Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/19/24
Area Forecast Discussion
National Weather Service La Crosse WI
1054 PM CDT Thu Jul 18 2024
.KEY MESSAGES...
- Great weather continues through at least Friday with the
potential exception of morning fog. Rivers, now all below
flood stage for the first time in a month, will continue to
fall.
- Saturday through Thursday feature temperatures just a touch
below normal with diurnal chances for showers and
thunderstorms. At this time, no days appear to carry a risk
for heavy rain or severe thunderstorms.
&&
.DISCUSSION...
Issued at 203 PM CDT Thu Jul 18 2024
Through Friday: Great Weather and Valley Fog
This afternoon into tonight, surface high, currently centered over
the southern half of the CWA, will become centered over N IL. This
will drive very light south-southwesterly winds across the forecast
area tonight. With light winds and clear skies expected once again,
subtle moist advection should help valley fog re-develop late
tonight. Have therefore introduced patchy fog mentions into all
valley areas and the cranberry bog region. Otherwise, have moved
lows toward the cool side of consensus blends both tonight and
tomorrow night. With progged soundings suggesting temperatures aloft
remain too warm for convection Friday afternoon, have kept mentions
of precip out of the forecast.
Saturday through Thursday: Diurnal Convection
The remainder of the forecast will feature northwesterly flow aloft
as a persistent upper ridge dominates the western CONUS. The
relatively cool temperatures aloft look to both keep highs a few
degrees below normal - mainly around 80 - and introduce the
possibility for afternoon showers and perhaps a thunderstorm. Have
thus included at least some mention of precip each afternoon. Any
more notable upper shortwave arriving during the afternoon would
likely lead to more widespread convection, with Monday into Tuesday
looking to have the best chance for this occurring at this time.
Otherwise, this is not a pattern generally conducive for heavy rains
or severe thunderstorms. Indeed, CSU ML outlooks and LREF
CAPE/SHEAR/CIN joint probabilities bear this out, with these sources
of guidance failing to highlight any period with potentially
hazardous convection. Thus, while those with outdoor plans may be
inconvenienced, am not concerned about widespread hazardous weather
at this time.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1054 PM CDT Thu Jul 18 2024
VFR conditions are generally expected through the TAF period, with
valley fog considerations being the only exception to this. The low-
level wind fields and surface wind direction will be key for any
valley fog formation at KLSE early this morning with the 19.02z RAP
still wanting to display winds just off the deck to around 15 kts.
Guidance also suggests winds shifting to south and southwesterly
throughout by morning with a brief window of southeasterly possible
overnight. Consequently, if southeasterly drainage winds remain
present early this morning with marginally favorable dewpoint
depression trends (9 degrees at 0330z), valley fog may be possible
(20-40% chance) leading to category reductions at KLSE. As a result,
have added a BCFG group to address this potential. Otherwise, winds
shift to southwesterly during the daytime hours at around 5 knots
with generally increasing cloud cover at around 5kft.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
DISCUSSION...Ferguson
AVIATION...Naylor
Area Forecast Discussion
National Weather Service Cleveland OH
904 PM EDT Thu Jul 18 2024
.SYNOPSIS...
A ridge continues to affect northern Ohio and northwest
Pennsylvania through Friday as the parent high pressure center
moves from the Upper Mississippi Valley to the Lake Erie region.
The high pressure center is then expected to move little this
weekend and allow the ridge to continue to affect our region.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
900 PM Update...
Clouds have diminished and expect mostly clear to clear skies
for the rest of the night. Can`t rule out patchy valley and/or
radiational fog in southeastern zones early Friday morning. No
changes were needed with this update outside of small
adjustments to hourly temperatures and dew points based on
latest observations and forecast trends.
Previous Discussion...
Cyclonic flow aloft, varying between SW`erly and NW`erly, and
embedded shortwave disturbances affect our region through Friday
night. At the surface, a ridge associated with an unusually-
cool and less-humid air mass continues to affect our region as
the center of the ridge drifts from the Upper MS Valley toward
Lake Erie and weakens. Fair weather is expected to persist as a
stabilizing subsidence inversion accompanies the low-level
ridge. Overnight lows are expected to reach mainly the 50`s to
lower 60`s around daybreak Friday morning and Saturday morning,
respectively, as mainly clear to partly cloudy sky, weak or calm
surface winds, and surface dew points mainly near 50F to 55F
promote efficient radiational cooling during evening hours
through daybreak. The warmest lows are expected over/very near
~76F Lake Erie. Localized river valley steam fog is expected and
patchy radiation fog is possible around daybreak both mornings,
especially in interior NW PA and NE OH. Any fog will dissipate
soon after daybreak via the onset of diurnal heating/convective
mixing of the boundary layer tapping into drier air aloft.
On Friday, late afternoon highs are expected to reach the mid 70`s
to 80F as diurnal convective mixing of the boundary layer occurs
amidst 850 mb temperatures near 11C to 12C. Despite a very marginal
temperature contrast between relatively-warm surface air over
surrounding land and Lake Erie, a very weak synoptic MSLP gradient
and the anticyclonic circulation of the synoptic surface high
pressure center settling over the lake are still expected to allow a
lake breeze to occur Friday afternoon through early evening. The
N`erly synoptic MSLP gradient in most of our CWA will allow the lake
breeze to have significant inland extent, especially from roughly
the longitude of the Lake Erie Islands and points farther east. This
has been a consistent signal in the last few runs of the HRRR and
other mesoscale NWP models. The coolest highs on Friday are expected
over/within a couple miles of Lake Erie.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
The weekend forecast appears quiet for the local area. A weak upper
low to the west over Minnesota and Iowa will block an upper trough
moving through eastern Canada from overtaking the Great Lakes
region. This will actually allow for some upper ridging to form over
the local area and keep high pressure in place across the region.
With that, will keep the forecast dry with relatively seasonable
temperatures with 80s for highs. Lows on Saturday night could
continue to be a bit cool with mid 50s under clear conditions. Lows
should recover somewhat for Sunday into the 60s.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
After a weekend reprieve of weather, the forecast for next week
returns to conditional shower/storm chances before a bonafide
weather system will approach the area for the middle of the week.
For Monday, the weak upper low over the Midwest will open up and the
energy will push east toward the Great Lakes region. A warmer air
mass with temperatures in the mid to upper 80s should be in place to
generate some instability to help diurnally force convection.
However, moisture in the region will be fairly limited and will be
the main factor to prevent much from happening. With the western low
gone, a larger upper trough will swing into the Great Lakes region
on Tuesday and Wednesday. This system will bring a more formal low
pressure system with a cold front through the area, which should
force more widespread shower and storm chances and have PoPs to
likely levels. A stronger upper wave of the trough will move through
on Thursday and allow even better support for showers and storms on
Thursday. However, several rounds of rain and lingering clouds could
make Thursday more conditional thermodynamically, but will keep some
likely PoPs in the forecast for now. Overall, Tuesday through
Thursday will be a period to watch for shower and storm chances and
potential summer weather hazards.
&&
.AVIATION /00Z Friday THROUGH Tuesday/...
Scattered to broken mid-level ceilings will clear near or
shortly after sunset and generally expect VFR conditions through
the TAF period. Can`t rule out a brief period of patchy river
valley and perhaps radiational cooling fog southeast of a line
from roughly KMNN to KGKJ with KYNG having the best shot at non-
VFR out of all of the TAF sites. May need to introduce a period
of non-VFR to KCAK if the fog forecast trends a bit farther
north, but confidence is low at this point.
Winds will be out of the north at 5 to 10 knots through sunset
before becoming light and variable overnight. Inland terminals
will likely remain light and variable through 00Z Friday, but
expect winds to become north/northwesterly at 5 to 10 knots at
lakeshore terminals by Friday afternoon.
Outlook...VFR expected through Monday morning. Isolated
showers/thunderstorms with non-VFR possible Monday afternoon
and evening with better chances for showers and thunderstorms
Tuesday.
&&
.MARINE...
One final push of a surface trough across the lake tonight will
allow for a window of enhanced northerly winds, especially for the
central basin of Lake Erie. Waves will marginally respond to 3 ft,
but should stay controlled enough to not need a Small Craft
Advisory. High pressure will be in control of the Great Lakes region
for Friday through Sunday and marine weather should be quiet. Winds
will be light, less than 10 kt, and variable through the period, as
there will be directional changes with lake and land breezes. Waves
will respond by staying 2 ft or less through the period and likely
just flat through Sunday. High pressure will move out starting on
Monday and a warm front will approach the lake. Winds will shift
from the northeast to east during the day and then southeast at
night, all at 10 kt or less.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka/Maines
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Maines
MARINE...Sefcovic
Area Forecast Discussion
National Weather Service Quad Cities IA IL
619 PM CDT Thu Jul 18 2024
.KEY MESSAGES...
- Dry and pleasant summer weather for the rest of the work
week and into the weekend.
- Very low chance (15-20%) of diurnally driven showers/storms
Sunday and Monday.
- Moderate to major river flooding continues on the Mississippi
River. The Rock River to crest in the Moderate category at
Joslin and Moline by the end of the week.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 202 PM CDT Thu Jul 18 2024
Beautiful summer conditions were seen today, with high pressure
overhead. Temperatures at 2pm, were in the middle 70s, with
dewpoints in the 50s making it feel more like September outside!
Tonight...clouds will diminish after sunset tonight, as the surface
high slides east. Another cool night is forecast, with clear skies
and light wind. Overnight lows will drop into the mid 50s.
Friday...weak WAA will commence on the back side of the high. RAP
925-850mb RH progs will rise near 70% suggesting that more fair wx
Cu will develop during the afternoon. Otherwise, another beautiful
day will be seen with highs in the upper 70s/low 80s.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 202 PM CDT Thu Jul 18 2024
While surface high pressure remains in the Midwest through Sunday, a
weak upper low is forecast to slowly drop into the Plains, and shift
east into Iowa for Sunday and Monday, as it weakens. At the very
least, this will allow for more of a diurnal increase in cloud cover
each day, but should also allow for a isolated to scattered shower /
storm chance. The flow aloft will be weak, and moisture depth
appears limited. Thus, these pop/drop showers should not move
quickly, and would only offer an isolated rainfall potential. Taking
a look at the model ensembles, the probabilities of any measurable
rain through 18z Sunday is less than 40%, with the highest values in
the far western counties. The GEFS is the wettest and the 12z GFS
deterministic run remains in this camp.
Temperatures will be warming only modestly through the period, with
dew point temperatures rising to only the lower to mid 60s, which is
largely driven by evapotranspiration as opposed to moist advection.
Highs in the lower to mid 80s are forecast Monday through Thursday.
Lows in the lower to mid 60s are expected.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 618 PM CDT Thu Jul 18 2024
VFR conditions will prevail through the TAF period, with light
and variable winds and diurnal cumulus through the daytime.
Otherwise, no sig wx is expected at this time.
&&
.HYDROLOGY...
Issued at 1125 AM CDT Wed Jul 17 2024
The Mississippi River has crested at all sites, with some reaches
continuing to experience somewhat stalled falls or steady trends
over the next few days due to recent bouts of heavy rain, local run-
off, and tributary input. L&D 19 at Keokuk and Gregory Landing will
even experience secondary rises into the weekend.
Tributary Rivers:
The recent rounds of heavy rain on the Rock River basin will
continue to produce significant rises on the Rock, but after
assessing the extent of run-off and upstream flow trends, Joslin and
Moline are now projected to remain below the Major flood stage. The
Rock at Como will be in Minor flood through Friday evening.
The Pecatonica River is projected to rise into Minor flood at
Freeport IL Friday night.
The lower Wapsipinicon River near Dewitt, IA performed a secondary
crest around 11.2 feet yesterday/Tuesday evening, but is now
dropping below flood stage. With the dry weather into the weekend,
the Wapsi is now expected to remain in the decline mode and remain
below the flood stage.
Backwater effects from the Mississippi River will keep the lower
Iowa River just below flood stage through early next week.
Further south, torrential rainfall and run-off from Monday night may
produce a large rise to action stage on the La Moine River near
Colmar in west central IL by Thursday. But the extent and speed is
still somewhat uncertain and will have to watch river rise trends
over the next 24 hours.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Gross
LONG TERM...Gross
AVIATION...Gunkel
HYDROLOGY...12
Area Forecast Discussion
National Weather Service Glasgow MT
209 PM MDT Thu Jul 18 2024
.DISCUSSION...
KEY MESSAGES:
- Scattered thunderstorms from Thursday evening into Friday
morning for most of the area. A few isolated thunderstorms
Friday afternoon and Saturday afternoon.
- Above average to well above temperatures expected for the next
week.
- Scattered haze from Canadian wildfires is expected to sneak
into the area the next couple days.
WEATHER PATTERN OVERVIEW:
High pressure has built in over the Great Basin with the top of
the ridge located over Montana. A shortwave will rotate around the
top of the ridge and bring some scattered thunderstorms across the
area this afternoon into Friday morning. Low level moisture will
mix out during the afternoon so these will be high based storms
with gusty downdraft winds occasionally approaching severe levels
and dry lighting being the main hazards. Precipitation amounts
will be below wetting rains with only a trace to a few hundredths
expected.
The shortwave is expected to exit by Friday afternoon with a few
isolated convectively driven showers or dry thunderstorms possible
during the afternoon and again on Saturday afternoon.
By next week the ridge intensifies and precipitation chances dry
out with temperatures potentially flirting with the 100 degree
mark by Tuesday.
FORECAST CONFIDENCE & DEVIATIONS:
+++ Afternoon Update: Main update to the afternoon forecast
package was adjusting this afternoon and evening`s PoP grid. I
blended in guidance with the 12Z HRRR which shows the present line
of showers moving across the central and eastern zones this
afternoon, ahead of the more prominent line that will mostly move
south of the Missouri/Milk Rivers. Main threat will be gusty
winds. As such, adjusted the wind/wind gust grids accordingly to
blend in some of the CAM guidance. +++
High confidence of the ridge intensifying to bring temperatures
back up to above normal over the next few days. Medium confidence
on scattered showers and storms this afternoon with POPs in the
35-65% range. Low confidence on precipitation chances Friday and
Saturday with POPs only in the 15-40% range Friday and 15-25%
range Saturday.
-Bernhart/Enriquez
&&
.AVIATION...
FLIGHT CONDITION: VFR
DISCUSSION: High based thunderstorms will move into the region
this afternoon. Main hazard is gusty outflow winds. Storm chances
last overnight into Friday morning with a few isolated storms
redeveloping in far eastern Montana during the afternoon.
WINDS: E-SE 5-10 knots.
-Bernhart/Enriquez
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Grand Rapids MI
720 PM EDT Thu Jul 18 2024
.KEY MESSAGES...
- Dry and pleasant next few days
- Daily chances of summer pop-up showers/storms next week
&&
.DISCUSSION...
Issued at 245 PM EDT Thu Jul 18 2024
- Dry and pleasant next few days
Upper-level flow and dynamics will be weak over the next few days,
with one jet rounding a low over northern Ontario/Quebec and
another faint jet over the mid-southern CONUS. High pressure in
the lower levels will be in place over the Midwest and Great Lakes
through Saturday while slowly weakening.
Patchy fog is possible in southern Michigan late tonight with the
center of the high moving closer. Dew points tomorrow will be in
the 50s again, quite comfortable, with temperatures a little
cooler than normal for mid July. Some daytime cumulus clouds are
expected to develop away from Lake Michigan.
- Daily chances of summer pop-up showers/storms next week
Despite fairly weak flow overhead through much of the troposphere
early next week, the tendency for broad upper-level troughing over
the Midwest will erode the surface high, favoring slightly better
dynamics for lift as well as weaker capping atop the diurnal
boundary layer. Moisture content of the lower troposphere may
creep up slightly each day, presumably in part due to
evapotranspiration across the region. A reinforcing shortwave
trough is likely to dive into the midwest from central Canada
midweek.
Shower and thunderstorm chances will increase between Sunday and
the middle of next week, peaking daily each afternoon-evening.
Slight chances begin in Central Michigan on Sunday. Better
instability and dynamics around Tue-Wed-Thu will support higher
chances for scattered storms.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 720 PM EDT Thu Jul 18 2024
Light winds and clearing skies on the way this evening. This
could bring some MVFR visibilities in fog between 06z and 12z.
Otherwise, expect VFR conditions.
&&
.MARINE...
Issued at 245 PM EDT Thu Jul 18 2024
Moderate to high swim risk at Lake Michigan beaches, and hazardous
winds and waves for small craft, are expected to persist into
Thursday evening south of Whitehall toward South Haven. High
resolution models including the HRRR have been indicating north
winds (due to high pressure west of us), combined with a daytime
lake breeze circulation, will pull the wind direction northwest
and intensify the wind speeds slightly this afternoon. North sides
of north piers will be particularly hazardous due to stronger
currents. On Friday, lighter west winds are expected with waves
around 1 foot.
&&
.HYDROLOGY...
Issued at 245 PM EDT Thu Jul 18 2024
Lingering water swamping of low-lying and slow-draining areas in
locations near and south of I-94, following the Monday night
thunderstorms, will very gradually improve through a dry weekend.
This includes river forecast points at Comstock Twp, Vicksburg,
Burlington, Marshall, and Jackson.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ050-
056-064-071.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>847.
&&
$$
DISCUSSION...CAS
AVIATION...Maczko
MARINE...CAS
HYDROLOGY...CAS
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
956 PM EDT Thu Jul 18 2024
.SYNOPSIS...
A nearly stationary front will meander across our region through
early next week providing a focus for above normal chances of mainly
afternoon and evening showers and thunderstorms. Another cold front
will approach from the north later next week. Temperatures will be
near normal or just a bit cooler than normal.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 954 PM Thursday: Just a few patches of lingering light anvil
rain over parts of the eastern Piedmont of SC at this hour, so
we have knocked down the precip chances and all but eliminated
the thunderstorm probs. Temps have been cooled by the rain in
most places. Already seeing some low dewpt depressions out there,
so fog is looking like a better and better possibility later this
evening and overnight. Nothing as of yet...
Otherwise, broad upper troffing will linger to our north over the
Great Lakes while broad upper ridging persists to our west and to
our east. At the sfc, Canadian high pressure will linger to our
NW while the Bermuda High keeps moist, southerly low-lvl flow
to our south. Between these two highs, a weak frontal boundary
that is currently draped across our area will slowly move south
and east of our CWA this evening. Nonetheless, the deeper moisture
associated with the broad region of low-lvl convergence will persist
over the Southeast well beyond the near-term period. The drier air
to our north, associated with the Canadian high, will make little
progress southward over the next few days. For Friday, we can expect
another round of sct to widespread convection across our area as
we remain under the moist airmass. The model profiles, however,
appear less supportive of strong to severe thunderstorms. Thus,
our primary threat will likely be localized heavy rainfall and
the potential for isolated flooding. As for temperatures, they
will trend cooler with highs on Friday expected to remain in the
80s over the lower terrain and 70s over the mtns.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 100 PM Thursday...A rather stationary pattern will persist
over the short range as a strong Canadian high builds south and
traps a frontal zone against the Bermuda High. The flow around the
subTrop ridge will will allow for very good moist advect each day
and cross sections indicate high saturation thru the mid levels. Fri
night into Sat may see the best chance for widespread showers and an
increased hydro threat as s/w forcing crosses the area. High cloud
cover and rather warm mid-levels will limit sbCAPE potential each
day as sfc heating and max temps are curtailed a cat or so below
normal, yet diff heating will likely allow for more robust and
longer lived tstms, possibly leading to a multi-cell mode. The
various guidance continues to disagree sigfnt/ly on the location of
the sfc convg zone which will be key in the generation and amts of
precip each day. Models aren`t too excited about over all precip
totals either, but localized areas could see arnd an inch in a short
amt of time potentially leading to flood issues depending on where
the sfc front interacts more with the stronger updrafts. Training
cells with high rainfall rates will also be possible as the mean
steering flow aloft aligns parallel with the stationary front thru
the period. Pops were maintained quite a bit abv climo each day with
lower noctural precip likely continuing each night.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 140 PM Thursday...The ext range fcst remains quite active as
the latest guidance continues to show an activated stationary front
draped across the area each day. A strong subTrop ridge will hold
it/s own against upper energy diving out of Canada and possibly
strengthen and shift west by Tue. Decent agreement is seen in the
llvl mass fields Mon thru Wed with the GOM wide open for efficient
moisture flux each day. This could be a period of increased hydro
issues as antecedent water level conds by that time may be quite
elevated. A lot will depend on the areas where the front situates as
it wafts north and south thru the period, but the latest trends
begin to shift the heavy rain focus across the srn BR as the Bermuda
High becomes more dominant across the SE region. The going high-end
PoPs have been maintained thru the period including abv normal PoPs
during the overnight periods. Max temps will likely be held below
normal each day by a few degrees while mins remain abv normal.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: The immediate concern is a new patch of
storms just west of the KGSP/KGMU terminals, so brief MVFR can be
expected over the next hour or two. Otherwise, we have stabilized
in the wake of earlier storms. Moisture will remain pooled across
the region with a sfc front strung out along the I-85 corridor into
the overnight hours. Dewpoint depressions are already fairly low
for this time of day, giving confidence to the model depiction of
fog developing late this evening at all terminals, at least to an
MVFR vis restriction. Wind will be light/variable overnight. Some
locations should see at least temporary IFR in the pre-dawn hours,
with KAVL most likely to end up LIFR or VLIFR. There should be
some quick improvement by 13Z. For Friday, a bit of a later start
to the shower/tstm activity possibly because of extensive morning
cloud cover. The guidance eventually develops the convection in
the late afternoon and moves it northeast across the region. Will
keep that mention to a PROB30 at all terminals, but a TEMPO at
KCLT in the evening hours based on the HRRR timing.
Outlook: Expect sct to numerous showers and thunderstorms each
aftn/ evening thru the weekend. Morning fog/low stratus will be
possible each day, especially in the mtn valleys and over areas
that received rainfall from the previous day.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...JPT/PM
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...PM
Area Forecast Discussion
National Weather Service Medford OR
456 PM PDT Thu Jul 18 2024
Updated Aviation Discussion.
.DISCUSSION...High pressure rests over the region with a Pacific
trough grazing the PacNW coast. Temperatures are expected to
slowly climb Friday into Saturday. The main feature on satellite
is smoke from the newly ignited fires from early week
thunderstorms. These fires are seen near Diamond and Lemolo
Lakes, and scattered across eastern Douglas, southeastern Lane and
far northern Klamath counties. These fires and smoke from them
will be a focus for operations in the near future.
A weak disturbance off the southern California coast will be
making its way northward tonight through Friday, and then will
pass through the area Saturday. A slight chance (10-20%) for
thunderstorms continues or has been re-introduced to the area as
this wave lifts north Saturday afternoon and night. More 10-20
percent chances continue Sunday afternoon and evening across the
east side as weak short waves continue to target the area in SW
flow aloft.
Thereafter the main story will be drier more stable southwest
flow aloft and temperatures closer to normal as low pressure
centers near British Columbia and the 4-corners high gets pushed
to the southeast through late week. Stavish
&&
.AVIATION...July 19/00Z TAFS...VFR conditions prevail over the
entire aviation forecast area. Any remaining low clouds at the
immediate coast are quickly dissipating. VFR is expected for the
next 24 hours for all areas except for the coast from Cape Blanco
northward where IFR and MVFR ceilings will develop after sunset.
These ceilings will push inland overnight but are not expected to
reach Roseburg (KRBG). Typical diurnal breezes are expected through
this cycle. -CC
&&
.MARINE...Updated 245 PM Thursday, July 18, 2024...Weak low pressure
offshore has disrupted the thermal trough pattern. Weak winds and
low seas will persist into Friday morning. A weak thermal trough is
expected to return Friday and strengthen this weekend with the
strongest winds south of Cape Blanco. Advisory strength northerly
winds and steep seas are possible Saturday, then gales and steep to
very steep seas are possible early next week. -DW/Hermansen/Sargeant
&&
.FIRE WEATHER...Issued 200 PM Thursday July 18, 2024...
A dry and stable southwest flow continues through Friday with no
concerns for thunderstorms. However, afternoon relative humidities
will trend lower for most interior locations with values in the
single digits for portions of the East Side through Friday along
with the typical gusty afternoon and early evening breezes. This
will result in near critical conditions for portions of Fire zones
624, 625 and 285, but were not expecting the combination of wind and
RH to result in Red Flag conditions.
The other concern for those involved in air attack on the various
fires in our area will be visibilities lowering to 3-4sm in the
vicinity of the Shelly and Trail Fires. The latest run of the HRRR
smoke fields show the smoke being transported east to southeast of
those fires late this afternoon and evening, therefore visibility
could be reduced to 4-6sm into early this evening. Tonight, as the
mixing height decreases, the smoke will settle and be confined to
around the fire perimeter of the fires resulting in MVFR visibility
between 3-5sm. Also smoke could also settle in the valleys adjacent
to the Shelly Fire.
There`s still a concern for thunderstorm this weekend. Saturday, an
upper trough will move up from the south just off the California
coast and could tap into some monsoonal moisture with a southeast
flow aloft. At the same time, there`s good agreement, the upper
trough will become negatively tilted Saturday afternoon into
Saturday night. Based in part on pattern recognition, this could be
problematic in that we could see storms break out mid to late
Saturday afternoon in portions of fire zones 280, 281 and 284.
Saturday night, the axis of the upper trough is still south of our
area which heightens the concern for nocturnal storms west of the
Cascades, and portions of the east side in Oregon Saturday night.
Many times the models will not show signs of unstable conditions
with this type of pattern, then the next thing you know something
breaks out of nowhere. The pattern that is setting up is one where
the instability is elevated, and thus the convection will be
elevated as well. Not saying this is a slam dunk, but at the same
time it cannot be discounted.
The upper trough axis shifts north during the day Sunday. Any threat
for storms could be confined to the early morning hours over the
northwest part of our area, then shifting north late Sunday morning
through Sunday afternoon with a drier and stable southwest flow
moving into the area. The exception could be in portions of Fire
zone 623, 624 and 625 where isolated storms are possible late Sunday
afternoon. Not convinced anything will happen in these areas, but
there are some signals suggesting it cannot be discounted either.
Monday, a dry and stable southwest flow will set up with any chance
for storms shifting east and northeast of our area. It will be
cooler with gusty afternoon and early evening breezes for the
interior westside valleys and east of the Cascades.
The rest of next week is pointing towards dry and cooler weather,
but afternoon temperatures will still be above normal for the
interior. However, the concern will shift towards moderate to locally
poor overnight recoveries for the mid slopes and ridges in southwest
Oregon and western Fire zone 280, and the typical gusty afternoon
and early evening breezes for the interior westside valleys and east
of the Cascades with low afternoon RH`s. -Petrucelli
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.
CA...None.
PACIFIC COASTAL WATERS...None.
&&
$$
Area Forecast Discussion
National Weather Service New York NY
1056 PM EDT Thu Jul 18 2024
.SYNOPSIS...
A secondary cold front will move through the area this evening,
followed by high pressure building in from the west into Saturday.
The high weakens over the area into early next week as a
stationary front over the Mid Atlantic begins to work slowly
north as a warm front. The front is forecast lift across the
area mid week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The forecast is on track with only minor changes needed.
Upper trough lifting across the Northeast tonight will send a
secondary cold front through the area. It should be dry. Latest
HRRR shows a spotty shower or two. This seems unlikely, but if
it did occur expect it to be real brief.
Surface high pressure builds in from the overnight with clearing
skies and northerly flow. Dew points will slowly fall into the
mid to upper 50s overnight, with weak cold advection. This
combination will allow temperatures to drop to a few degrees
below seasonal normals.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
The upper trough lifts north of the area during Friday, with a
light westerly flow through Saturday. Meanwhile the surface
high will remain over the region Friday into Saturday, and begin
to weaken late Saturday as a cold front begins to approach to
the north. A relatively dry airmass remains through Friday
night, and then dew points begin to increase into the lower to
mid 60s during Saturday. Temperatures Friday through Saturday
will be near seasonal normals.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
An upper trough across eastern Canada and the Northeast gradually
lifts out to the north through mid week, while a weaker trough over
the mid section of the country amplifies as jet energy dives south
from central Canada. This will allow for backing of the upper flow,
sending a stationary front across the Mid Atlantic northward and
into the area by midweek.
Airmass during this time gradually destabilizes as conditions become
increasingly more humid with an onshore shore S/SE flow.
Temperatures will start off slightly above normal, however, with a
forecast increase in cloud cover and showers and thunderstorms,
highs will be a bit lower by mid week. Generally looking for highs
in the mid and upper 80s, except cooler along the immediate coast.
Lows are forecast to me in the 60s inland, to the lower 70s along
the coast.
The best chance for showers and thunderstorms looks to be Tuesday
afternoon into Wednesday as the warm front approaches from the
south. Before then though, focus may be along an inverted/thermal
trough from the Mid Atlantic states northward into western portions
of the area along with some shortwave energy in the westerlies.
Chances are low on Saturday night and again Monday/Monday night.
PWATs are forecast to increase to around 2 inches by mid week, thus,
heavy rain become more likely with any convection later in the
period. However, it is much too early to be specific with any
details. Frontal timing and location will will be critical.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A cold front moves through this evening. High pressure
gradually builds towards the region from the west through
Friday.
VFR through the period.
NW to N winds overnight at 5 to around 10 kt with gusts 15 to
20 kt in wake of cold frontal passage.
On Friday, N winds less than 10 kt, shift W in the afternoon,
giving way to afternoon coastal sea breezes.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
NW to N winds with gusts to 15-20 kt likely through 09Z-10Z. N
winds around 10 kt for Fri AM push.
Some uncertainty in KEWR and KTEB wind direction forecast as
sea breeze may push through these terminals late Friday
afternoon, shifting the direction more toward 150.
Amendments may be needed to fine tune any wind direction
changes this eve.
OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
Friday night-Sunday: VFR.
Monday: VFR. Potential MVFR for PM/Night in SHRA.
Tuesday: Potential MVFR with SHRA/TSRA.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Ocean seas will continue to very slowly subside west to east
this evening and into the overnight. A SCA remains up for the
eastern ocean waters east of Moriches Inlet until 200 AM
Friday. Thereafter, winds and seas remain below advisory levels
on all the waters into early next week.
&&
.HYDROLOGY...
No hydrologic impacts are expected into early next week.
Chances of showers and thunderstorms increase Tuesday into
Wednesday, but it is still too early to be specific with
hydrologic impacts.
&&
.TIDES/COASTAL FLOODING...
A high risk of rip currents will continue for the eastern
beaches of Suffolk county on Friday due to a linger southerly
swell. Elsewhere, expect a moderate risk. A low risk is
forecast for all beaches on Saturday.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Risk for Rip Currents through Friday evening for NYZ081.
NJ...None.
MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ350.
&&
$$
SYNOPSIS...MET/DW
NEAR TERM...JP/MET/DW
SHORT TERM...MET
LONG TERM...DW
AVIATION...JP
MARINE...MET/DW
HYDROLOGY...MET/DW
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Spokane WA
505 PM PDT Thu Jul 18 2024
.SYNOPSIS...
Strong high pressure will begin to amplify over the Inland
Northwest during this period continuing our string of hot weather
which began around July 5th. The heat will likely peak this
weekend with widespread triple digit high temperatures and
possible records. There are hints the heat will finally relent by
the middle of next week.
&&
.DISCUSSION...
After further coordination with neighboring NWS offices, a Heat
Advisory has been adjusted to end 11 AM Saturday, with an
Excessive Heat Warning issued from 11 AM Saturday - 8 PM Monday.
JW
&&
.AVIATION...
00Z TAFS: The Inland NW expect VFR conditions to continue through
the period. The only exception will be some hazy conditions from
increasing smoke from the regional fires this afternoon/evening,
including the Pioneer Fire near Lake Chelan. The HRRR smoke model
suggests this will drift N-NW late today and tonight and should
remain out of the KEAT area.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
With the exception of smoke near wildfires confidence is high for
continued VFR conditions.
-----------------------
Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance
For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard
&&
.PREV DISCUSSION... /issued 304 PM PDT Thu Jul 18 2024/
Tonight through Sunday: The ridge is rebounding across the
Pacific Northwest. It will bring another weekend of major to
extreme heat across the Inland Northwest. Temperatures will
gradually increase and peak on Sunday. Highs will generally be in
the upper 90s and low triple digits. Overnight lows will bring
little relief as they are expected to be in the upper 50s and
60s. Winds will generally be light and calm from a south to
southwest direction. Ensembles are hinting at another shortwave
sliding along the Cascade crest on Sunday. It will lead to an
increase in winds down the Cascade Gaps and the Waterville Plateau
for Sunday afternoon and evening. Winds will sustained into the
teens and gusts near 30 MPH are possible. There are indicators of
weak convection in the North Cascades. But being so small, there
is little no confidence of any thunder activity in the area.
Monday through Thursday: A Low over the Gulf will push a trough
across the region and shift the ridge to the East and South
finally breaking the very hot period for the Pacific Northwest.
While precipitable waters are expected to increase in the region,
ensembles are little to no precip expected for the Inland
Northwest. Monday is expected to be last major day of heat as
cooler begins to filter into the the region with the trough. Highs
will drop to more seasonable temperatures with upper 80s and 90s
expected. Overnight lows will be in the 50s. It is expected to be
a gradual cooling and moistening of the region. Winds will
continue to be breezy and slightly stronger. This could lead to
potential fire weather concerns. /JDC
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 65 98 65 101 67 106 / 0 0 0 0 0 0
Coeur d`Alene 62 96 63 99 65 104 / 0 0 0 0 0 0
Pullman 59 93 60 97 62 102 / 0 0 0 0 0 0
Lewiston 70 103 71 107 71 112 / 0 0 0 0 0 0
Colville 55 97 54 100 56 104 / 0 0 0 0 0 0
Sandpoint 58 94 57 98 59 102 / 0 0 0 0 0 0
Kellogg 67 94 69 98 71 102 / 0 0 0 0 0 0
Moses Lake 62 100 61 103 66 109 / 0 0 0 0 0 0
Wenatchee 70 99 69 102 76 108 / 0 0 0 0 0 0
Omak 67 103 65 105 68 110 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory until 11 AM PDT Saturday for Central Panhandle
Mountains-Coeur d`Alene Area-Idaho Palouse-Lewis and
Southern Nez Perce Counties-Lewiston Area-Northern
Panhandle.
Excessive Heat Warning from 11 AM Saturday to 8 PM PDT Monday
for Central Panhandle Mountains-Coeur d`Alene Area-Idaho
Palouse-Lewis and Southern Nez Perce Counties-Lewiston Area-
Northern Panhandle.
WA...Heat Advisory until 11 AM PDT Saturday for Central Chelan County-
Lower Garfield and Asotin Counties-Moses Lake Area-
Northeast Blue Mountains-Northeast Mountains-Okanogan
Highlands-Okanogan Valley-Spokane Area-Upper Columbia Basin-
Washington Palouse-Waterville Plateau-Wenatchee Area-
Western Okanogan County.
Excessive Heat Warning from 11 AM Saturday to 8 PM PDT Monday
for Central Chelan County-Lower Garfield and Asotin
Counties-Moses Lake Area-Northeast Blue Mountains-Northeast
Mountains-Okanogan Highlands-Okanogan Valley-Spokane Area-
Upper Columbia Basin-Washington Palouse-Waterville Plateau-
Wenatchee Area-Western Okanogan County.
Heat Advisory from 11 AM Saturday to 8 PM PDT Monday for Western
Chelan County.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
451 PM MST Thu Jul 18 2024
.UPDATE...Updated 00z Aviation Discussion.
&&
.SYNOPSIS...
Daily chances for showers and thunderstorms will exist through at
least the next 7 days. Better chances will continue to be focused
over the Arizona high terrain, but thunderstorm chances for the
lower deserts increase notably over the weekend and into early next
week. Widespread excessive heat conditions are expected to develop
Friday and continue into this weekend across the lower deserts,
with forecast highs peaking up to 114 to 118 degrees for the
typically hotter locales.
&&
.DISCUSSION...
THUNDERSTORMS: The Desert Southwest has entered a more active
period for monsoon thunderstorms, especially when it comes to
coverage. Thunderstorms are expected daily for the next week,
primarily over typical higher terrain areas of AZ and out into
SoCal. The forecast challenge will be figuring out which days are
more likely to see afternoon and evening thunderstorms survive
into the the lower deserts. Survivability and further initiation
is often heavily dependent on mesoscale interactions like deep
outflows, colliding outflows, and mid-level gravity waves, which
models are not always the most adept at resolving. That being
said, seasonal to above seasonal moisture is in place and does not
look like it will drop off significantly during the next week,
and daily instability will be sufficient to support showers and
storms across the region. Global ensemble models do indicate a
potential larger change to the synoptic pattern toward the end of
next week when a deeper Pacific trough pushes into the Northwest
CONUS and may flatten and weaken the monsoon high. It is uncertain
this far out if this change could have a major impact on the
storm activity, but it may at least lower temperatures down a bit.
Time will tell.
There does not look to be too much difference in the day-to-day
thunderstorm outlook today through Saturday besides subtle
differences in instability, moisture, and the position of the
monsoon high. The monsoon high is expected to gradually shift west
over the next few days, with mid-level steering flow going from
E-SE in eastern AZ today to more pronounced NE heading into the
weekend. Instability will be marginal the next few days, with
MLCAPE forecast to mostly fall in the 500-1000 J/kg range. So, not
expecting considerable severe thunderstorm threats and coverage,
but there is still potential for a few severe storms. DCAPE will
remain fairly high, with magnitudes around 1500 J/kg in the
afternoons and evenings. So, strong gusty downdraft winds are
anticipated and outflows traveling into the lower deserts during
the evenings and early overnight hours are likely. These evening
outflows will be capable of initiating storms over the lower
deserts, especially with any outflow collisions. Several runs of
the HRRR model have indicated potential for storms over the lower
deserts, including in Phoenix, this evening-tonight, but it will
still come down to the evolution and depth of the outflows as to
whether this can come to fruition. Similar conditions may happen
in the following days as well. NBM PoPs over the lower deserts
today through Saturday are generally around 15-25% in the
evenings. The flash flooding threat is still fairly marginal as
mean mixing ratios will mostly be near or just below 10 g/kg. Most
rainfall will be enough to wet the ground and create some
nuisance flooding, but there still potential for localized flash
flooding with any storm that anchors to a lifting mechanism or if
multiple storms hit the same area.
Sunday into early next week continue to look like even more
favorable days to thunderstorm activity with potential for even
greater coverage as the monsoon high continues to shift off to the
northwest of the Desert Southwest and mid-level N-NE winds
increase. This will be a more favorable setup for storms to move
off the Mogollon Rim toward the lower deserts of South-Central AZ,
so long as thunderstorm anvils do not blow in the same direction
as steering flow and inhibit surface instability. Global models
also indicate a slight increase in moisture, with PWATs pushing a
little closer to 2.0" and mean mixing ratios pushing up to around
the 11-12 g/kg magnitude. This along with continued above normal
heat will in turn result in greater instability (i.e. higher
CAPE). Ultimately, there will be potential for stronger storms,
possibly more severe storms, and better potential for flash
flooding, so long as the environment can be realized.
HEAT: An Excessive Heat Warning remains in effect for most lower
desert locations this Friday and Saturday, and continues through
Sunday for Southeast CA and along the Lower CO River Valley.
Widespread Major HeatRisk is forecast for for Friday and Saturday,
with afternoon highs in the 112-118F range. There will also be the
added element of humidity, especially in Southeast CA, where heat
indices are forecast to reach up to 116-120F. There is still
potential, with the increased thunderstorm activity around the
region, for some disruption in the heat, but it is still best to
plan for more extreme heat. High temperatures are expected to
lower slightly by early next week with the further increase in
thunderstorm activity anticipated and a slight decrease in the
height field. Even more "cooling" may come toward the end of next
week with the potential pattern change previously mentioned.
&&
.AVIATION...Updated at 2350Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Westerly winds with speeds generally around 10 kts with occasional
gusts 15-20 kts will continue into the evening. Forecast
confidence remains low (20%) on if any showers or storms will make
it into the Valley and if they will move over any terminals, but
SHRA/TSRA should be in the vicinity during this time frame.
Forecast confidence is increasing that there will be at least one
outflow boundary with some gusty winds moving through the Valley
tonight, with the likely direction of this outflow boundary will
be from the northeast. Wind gusts with this outflow will be in the
20-30 kt range. There is a 30% chance of gusts exceeding 30 kt. FEW-
SCT mid and high level clouds will continue into the evening when
they will become more BKN and continue into the overnight hours.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds at KBLH will favor a southerly/southwesterly component
through the TAF period with speeds generally aob 12 kt. At KIPL,
initially westerly/southwesterly will back towards the SE later
this evening. The probability of storms directly impacting KIPL
remains low (<15%), but it still bears watching in case storms
coming off the mountains try to wander towards the terminal this
evening. FEW-SCT mid and high level clouds will continue across
the region.
&&
.FIRE WEATHER...
Daily scattered to widely scattered thunderstorm activity is
expected over the AZ high terrain through the end of the work week,
with only isolated chances elsewhere. The main hazards with any
thunderstorm activity will be strong, gusty outflow winds, which
could exacerbate issues with any ongoing wildfires or new starts.
Over the weekend, chances for thunderstorms over the South-
Central AZ lower deserts increase upwards of 35% as we enter an
active northeast flow monsoon pattern. Winds outside of the
influence of thunderstorms will exhibit diurnal tendencies with
afternoon and early evening gusts commonly between 20-25 mph.
MinRHs through the next several days will range from 15-25%, with
fair to good overnight recoveries between 30-60%. Moisture will
increase over the weekend, leading to overnight recoveries in
excess of 40% across much of the region.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning from 10 AM Friday to 8 PM MST Sunday for
AZZ530.
Excessive Heat Warning from 10 AM Friday to 8 PM MST Saturday
for AZZ531>546-548>555-559.
CA...Excessive Heat Warning from 10 AM Friday to 8 PM PDT Sunday for
CAZ560>570.
&&
$$
DISCUSSION...Benedict
AVIATION...Young/Berislavich
FIRE WEATHER...Whittock