Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/24
Area Forecast Discussion
National Weather Service Boise ID
839 PM MDT Wed Aug 14 2024
.DISCUSSION...Latest HRRR model predicts near-surface smoke to
decrease tonight and Thursday except near the fires northeast
of Boise, and showers should help further as a Pacific upper
low moves inland across Oregon. The low is forecast to turn
northeastward into eastern WA Thursday, then weaken to an
open trough in northern Idaho Thursday night, but still
produce showers throughout eastern OR and north of the Snake
Basin in ID. Showers and scattered weak thunderstorms will
dominate in the morning, but scattered stronger thunderstorms
will dominate in the afternoon. Clearing Thursday night, then
drying and warming Friday and Saturday. Current forecast
covers things well. No updates.
&&
.AVIATION...Mostly VFR, but due to wildfire smoke there will be
areas of IFR and mountain obscuration. Showers and thunderstorms
across eastern OR after 06Z tonight, spreading across SW Idaho
by 12z/Thu. These will bring brief MVFR to IFR visibility and
ceilings. Surface winds: SW-NW 5-10kt, becoming NW 10-20kt
early Thu morning, strongest between KBKE and KONO. Gusty
erratic outflow winds from showers and thunderstorms up to
40kt possible. Winds aloft at 10kft MSL: SW 10-20kt.
KBOI...VFR. Isolated showers and thunderstorms 14Z-18Z Thursday
morning may bring brief MVFR conditions. Surface winds: becoming
SE around 5 kt overnight, then NW 5-10 kt Thursday after 18Z.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Friday night...Wildfire smoke from
the Shelly and Boise fire in northern CA visible on the Geocolor
continues to stream northeast into the area this afternoon.
A shortwave off the California coast will move inland late
tonight and trigger two rounds of showers and thunderstorms.
Scattered showers and thunderstorms begin across eastern OR on
Thursday morning as the shortwave moves northeast into central
ID. After a brief lull, showers and thunderstorms redevelop on
Thursday afternoon with the heating of the day, especially
across eastern OR and the central ID mountains. Main threats
from the storms will be brief heavy rain, gusty winds up to 50
mph, and new fire starts from lightning. After the system moves
through, drier air from the southwest arrives, leading to a
warming trend through Saturday.
LONG TERM...Saturday through Wednesday...An upper level trough
will remain off the coast through the long term. Southwest flow
over the area, and a dry slot, will lead to breezy and warm
conditions over southeast Oregon and southwest Idaho. Saturday
is forecast to be the warmest day with temperatures around 5-10
degrees above normal, lowering to around 5 degrees above normal
for the remainder of the period. Monsoon moisture should stay
east of Twin Falls through the period.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning from noon to 10 PM MDT Thursday IDZ402-403.
OR...Red Flag Warning from midnight MDT /11 PM PDT/ tonight to 10
PM MDT /9 PM PDT/ Thursday ORZ636-637.
Red Flag Warning from 6 AM to 9 PM PDT Thursday ORZ646.
&&
$$
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DISCUSSION...LC
AVIATION.....SP
SHORT TERM...KA
LONG TERM....KA
Area Forecast Discussion
National Weather Service Boston/Norton MA
1032 PM EDT Wed Aug 14 2024
.SYNOPSIS...
Mostly dry and pleasant weather continues this afternoon e. Another
round of scattered showers thunderstorms is expected Thursday
afternoon and evening. Dry weather returns Friday and may linger
into Saturday, especially across RI and eastern MA. Then a frontal
system may bring scattered showers and thunderstorms Sunday through
Tuesday. Probably not a washout, with periods of dry weather too
during this time. Meanwhile, Ernesto will track well southeast of
New England, but it will bring rough surf and strong rip currents to
south-facing ocean beaches of RI and MA this weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Expecting convection moving south from Maine to remain well
offshore overnight. Relatively quiet weather continues tonight.
Mainly adjusted rainfall chances through the overnight, as well
as temperatures. Also expecting a brief period of fog across the
outer Cape and Nantucket, as well as the adjacent coastal
waters.
8 PM Update...
Diurnal showers across western MA and CT have died off as
daytime heating has decreased with sunset. Based on the 18z
HRRR vertically-integrated smoke and observations from today,
there`s higher confidence in haze primarily across eastern MA
affecting visibilities. Previous discussion is on track.
Previous discussion...
Clear skies this afternoon with some
diurnal cumulus. The exception at the moment is for far western
MA and CT where terrain is helping to kick off some scattered
showers and thunderstorms. Even though low level lapse rates are
favorable, poor mid level lapse rates and dry mid/upper levels
are keeping these storms low topped and sub severe. Garden
variety t-storms will continue over the interior until loss of
daytime heating with sunset. Tonight we`ll see some radiational
cooling but incoming clouds after midnight associated with a
subtle shortwave aloft will help to stem the cooling; expecting
lows in the 60s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The main weather story for Thursday is the return of more widespread
thunderstorms in the afternoon and evening as the upper trough
lingers overhead with a shortwave rotating through. Skies will be
mostly clear so plenty of sun for surface heating (highs in the low
to mid 80) and with dewpoints in the mid to upper 60s this will lead
to MUCAPE values over 1000 J/kg; plenty of instability and moisture
for some thunderstorms. Fortunately shear is quite weak (20 kts or
less) and mid level lapse rates aren`t impressive so we`re not
expecting anything severe out of these storms. That said, with PWATs
over 1 inch localized heavy downpours are possible along with some
gusty winds. Storms dissipate with sunset but onshore flow may bring
low clouds into eastern MA, RI, and even CT.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Key points:
* Drier pattern coming to an end after Friday night with surface
high pressure moving out of SNE
* Upper level trough moving in over the weekend into early next week
aiding in return of unsettled weather into mid-week
* Surface high pressure looking to return going into Wednesday
Details:
The drier weather we`ve been seeing for most of this week looks to
come to a close going into Friday night as the surface high pressure
begins to make its exit. In its place, an upper level trough and its
associated cold front looks to push through SNE over the weekend,
bringing with it more SW flow aloft, higher dew points, and
generally unsettled weather. PWATs during this period do not look to
be higher than seasonably average (staying within about the 1.45-
1.68" range at their highest), and nothing in the guidance overall
is indicating any high chances for heavy downpours. Highs for most
of this period look to be in the 80s for most of our area, with
Sunday being slightly cooler than the other days following the
passage of the aforementioned cold front.
This moisture looks to start moving out of SNE around Tuesday night
into Wednesday morning as a surface front passes through. Most of
the deterministic guidance suggests the return of the surface high
pressure by mid-week, with the ensembles being a bit more neutral
when looking at MSLP anomalies. Generally, there is decent support
from the guidance for more comfortable dew points and less rain
coming in mid-week.
As of right now, there is high confidence in Hurricane Ernesto
staying far offshore for New England, but there could be some slight
risks for rip currents and higher surf over the weekend along the
southern coastlines. Will continue to monitor for the possibility
for issuing headlines for the outer waters.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight and Thursday...High Confidence.
VFR. Winds light and variable. Seabreezes developing by
Thursday afternoon along both coasts. Risk for afternoon
showers and thunderstorms with brief MVFR conditions. Smoke
aloft may lead to visibility reductions and pseudo-overcast
conditions around 4000 ft.
Thursday night...High Confidence.
VFR. Winds light and variable.
KBOS TAF...High Confidence
KBDL TAF...High Confidence.
Outlook /Friday through Monday/...
Friday through Friday Night: VFR.
Saturday: VFR. Breezy. Slight chance SHRA.
Saturday Night: Mainly VFR, with local MVFR possible. Chance
SHRA, isolated TSRA.
Sunday through Sunday Night: Mainly VFR, with local IFR
possible. Chance SHRA, isolated TSRA.
Monday: Mainly VFR, with local MVFR possible. Chance SHRA,
isolated TSRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Thursday night...High Confidence.
Relatively light winds and seas through Thursday night.
Visibility should be quite good as well. Risk for a few showers
around Cape Ann this afternoon and evening, with a greater risk
for nearshores showers and thunderstorms Thursday afternoon.
Outlook /Friday through Monday/...
Friday: Winds less than 25 kt.
Friday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.
Saturday: Winds less than 25 kt. Seas up to 5 ft.
Saturday Night: Winds less than 25 kt. Local rough seas. Slight
chance of rain showers.
Sunday through Sunday Night: Winds less than 25 kt. Areas of
rough seas. Chance of rain showers, isolated thunderstorms.
Monday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers, isolated thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...BW/Hrencecin/KS
NEAR TERM...Belk/BW/Hrencecin
SHORT TERM...BW
LONG TERM...Hrencecin/KS
AVIATION...Belk/BW/Hrencecin/KS
MARINE...BW/Hrencecin/KS
Area Forecast Discussion
National Weather Service Cheyenne WY
553 PM MDT Wed Aug 14 2024
.KEY MESSAGES...
- Scattered afternoon and evening showers and thunderstorms are
expected today. Storms will have the potential to produce
brief, heavy rainfall and strong gusty winds.
- Seasonable temperatures will continue through the period. Showers
and thunderstorms will be most likely on Sunday, Monday and
Tuesday, with dry conditions for Saturday.
- Fire weather concerns begin to increase Friday as well as
Saturday with warmer temperatures and low afternoon humidity.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 200 PM MDT Wed Aug 14 2024
Isolated showers are beginning to pop up on radar early this
afternoon. A few isolated lightning strikes are accompanying the
weak thundershowers further west of our cwa. Wind gusts of
40-50mph have been observed with some of the weak rain showers
further west near the UT/WY/CO state borders. With the modeled
upper air soundings depicting an Inverted-V signature in the
lower boundary layer, and skinny CAPE further aloft, this
afternoon and evening is favored to see strong wind gusts with
the rain showers and thunderstorms. In fact, the HRRR is the
most aggressive with the deterministic output of wind gusts
between 45-75mph along the I-80 corridor of southeast WY between
21Z and 1Z this afternoon/eve. With the modeled soundings
depicting 30-40 knots from the surface to 500mb, the high-based
rain shower and thunderstorm activity may not have those highest
wind gusts realized in actuality. However, it is a possibility
as DCAPE readings over 1000 J/kg are also modeled, which is a
good rule of thumb for the higher potential of stronger wind
gusts. The rain showers and thunderstorm activity should wind
down by 6Z for most areas.
Thursday will be another mild to warm day. Scattered cloud cover
over the region will keeps temperatures slightly reduced near
seasonal averages. Model soundings show another afternoon and
early evening timeline of inverted-V signatures, so would expect
there to be elevated to potentially strong wind gusts when rain
showers and isolated thunderstorms occur. Similar timelines of
the mid-afternoon to early evening looks good for the slight
chance of showers and thunderstorms. PWATs will be slightly
lower, so the potential for brief downpours is limited. An upper
level ridge will amplify from the Four Corners region overnight
Thursday into Friday. This will bring the next round of warmer
temperatures to the area. A weak shortwave disturbance will be
embedded within the H5 upper level flow on Friday. A slight
chance of rain showers during the afternoon is progged, but the
concerns for fire weather will begin to creep upwards. Daytime
minimum humidity readings will range from 10-15% along and west
of the Laramie Range. Breezy winds will also be present during
the afternoon in this same area, so a possible fire headline may
be prudent in the coming forecast updates. Overall a warm
forecast remains on track, and the chances of rain showers
reduce slightly in the short term period.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 213 AM MDT Wed Aug 14 2024
Friday night/Saturday...West flow aloft will continue to dry out the
airmass and thus we will see correspondingly warmer temperatures
from the mid 80s to mid 90s. With precipitable water values lowering
to 0.4 to 1 inch and warm temperatures aloft increasing the
convective inhibition. it looks dry.
Sunday...Despite ridging aloft developing, we will see an increase
in atmospheric moisture content with precipitable water values
increasing to 0.6 to 1.4 inches. Thus, we expect an increase in
widely scattered to scattered late day showers and thunderstorms,
most numerous from the Snowy Range to far southeast Wyoming.
Monday/Tuesday...Atmospheric moisture content remains about the same
as on Sunday, and thus we expect another round of scattered late day
showers and thunderstorms each day, most numerous near the Colorado
state line from the Snowy Range to far southeast Wyoming. With
similar 700 mb temperatures, maximum temperatures should be about
the same as those from Sunday.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 553 PM MDT Wed Aug 14 2024
Scattered showers and thunderstorms possible across southeast
Wyoming and western Nebraska this evening. Wind gusts up to 50 kts
could be possible in these storms. Moderate to heavy rain could also
briefly reduce visibility down to 2SM at times. Storms will likely
clear out by 06Z, leading to a quieter overnight.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...BW
LONG TERM...RUBIN
AVIATION...SF
Area Forecast Discussion
National Weather Service Hastings NE
646 PM CDT Wed Aug 14 2024
.KEY MESSAGES...
- A few strong to severe thunderstorms will be possible for the
area this afternoon and evening. Hail and gusty winds will be
the main concerns with any storms that develop, although an
isolated tornado cannot be entirely ruled out.
- Warmer temperatures are expected Thursday, with widespread 80s
and 90s expected.
- A ridge sets up over the area late this week and through the
extended forecast period.
&&
.DISCUSSION...
Issued at 313 PM CDT Wed Aug 14 2024
After some morning fog and overcast conditions this morning, much of
central Nebraska remains under cloud cover this afternoon. As a
result, high temps were lowered slightly. Portions of north central
Kansas have experienced some clearing today and have been able to
warm into the 80s and 90s. A few isolated showers are moving across
areas north of Interstate 80 and also through north central Kansas.
Low pressure continues to slide across Kansas today, with a warm
front located over southeastern Nebraska and a cold front
located from around Kearney, Nebraska to Norton, Kansas. Areas
within the warm sector and to the north of the front will be the
main focus for any strong to severe thunderstorms this
afternoon and evening. Visible satellite imagery shows an area
of cu development in southeastern and south central Nebraska,
with some low-level clouds moving overhead in south central
Nebraska.
Thunderstorm chances increase (20-40%) later this afternoon into
this evening, particularly for areas along and east of Highway
281. The main concerns with any severe storms that develop will
be the potential for hail up to the size of quarters and winds
gusting to around 60 MPH. With the location of the front, decent
shear, and modest moisture in the region, can`t rule out the
chance for an isolated tornado, particularly for the easternmost
portions of the Hastings CWA, along the front, although the
current thinking is that better chances for this will be further
east, in Topeka and Omaha`s area. Thunderstorm activity is
expected to diminish after midnight.
Zonal flow sets up over the region Thursday, with much of the day
expected to be dry. Expected highs will be in the mid-80s for much
of south central Nebraska. Areas along and south of the Kansas-
Nebraska state line will be in the low 90s. Lows will range from the
upper 50s to mid-60s.
Friday, there will be a 20-30% chance for a few showers and
thunderstorms across portions of the CWA. This will be as a
shortwave advanced through the region. At this time, models are
favoring the western and southern portions of the area. Confidence
is fairly low in just how widespread thunderstorm coverage will
be.
An upper ridge will move over the center of the nation over the
weekend, remaining in place through the extended forecast. A few
models are trying to bring in some chances for precipitation and a
series of shortwaves. Not fully confident that this will transpire,
but did at least make mention of it with some low PoPs in the
extended part of the forecast.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 639 PM CDT Wed Aug 14 2024
For KGRI/KEAR Airports:
Thunderstorms are expected to remain well east of our TAF sites
tonight. We could see some shower and thunderstorm redevelopment
Thursday morning mainly north of the Tri-Cities. These would be
non-severe and have introduced just a slight (20%) chance for
thunderstorms based mainly on recent HRRR and 18Z NAM NEST
model runs just north of the Tri-Cities. The wind will remain
light and variable most of tonight, gradually becoming more
west northwesterly as we near dawn. Clear skies are expected
this evening with scattered lower level VFR clouds eventually
returning mainly after dawn on Thursday. Northwesterly winds
are expected throughout the day on Thursday, generally around 10
kts.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
DISCUSSION...Wekesser
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Gray ME
1059 PM EDT Wed Aug 14 2024
.SYNOPSIS...
Isolated showers and storms dissipate this evening. Another
round of showers and storms is expected Thursday before some
improvement Friday. By this weekend, periods of more unsettled
weather are possible through the weekend into early next week.
Hurricane Ernesto passes offshore late this weekend and Monday,
bringing an increasing swell and dangerous rip currents by
Saturday through midweek next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
1050 PM Update...A discontinuous N-S corridor of thunderstorms
continues from near Jackman ME southward all the way to the
coast east of Portland. This thanks to a weak convergence zone
and steep mid level lapse rates. This will continue for the next
1 to 2 hours before waning. In the meant time, small hail, gusty
winds, and very heavy downpours will be possible.
7 PM Update...One strong/severe storm in southwestern Somerset
County ME continues to move southward and is currently
weakening. The rest of the region is dry. However, we cannot
rule out a few more storms this evening with another short wave
trough moving southward in the cyclonic flow regime aloft.
Previously...
Isolated showers and storms have developed this afternoon. At
time of publishing, these are mostly over central and southern
Maine. The cu field has been slow to show much deeper growth
through the afternoon, perhaps stunted by earlier smokey cast
deterring some solar insolation through the first half of the
day. There should remain instability off the surface however as
upper low stalls over Nova Scotia/New Brunswick. Embedded
shortwave will be forcing that taps into this instability into
the evening and early overnight to keep showers and some thunder
possible.
With the low shear and dry low levels, will continue to have
some of these storms produce gusty winds through the early
evening. This shouldn`t be a widespread impact unless a cluster
of storms forms a uniform outflow, but the deeper/stronger
storms will be capable of these winds.
A few pockets of showers may continue up to midnight, but a
general clearing trend is forecast. This will again bring in fog
chances for the CT River Valley late. HREF vis and ceiling
guidance has also hinted at a low deck of clouds advancing along
the coast and interior from the east overnight. Probabilities
aren`t the highest, but patchy fog could form over damp areas as
the night cools.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
A similar setup possible for Thursday where a chance for
afternoon showers and thunderstorms exists. Shear parameters are
again marginal compared to available instability. Theoretically
gusty winds and small hail would again be possible in stronger
cells. Will continue to assess how this trends, and how this
afternoon plays out to increase confidence. HRRR Smoke/RAP
models do portray additional high level smoke passing through
the region, and this may further impede afternoon convection.
Surface temps may be a couple degrees cooler as more morning
cloud cover is possible and the upper low retrogrades west.
While highs topped out around 80 today, highs may only make it
into the mid to upper 70s for ME and the northern half of NH
Thursday.
A similar evening trend is anticipated as daytime heating wanes
and clearing begins. At this time, overnight showers look less
likely compared to Wed night.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Overview...
A series of troughs affect New England this weekend and into
early next week. Generally cool and showery conditions are
expected, with some brighter periods in between. Hurricane
Ernesto passes offshore late this weekend and early next week,
bringing building surf and increasing rip currents.
Details...
A weak shortwave ridge passes through New England, bringing a
relatively drier and brighter day on Friday. Scattered showers
are still likely during the afternoon hours across the higher
terrain, but don`t look to be as widespread as on Thursday.
By Saturday, the ridge passes and a trough begins to deepen
through the Great Lakes, with low pressure developing across the
Great Lakes as well. The low is very slow to make any eastward
progress over the following few days as the ridge stalls and
builds across Atlantic Canada through the weekend. With this
pattern, showers and scattered thunderstorms likely begin to
move into western areas late in the day Saturday, and make slow
progress eastward overnight Saturday. The progress mostly stalls
by Sunday, with western areas seeing a greater chance for
showers than eastern areas. There remains some question as to
just how far east it will progress, but at this point the coast
stands the best chance to see the driest conditions.
By Monday, a shortwave dives in and deepens the trough, while
also causing it to become more amplified and help the pattern
begin moving along again. With this, the greatest chance for
rain and showers in the forecast arrive late Monday as the low
progresses east. The trough continues to transit through on
Tuesday and possibly into Wednesday, keeping the chance for
scattered showers around.
While all this is going on, Hurricane Ernesto is expected to
pass near Bermuda on Saturday, and making it`s closest pass to
Nova Scotia on Monday. Ernesto helps to amplify the ridge
across Atlantic Canada, aiding in the slow down of the trough
progression, while also bringing it`s own effects. Building surf
and increasing rip currents remain the biggest concerns from
Ernesto, with a southeasterly swell building by Saturday. The
swell builds through Monday, and then will be slow to subside
through Wednesday. Rip currents become increasingly more
dangerous by Sunday, and continue through at least Tuesday. High
astronomical tides are also occuring early next week, so some
splashover is also possible. The track is favorable overall for
a long duration swell event, with the storm tracking mostly
northward for two days around Bermuda.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term...patchy fog to reduce vis tonight, especially in the
wake of thunderstorms. This lifts Thursday, with another round
of SHRA/TS in the afternoon.
Long Term...Mainly VFR conditions are expected on Friday, with
brief showers possible across interior terminals. VFR conditions
prevail more often than not Saturday through early next week,
but periods of MVFR ceilings and showers are likely at times
through early next week, especially across interior terminals
during the afternoon and evening. Nighttime valley fog is also
likely at LEB and HIE each night.
&&
.MARINE...
Short Term...Below SCA conditions expected. Stacked upper low
over New Brunswick and Nova Scotia will slowly retrograde west
over the next few days. This should give little wind at the
surface outside of daytime sea breeze that turn onshore in the
afternoon. Some marine fog is possible tonight.
Long Term...Weak pressure patterns prevail as broad high
pressure builds across Atlantic Canada into this weekend.
Hurricane Ernesto passes east of the Gulf of Maine late this
weekend and early next week, bringing an increasing
southeasterly swell starting on Saturday. The swell builds to
greater than 5ft by Sunday, and continues through midweek next
week.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
SYNOPSIS...
NEAR TERM...Ekster
SHORT TERM...Cornwell
LONG TERM...Clair
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Wilmington NC
1029 PM EDT Wed Aug 14 2024
.SYNOPSIS...
High pressure will build down from the north bringing drier
weather with relatively cooler nights through Friday. A rain-free
end of the work week will transition to warmer, more humid
weather over the weekend with increasing rain chances ahead of
an approaching cold front.
&&
.UPDATE...
Radar continues to show weak showers moving in from the
northwest and dissipating over the area. The 01 UTC run of the
HRRR indicates the showers activity will cease by 04 UTC.
Therefore will continue a 20% chance of showers for Southeast
North Carolina.
&&
.NEAR TERM /THROUGH THURSDAY/...
Surface high pressure will build in from the north/northeast
through tonight and early Thursday. The axis will become more
diffuse in time beginning Thursday afternoon. No pops through
the period and any shallow convective clouds that have developed
today will dissipate with the loss of daytime heating. Lows
tonight will generally be in the middle 60s perhaps cooler in a
few isolated spots with highs Thursday similar today`s values
perhaps a degree or two warmer.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
High pressure over the East Coast will shift off the coast
Friday, maintaining dry weather for the end of the work week.
Another unseasonably cool night Thursday night with lows in the
mid 60s (low 60s in traditional cool spots). Highs in the upper
80s Friday with sunny skies. Low temps in the upper 60s Friday
night.
Hurricane Ernesto will be passing over 700 miles east of the
Carolinas on Friday, near Bermuda. Swells from Ernesto will
create rough surf conditions beginning early Friday and
continuing into the weekend. See Tides/Coastal Flooding section
below for more details.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
With high pressure offshore, will see a rise in dewpoints and
PWATs heading into the weekend. Dewpoints in the 70s return
Saturday, increasing to mid 70s Sunday. With high temps
seasonable near 90F both days, it will be humid (but not enough
for any heat products). A longwave upper trough builds across
the Eastern US late Saturday, lingering through next Tuesday.
PVA associated with initial approach will lead to scattered
storms late Saturday into Saturday night. A cold front
approaches the area on Sunday, before stalling nearby into early
next week as the upper trough lingers. Have chance pops
forecasted each afternoon/evening Sunday through Tuesday.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR conditions with light winds inland and an afternoon
seabreeze at the coastal TAFS. The only fly in the ointment is
diminish showers near KILM which should dissipate by issuance
time.
Extended Outlook... Predominantly VFR is expected outside of
early morning fog/low clouds as dry high pressure builds in for
the remainder of the week. As the high moves offshore this
weekend, returning moisture will lead to isolated pop-up showers
and storms more typical of summer.
&&
.MARINE...
Through Thursday...NE winds will continue through Thursday as
high pressure builds in. Wind speeds will be 10-15 knots
overnight and weaken slightly Thursday to more like 10 knots.
Significant seas will be 2- 4 feet.
Thursday Night through Sunday...Long period swells from
Hurricane Ernesto will be arriving at local coastal waters
Thursday night, peaking Friday evening from the SE at 5-7 ft at
14 seconds. Ernesto swells linger through the upcoming weekend,
becoming easterly late Saturday, around 3-5 ft at 12 seconds.
High pressure over the East Coast will shift offshore on Friday
with light ENE winds late week shifting to southerly Saturday
afternoon. 10-15 kts SSW winds late Saturday through Sunday will
generate a 2-3 ft 5 second wind wave to mix with the long
period swell. A cold front approaches the waters late Sunday
before stalling nearby, with a chance for storms over the waters
Saturday night and late Sunday.
&&
.TIDES/COASTAL FLOODING...
Other - Rip Currents: Swells from Ernesto will arrive Thursday
night into Friday and continue into this weekend. Dangerous surf
and strong rip currents will develop Friday and persist through
the weekend, especially for east and southeast facing beaches.
A High Surf Advisory may be needed for the beaches of New
Hanover and Pender counties Friday afternoon and night for
breaking waves of 6+ feet.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
NC...None.
SC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
UPDATE...RH
NEAR TERM...SHK
SHORT TERM...VAO
LONG TERM...VAO
AVIATION...RH
MARINE...SHK/VAO
TIDES/COASTAL FLOODING...
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
843 PM CDT Wed Aug 14 2024
.KEY MESSAGES...
- Two periods of thunderstorms are expected Thursday, one early in
the morning and the other in the mid to late evening. Of these,
the latter storms have the highest chances for severe weather,
with damaging winds the greatest concern.
- Locally heavy rain will accompany the showers and storms, though
probabilities of a widespread 1+" of rain are fairly low.
- After Friday, an extended period of quiet weather is expected
through the first half of next week.
&&
.UPDATE...
Issued at 841 PM CDT Wed Aug 14 2024
This evening, low pressure is located over SD/NE with a broad
corridor of warm air advection inching east across portions of the
mid Mississippi Valley. A few showers and storms are noted near
the Mississippi River, but 00Z KILX sounding showed dry
conditions up to around 600mb with very weak and capped
instability. As such, this convection forming in the WAA to our
west should struggle as it moves into central Illinois late this
evening. Meanwhile, a more organized line of storms currently over
KS/NE will spread east overnight on a veering LLJ. This will
advect weak instability into portions of the lower Illinois River
Valley late tonight into Thursday morning supporting a decaying
line of showers and storms into the local area.
Deubelbeiss
&&
.SHORT TERM... (Through Late Thursday Night)
Issued at 302 PM CDT Wed Aug 14 2024
Latest radar mosaics show scattered thunderstorms across central
Missouri into southeast Iowa, in the wake of the earlier MCS which
continues to sink southeast and weaken. Latest HRRR has latched
onto this activity and sneaks it into west central Illinois by 5-6
pm, before weakening. However, orientation of the instability
axis would suggest a southeast motion as well. Will keep some 20%
PoP`s going through late afternoon from about Peoria-Springfield
westward.
Main focus remains with a couple periods of thunderstorm activity
late tonight into Thursday night. Morning high-res models continue
to suggest linear convective initiation across Nebraska and
Kansas very late in the afternoon, with upscale growth into an MCS
during the evening. While the main line still looks to arrive in
our forecast area after 3 am, a few showers may develop ahead of
it on the fringe of the upper jet spreading toward the Mississippi
River. By midday, what`s left of the line should be close to the
I-70 corridor. Severe potential during this period appears low.
Main period of concern for severe weather still appears to be in
the evening. A low level jet will help with renewed storm
development to our west early in the evening. Some variety noted
on the CAM`s with the extent of this development, though most are
pointing toward a period from about 9 pm Thursday to around 2 am
Friday with the highest potential. Damaging winds appear to be the
main focus, though some hail can`t be ruled out if the storms
remain more discrete as they enter the area. In terms of the heavy
rain potential, there remains some fluctuation with the heavier
QPF axis, though precipitable water values peak toward sunrise
Thursday. HREF probabilities of 6-hour rainfall amounts over 1
inch of rain peak around 30% west of Springfield with the early
morning activity, and near Peoria (40-50% chance) with the evening
storms.
Temperature-wise, assuming clouds break up enough by afternoon,
highs should be a few degrees warmer than today, mainly in the mid
80s. However, with a substantial increase in dew points (mid 70s),
heat index values in the low-mid 90s are expected west of Peoria
and Springfield.
Geelhart
.LONG TERM... (Friday through Next Wednesday)
Issued at 302 PM CDT Wed Aug 14 2024
The longer range pattern will be dominated by an amplifying upper
ridge along the east slopes of the Rockies, which will persist
into the middle of next week. An upper low will slide across the
Great Lakes through the weekend, as a longer wave upper trough
develops. These two features will keep a northwest flow across
Illinois, with temperatures running a few degrees below normal and
no significant surges of low level moisture to add to the
humidity. Some wraparound showers can`t be ruled out on Friday and
Saturday in the cyclonic flow around the low, though better
chances appear closer to the Great Lakes and thus our forecast
will be kept dry for now. After that, surface high pressure will
dominate the Midwest with continued dry conditions.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 623 PM CDT Wed Aug 14 2024
Thunderstorms are expected to develop and expand in coverage over
MO/IA late this evening and eventually move across central
Illinois late tonight into Thursday morning, likely in a weakening
phase. MVFR or IFR ceilings may accompany the precip and linger
for a few hours Thursday morning. SE winds tonight into Thursday
morning will turn southerly Thursday afternoon and will gust to
around 20kt as conditions return to VFR.
Deubelbeiss
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Medford OR
645 PM PDT Wed Aug 14 2024
.Updated Aviation Discussion.
.AVIATION...15/00Z TAFS...Along the coast and just offshore. VFR
conditions will continue into this evening, then ceilings will lower
tonight, bordering on IFR late tonight. However, odds are they will
remain MVFR due to increasing instability.
Inland, VFR conditions will continue through the TAF period. The
exception will be in the vicinity of the complex of fires in central
and eastern Douglas County and western Siskiyou County as smoke from
the Boise Fire gets transported there.
An approaching upper trough will result in increasing instability.
Satellite image is already showing signs of convective clouds and
possible storm development over the waters off the California coast,
which could be a precursor of things to come later this evening and
tonight.
Several high res models show the best chance for thunderstorms will
be east of the Cascades with thunderstorms could pop up between 2-4z
and lasting into the overnight hours. Thunderstorms have since
developed south of Klamath Falls and have moved over the airfield.
Storms are expected to last for another 2-3 hours bringing gusty and
erratic winds.
The main hazard with thunderstorms will be gusty outflow erratic
winds near storms, but they can also occur well outside of the core
of the storms.
&&
.DISCUSSION...Cumulus clouds are starting to build generally in
southern Jackson county...south central Siskiyou county...and much
of Klamath and Lake counties...where thunderstorms are forecast.
There is quite a bit of uncertainty with the westward extension of
thunderstorms...especially for the rogue valley...where smoke may
keep us from getting to the convective temperature. Either
way...the short term models have been very consistent in
thunderstorms initiating generally along a line from Yreka into
Klamath Falls between 3 and 5 pm. Showers and thunderstorms will
move northeast...impacting the northern half of Klamath and Lake
counties around 10 pm. The activity will move out of the area
around 5 am Thursday before a very short break in the action.
The second round of thunderstorms is expected develop in Klamath
and Lake counties early Thursday afternoon. The best chance for
thunderstorms (25% to 35% chance) will be mid Thursday afternoon
into the early evening hours over northern Lake county. Please see
below for more information regarding fire weather concerns.
Otherwise...our focus shifts to this weekend as an upper low drops
south along the PacNW coast Friday into Saturday. There is a lot
of uncertainty with the position of the low and how it impacts the
precipitation forecast over the weekend. For instance, about a
third of the clusters indicate precipitation across much of the
area Saturday with the upper low a bit more to the east...compared
to two thirds to the clusters indicating the low position more to
the west...leading to a lesser chance of precipitation. About a
third of ensemble members show absolutely no precipitation for
Medford...where some show upwards of a half inch of rain.
Additionally...depending on the position of the low...there will
be the possibility of thunderstorms. Again...still a lot of
uncertainty with the weekend storm...but we will continue to
monitor closely and hone in on details over the next few days.
-Riley
&&
.FIRE WEATHER...Issued 245 PM Wednesday August 14, 2024...Upper
level troughing will remain the dominant weather pattern through the
forecast period. This will continue the trend of cooler than normal
temperatures, moderated humidities and breezy afternoon winds. The
two main fire weather concerns on the horizon are thunderstorm
potential today through Thursday and the development of a deep upper
low offshore over the weekend which could bring some strong winds to
the area.
First the thunderstorm potential...a shortwave trough will be moving
into the region today and linger over the area through Thursday.
With ample moisture and modest instability, isolated to scattered
thunderstorms are expected. Initially, isolated thunderstorms are
expected over portions of northern California, then spreading north-
northeastward into Oregon after sunset and into the overnight hours.
Isolated thunderstorm coverage is the most likely scenario today
mainly along and east of the Cascades (possibly as far west as the
Rogue Valley/Medford), but scattered coverage is possible as storms
move into Oregon across Fire Weather Zones (FWZ) 624/625. There will
be a break in thunderstorm activity early Thursday morning. The
trough will linger over the region Thursday afternoon, however, and
this will provide a better opportunity for scattered thunderstorms
over FWZ 624/625 due to daytime heating effects. Due to these
factors, a Red Flag Warning for abundant lightning on dry fuels will
be in effect starting this evening, and details can be found at
RFWMFR. Storms are expected to have some precipitation with them,
but lightning strikes outside of precipitation cores are possible
and cause for concern. Additionally, expect gusty and erratic winds
near thunderstorms with strong outflows that can travel a good
distance from the originating storm.
There has been a concern for the smoke moving to areas east of the
Cascades in the coming days with westerly flow. The HRRR smoke model
is matching well with the current satellite picture. With this in
mind, the westerly winds are on track to move the smoke to areas
east of the Cascades with the highest concentrations in Klamath
County. The smoke may be heavy enough to hinder thunderstorm
development, but convective temperatures are in a reasonable range
to reach, even if smoke does stay in the area of the Red Flag
Warning. The atmosphere will stabilize some on Friday. There will be
lingering moisture and instability, but without a sufficient
trigger/forcing mechanism, it`s likely there will be some cumulus
buildups east of the Cascades and over the higher terrain.
The next concern turns to a deep, large scale trough that develops
off the PacNW Coast late Friday into Saturday and lingers there well
into next week. This will bring some precipitation chances to the
region, though confidence is low on the details regarding where and
amounts. Ensembles suggest the best chances are along and west of
the Cascades, but there could be thunderstorms to accompany these
precipitation chances. The other element of concern with this low
pressure (and where the higher confidence lies) is the potential for
strong south to southwest winds. Guidance suggests gusts of 30-40
mph for areas east of the Cascades and in the Shasta Valley on
Saturday and Sunday afternoons. These strong winds could combine
with low humidities (which ultimately depends on where precipitation
chances occur) and result in critical fire weather conditions. Stay
tuned for updates as subtle shifts in the position of this low could
have big changes on the forecast. /BR-y/Hermansen
&&
.MARINE...Updated 230 PM Wednesday, August 14, 2024...Relatively
calm conditions are expected for the next several days with light to
moderate winds and seas remaining 6 foot or less. There will be a
slight uptick in winds Thursday into Friday south west of Gold
Beach, but they will remain below advisory levels. A rather strong
upper low for this time of the year will move into the waters
Saturday and will likely bring showers over the waters.
-Petrucelli
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 8 PM this evening to 11 PM PDT Thursday
for ORZ624-625.
CA...None.
PACIFIC COASTAL WATERS...None.
&&
$$
Area Forecast Discussion
National Weather Service Omaha/Valley NE
603 PM CDT Wed Aug 14 2024
.KEY MESSAGES...
- Severe storms are possible this evening (10-20% chance). Large
hail, damaging winds, tornadoes, and localized heavy rain
leading to flooding will be possible.
- There will be another chance for severe storms Thursday
afternoon and evening (5-15%) with primary hazards being
damaging winds and large hail.
- Temperatures stay seasonably warm through early next week with
additional chances for nighttime storms.
&&
.DISCUSSION...
Issued at 153 PM CDT Wed Aug 14 2024
This afternoon - tonight:
Skies are clearing across eastern Nebraska and southwest Iowa
this afternoon, preparing our area for the potential for severe
storms this evening. A shortwave trough will bring a dry line
boundary through triggering storms sometime between 5 and 8 PM,
with some CAMs showing earlier convection in Kansas expanding
north and developing storms near Gage County around 5 to 6 PM,
and the HRRR holding off on convection until closer to 8 PM. In
either case, the environment is looking very unstable this
afternoon with 3000-4000 J/kg of SB CAPE and strong low-level
shear. Some models have as much as 400+ m2/s2 of 0-3km shear.
Looking closer to the ground, 0-1km shear will be 200+ m2/s2.
This is looking like a much better set-up for severe weather
than 24 hours ago, with potential for 2+ inch hail and damaging
winds of 75 mph. Tornadoes will also be possible due to the high
amount of low-level shear, and LCLs below 1000 m. The area of
greatest potential for severe weather is generally east of
Highway 77 in Nebraska through southwest Iowa. We`re expecting
storms to develop initially into supercells, merging into a line
around or just west of the Missouri River. Once the line
develops, the tornado threat will lessen, but not completely go
away, and transition into more of a damaging wind and heavy rain
threat. The severe weather threat should be out of our area by
midnight at the latest.
Thursday:
We have another severe weather threat on Thursday as another
shortwave moves through during the afternoon/evening. This looks
less menacing as we won`t be quite as unstable, with SB CAPE
only around 1800-2500 J/kg, and significantly less low-level
shear. There will still be sufficient shear and instability for
a severe potential, however, with the greatest threats being
large hail up to half-dollar-size and damaging winds of 60 mph.
These storms appear to initiate north of I-80 and track into
southeast Nebraska and southwest Iowa during the evening. They
will likely be out of our area by 10 PM.
Friday-Tuesday:
Over the weekend we see the summertime ridge build back up over
the Rocky Mountain region, with temperatures trending upward
across our area. Dry weather is expected on Friday through the
day on Saturday, but we`ll have to watch Saturday night into
Sunday as the UL-Jet moves across our area for the potential for
the development of an overnight MCS. Several models develop one,
but vary in location of the system from as far north as the
Dakotas to right over our area. With more of the models staying
dry over our area, right now precipitation potential is low
around 15-20%.
Early next week we see the ridge expand eastward leading to
seasonably warm daytime temperatures and additional chances for
nighttime storm potential.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 603 PM CDT Wed Aug 14 2024
Showers and thunderstorms are developing across portions of
eastern NE as of 6 PM (23z) and that activity will become
increasingly widespread over the next 2-4 hours with KLNK and
KOMA the most likely locations to be impacted. MVFR to
potentially IFR conditions are possible in the heaviest
downpours with locally strong wind gusts as well. The storms are
expected to shift east of the area by 05-06z with winds
switching to west and then northwest.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch until 4 AM CDT Thursday for NEZ052-053-067.
IA...Flood Watch until 4 AM CDT Thursday for IAZ079-080-090-091.
&&
$$
DISCUSSION...McCoy
AVIATION...Mead
Area Forecast Discussion
National Weather Service Pocatello ID
210 PM MDT Wed Aug 14 2024
.SHORT TERM...Tonight through Thursday Night.
Early afternoon satellite imagery shows a departing H5 trough
situated along the Continental Divide which will continue to lead
to scattered shower and thunderstorm development through this
evening ahead of dry conditions returning back overnight tonight.
With a similar convective environment to yesterday with 600-1200
J/kg of SBCAPE and 25-35 kts of 0-6 km shear, the bigger
difference will be the drier PWATs in place behind yesterdays cold
front. PWATs will generally be about 50-70% of what they were
yesterday in that 0.50-0.80" range but conditions will still
remain favorable for isolated strong to severe thunderstorm
development, just not to the degree we saw yesterday. Stronger
storms today will be capable of producing wind gusts to 40-50 mph,
small hail, and heavy rain. Highs today will be in the low 70s to
low 80s with overnight lows tonight in the 30s/40s/50s. Outside
of convection, wind gusts will remain less than 30 mph regionwide.
Starting tonight, our next H5 low will move inland from the
Pacific over Oregon before turning NE into NRN Idaho throughout
the day into Thursday night. This will support our next round of
scattered showers and thunderstorms which will build in west to
east throughout the daytime hours. Even with more marginal
instability of only around 300-600 J/kg of SBCAPE and 0-6 km of
25-35 kts, the strong to severe threat will continue to exist with
stronger storms again being capable of producing wind gusts to
40-50 mph, small hail, and heavy rain. As this H5 low shifts NE
into Canada Thursday night into Friday, isolated showers and
thunderstorms will continue to be possible overnight before
departing north, leading dry conditions to start the day on
Friday. Highs on Thursday will be slightly warmer than today
courtesy of SW flow tomorrow with highs reaching the mid 70s to
mid 80s. MacKay
.LONG TERM...Friday through next Wednesday.
Friday looks to be a dry day across the region as we begin to
feel the influence of weak high pressure building over the area.
Eastern Idaho will stuck between a persistent ridge across the
east of the Four Corners and a slow moving upper level trough over
the Pacific NW. Not expecting any significant systems to move
through the region during the extended portion of the forecast but
it does appear that we`ll slowly be able to sneak in some monsoon
moisture by Saturday afternoon as our southwesterly flow becomes
enhanced. Most locations will likely remain dry but by Sunday, and
into early next week, we`ll probably see 20-40 PoPs across the
eastern half of the forecast every just about every day.
Temperatures will remain generally stagnant with the lack of any
real pattern change so expect daytime highs to run near average
which is mid to upper 80s in the lower valleys. McKaughan
&&
.AVIATION...For the 18Z TAFS through 18Z Thursday.
VFR conditions expected to prevail outside of any showers and
thunderstorms although we will have a period of mid/high clouds
over the region for the next few hours. An upper trough moving
north of the area is to blame and this feature is helping to
produce some scattered showers and storms across the northern half
of the forecast area. Gusty winds and small hail will be possible
in the strongest of storms. Continue to maintain VCTS for now at
KIDA, KSUN, KDIJ and KPIH but thus far, the thunderstorms that
have developed are generally unimpressive. Expecting quick
clearing later this evening as the trough departs to our east with
mostly clear skies taking over for the first half of the day
Thursday. Just beyond the 18Z forecast period, cloud cover and
rain chances begin to increase ahead of the next trough. Winds
will be light through the period aside from any potential
thunderstorm outflows. McKaughan
&&
.FIRE WEATHER...
A H5 trough situated on the Montana border this afternoon will
continue to lead to isolated to scattered showers and
thunderstorms ahead of dry conditions returning for overnight
tonight. Our next Pacific system will move onshore tonight and
pass overhead on Thursday, supporting another round of scattered
thunderstorms. As a result, a RED FLAG WARNING has been issued for
FWZ 422, 475, and 476 to capture the highest coverage of
thunderstorms but this may ultimately need to be expanded further
dependent on coverage in further forecasts. Predominantly dry
conditions will return for Friday outside of isolated showers and
thunderstorms along the Montana border region as Thursday`s system
departs NE into Canada. As a secondary low begins to work south
in the NE Pacific to being off the PacNW coast by this weekend, a
favorable monsoon moisture axis will begin to push north leading
to a return of isolated shower and thunderstorm chances
primarily across ERN Idaho. Competing, dry SW flow from the
Pacific will work against this trend so will have to see how much
of this moisture is able to build in or is that SW jet keeps
conditions drier. The overall trend outside of thunderstorms will
be warming temperatures through the weekend as predominant SW flow
returns aloft. MacKay
&&
.AIR QUALITY...
An Air Quality Advisory from Idaho DEQ remains in effect for
Custer County until 1 PM MDT Thursday August 15th due to increased
wildfire smoke concentrations leading to degraded air quality.
The latest HRRR smoke model shows the bulk of wildfire smoke in
the CNTRL Mountains originating from wildfires immediately to the
west with much better air quality elsewhere. Following increased
wildfire smoke in place through this evening in Custer County, a
return to SW flow tonight into Thursday as our next system builds
in will aid in pushing the smoke NE and out of Custer County with
only light concentrations in place expected for Thursday. MacKay
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 9 PM MDT Thursday for IDZ422-475-
476.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
405 PM MST Wed Aug 14 2024
.Update...00Z Aviation Discussion
&&
.SYNOPSIS...
Quieter weather conditions will prevail during the latter half of
the work week, with relatively stable daily high temperatures
reaching up to around 110 degrees for the typically warmer lower
desert communities through this weekend. High pressure will begin to
shift back over the southern plains this weekend resulting in a
slight increase in moisture and increased thunderstorm initiation
chances mainly over Arizona high terrain into early next week.
&&
.DISCUSSION...
Current WV imagery and 500 mb RAP analysis depicts a trough moving
eastward over the Intermountain West, with another upstream
approaching the Pacific Northwest coast. The persistent Pacific
Northwest negative height anomalies coupled with a strong westerly
jet streak over the Great Basin region has acted to displace/dampen
the subtropical high pressure over the region. An anticylonic
circulation is in place overhead, with very dry air and subsidence
aloft. The 12Z KPSR sounding this morning depicted a strong
inversion between ~600-500 mb associated with the subsidence aloft,
and model soundings show this feature persisting to some extent
through the next several days, becoming less prominent later in the
day on Friday. Considering the strong cap and drier air in place,
shower/thunderstorm chances through the end of the work week will be
near zero, but Friday may bring some very isolated development over
the typical prominent terrain features of Southwestern Maricopa
County, Northeastern La Paz County, and Gila County.
Late Friday, the upper level pattern shifts such that upstream
troughing amplifies just off the West Coast and the subtropical high
builds as it centers itself over the southern plains/eastern New
Mexico. This shift in the pattern will allow south/southeast flow to
reestablish over Southern AZ, drawing moisture back into the region
for this weekend. Global ensembles are in excellent agreement with
respect to the trends in moisture through this weekend, suggesting
PWATs (and lower desert storm chances) will peak late Saturday,
though the GEFS shows the driest ensemble mean compared to the ECMWF
and CMC ensembles. Despite the increase in moisture this weekend,
forecast near-surface mixing ratios (peaking around 10-11 g/kg)
will only be marginally supportive of lower desert storms, and
much of the daily thunderstorm activity will be confined to the
Arizona high terrain and some of the typical mountains/terrain
features of South-Central and Southwestern AZ. NBM PoPs peak
around 10-20% for the AZ lower deserts on Saturday and Sunday and
around 20-40% for the high terrain east/north of Phoenix and for
Southeast AZ. Early next week, the upper level flow pattern does
not seem to change significantly, though the trough off the west
coast and subtropical high both seem to shift slightly westward,
and ensemble mean H5 heights modestly increase over the eastern
CWA to around 595-597 dam. With increased subsidence aloft,
convection would be even more confined to the AZ high terrain
early next week, and lower desert PoPs decrease to 10% or less
starting Monday.
Temperatures will be quite stable through the next 7 days, with
daily highs reaching around 108-112 deg F each afternoon across the
typically hotter lower desert locales. These temperatures will lead
to widespread Moderate HeatRisk through at least the middle of next
week, so sensitive groups will be at risk of heat-related illness
during the heat of the day, and all should continue to practice
proper heat safety measures. As current global guidance indicates
heights aloft increasing over the eastern CWA next week, areas of
Major HeatRisk develop over the San Carlos area as early as
Monday, however, subtle differences in the locations and
orientations of the previously discussed synoptic features could
lead to considerable changes in moisture, magnitude of heights
aloft, and the subsequent temperature forecast, so excessive heat
products are not necessary at this time.
&&
.AVIATION...Updated at 2305Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are expected during the TAF period. Winds
will follow typical diurnal trends, with occasional gusts 15-20
kts during the afternoon and early evening hours. Other than a FEW
clouds around 10k ft, skies will be mostly clear through tomorrow
afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are anticipated through the next 24
hours. Winds will follow familiar diurnal trends, with some
periods of variability during directional shifts, especially at
BLH. Mostly clear skies will prevail during the next 24 hours.
&&
.FIRE WEATHER...
Drier conditions and slightly above normal temperatures will
prevail through the end of the work week, with only isolated (10%
or less) chances for showers and thunderstorms returning late
Friday. Over the weekend, a modest increase in moisture will lead
to better storm chances and coverage. Today and Thursday, with
drier air in place, afternoon MinRHs will bottom out around 10%
for the western districts and between 15-20% for the Arizona
districts. By Friday, these values will increase across the
region to between 15-25%. Overnight recoveries will be fair at
between 25-50% and increase up to 60% for portions of southern
Arizona over the weekend. Wind patterns should follow a more typical
upslope/drainage pattern through the next several days without
much chance of gusty outflows. However, local afternoon upslope
gusts of 20-25 mph will be common.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Whittock
AVIATION...RW
FIRE WEATHER...Whittock