
weekend. Mostly trace amounts of rainfall are expected, with
locally a hundredth or two. The low-level inversion is forecast to
gradually weaken late in the weekend and early next week. /SEC
&&
.AVIATION...Marine stratus continued to "limitedly" impact the Del
Norte and Humboldt Coasts today. The marine layer was slightly deeper
with tops 020-025 feet as confirmed by a late morning CEC PIREP. The
Mendocino Coast was mostly SKC except south of PT. Arena. Most areas
of clouds began to erode or peel back to the immediate coast by late
morning/early afternoon. Exception: Humboldt Bay, local coastal
hills, and well into Eel River Valley. Residual afternoon stratus
lifted morning LIFR/IFR to MVFR. Through the forecast period, a quick
return is expected along the coast in late afternoon/early evening,
although EKA and vicinity may see only partial clearing if any.
Guidance is indicating a more compressed marine layer
overnight/morning. Inland areas will remain VFR/SKC. /TA
&&
.MARINE...Winds are light, generally under 15 kt in the northern
zones this afternoon. Advisory level northerlies and isolated gusts
to gale strength will continue in the southern waters. The focus of
the strongest winds remains around and south of the cape, while the
northern inner waters remain below advisory level in seas and wind.
The northerly winds will begin to increase overnight. Advisory level
northerlies will exist in most of the waters by early Friday, as the
gale force gusts in the southern zone expand in coverage. The
extended forecast for early next week continues to hold lighter
northerlies in the 10 to 20 kt range. This weakening of the pressure
gradient will be the result of troughing moving through, and
confidence is high on this occurrence.
&&
.FIRE WEATHER...Interior winds are forecast to remain fairly light,
but W to NW up-valley winds may become gusty through channeled
terrain and exposed ridges each afternoon this week. This will also
be accompanied by increasing temperatures through Friday. The driest
air and poorest nighttime recoveries are expected across E portions
of fire wx zones 264 and 277. Have continued near-critical headlines
in both these zones. Dry weather will continue through the weekend,
but with a gradual cooling trend. /ZVS&SEC
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 11 AM Friday to 11 PM Saturday for CAZ114-115.
NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory until 3 AM Sunday for PZZ455.
Small Craft Advisory from 3 AM to 9 PM Friday for PZZ470.
Small Craft Advisory until 3 PM Friday for PZZ475.
Gale Warning from 3 PM Friday to 3 AM Sunday for PZZ475.
$$
Visit us at https://www.weather.gov/eureka
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https://www.facebook.com/NWSEureka
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For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Forks ND
1043 PM CDT Thu Jul 20 2023
.UPDATE...
Issued at 1040 PM CDT Thu Jul 20 2023
Continued clearing and quiet weather prevails this evening.
Temperatures are on track to fall into the 50s overnight with
light and variable winds.
UPDATE Issued at 701 PM CDT Thu Jul 20 2023
Skies are gradually clearing this evening, with mostly clear to
partly cloudy skies across much of the area. Satellite images show
a thicker layer of smoke working into the area just north of the
International Border. HRRR smoke brings this thicker layer into
the northern Red River Valley by sunrise; however, surface smoke
is expected to be minimal.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 344 PM CDT Thu Jul 20 2023
Key Messages:
- Overall quiet and dry conditions will continue through the
afternoon and tonight.
- Isolated to scattered showers and weak thunderstorms are
expected Friday afternoon into early evening.
Discussion:
Northwest flow aloft behind a departing upper trough with surface
high pressure centered over the northern High Plains influence the
region today into tonight. Daytime mixing has resulted in a
widespread fair weather cumulus field along with a breeze out of north-
northwest. This ceases as night falls, with mostly clear skies and
calming winds. Winds aren`t expected to go fully calm, which
combined with some high level clouds streaming in, should prevent
fog formation.
Within the northwest flow aloft, a small and relatively weak
shortwave trough is expected to clip the area. This will help
provide lift for convection, utilizing the marginal moisture and
instability expected over the area. This will promoted isolated to scattered
showers and weak thunderstorms Friday afternoon into early
evening. There is very little sign of shear to organize
thunderstorms, thus expecting pulse-like convection, and thus not
expecting impacts.
.LONG TERM...(Saturday through Thursday)
Issued at 344 PM CDT Thu Jul 20 2023
Similar to Friday, another progressive, weaker shortwave trough
clips the area Saturday with similar thermodynamics and
kinematics. As such another day of isolated to scattered
showers and weak thunderstorms are expected Saturday, with perhaps
some favoring in Minnesota given ensemble`s favored trajectory of
the shortwave.
Ensembles still strongly agree in large upper ridging over the
western two thirds of the country. This will promote warming
temperatures, perhaps bringing one to three days of nearing or
meeting excessive heat criteria. Ensemble clusters and EFI
highlights Tuesday through Thursday holding best chance for
hottest conditions, with some uncertainty after Thursday given
ensemble`s insistence of maintaining upper ridging into late next
week.
There are indications of shortwave troughs ridging the crest of
the upper ridge. There is a chance that one or more of these ridge
riders may bring forcing into the area to promote periods of
thunderstorms. However, more precise details that would dictate
coverage and timing of thunderstorms is unclear. Should forcing
encroach our area to promote thunderstorms, the amount of heat and
accumulated moisture content could promote stronger, organized
convection, especially since these shortwave troughs tend to bring
higher kinematics with them.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1040 PM CDT Thu Jul 20 2023
VFR conditions prevail through the period. There remains a slight
chance for stratus development briefly just prior to sunrise.
Friday afternoon brings the chance for isolated showers and
thunderstorms as a weak shortwave traverses the region. Confidence
is rather low regarding exact location and timing, thus keeping
-SHRA and -TSRA out of prevailing groups at this time.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Lynch
SHORT TERM...CJ
LONG TERM...CJ
AVIATION...Lynch
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
911 PM EDT Thu Jul 20 2023
.SYNOPSIS...
Showers and thunderstorms are expected this afternoon and evening
ahead of a cold front. Some of the storms could be strong to severe.
Dry weather returns Friday through at least Sunday afternoon when
the next chance of thunderstorms arrives.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Updates this evening will be concerned with timing and placement
of thunderstorms that are currently running along the I-70
corridor and moving east with a slight southeastward component.
Upstream storms running along the cold front from west of Wayne
County IN and to the southwest will not have the favorable
atmosphere to work through with regards to severity, and the
HRRR has been noting this to split over the Cincy metro area.
While this seems reasonable, will not be lowering pops nor
removing thunder until a definitive signal says there will not
be any further firing along the front.
Watch has been expanded by 3 counties this evening to account
for the strong storms merging with the cell moving northeast
from near KILN.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Dry weather returns behind the front for Friday and Friday night as
high pressure builds in from the west. Northwesterly flow keeps
bringing in drier, relatively cool air (for July standards) under
partly cloudy skies. Forecast highs on Friday are near 80 and
forecast lows are near 60.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Mean trough still over the area will have various short waves moving
through. Stronger impulses, with accompanying higher chance of
showers and storms mainly in northern counties, will occur on both
Sunday and Monday. After the Monday system moves through, heights
will be rising resulting in increasing heat along with a drying out.
There is some potential that there could eventually be some weak
disturbances moving over the front side of ridge which could spark
some convection. But at this stage, that far out in time, the
probability looks quite low.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Line of thunderstorms moving into DAY and shortly thereafter
CMH/LCK will be through these stations around 3Z with clear
skies following. KILN can expect vcsh with a better chance of
thunderstorms from 3-4Z, while CVG/LUK are not expecting much
and the VCTS from 3-5Z was to time the frontal passage. A number
of models are showing storms still firing along the front but
the HRRR bypasses the tri-state with convection and this model
is the one this evening`s forecast is leaning heavily towards.
Outside of storms, conditions should be VFR with little in the
way of cloud cover once they are through. Sct cu in the morning
will be broken in the afternoon and clear out at the end of the
day, along with the northwest winds 8-12kt decreasing to under
6kt.
OUTLOOK...Scattered thunderstorms possible Sunday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Campbell
NEAR TERM...Franks
SHORT TERM...Campbell
LONG TERM...
AVIATION...Franks
Area Forecast Discussion
National Weather Service North Platte NE
621 PM CDT Thu Jul 20 2023
.SYNOPSIS...
Issued at 322 PM CDT Thu Jul 20 2023
Key Messages:
- Showers and a few thunderstorms will move across the southeast
panhandle and southwest Nebraska this evening. Brief heavy
rainfall is possible. However no severe weather is expected.
- Isolated thunderstorms are possible Friday afternoon and
evening, with the potential for a few strong storms across the
eastern panhandle and southwest Nebraska.
- Heat arrives Sunday and persists into next week. The combination
of heat and humidity could lead to heat index values from the mid
90s to around 100.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 322 PM CDT Thu Jul 20 2023
Strong to severe thunderstorms currently moving off the Front
Range of Colorado will move across western Kansas this evening.
The latest HRRR brings scattered convection across the southern
panhandle into southwest Nebraska through mid evening, then
diminishing and ending. Do not expected any strong storms due to
weak mid level lapse rates from the ongoing showers currently
across western Nebraska. Brief heavy rain is possible, especially
across the far southwest including Chase County. Clearing skies
overnight with lows on the cool side from the low to mid 50s.
Friday, Northwest flow will exist across western and north central
Nebraska. Highs to reach the lower 80s . Steep H85-H7 lapse rates
near 10C/KM and 0-6KM shear to 40kts will promote the development
of isolated thunderstorms during the afternoon and evening.
Bufkit soundings show an inverted-V, where damaging winds would
be the main threat, although hail up to 1 inch diameter is also
possible. The area where a few strong storms are favored is across
the eastern panhandle and southwest Nebraska into the evening
hours.
.LONG TERM...(Saturday through Thursday)
Issued at 322 PM CDT Thu Jul 20 2023
Dry conditions will persist through the majority of the long term
period, as an upper ridge center begins to expand from the Four
Corners into the Central and Southern Plains. This will bring hot
temperatures to the region on Sunday and persisting through at
least Thursday of next week. Highs from the mid 90s to near 100
are forecast for next week. The ECMWF EFI is a concern, as it
continues to show a number of members suggesting anomalous high
temperatures Tuesday through Thursday, with a SOT >0 from 0.0 to
0.8 for portions of the area Tuesday through Thursday. When
considering this is the climatologically time warm of the year,
this is especially concerning. This would suggest some highs in
the lower triple digits mid-week, though this remains low
confidence. The lowered confidence is primarily tied to the amount
of low level moisture across the area with recent rainfall and
adequate greenness. The more likely scenario looks to be highs in
the upper 90s to near 100 with surface dewpoints remaining
elevated in the upper 50s to middle 60s. This combination of heat
and humidity will lead to increasing heat concerns, and heat
headlines may be needed into the middle of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 620 PM CDT Thu Jul 20 2023
For the KLBF terminal: Periods of showers this evening will
gradually end overnight. There will be a threat for patchy fog
development toward daybreak Friday. The lowest visibilities,
should remain west of the terminal, however, some periodic
visibilities down to 3 miles are possible at the terminal. Skies
will then begin to clear out Friday afternoon with scattered
ceilings around 25000 FT AGL. At the KVTN terminal, expect
scattered to broken ceilings around 20000 FT AGL tonight into
Friday. Some clouds around 5000 FT AGL are possible overnight into
Friday morning.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...Roberg
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Louisville KY
822 PM EDT Thu Jul 20 2023
...Updated Aviation Discussion...
.Forecast Update...
Issued at 757 PM EDT Thu Jul 20 2023
...A Few Mini Supercells Ongoing This Evening...
Low topped convection over the east central parts of the CWA is
yielding some mini-supercell structures, with a few notable splits
in the past hour or so. The first was over eastern Jefferson/Shelby
counties, where the right mover become dominant and still has a nice
look over Spencer county. Watching it closely. Another split
occurred over Lincoln county, with the left mover becoming dominant
as it moved into Rockcastle county. Straight hodographs (deep layer
unidirectional speed shear) does support some supercell structures,
and would favor the splits that we have seen. Looks like we are
lacking just enough shear in the low levels to really be worried
about a tornado threat, nonetheless watching these storms closely
and taking note of the impressivWent ahead and cancelled the Flood
Watch across southern Kentucky a little early. There is some
scattered shower development to the north of where the watch was,
but it is remaining pretty tame, and will mostly skirt north of that
area anyway. As a result, don`t see a need to keep the watch going
any longer.
The next focus will be on a broken line of showers and storms
dropping southeastward into our area later this evening ahead of the
cold front. Some of these storms could still be strong as they enter
our northern CWA around 10-11 PM EDT, however expect gradual
weakening as they sink south toward the Ohio River and southward
deeper into the night. Deep layer shear is expected to drop off from
40-50 knots around 02z, to around 30 knots by 06z. In addition,
instability is expected to wane below 1000 J/KG between 03-06z. As a
result, like the idea that current HRRR runs are suggesting, however
will continue to monitor upstream for some strong storm potential,
at least initially as they enter our CWA.e mid level rotation.
Effective SRH values look to be 100 m2/s2, but will watch for
enhancements into the evening.
&&
.Short Term...(This evening through Friday)
Issued at 320 PM EDT Thu Jul 20 2023
The severe weather threat that prompted the Severe Thunderstorm
Watch has moved south into central Tennessee, so the watch has been
dropped.
For the rest of the day, central Kentucky will continue to see
enough instability to support isolated to scattered convection
through the afternoon hours. Shear values continue to be weak, and
precipitable water values have dropped slightly to around 1.5-2". We
still have a deep warm cloud layer, around 13,500 feet. The threat
for heavy rainfall and lightning is there, but it continues to fall.
The progressive nature of current and expected convection will
likely allow us to drop the Flood Watch early, after the heaviest
convection moves out of our southern counties that received rain
earlier this morning.
Tonight, a broad mid-level ridge over the eastern two-thirds of the
US, north high pressure over the south, will continue to push a
surface low over the Great Lakes. Its trailing cold front will begin
dropping south through the CWA during the first half of the night.
Around 3z, a relatively thin layer of convection along the front is
expected to be in southern Indiana. The line will slowly work south
over central Kentucky in the flowing hours. Instability will
continue to weaken into the night, causing the line to dissipate.
Lows tonight across southern Indiana behind the front are expected
to fall into the mid 60. Farther south in central Kentucky, lows
will reach the upper 60s to low 70s.
Tomorrow, surface high pressure behind the front will move over the
Lower Ohio Valley. We should stay dry and see periods of sunshine.
Light CAA will limit high temperatures to the low to mid 80s.
.Long Term...(Friday night through Thursday)
Issued at 222 PM EDT Thu Jul 20 2023
The upcoming weekend is shaping up to be fairly nice and calm as
broad high pressure with Canadian origins (albeit highly modified)
spreads into the Ohio and Tennessee Valleys. As is typical with this
time of year, dewpoints will be more impacted by the post-frontal
airmass vs temperatures which will help make things feel a bit more
comfortable outside despite the warm temperatures. Should stay dry
for most of the weekend, though can`t rule out isolated
showers/storms Sunday afternoon ahead of a weak upper level wave.
The weekend upper level pattern of amplified ridging in the western
CONUS and troughing in the eastern CONUS will begin to evolve going
into next week. Most mid to long range guidance show the western
CONUS ridge flattening and shifting east a bit as a trough swings
into the upper Pacific NW and northern Intermountain West. The deep
troughing in the east will begin to break down at the same time and
become less pronounced over the Ohio/Tennessee Valleys. This should
result in a gradual warming and low level moisture/Td increase going
through next week. Will also have to keep an eye on waves riding
along the northern periphery of the ridge in case they swing into
the region, though timing these individual waves this far out is
problematic. As such, very low chance PoPs are generally in place
for much of next week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 822 PM EDT Thu Jul 20 2023
Current convection is diminishing over our region at this hour,
however we do still have some showers and storms that could impact
the northern TAF sites as we get to the couple hours on either side
of Midnight. Have continued to depict the best timing in a brief
TEMPO. Outside of that, look for mostly VFR conditions. The one
exception could be for a little bit of fog (most likely BWG), toward
dawn. The northern TAF sites could see some very brief vis
restrictions, but dew points will also be falling off behind the
passing cold front which should mitigate most fog concerns across
the north. Look for VFR on Friday, with steady NW winds. A few gusts
up around 20 mph are possible in the afternoon.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...BJS
Short Term...KDW
Long Term...DM
Aviation...BJS
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1046 PM CDT Thu Jul 20 2023
.SHORT TERM... (Through Late Friday Night)
Issued at 216 PM CDT Thu Jul 20 2023
After showers and thunderstorms produced another round of widespread
rainfall across much of the area this morning, particularly
across southeast Missouri and southwest Illinois, precipitation
has largely ceased as of 2 PM, with a broad cold pool draped
across roughly the southern half of the area. In these areas
impacted by thunderstorm outflow, temperatures have been
significantly stunted and the atmosphere at least temporarily
stabilized. Meanwhile, a cold front is approaching gradually from
the north, and has now reached as far south as central Missouri
and very near the St. Louis metro area.
While many areas have stabilized after this morning`s thunderstorms,
there remains a narrow corridor of unstable air immediately ahead of
the advancing cold front, with RUC mesoanalysis indicating around
2000 J/kg of ML CAPE. Meanwhile, around 35 to 40 kt of 0-6km bulk
shear remains in place area-wide, leaving the door ajar for
redeveloping thunderstorms along the advancing cold front over the
next few hours. At this point, the most likely area for this is
expected to be across west-central Illinois and east-central
Missouri, where the environment is not quite as worked-over as areas
farther south. In these areas, isolated thunderstorms will be
possible, and it wouldn`t be impossible to see a few large
hailstones and gusty winds with this activity. Coverage is not
expected to be widespread, and storms are not likely to be very
long-lived as they move southeast and into more stable air.
As the night progresses, a much drier (and more comfortable) airmass
will steadily filter into the area as northerly flow becomes
established. These north winds may become a bit gusty this afternoon
and evening, but will quickly weaken overnight. In areas that saw
another round of rain this morning, some patchy shallow fog will be
possible in spite of the lower humidity in the arriving airmass.
This is likely to only occur in wind-sheltered valleys, and
especially in the Ozarks, although increasing overnight cirrus may
limit this a bit.
Late tonight through tomorrow afternoon, another shortwave will move
through the northwest flow aloft, but this time it is expected to
traverse south of our area and across southern Missouri. Considering
that the cold front will be well south of our area by then, we do
not expect additional thunderstorm activity to occur locally as this
shortwave passes. However, it will be possible for some trailing
post-frontal rain to extend as far north as the Ozarks Friday
morning through the early afternoon, with some inconsequential light
rain. Otherwise, Friday will feature dry conditions and comfortable
temperatures that fall well short of seasonal averages...likely
only near or slightly above 80 degrees.
BRC
.LONG TERM... (Saturday through Next Thursday)
Issued at 216 PM CDT Thu Jul 20 2023
The remainder of the forecast period (Saturday through Wednesday)
will feature a very slowly evolving weather pattern, as a large
upper level ridge across the intermountain west very slowly broadens
and slides eastward into the central plains. This will maintain
northerly to northwesterly upper level flow across the Mid-
Mississippi Valley through the week, although this does not mean
that temperatures will remain mild through this period, or that we
will continue to be free of precipitation.
Conditions during the day Saturday are likely to be similar to
Friday, just slightly warmer and with comfortable humidity levels.
Between late Saturday and Sunday afternoon though, a very subtle
shortwave will traverse the broad scale northwest flow across the
Great Lakes region, driving a very weak cold front into the area.
While a few showers will be possible along this boundary in our
northern areas late Saturday, this will be more likely across a
broader part of the area during the afternoon Sunday. While the
airmass will remain somewhat modified and lacking in significant
moisture, surface heating should result in at least modest amounts
of instability by the afternoon, and as a result we could see
isolated to scattered thunderstorms during this period. The expected
marginal instability and weak overall wind shear (25 to 30kt of 0-
6km shear) should limit the potential for storms to be strong or
severe.
From Monday through mid week, the previously mentioned broad upper
ridge will slowly expand eastward, and this will cause upper level
500mb heights to build. Meanwhile, persistent southwest to southerly
low level winds will return, and the combination of these two things
is likely to bring an overall warming trend Monday through
Wednesday. While confidence is high that temperatures will at least
climb back to seasonal averages, there is some uncertainty
regarding the upper end of the temperature potential.
For starters, it`s not clear that we will emerge from northerly
upper level flow at any time during this period, and as a result, we
will continue to be within range of passing shortwaves and their
associated weak cold fronts. Meanwhile, a non-trivial number of
ensemble members continue to produce daily precipitation through the
middle of the week, although never a significant amount and
probabilities for widespread or significant precipitation remain
low. Considering the return of southerly low level flow and an
expected gradual increase in humidity, plus the potential for
additional weak back-door cold fronts, there are plenty of factors
that could limit the potential for impactful heat...even if it will
be at least within the realm of possibility. Ensemble temperature
spreads continue to reflect this as well, with 6 to 10 degree
IQRs (25th to 75th percentile) shown in both the NBM and LREF
ensemble suites. Meanwhile, outliers range from well into the
triple digits, to even slightly below seasonal averages.
In other words, it`s likely that a warmup is on the way next week,
but it`s too early to say whether this will lead to noteworthy
impacts.
BRC
&&
.AVIATION... (For the 06z TAFs through 06z Friday Night)
Issued at 1045 PM CDT Thu Jul 20 2023
Light northerly flow expected through the night with only some
passing high clouds. Winds become even more light and variable
through the day tomorrow as high pressure settles in with
continued VFR conditions.
Kimble
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Lubbock TX
612 PM CDT Thu Jul 20 2023
...New AVIATION...
.SHORT TERM...
(This evening through Friday)
Issued at 200 PM CDT Thu Jul 20 2023
Subtropical ridging persists across the southwestern U.S. and into
the western High Plains this afternoon, with the CWA positioned
within the eastern tranche of the center of the 250 mb anticyclonic
circulation analyzed on the 12Z upper air maps. A weak, mid-level
deformation band is present on water vapor imagery over the extreme
southern Texas Panhandle, and is associated with the remnants of a
Mesoscale Convective System (MCS) that occurred last night across
the TX PH. This feature is also delineated by an arcing band of
ACCAS on visible imagery. At the surface, a quasi-stationary front
exists in congruence with the mid-level deformation as per recent
West Texas Mesonet (WTM) data with a 10-15 deg F difference in
dewpoints across front; with drier, more-mixed air evident across
the Caprock Escarpment where surface flow remains weak and backed to
the south, and higher dewpoints on the northern periphery of the
front where the boundary-layer remains modified from the remnant MCS
the previous night. Differential heating is not particularly strong
along the immediate vicinity of front, with the hotter air situated
across the CWA where full insolation is underway. Temperatures were
increased slightly compared to the previous assessment for this
afternoon to align with the 20/12Z statistical guidance, and winds
through 12Z tomorrow were populated with the HRRR to better capture
the presence of quasi-stationary front observed by WTM data.
Another MCS is expected to surge southeastward across southwestern
Kansas tonight, with the outflow(s) accelerating southward across
the TX PH and towards the aforementioned quasi-stationary front. The
southward progression of the front will be reinforced by the
convective outflow, with the front stalling once again in the
vicinity of the South and Rolling Plains late tomorrow morning as
diabatic heating occurs upon the erosion of the mid-level stratus
layer. Moderate baroclinity should exist along the quasi-stationary
front tomorrow, and the trend towards cooler temperatures has been
maintained for the afternoon prognostication. High temperatures
tomorrow were lowered once again from the blended guidance with the
bias-corrected MOS, as boundary-layer moistening will occur within
the airmass across the northern side of the stalled front. Confluent
surface flow will exist, with northeasterly winds across the Rolling
Plains veering to the east across the Caprock Escarpment by tomorrow
afternoon beneath weak geopotential height falls as high-level flow
backs to the west as a northern-stream shortwave trough translates
over the central Great Plains. This will set the stage for the
thunderstorm chances tomorrow evening across the extreme southern
Texas Panhandle and adjacent areas. Please read the discussion below
for more details.
Sincavage
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 200 PM CDT Thu Jul 20 2023
By late Friday afternoon a trough of low pressure off the coast of
the Pacific Northwest remains offshore, while the upper level ridge
and associated dome of high pressure has shifted to our west
allowing for a slight cooling trend into the weekend. To our north a
shortwave trough continues to scoot across NE CONUS. A disturbance
in the upper level ridge with modest northwest flow aloft on Friday
evening will help spark convective activity across NE New Mexico,
transversing to the southeast. There remains uncertainty on areal
coverage of these showers, however conditions remain favorable for
convection with ample low level moisture at the surface,
conditionally unstable ML lapse rates, and upslope surface flow
present. PoP chances look best for the northern South Plains and the
extreme southwest Texas Panhandle, with the best instability
centered over these areas. However, we will maintain low PoPs area-
wide Friday night. Expect a similar synoptic pattern on Saturday
with a chance of convective activity possible with another small
passing shortwave trough Saturday evening. The cooling trend
continues for Saturday with high temperatures focused in the high
80s to low 90s across the CWA as the upper level ridge remains to
the west with broad surface ridging centered over the region. Best
chance of rainfall looks to be for the Caprock with upslope
convection continuing into the West Texas region overnight as flow
remains out of the northwest aloft supporting similar storm relative
motions as Friday night. Though models have been inconsistent
with this outcome, so we have decided to stick with the drier
ECMWF guidance. This will be something we monitor closely within
the next 48 hours. Sunday the heat will slowly begin making its
return as the upper level ridge begins making its return back into
the area, shifting its way back over NM/CO by the beginning of
next week. Where it plans to remain for the latter end of the week
next week. Thus expect another hot and dry week next week as high
temperatures begin to build under the ridge into next week. JM/JLS
&&
.AVIATION...
(00Z TAFS)
Issued at 603 PM CDT Thu Jul 20 2023
VFR conditions are expected to continue through the TAF period
while thunderstorms that move across the Texas Panhandle tonight
remain north of the terminals. A weak cold front supported by
outflow from the Panhandle storms will push past the terminals
later tonight with east to northeast winds expected to prevail
Friday.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...09
LONG TERM....55
AVIATION...07
Area Forecast Discussion
National Weather Service Medford OR
848 PM PDT Thu Jul 20 2023
.UPDATE...The forecast for northern California and southern Oregon
remains on track. Smoke from the Flat Fire and above average
temperatures remain a concern, so anyone with vulnerability to
either heat or low air quality should take extra caution when
going outside. This weekend still looks to see lower temperatures
as an upper trough passes to the north, then warming back up into
next week. -TAD
&&
.AVIATION...21/00Z TAFs...Westerly flow aloft is moving smoke
from the Flat Fire to the east, with smoke possibly reaching as
far as western Klamath County. KLMT may see some patchy smoke, but
no impact to visibilities are expected. KMFR had some brief drops
in visibility through Thursday, but still stayed at VFR.
Occasional local drops in ceilings and visibilities are possible,
especially over Curry and Josephine counties.
The last scraps of marine clouds remain over westernmost Douglas
County, but do look to be rebuilding in the most recent satellite
images. MVFR levels are expected along the Oregon Coast north of
Cape Blanco as well as over Brookings this evening, with IFR
ceilings and MVFR visibilities possible mid-Friday morning. Marine
stratus looks to clear out by Friday afternoon, with gusty
northerly winds following.
Other inland areas will see VFR conditions under clear skies. -TAD
&&
.MARINE...Updated 730 PM PDT Thursday, July 20, 2023...A Small Craft
Advisory has been issued for south of Port Orford between roughly 2
nm out to 40 nm from shore, for late tonight through late Friday
night.
A thermal trough dominated pattern will persist through the weekend
into early next week. The thermal trough will be of weak to moderate
intensity, with winds remaining strongest south of Cape Blanco.
-DW
&&
PREV DISCUSSION... /Issued 247 PM PDT Thu Jul 20 2023/
DISCUSSION...
Radar imagery shows clear conditions except for some weak echos
right over the Flat Fire lofting smoke to 15000 feet at times this
afternoon. This has been pretty typical of what we`ve seen the
last few days, although the smoke will make a stronger eastern
push today. It`s worth noting we`re already observed some thicker
smoke in places with the visibility dropping to 6 miles near the
airport this afternoon.
As for this evening, thicker smoke and unhealthy air has a 85%
chance of developing in valleys west of the Cascades later this
evening as fresh smoke from the Flat Fire moves eastwards. The
HRRR smoke is predicting smoke concentrations in excess of 100
ug/m3 within the Illinois Valley and 25 ug/m3 at times in the
Rogue Valley, which usually produces air quality unhealthy for
sensitive groups at the very least.
This trend is anticipated to continue through the weekend as the
west to east pressure gradient shows no signs of stopping. The
upper level winds turn north at times, although revert to
northwest in the afternoon and evenings as a thermal low continues
to build over Nevada.
Aside from smoke through this weekend, temperatures will remain
fairly warm and remain about 5 to 10 degrees above normal across
the region. The Shasta Valley and Klamath River Valley will remain
the hot spots with temperatures exceeding 100 degrees. Heat risk
remains moderate for the forecast area as these high temperatures
may stress out those sensitive to heat. The good news is low
temperatures have a high probability of falling into the upper
50`s and lower 60`s, which is low enough to avoid heat risk.
Lastly, the addition of smoke in the forecast could help keep
temperatures a degree or two lower if a thick layer is able to
develop in the upper sections of the atmosphere.
By late Sunday into Monday, ensembles are predicting a low settle
in off the Coast of Washington with a cold front charing down the
coast. This low will help break down the ridge of high pressure
aloft in addition to building some cloud cover over the forecast
area. High temperatures will trend lower Sunday into Monday with
highs right around near normal. The NBM has a 10 to 15 percent
chance of rain around Coos Bay and Florence when this cold front
does make it`s charge down the coast. This period will most likely
occur on Monday evening based on the latest guidance.
As for Tuesday through Thursday, that low is anticipated to make a
track to the east, which will result in some clearing skies and
weak north east flow across the forecast area. The NBM is keeping
us near normal temperatures with pretty quiet conditions.
Manually added smoke and haze to the forecast given where the fire
is burning. It could turn out to be fairly smokey across the
forecast area next week.
-Smith
FIRE WEATHER...Updated 200 PM PDT Thursday, July 20, 2023...We are
still looking at a dry end to the month with no precipitation in the
forecast for the foreseeable future. This means our hot, dry, and
breezy winds (afternoon/early evening) look to be a common theme
going forward for the next several days.
Only slight fluctuations in the thermal trough are forecast through
the weekend and into early next week, and this should allow for
onshore flow each afternoon in addition to breezy winds in the
afternoon and early evening. The onshore flow should help moderate
RH values slightly. However, we are generally expecting at least
elevated RH values for a good chunk of the area in the afternoons,
especially for westside valleys and east of the Cascades where
values may actually be in/close to critical thresholds. Wind speeds
are going to be marginal, so the key for us going forward is
pinpointing those days when critical values do overlap. With
marginal days ahead for wind, this may be somewhat tricky. That
said, Haines values are a solid 5 to 6 across most of the area.
Given the ongoing Flat Fire and these Haines values around 6, we
still have a Red Flag Warning in effect until 9pm tonight. The big
question is whether or not tomorrow will need one. Its
borderline, so for now have left hazards to one headline (today).
Subsequent forecast or coordination may yield another warning for
tomorrow in and around the Flat Fire.
-Guerrero
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 9 PM PDT this evening for ORZ619.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory from 5 AM Friday to 3
AM PDT Saturday for PZZ356-376.
&&
$$
Area Forecast Discussion
National Weather Service Norman OK
1039 PM CDT Thu Jul 20 2023
...New AVIATION...
.SHORT TERM...
(This evening through Friday)
Issued at 334 PM CDT Thu Jul 20 2023
A large scale upper trough will continue to dig across the eastern
half of the country. A shortwave propagating through the trough
currently producing convection over the Central High Plains is still
expected to dig through late tonight into northern Oklahoma. A cold
front extending from a surface low over the Great Lakes Region
through the Central Plains will also be pushing into the Southern
Plains later tonight and will be overtaking a weaker cold front
currently stalled northern and western Oklahoma. Surface-based CAPE
values will be in the moderate range (2000-3000 J/kg) for convection
that develops along the front, with MUCAPE values in the upper-weak
to lower-moderate range for the elevated convection. Although the
ECMWF is somewhat weak in our area with the Bulk Shear magnitudes,
both NAM & GFS are keeping it fairly strong (35-40 kts) across our
northern Oklahoma. As a result, the instability and shear will be
sufficient for organized severe storms when this system comes
through tonight, with damaging wind gusts of 60-80 mph possible as
forecasted DCAPE values support it. Although winds being the primary
severe hazard, large damaging hail will also be possible up to golf
ball size. Unseasonably high PW values exceeding 2-inches across
northern Oklahoma could also pose an additional flooding risk as the
highest QPF will be across the Central High Plains into northwest
Oklahoma. Could see some heavy rainfall rates should the storms
start moving slowly or with additional convection training behind.
The northern half of our CWA will be in a severe risk, generally
along and north of I-40. However, the severe risk will be higher
(SPC Slight) across northern Oklahoma and highest (SPC Enhanced)
across northwest Oklahoma. Because of the potential heavy
rainfall/flooding risk, we will also start a Flood Watch around 10
PM into the overnight hours across our northern two-tiered Oklahoma
counties. As far as timing, expecting the surface boundary/cold
front to push into northwest Oklahoma close to midnight when the
severe storm activity is expected and perhaps reach I-35 and the
H.E. Bailey Turnpike corridor as well as the OKC Metro toward 4 AM,
although just an estimate based on latest HRRR guidance. We could
see the entire system out of our area toward late morning, or
perhaps a few hours after sunrise Friday when the cold front should
have moved through our entire Oklahoma/Texas CWA.
Latest HREF guidances keeps cloud cover through Friday morning,
although could see some sun in the afternoon. North winds behind
the front will bring in cooler and drier air coming down off the
Central Plains, so not expecting to see any triple digit high
temperatures across the area, although areas along and south of the
Red River will still be on the hot side (upper 90s). Did lower
Friday afternoons MaxTs across our southwestern CWA using the NBM 10
Percentile temperatures.
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 334 PM CDT Thu Jul 20 2023
It will be fairly quiet as far storm activity in the long term.
Another shortwave rotating through the upper high ridge may initiate
some elevated storms across the Southern High Plains overnight
Friday which could affect our southwestern CWA. However, GFS is the
wetter outlier as other guidance (including NAM) keep it dry, and
NBM is also starting to trend dry. For now, will only keep a small
area of low storm POPs for Friday night across far southwest
Oklahoma. Otherwise, no POPs will be in the grids through the
remainder of the long term. Our area will be under a large scale
trough through Saturday, as temperatures should be cooler than
average, although still warm but much less muggy with those lower
60s dewpoints. The upper trough starts moving east and out on
Sunday as a large scale ridge across the western half of the country
starts to build in and we gradually start heating up again. Triple
digit temperatures make their return across western north Texas on
Sunday and become more widespread into western Oklahoma by midweek
with increasing south winds.
&&
.AVIATION...
(06Z TAFS)
Issued at 1024 PM CDT Thu Jul 20 2023
Thunderstorms are expected to arrive in northern Oklahoma early
this morning and last until around daybreak Friday. Otherwise a
slowly-moving cold front will cross the Red River early Friday
and northeast wind will continue to its north most of the day.
Northern Oklahoma may keep MVFR ceilings until around midday.
Gusts will subside during the evening.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 71 84 64 87 / 20 20 10 0
Hobart OK 71 88 63 89 / 10 10 10 0
Wichita Falls TX 76 96 68 93 / 0 0 10 0
Gage OK 66 80 59 88 / 70 20 10 0
Ponca City OK 67 79 62 86 / 70 50 0 0
Durant OK 77 95 70 88 / 0 10 10 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch until 7 AM CDT Friday for OKZ004>013.
TX...None.
&&
$$
SHORT TERM...68
LONG TERM....68
AVIATION...09
Area Forecast Discussion
National Weather Service Mount Holly NJ
1035 PM EDT Thu Jul 20 2023
.SYNOPSIS...
A stationary front remains over the area through today
before returning back north as a warm front tonight. A cold front
then passes through the region on Friday. High pressure builds in
from the west on Saturday then weakens and moves offshore Sunday
night. A few weak disturbances may affect us early next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
Severe Thunderstorm Watch #530 is now in effect until 5 am for
most of southeast Pennsylvania, including Philadelphia, and
parts of northern New Jersey.
A line of severe thunderstorms is currently moving through
western New York and western Pennsylvania. This system is on
track to impact Berks county and the southern Poconos around
midnight, and then the I-95 corridor, including Philadelphia and
surrounding suburbs, and northern New Jersey around 2 am, and
then eastern New Jersey thereafter.
These storms are about 2 to 3 hours faster than previously
forecast, and are faster than latest HRRR and 18Z NAM have
indicated. Damaging winds are likely, as well as large hail.
Heavy rain and localized flash flooding is also possible.
Surface-based CAPE values are up around 1500 to 2000 J/kg along
with 25 to 35 kt of 0-6 km Bulk Shear.
By the time early Friday morning arrives, storms will have
moved in with coverage potentially be relatively widespread for
areas near and N/W of the I-95 corridor. By this time, the
strongest upper level forcing should be just moving through with
low pressure centered near Lake Ontario and the system`s triple
point over eastern PA with the warm front extending eastward
through NJ and the cold front extending S/W into Maryland and
Virginia. The overall evolution of the convection becomes a bit
more uncertain beyond this time as initial shortwave aloft
swings through to the north and east but the main upper level
trough only chugs slowly east across southern Ontario into
upstate NY. This means that the low at the surface and its
associated fronts should be slow to move east as well. The
upshot of this is that stormy weather is likely to continue
through at least the first half of Friday as initial convection
could even start to train for a time over eastern PA into
northern NJ. Even as this first round should be moving out by
around midday there could be more storms that develop in the
afternoon. It`s uncertain though how much instability there will
be due to AM storms so the SPC keeps area in a MARGINAL risk
for severe weather for Day 2 (starting 12z Friday) with a
MARGINAL threat for excessive rain and flooding/ flash flooding
also be indicated by WPC. By the time the system moves through
by Friday evening with winds turning westerly and conditions
drying out, think much of the area could see 1.0 to 2.0 inches
of rain with locally higher amounts. Heaviest amounts should be
in the north. Again, still some uncertainty on this so forecast
will continue to be refined through the day today. The
showers/storms should help keep temps cooler for Friday with
highs mostly in the low to mid 80s except some upper 70s over
the higher terrain where clouds are most likely to remain in
place through the day.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Cold front will be rapidly pushing off the coast Friday evening.
Still a little uncertainty in timing so held some chance pops early
but back them off below slight chance after 00Z. Otherwise,
clearing, cooler and drying out Friday night. Lows overall will drop
3-5 degrees compared to Thursday night, with 60s across most of the
region.
High pressure slowly builds in Saturday and Saturday night. We`ll
see plenty of sunshine, which will help allow temps to rise back to
near the same readings we`re expecting Friday (mid-80s), but dew
points will be 5-10 degrees lower, mostly in the low-mid 60s. This
will result in a considerably more comfortable day compared to
Friday.
A weak secondary front passes Saturday evening, ushering in slightly
cooler and drier air. This will help lows drop a few more degrees
compared to Friday night, settling down into the upper 50s to low
60s overall, except still mid-upper 60s in the urban centers and
near the waters. Otherwise, clear skies and light winds will prevail.
Sunday will see continued mostly sunny skies as high pressure
remains in overall control, thought it will be shifting off-shore
with warm advection just beginning later in the day. Thus, expect
highs to nudge back up a degree or two compared to Saturday, but dew
points will do the opposite, so overall, another nice, dry day.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
High pressure will be firmly offshore by Monday, with a return
southerly flow starting to nudge dew points back up, though they
still remain in the 60s. Warmth will build ever so slightly,
tempered by the potential for some afternoon clouds or even a stray
shower or storm as an upper level shortwave moves toward us, but
overall still dry. This pattern more or less continues Tuesday, with
some morning sun followed by afternoon clouds and a stray shower/t-
storm with another upper-level disturbance, but more dry than not
for sure.
By Wednesday, a warm front starts to lift back north of the region,
decreasing the threat of isolated showers/storms as a ridge builds
toward us, but also allowing temps and dew points to creep back up a
few more degrees. Still not quite oppressive for this time of year,
but more uncomfortable than the prior two days, with dew points
mostly in the upper 60s and temps rising toward the upper 80s.
Temperatures warm even further Thursday with afternoon highs in the
low 90s for most and dew points creeping back into the low 70s.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas...
Tonight...Mainly VFR this evening as initial showers and storms
dissipate. Next round of showers/storms begin to move in from
the west most likely after 6z with lowering cigs as well. This
should result in sub VFR conditions occuring at all sites by
around 09Z. Winds mainly southeast 5 to 10 knots. Moderate
confidence.
Friday...Sub-VFR in SHRA/TSRA in the morning, then another
round of SHRA/TSRA with sub-VFR conditions possible in the
afternoon. South winds 5 to 10 kt, becoming southwest to
westerly by late day. Moderate confidence in morning
restrictions, low confidence for the afternoon.
Outlook...
Saturday through Sunday night...VFR. W to NW winds 10 to 15 kt
during the day, then LGT/VRB at night. High confidence.
Monday through Tuesday...VFR overall. Scattered afternoon SHRA/TSRA
possible. S winds 5 to 10 kt. Moderate confidence.
Wednesday...VFR. SW winds 5 to 10 kts. Moderate confidence.
&&
.MARINE...
Sub-advisory conditions on the waters through today with winds
around 10 kts easterly becoming southeasterly tonight. Waves
2-4 ft. A round of showers and thunderstorms with gusty winds
and heavy rain possible late tonight and Friday morning, then
again late Friday afternoon and evening.
Outlook...
Friday night through Wednesday...A prolonged period of sub-SCA
conditions anticipated. No chance of showers or storms over the
weekend, with only a slight chance Monday and Tuesday with mostly
dry weather expected Wednesday. Winds will mostly be west to
northwest 10-15 kts over the weekend, becoming southeasterly 10-15
kts Monday and Tuesday then southwesterly on Wednesday. Seas 2-4 ft.
Rip Currents...
Although there will be showers and thunderstorms Friday
morning, and then possibly again Friday afternoon and Friday
evening that could produce locally strong thunderstorms winds,
the overall winds will be out of the south to southeast at 5 to
10 mph. There should be a medium period southeast swell up to 10
seconds. There is a LOW risk for the develop of dangerous rip
currents, outside of thunderstorms, at New Jersey and Delaware
beaches on Friday.
On Saturday, winds turn to the northwest at 5 to 10 mph. A
light easterly swell will be in place. Once again, there will be
a LOW risk for the development of dangerous rip currents at New
Jersey and Delaware beaches.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
SYNOPSIS...MJL
NEAR TERM...AKL/Fitzsimmons/MPS
SHORT TERM...MJL
LONG TERM...MJL
AVIATION...AKL/Fitzsimmons/MJL
MARINE...AKL/Fitzsimmons/MJL/MPS
Area Forecast Discussion
National Weather Service Portland OR
142 PM PDT Thu Jul 20 2023
.SYNOPSIS...Dry southwest flow aloft and low-level onshore flow
will persist through the upcoming weekend, resulting in
slightly above normal temperatures and continued dry weather. An
upper level trough will approach the Pacific Northwest early
next week bringing relatively cooler temperatures and a chance
for rain or drizzle, mainly along the coast and across SW
Washington.
&&
.SHORT TERM...Today through Saturday...Visible satellite imagery
early this afternoon shows the marine stratus dissipating to
west of the Coast Range. Stratus lingered over the southern
Willamette Valley until nearly noon today, a little longer than
expected. Due to a combination of the lingering marine stratus
plus smoke cover this morning, temperatures in the southern
Willamette Valley at 1 pm are around 5-10 degrees cooler than
temperatures in the northern Willamette Valley, generally low
70s compared to upper 70s. We will see if temperatures in the
southern Valley will be able to bounce up to the mid to upper
80s that was originally expected for today across the entire
Valley, but at this point, it does not seem likely.
The overall weather pattern is expected to remain steady through
the next few days. Very strong high pressure aloft over the
Four Corners region has a ridge that extends northward along the
Rockies into Canada. This strong ridge will more or less remain
in place through Saturday, while low pressure slowly moves
southeast from the Gulf of Alaska. The upper low will eventually
settle off the BC Coast, maintaining a southwest flow regime
aloft through the upcoming weekend. This will continue weak to
moderate onshore flow in the lower levels, though the marine
push is not expected to be as strong as it was this morning with
the weak upper level disturbance. Model soundings as well as
HREF guidance indicate marine stratus and patchy fog will be
possible along the coast each morning, but marine stratus is not
likely to make it into the Willamette Valley (only a 20-40%
probability). Therefore, temperatures should meet the forecasted
mid to upper 80s over the next couple days unless smoke aloft
impacts temperatures. The latest HRRR smoke forecast keeps smoke
from the Flat Fire in southwest Oregon just south and east of
the forecast area tomorrow morning as the upper level flow will
become just slightly more west- southwest compared to this
morning when the upper level disturbance shifted winds a bit
more south-southwest temporarily, which is what allowed smoke to
funnel north into the southern Willamette Valley. -HEC
.LONG TERM...Sunday through next Wednesday...Very little change
to the extended forecast. Confidence has increased slightly
that temperatures will slowly cool off starting Sunday, as the
Gulf of Alaska upper trough slowly moves inland into western
Canada. While models vary on the details, the big picture
suggests a transition to near-normal 500 mb heights and
continued onshore flow. Assuming today`s models are generally
correct, this will lead to a prolonged period of "abnormally
normal" weather with inland areas experiencing seasonable highs
in the upper 70s to mid 80s each day. This is what the National
Blend of Models is suggesting, so we more or less leaned on the
NBM for forecast temps in the extended. Weak disturbances
continuing to move onshore in W-SW flow aloft will lack
moisture, but may be sufficient to wring out some drizzle from
the marine layer from time to time. Wetting rains are unlikely,
but NBM does show a 15-40% chance of showers northwest of a line
stretching generally from Newport to northeast Skamania County
associated with a cold front Monday into Tuesday. We`ll get a
better idea of how realistic this is as we get closer to next
week. -Weagle/HEC
&&
.AVIATION..Dry southwest flow aloft will maintain mostly clear
skies across region. High pressure offshore will maintain light to
moderate onshore flow through Friday. MVFR marine stratus along
the coast, mainly Washington coast and from Lincoln City to North
Bend This stratus will break up and dissipate through the
afternoon. However, with the onshore flow still in play, will see
marine stratus over the Pacific surge back onshore this evening,
and into the coast range overnight.
Not expecting as much stratus inland for Fri am. That said, think
will have areas of MVFR stratus through the Cowlitz Valley, and
along the Columbia River up to Portland metro. Will have pockets
of MVFR stratus from near Albany to Eugene and Cottage Grove as
well late tonight into Fri am. Inland stratus should dissipate
faster than it did today.
For detailed Pac NW aviation weather information, go online to:
http://weather.gov/zse
KPDX AND APPROACHES...Scattered to broken MVFR deck through 20Z, the
clear skies for rest of today into tonight. Does appear will have
repeat of MVFR stratus early Fri am.
&&
.MARINE...Not much change, as surface high pressure remains
anchored offshore. This will maintain north to northwest winds on
the waters, mostly 10 to 15 kt. Could see gusts closer to 20 kt
at times in the afternoons/evenings, mainly closer to shore. Seas
stay in the 2 to 5 ft range. Again, not much change until early
next week, when a weakening front will approach the region.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&
$$
www.weather.gov/portland
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Area Forecast Discussion
National Weather Service Raleigh NC
1056 PM EDT Thu Jul 20 2023
.SYNOPSIS...
A couple of mid-level disturbances will cross the southern
Appalachians and Carolinas through this evening. A surface trough
will otherwise remain in the lee of the southern and central
Appalachians until a cold front crosses the region Friday afternoon
and evening.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1045 PM Thursday...
A shortwave trough an associated area of surface low pressure will
swing across the eastern Great Lakes region tonight. While the main
forcing for precipitation associated with that system will pass well
to our north, an MCS is about to reach central NC from the west,
which has already merged with an area of convection over eastern SC.
This is resulting in a line of showers and storms (some strong to
severe), but it is passing to our south across SC and GA where the
best moisture and instability are, with radar returns quickly
dissipating farther north. Outflow from this convection is still
currently passing through the Piedmont and is best identified by a
MLCAPE gradient as well as dew points dropping to upper-60s/lower-
70s behind it. As this outflow boundary continues to move east, the
latest HRRR and RAP runs show some showers and storms developing
along it in the Coastal Plain later tonight from about 04z-08z.
Think coverage should be limited given the widespread CIN that is
already out there and the best moisture transport to our south, but
there is still near 1500 J/kg of MLCAPE in the Coastal Plain with
dew points in the mid-to-upper-70s. Observations at KSOP, KTTA,
KHRJ, KPOB, and KLHZ are beginning to show some cloud development
around 4-8 kft. So carry some low chance POPs in the far east
through 09z as drier air filters in with the flow turning W/NW
behind the trough`s passage. Low temperatures will be mainly in the
lower-to-mid-70s, with isolated upper-60s possible in the far north
and west.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
As of 330 PM Thursday...
Friday will be another hot and muggy day, however relief is on the
way. A cold front will dig southeast across the area during the day
into the evening, with drier air filtering in behind. Conditions
look more dry and stable as the front moves by, therefore widespread
showers and thunderstorms are not expected at this time. Best chance
of a shower or thunderstorm will be near the NC/SC border, otherwise
most areas may remain dry. Northwesterly winds will be a bit breezy
through the afternoon, with gusts near 20 mph possible as the front
moves across the area. Highs in the upper 80s to mid-90s and high
dewpoints will yield another day with heat index values in the 90s
and low 100s. Dry conditions will persist into Friday night, with
lows in the upper 60s to low 70s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
As of 335 PM Thursday...
The surface low will be off the Mid-Atlantic coast Saturday morning
with a trailing cold front to the south of our region. With the low
off the coast, and the front to the south, Saturday looks to be
mostly dry with slight chance PoPs along the far southeast region in
the late afternoon. With the front stalling out to the south and
along the coast in the beginning of next week, expect afternoon
scattered thunderstorms each day especially in the Sandhills and
Coastal plain regions. However, best chance of showers and storms
next week will be on Monday as a deepening upper level trough moves
into the Mid-Atlantic and will bring tropical moisture from the
south ahead of the trough. As the trough moves across the region
Wednesday into Thursday expect scattered showers and storms mainly
across the Sandhills and Coastal Plain region.
As the front moves across the region Saturday, temperatures will be
pleasant for mid July with highs in the mid to upper 80s over the
weekend and into early next week. Temperatures rebound to
near/slightly above normal with highs in the low 90s Wednesday and
Thursday.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 840 PM Thursday...
VFR conditions will dominate over the next 24 hours across central
NC, although there is concern for a cluster of storms that could
develop near FAY and affect that site during 02z-05z. These storms,
should they form, would then track to the NE and may pass near RWI
during 03z-06z. Also, INT/GSO may see a few showers through 05z, but
restrictions below VFR are unlikely. Isolated fog banks, mainly over
or near bodies of water, can`t be ruled out late tonight into early
Fri with light winds and high humidity, however the chances at any
one TAF site are very low. Otherwise, a mix of VFR cloud decks are
expected through Fri morning, followed by fair skies for much of Fri
along with mostly dry weather as storm chances will be low. Surface
winds will be light through daybreak from the SW or W, then from the
WNW or NW from late Fri morning onward at 9-13 kts sustained, and
gusts up to 18-24 kts.
Looking beyond 00z Sat, pockets of sub-VFR stratus in the late-
night/early-morning hours are possible each day, but mainly W Sat
morning and mainly E Sun morning. Otherwise, VFR conditions will
dominate central NC. Scattered showers and storms are possible
across the far S and SE sections Sat, and areawide Sun-Tue, mainly
each afternoon into early evening. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...MWS/JJT
NEAR TERM...Danco
SHORT TERM...JJT
LONG TERM...CA
AVIATION...Hartfield
Area Forecast Discussion
National Weather Service Tucson AZ
223 PM MST Thu Jul 20 2023
.SYNOPSIS...An Excessive Heat Warning continues through Saturday,
with record high temperatures likely. Isolated to scattered showers
and thunderstorms will continue through Friday, mainly from Tucson
south and eastward. This weekend through the middle of next week
storm chances expand to most of southeast Arizona. The main
thunderstorm threats will be strong outflow winds, localized
flooding and the potential for blowing dust.
&&
.DISCUSSION...Visible satellite imagery show cumulus clouds
building up along the higher terrain and the radar has been
registering a few returns up in the White Mountains. The
atmosphere is a little more stable than 24 hours ago which will
delay thunderstorm development across southeast Arizona. The
latest RAP analysis has CAPE within 500-100 J/kg and the PWAT is
around an inch from the water vapor imagery. Just enough
ingredients to get isolated thunderstorms for the mid-to-late
afternoon for Tucson east and south. The 19Z HRRR shows the later
start for the storms and focusing on Cochise County to Santa Cruz
county. With thunderstorms, expect strong gusty winds, some
localized blowing dust, and brief rainfall. Outside of storms,
temperatures will climb another 1-3 degrees with locations tying
or breaking daily records. Thus, the Excessive Heat Warning is
still in effect through Saturday night.
Friday and beyond...Heat will still be around through most of the
weekend. The 500mb High Pressure will start to wobble towards the
4 Corners to allow for a better setup for thunderstorms starting
Saturday and lasting into first half of the new week. Saturday at
this moment appears to be the better day for storms across
Southeast Arizona. The longer range CAM models depict storms
forming along the Mogollon Rim in the afternoon and moving
southeast down to the International Border by nighttime. Main
threats are gusty winds, blowing dust, lightning, and locally
heavy rainfall. If the storms do develop Saturday afternoon and
lasting into the late evening, the outflows and rain can help
bring temperatures down several degrees for Sunday from the very
hot temperatures and record breaking heat that region has felt
over the last week. Yet, temperatures will still be 2-5 degrees
above seasonal normals for the new work week.
&&
.AVIATION...valid through 22/00Z.
FEW-SCT clouds AOA 10k-15k ft AGL this afternoon and diminishing aft
21/09Z before redeveloping aft 21/21Z. Between 20/23Z and 21/04Z,
SCT-BKN clouds AOA 10-15k ft AGL with ISOLD-SCT SHRA/TSRA for
KOLS/KDUG bringing gusty outflow winds with speeds ranging btwn 30-
40 kts. From SHRA/TSRA, localized visibility could drop to 3SM or
less. SFC winds remain NWLY with speeds ranging btwn 10-15 kts
through 21/05Z before becoming light and variable overnight. NWLY
SFC winds pick back up aft 21/20Z with speeds btwn 10-15 kts.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Isolated to scattered afternoon and evening showers/
thunderstorms are expected today and tomorrow, mainly from the
Tucson area east and southward. Storm chances expand Saturday to
include Tucson and then most of SE Arizona by Sunday. These
storms will be capable of producing strong, gusty and erratic
outflow winds of 45 mph or more. 20-foot winds will continue to
generally come from the northwest each day this week, with
occasional gusts to 30 mph due to intense surface heating in the
afternoon. Valley min RH values range from 10- 20% through the
weekend.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 10 PM MST Saturday for AZZ501>509.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Las Vegas NV
849 PM PDT Thu Jul 20 2023
.SYNOPSIS...Isolated showers and thunderstorms will be possible
later this afternoon/early this evening in the southern Great
Basin and southern Sierra. Otherwise, the rest of the region will
remain dry. The overhead ridge responsible for this week`s hot
temperatures will strengthen as we head into the weekend, bringing
another round of dangerous temperatures to the region. As this
ridge shifts eastward, it will open the door for moisture to push
into the region on Sunday and Monday. This will result in
increased precipitation chances in Northwestern Arizona.
&&
.UPDATE...Earlier storms across southern Nevada and Inyo County
dissipated a few hours ago leaving only a few thunderstorms
continuing at this hour in the hammerhead of Nye County and
southwest Utah. Therefore, looking at another quite night under
clear to mostly clear skies. For tomorrow, HRRR and 00Z NAM indicate
a slight chance of showers/thunderstorms over Mohave and Lincoln
Counties, as well as the Spring Mtns and Sheep Range.
Heat continues into the weekend with two record high today. Needles
broke their record while Barstow-Daggett tied.
&&
.SHORT TERM...through Saturday.
Isolated showers and thunderstorms will be possible (15-25%)
later this afternoon into the evening hours for the higher
elevations of the southern Great Basin. This is due to the
anomalous moisture (PWATs 100-150% of normal), lingering across
south central Nevada. This moisture will be forced out as our
persistent ridge amplifies and shifts eastward over the weekend.
As this ridge amplifies and shifts over the weekend, we will see
temperatures increase tomorrow and Saturday. These increasing
temperatures will bring another round of Major HeatRisk to the
southern Great Basin, with widespread Extreme HeatRisk in the
lower elevations of northwesterly arizona, southern Nevada, and
east central California. Those planning on recreating outside this
weekend should consider avoiding or canceling outdoor activities
between 10:00 AM and 5:00 PM. If you must be outdoors during these
times, make sure to stay hydrated with water and sports drinks,
wear lightweight, light-colored clothing, and try to stay in the
shade as much as possible.
.LONG TERM...Sunday through next Thursday.
By Sunday the ridge will have moved off to our east, over the
Four-Corners region. This classic North American Monsoon setup
will open the door for moisture to begin to creep into the
southern and eastern portions of our forecast area. This moisture
increase will initially manifest as increasing mid/high cloud
cover, which will help temperatures cool slightly from Saturday to
Sunday. While temperatures will be a few degrees cooler on Sunday,
there will still be widespread Moderate to High HeatRisk, with
isolated pockets of Extreme HeatRisk in urban areas. At this
point, moderate uncertainty exists as to whether or not the heat
products will need to be extended through Sunday.
Outside of slightly cooler temperatures and increasing cloud
cover, we also see precipitation chances increase early next week. PoPs
begin to increase to around 20-30% for areas south and east of
the I-15 corridor on Sunday and Monday, with the highest PoPs in
eastern Mohave County. Forecast confidence remains low regarding
potential precipitation impacts due to interensemble
discrepancies regarding how much moisture will move in and the
spatial extent of said moisture. Additionally, long-term guidance
shows uncertainty regarding whether or not the ridge will remain
positioned over the Four-Corners region or if it will push
further to the east over New Mexico/Texas.
&&
.AVIATION...For Harry Reid...Light east-southeast breezes continue
through 21-22z, before shifting to the south-southwest. Sustained
winds after the shift around 10 knots, with gusts up to 16 knots
possible. Low chance (~20%) of an isolated storm south-southeast of
the Las Vegas Valley. Not confident enough in potential and/or
proximity to include VCTS in TAF. Around sunset, any convective
activity will cease along with wind gusts. Winds remain from the
southwest through the night. A few afternoon cumulus around 14 kft
along with FEW-SCT high clouds.
For the rest of southern Nevada, northwest Arizona and southeast
California...Light winds in the Las Vegas Valley through 20-23z,
before breezy southwest winds kick in. Gusts up to 16 knots. Typical
southerly breezes at KBIH this afternoon, turning northerly after
sunset. West winds prevail at KDAG, with gusts around 25 knots
during the afternoon. Light southerly breezes in the Colorado River
Valley. An isolated afternoon storm will be possible in the vicinity
of the Las Vegas Valley and KBIH, but confidence is low and airport
impacts are not anticipated. A few afternoon cumulus and high clouds
across the region.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Pierce
DISCUSSION...Stessman
AVIATION...Woods
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter