Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/30/24
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
557 PM MDT Thu Aug 29 2024
...New AVIATION...
.SYNOPSIS...
Issued at 347 PM MDT Thu Aug 29 2024
Scattered storms will cover much of eastern and central NM through
the evening. A backdoor cold front will move into eastern NM through
the night and may develop some east winds in the ABQ metro. Friday
will see additional storm coverage across the northern and western
parts of the state with burn scar flash flooding possible in the
Sangre de Cristo Mountains. Storms will focus on the southern parts
of the state through the weekend, and chances overall decrease into
next week. Temperatures may begin to increase into the latter half
of next week.
&&
.SHORT TERM...
(This evening through Friday night)
Issued at 347 PM MDT Thu Aug 29 2024
The latest water vapor imagery shows an upper level trough passing
north of NM with much drier air advecting into western NM. A remnant
convective vortex from last night across Sandoval County is drifting
southeast toward ABQ within a broad trough axis draped from SW to NE
across NM. Storms have already fired up over the Sangre de Cristo
Mts and parts of eastern NM with better sunshine and destabilization
early this afternoon. The latest suite of short-term models and hi-
res ensembles are in very good agreement with increasing coverage of
storms along and ahead of the broad trough axis as it shifts across
eastern NM this evening. The area beneath the remnant vortex may be
a favored location for a few stronger cells later today between the
Sandia Mts, Las Vegas, and Vaughn. Given the gradient of drier air
approaching from the west a few of these cells may contain hail with
gusty outflow winds and frequent lightning strikes along with heavy
rainfall. Meanwhile, a backdoor cold front along the Front Range
today will move southwest into eastern NM in the wake of convection
over eastern NM tonight. This may generate a period of moderate
canyon winds in ABQ overnight, especially if aided by storms to the
east. Some low stratus is also possible along the central mt chain
with increasing easterly upslope flow around sunrise Friday.
Another active day is expected Friday but with a delayed onset to
storm initiation. There may actually be areas of rain and embedded
thunder still lingering over southeast NM and the Ruidoso area thru
late morning. Guidance is in decent agreement with storms firing up
over the northern and western high terrain near the remnant backdoor
frontal boundary. This will also be an area with greater sunshine
and heating Friday morning compared to eastern NM. Storms will then
move southward toward the I-40 corridor and ABQ metro area Friday
afternoon. The Ruidoso area may catch a break with a potentially
more stable airmass still in place thru the afternoon. Flash Flood
Watches may be needed for the HPCC and perhaps Cerro Pelado burn
scar areas. Confidence is too low for the Sacramento Complex at this
time. Forecast models show storms tapering off more quickly Friday
evening than recent days.
&&
.LONG TERM...
(Saturday through Wednesday)
Issued at 347 PM MDT Thu Aug 29 2024
A broad upper level high pressure system will set itself over
CO/UT/WY for much of Saturday into Sunday. East surface winds will
encompass the majority of NM, save for northwest NM on Saturday
where northwest winds will be in place. Easterly upslope flow will
aid in development of storms along the central mountain chain.
However, an area of mid to upper level dry air will be advected into
the region via the high pressure which may cap storm development,
mainly in the northern half of the CWA. The forecast further
complicates as a shortwave trough deepens over AZ Saturday
afternoon. Ascent will increase over NM downstream of the 50-60kt
jet streak associated with the AZ shortwave. Storm development will
depend on the amount of lift and strength of surface upslope flow
overcoming the drier mid-level air. Models disagree on location and
coverage of storms on Saturday, due to difference in placement of
the mid-level dry air. The GFS has storms firing over the central
mountain chain and western high terrain, while the ECMWF has storms
along the south central and southwest mountains. Any storms that do
develop in this setup will flare up with slow west-southwest storm
motions. Sunday will see a decrease in storm coverage for the
central mountains as the high moves almost directly over CO, pushing
drier air further south and west. The AZ shortwave trough will
continue to push south and east which takes the large scale ascent
and focuses it to the south of our CWA. Any storms that do form
would favor the southern high terrain.
Into next week, precipitation chances look to decrease across the
forecast area as the CO high begins to stretch itself southwest into
AZ and CA. The shortwave trough near southern NM will also flatten
out, creating near zonal 250mb flow. Models begin to disagree on the
strength and true location of the high moving into Tuesday and
Wednesday. The GFS develops a minor secondary shortwave that pushes
Gulf moisture northwards, where the ECMWF has substantial zonal flow
resulting in an east-west low-level moisture gradient across the
southern border of the CWA. Regardless of positioning and moisture,
temperatures will likely begin to climb to near early-September
average as dry air from the high continue to seeps into the region.
&&
.AVIATION...
(00Z TAFS)
Issued at 545 PM MDT Thu Aug 29 2024
Complex forecast with main challenges of convective timing and
progression of outflow boundaries, along with effects of a
cold front currently moving into far northeastern NM, per WPC
analysis. Thunderstorms ongoing in the vicinity of KTCC should
move away from the terminal by around 02Z, per radar trends and
latest HRRR model run. Moderate confidence that gusty easterly
winds will materialize at KABQ early this evening as showers
collapse over the Sandia Mountains and/or outflow from storms to
the north pushes through Tijeras Canyon.
As upslope flow develops behind the frontal boundary later
tonight and into tomorrow, MVFR cloud decks are likely to form at
KLVS, KTCC, and KROW, but confidence in MVFR ceilings is
relatively low (30%). Light rain/showers may also persist through
much of the night over the eastern plains of NM.
&&
.FIRE WEATHER...
Issued at 347 PM MDT Thu Aug 29 2024
There are no critical fire weather conditions forecast for at least
the next 7 days. Storms with locally heavy rainfall will focus over
eastern NM today then across more of northern, central and western
NM Friday. A ridge of high pressure developing to the north of NM
over the weekend will spread drier air into northern and eastern NM
thru early next week. The main focus for storms with heavy rainfall
is likely to shift into southern NM during this time. High temps
will gradually warm closer to normal as well.
&&
.PRELIMINARY POINT TEMPS/POPS...
Farmington...................... 57 87 58 87 / 0 20 5 0
Dulce........................... 44 82 44 81 / 20 40 30 20
Cuba............................ 51 80 50 81 / 20 40 40 20
Gallup.......................... 48 83 49 84 / 5 30 10 30
El Morro........................ 51 78 50 77 / 5 40 30 50
Grants.......................... 51 81 51 82 / 5 40 30 30
Quemado......................... 52 79 51 79 / 10 50 30 60
Magdalena....................... 57 77 55 78 / 10 50 30 40
Datil........................... 51 77 50 77 / 10 40 30 50
Reserve......................... 50 86 49 84 / 10 50 30 70
Glenwood........................ 61 89 60 88 / 10 50 30 60
Chama........................... 45 74 43 74 / 20 60 50 20
Los Alamos...................... 56 78 53 78 / 20 60 40 30
Pecos........................... 53 74 50 76 / 30 60 40 30
Cerro/Questa.................... 44 73 41 75 / 20 60 40 20
Red River....................... 44 64 41 65 / 20 60 50 20
Angel Fire...................... 37 67 38 70 / 20 60 40 20
Taos............................ 46 79 47 79 / 20 60 40 10
Mora............................ 49 71 46 73 / 20 70 40 30
Espanola........................ 55 86 53 85 / 20 50 40 20
Santa Fe........................ 55 78 53 76 / 30 60 40 20
Santa Fe Airport................ 54 82 52 82 / 30 50 40 20
Albuquerque Foothills........... 61 83 59 84 / 30 40 40 20
Albuquerque Heights............. 61 85 60 84 / 30 40 40 20
Albuquerque Valley.............. 60 87 58 86 / 30 40 30 10
Albuquerque West Mesa........... 62 87 60 86 / 30 40 40 10
Belen........................... 59 86 57 86 / 20 30 30 10
Bernalillo...................... 60 88 58 87 / 30 40 40 10
Bosque Farms.................... 58 86 56 85 / 30 40 30 10
Corrales........................ 60 87 59 87 / 30 40 40 10
Los Lunas....................... 59 86 57 85 / 30 30 30 10
Placitas........................ 59 83 56 83 / 30 40 40 20
Rio Rancho...................... 61 86 59 86 / 30 40 40 10
Socorro......................... 62 87 60 88 / 20 40 30 30
Sandia Park/Cedar Crest......... 54 76 50 77 / 30 50 40 20
Tijeras......................... 57 79 54 79 / 30 50 40 20
Edgewood........................ 53 77 49 78 / 30 50 30 20
Moriarty/Estancia............... 51 78 47 80 / 30 50 30 20
Clines Corners.................. 52 72 49 75 / 40 40 30 30
Mountainair..................... 53 76 49 78 / 30 50 30 30
Gran Quivira.................... 54 76 51 79 / 30 50 40 30
Carrizozo....................... 59 79 56 80 / 30 40 50 50
Ruidoso......................... 54 69 51 72 / 40 50 60 60
Capulin......................... 52 72 49 77 / 30 50 20 5
Raton........................... 53 77 49 83 / 20 50 20 5
Springer........................ 53 79 50 82 / 20 50 20 5
Las Vegas....................... 51 74 48 78 / 30 60 30 20
Clayton......................... 59 77 55 80 / 60 30 10 0
Roy............................. 56 75 53 78 / 60 40 30 10
Conchas......................... 61 81 59 83 / 70 50 30 10
Santa Rosa...................... 59 78 57 79 / 70 50 40 20
Tucumcari....................... 59 78 56 82 / 80 50 40 10
Clovis.......................... 63 78 60 84 / 80 70 50 40
Portales........................ 63 78 60 84 / 80 70 60 40
Fort Sumner..................... 63 81 59 84 / 80 50 50 30
Roswell......................... 68 83 65 86 / 60 70 70 50
Picacho......................... 60 77 58 78 / 40 70 60 50
Elk............................. 56 75 55 74 / 30 70 60 60
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 8 PM MDT this evening for NMZ214-215-229.
&&
$$
SHORT TERM...42
LONG TERM....77
AVIATION...53
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
850 PM EDT Thu Aug 29 2024
.SYNOPSIS...
A backdoor cold front crosses the area this afternoon into tonight
before stalling across southern portions of the area Friday. This
will allow for scattered showers and storms from this afternoon
through Friday. Another cold front brings unsettled conditions this
weekend. Cooler and drier conditions eventually return early next
week behind the second cold front.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 845 PM EDT Thursday...
Key Messages:
- A Flood Watch remains in effect from this afternoon through
part of tonight for portions of the area from the Piedmont to
Richmond and the Tri-Cities.
Latest analysis reveals backdoor cold front bisecting the area
from NW to SE at 00z. The front has cleared the eastern shore,
RIC metro and tidewater areas, and will slowly drop SSW through
the evening.
While isolated convection has developed across the northern half
of the area this evening, mainly on convective outflows and the
front itself, the majority of convection has remained just north
of the area in S MD and NoVA to DC Metro area.
Past few runs of the HRRR have finally seemed to catch on to
this trend, keeping a fairly strong signal for heavy rain across
northern VA over to the eastern shore. Will keep the Flood Watch
in place north of Richmond Metro (Louisa/Goochland/Caroline),
where outflow from convective activity to the north will likely
still allow for heavier showers and storms tonight. However, given
convective trends, will let the Flood Watch go farther south.
Along the coast, marine stratus and fog will persist along the
Atlantic coast of MD/VA on the eastern shore, as well as the E
VA coast. Lows tonight in the low- mid 70s expected under mostly
cloudy skies.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
As of 355 PM EDT Thursday...
Key Messages:
- Continued unsettled but cooler on Friday with scattered
showers and storms.
- Hot and humid Friday through the weekend with heat indices of
100-105F possible across far S VA and NE NC Friday and
95-100F Saturday and Sunday.
- Isolated to scattered storms are possible on Saturday, with
the best chances along and west of I-95.
The backdoor front stalls near or just south of the VA-NC border on
Friday as upper heights continue to fall while the upper ridge
continues to slowly break down and retreat to our south. Even though
the front will be near our southern CWA border, there will be a
decent amount of deep-layered moisture just behind it. As such,
chances for scattered showers and storms will continue on Friday
(highest during the afternoon/evening across S VA/NE NC). Isolated
storms will be possible farther north (potentially to the Eastern
Shore). Will also note that there is a decent HREF prob for
showers/storms across the E side of the Eastern Shore Fri morning
with locally heavy rainfall possible. Storms gradually taper off
from NE to SW trough Fri evening. Given slow storm motions and a
very moist environment (similar to today) as well as the stationary
front nearby, we could be looking at another heavy rain/flash
flooding threat Fri across S VA and interior NE NC. HREF probs show
a 30% chance for 3"/3hrs across this area with even a small 50%
chance across SW Mecklenburg. While no Flood Watch will be
issued with this update (due to uncertainties in the front
location with respect to how today plays out), a Flood Watch may
need to be considered in future updates if the heavy rain
signal increases. Otherwise, the chance for severe wx on Friday
is low, but SPC does have extreme S VA and NE NC under a
marginal risk (level 1/5) for a few damaging wind gusts. Highs
Fri around 80F NE and around 90F S with most in the mid-upper
80s under mostly cloudy skies (some brakes possible in the
afternoon). Dew points remain high (mid 70s for most). As such,
heat indices of 100-105F are possible across S VA and NE NC with
mid 90s across most of VA.
The stationary front lifts back N as a warm front Fri evening into
Fri night with highs in the upper 80s to the lower 90s Sat and Sun.
Dew points remain in the 70s with heat indices of 95-100F each day
(100-103F possible Sun across SE VA/NE NC). Lows in the upper 60s to
lower 70s each night (most in the lower 70s). Isolated to scattered
showers and storms are possible Sat, but confidence in coverage is
relatively low (20-35% PoPs). The better chance for scattered
showers and storms is Sunday afternoon into Sun evening as another
cold front crosses from NW to SE. The entire FA is under a marginal
risk for excessive rainfall Sun due to the potential for localized
instances of heavy rain and flash flooding. Additionally, a few
strong storms will be possible.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 400 PM EDT Thursday...
Key Messages:
- Cooler and drier weather is expected early next week
(especially by Tuesday).
The cold front crosses the area Sun night into Mon with a strong
area of cold high pressure building in to the Great Lakes Mon and to
the Mid Atlantic by Tue-Wed. As such, below normal temps return as
well as drier conditions. Mon looks to be the warmest with
highs in the low-mid 80s and a lingering chance for scattered
showers and storms across far SE VA and NE NC through the
afternoon. Highs in the upper 70s will be common Tue-Thu. Lows
will also return to more pleasant values with temps in the mid-
upper 50s inland most nights.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 850 PM EDT Thursday...
Cloud cover increases tonight with initially VFR CIGs inland
and IFR/LIFR CIGs along the coast (due to a marine layer pushing
inland). CIGs low-end MVFR at SBY become IFR this evening
behind a backdoor cold front. Elsewhere, CIGs lower to MVFR and
then IFR/LIFR overnight behind the cold front from NE to SW with
all terminals IFR/LIFR by around 3-5z (apart from ECG, where IFR
will take until after 07-09z and will be short-lived). The
highest uncertainty is at ECG where IFR quickly improves back to
MVFR then VFR Fri morning. CIGs eventually improve to MVFR by
late Fri morning/early afternoon N terminals. Additionally, at
least patchy fog near the coast this evening, spreads inland
overnight into early Fri morning with MVFR/IFR VIS possible.
This is a result of marine stratus and fog pushing inland late
this evening.
Outlook: Additional showers will continue to be possible along
and E of I-95 Fri morning, potentially impacting SBY (perhaps to
RIC/PHF). Scattered afternoon and evening storms will again be
possible across S portions of the FA Fri afternoon into Fri
evening (best chance at ECG). Winds were generally SE/E 5-10 kt
this afternoon. Winds become NE behind the cold front this
evening/overnight, becoming light late. Winds remain NE/E 5-7 kt
Fri. MVFR-IFR CIGs likely recur Friday night into Saturday, with
VFR conditions to gradually return by later Saturday morning
into Saturday afternoon.
&&
.MARINE...
As of 330 PM EDT Thursday...
Key Messages:
- Small craft advisories in effect for the coastal waters N of
Parramore Island and the Chesapeake Bay from this afternoon into
tonight due to increasing NE winds and building seas.
- Quieter conditions expected this weekend as the flow turns
southerly.
-Potential Cold front next Monday into Tuesday that could bring
SCA conditions back to our coastal waters.
This afternoon, a 1022mb high pressure is now well offshore to
our SE, with an east-to-west oriented cold front located near
the VA-MD boarder stretching along the potomac river.
Southeasterly to easterly winds along the bay and NC coastal
waters. Behind the coldfront winds have shifted to the northeast
around 10-15 kt. Wave heights have begun to rise to 2-3 ft
behind the cold front but remain 1-2 ft south of the front in
the coastal waters and around 1 ft in the bay.
The current forecast continues to have the front stalling just
S of the NC/VA border in the later this evening. Behind the
front, winds will turn to the NE and increase to 15-20 kt for
the Chesapeake Bay and coastal waters N of the NC/VA border.
Have continued the small craft advisory on the coastal waters N
of Parramore Island through early Friday morning. These zones
are most likely to see seas approaching 5 ft and this is primary
reason for the SCA there. Have also added all of the Chesapeake
Bay to the SCA for the 15-20 kt winds (gusts to 25 kt),
starting at 20z/4 PM this afternoon. The higher winds will
likely be rather short- lived in the bay; thus, the SCA only
goes through 05z/1 AM Friday. Have left out the lower James
given higher uncertainty, but this may need to be added in
future updates. The front is also expected to spark tstms
inland, though cannot rule out a few showers or storms spilling
into the Chesapeake Bay tonight. Winds Friday will be lower, but
onshore flow continues in the 10-15 kt range. Winds become
southerly again for Saturday and Sunday as the front lifts back
N through the waters, but wind speeds should be sub- SCA. Then
by Monday model guidance suggest that a stronger cold front
could pass through and the coastal waters will see northerly
winds approach SCA levels behind it. Then by Tuesday a high
pressure slides to the north bringing NE winds approach SCA
levels once again.
Seas of 4-5 ft are then expected by this evening N of the
Parramore Island, with 2-3 ft elsewhere. 2-3 ft waves are also
forecast in the bay from the late afternoon through early
tonight. Seas slowly subside to 3-4 ft Friday and then 2-3 ft
Saturday/Sunday. Waves/seas potentially increase again behind
the front Monday/Tuesday.
A moderate rip current risk is forecast across all beaches
Friday and Saturday.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...Flood Watch until 1 AM EDT Friday for VAZ048-060>062-064-
067>069-080-081-509>516.
MARINE...Small Craft Advisory until 1 AM EDT Friday for ANZ630>632-634.
Small Craft Advisory until 10 AM EDT Friday for ANZ650-652.
&&
$$
SYNOPSIS...RMM
NEAR TERM...ERI/MAM/RMM
SHORT TERM...RMM
LONG TERM...RMM
AVIATION...RMM
MARINE...HET/SW
Area Forecast Discussion
National Weather Service Boise ID
830 PM MDT Thu Aug 29 2024
.DISCUSSION...Lots of smoke in the air over much of the area
today, and this smoke will extend west into eastern Oregon
Friday. Otherwise, there are no clouds to deal with and winds
will remain light. No update is needed at this time.
&&
.AVIATION...VFR in most of Oregon at this time, with mostly
MVFR/areas of IFR in ID due to smoke. Smoke will spread
into eastern Oregon tonight. Smoke and MVFR continuing tonight
through Friday. Surface winds: variable less than 10 kt. Winds
aloft at 10kft MSL: variable less than 10kt.
KBOI...MVFR visibility in smoke. Surface winds: variable around
5 kt, becoming SE around 5 kt after 29/06Z.
Weekend Outlook...MVFR visibility with local IFR in smoke, with
clear skies above through early Sunday. Increasing clouds
Sunday. A slight chance (15%) of thunderstorms Sunday evening
in southeast Oregon. Surface winds: variable less than 10 kt.
Winds aloft at 10kft MSL: variable 5-10kt, becoming S 5-15 kt
Sunday.
&&
.PREV DISCUSSION...
SHORT TERM...Tonight through Saturday night...A ridge of high
pressure building over the area will bring dry weather and light
winds to the area. Thick smoke from wildfires burning in the
central Idaho mountains will continue to affect large areas of
southwestern Idaho. The HRRR smoke model is correct in showing a
huge production of smoke each afternoon which will later be
trapped under a night time temperature inversion and then drain
into the lower valleys overnight. Smoke may thin out a bit in
the afternoons when atmospheric mixing improves, but new smoke
will replace it overnight. The smoke will likely spread westward
into Oregon as well, but is not expected to be quite as dense
on the Oregon side. Temperatures will be a little hotter each
afternoon reaching 10 to 15 degrees above normal by Saturday.
Clear skies above the smoke layer will allow for excellent
radiation cooling overnight with chilly morning lows
expected...especially in the mountains.
LONG TERM...Sunday through Thursday...Chance of showers and high-
based thunderstorms in eastern Oregon Sunday as a Pacific upper low
approaches southwest Oregon. Better chance of thunderstorms (20-
40%) Sunday night, Labor Day, and Monday night as the upper low
moves northeastward across Oregon. Low should move across central
Idaho Tuesday and into Montana Tuesday night. Better ventilation
and showers may lessen the smoke. Cooler Tuesday, then warming and
drying again the rest of next week as high pressure aloft rebuilds.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
www.weather.gov/Boise
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DISCUSSION...SP
AVIATION.....SP
SHORT TERM...JB
LONG TERM....LC
Area Forecast Discussion
National Weather Service Charleston SC
928 PM EDT Thu Aug 29 2024
.SYNOPSIS...
High pressure will remain across the region through the
weekend. A cold front could approach the region and stall in
the vicinity early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The main forecast challenge for the overnight period centers
around the potential for fog and stratus. Conditions are
largely unchanged from the past several nights. Abundant low-
level moisture is in place with a deep, dry layer noted aloft on
the 30/00z KCHS raob. The boundary layer has decoupled inland
which will spread to the coast soon resulting in calm/light
winds everywhere. Mostly clear skies and calm winds will
promote fog development early Friday. 1000 hPa condensation
pressure deficits are progged to remain fairly high per latest
RAP output so any fog/stratus should remain fairly shallow.
Confidence on anything outside of patchy dense fog remains
pretty low at this juncture given these high condensation
pressure deficit values. Fog with "patchy" and "areas of"
qualifiers were maintained for this update with no explicit
mention of dense fog. Lows will range from the lower 70s well
inland to the upper 70s at the beaches and Downtown Charleston.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
High pressure aloft will be almost directly overhead on Friday,
slowly retreating southwards towards the Gulf of Mexico Saturday and
into Sunday. To the north a broad upper level trough will be
positioned just to the west of the Great Lakes on Friday, slowly
pushing eastward through the weekend. By Sunday afternoon an almost
zonal flow will develop over the southeastern states as the high
pressure retreats south and the mid-level trough swings eastward. At
the surface high pressure Friday will be centered offshore, placing
the local forecast area along the western periphery. This high
pressure will slowly retreat into the Atlantic waters through the
weekend as a weak cold front approaches the region late on Sunday.
The strong upper ridging will keep warm and mainly settled
conditions in place, with only limited shower/storm activity each
afternoon.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A broader scale upper level low pressure will be located across the
Great Lakes and New England region during the latter half of the
weekend into early next week with suppressed heights down into the
Mid Atlantic region. Meanwhile, at the surface, a boundary/cold
front could eventually advance into the Carolina Midlands/eastern
Georgia region by early next week then potentially advance offshore
and stall by Tuesday, bringing the return of northeasterly flow and
cooler temperatures to the region heading into the middle part of
next week. Expect scattered to widespread showers and thunderstorms
to mainly follow a diurnal trend as the front slowly
approaches/crosses the region Monday and Tuesday.
Strong ridging over the NE looks to ridge down the eastern seaboard
later Tuesday through mid-week, with at least weak CAD taking shape.
As such, general expectation would be below normal temps and more
extensive cloud coverage, and perhaps enhanced shower activity,
through the middle of next week.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
30/00z TAF Discussion:
KCHS/KJZI/KSAV: Fog/stratus will be the primary concern again
tonight. Conditions favor another round of shallow ground fog
and patchy stratus. High 1000 hPa condensation pressure deficits
suggest the fog will remain quite shallow with any stratus that
forms remaining fairly patchy. A mention of MIFG was maintained
at all three terminals with TEMPO groups to address a brief
period of MVFR vsbys. Any fog could mix out by 13z.
Extended Aviation Outlook: Prevailing VFR, though some patchy/mainly
shallow fog is possible early each morning through this weekend.
&&
.MARINE...
Tonight: Atlantic high pressure will extend across the region,
yielding a weak pressure gradient across local waters. Given the
pattern, expect south-southeast winds around 10 kt early this
evening that gradually decrease to around 5 kt by midnight. Seas
will range between 1-2 ft.
Friday through Tuesday: Broad surface high pressure ridging
from the Sargasso Sea across the Southeast will dominate over
the marine zones through the weekend. Light to moderate
south/southeasterly flow will remain across the coastal waters
through Monday. Seas remain 1-3 ft in minimal SE medium period
swell through this weekend as well. High pressure ridging down
the eastern seaboard will tighten the gradient beginning
Tuesday, and breezy NE flow through mid-week could eventually
necessitate SCAs.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1006 PM EDT Thu Aug 29 2024
.SYNOPSIS...
Hot and humid high pressure will remain across the region
through the rest of the work week. The chance of showers and
thunderstorms will slowly increase through the Labor Day holiday
weekend. Temperatures will remain above normal through the weekend
falling to below normal for the middle of next week as a cold front
moves south of the area and cooler high pressure builds in from the
north.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1000 PM Thursday...Convection has waned across the forecast
area, but a stray shower or two cannot be ruled out over the
next few hours. Still some lingering debris clouds from earlier
convection mainly in the western NC mountains that should dissipate
overnight, allowing for the potential for mtn valley fog in the
pre-dawn hours. Low temps will be seasonably warm once again,
generally 3-5 degrees above normal.
For Friday, a convectively active day is expected, which we haven`t
had a lot of lately. The upper anticyclone over the Southeast will
continue to break down further through the day and the guidance
concurs that we should become normally unstable in the afternoon
with CAPE at least 2000 J/kg. RAP fcst soundings also suggest
sufficient dCAPE and weak shear for another pulse severe wet
microburst threat. Almost the entire fcst area is in a Marginal
Risk on the Day 2 outlook, so expect we will finally get some real
action on the radar for a change. High temps should end up maybe
a category less because of more cloud cover and shower activity
earlier in the afternoon.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 200 pm Thu: An upper anticyclone will remain centered over the
Southeast through Saturday, followed by falling heights/weakening of
the anticyclone as a series of short wave troughs sweep across the
northeast quadrant of the country. The large scale pattern is
therefore expected to become steadily more favorable for convective
development. Meanwhile, PWATs are expected to be AOA 1.75" through
the period, while at least moderate destabilization is expected each
afternoon. This is expected to result in good coverage (generally
60-70 PoPs) of diurnal convection across the mtns...and scattered
coverage (mainly 30-50%) across the Piedmont and foothills both
days. Wind fields/shear parameters will remain very weak in the
vicinity of the upper high center...so any severe storm potential
will be limited to perhaps a couple of pulse storms. Slow cell
movement along with enhanced moisture should result in some
potential for localized excessive rainfall. A slow cooling trend
will otherwise continue, with temps generally expected to be 3 or 4
degrees above normal through the period.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 215 pm Thursday: The southern extent of a long wave trough is
forecast to extend into the western Carolinas at the start of the
period, with the leading edge of an attendant frontal zone expected
to approach the CWA be early Monday. This should again enhance the
deep convective potential above climatology for Monday, with a
continued potential for locally excessive rainfall and perhaps a
couple of pulse severe storms. After Monday, the forecast becomes
more uncertain due to questions on how far the frontal boundary will
push before stalling. The deterministic runs of the ECMWF and the GFS
push deep dry air through the forecast area by mid-week. However,
there are enough members of their respective ensemble suites...not
to mention the Canadian deterministic run...that for one reason or
another (primarily due to upglide precip developing atop the
boundary) maintain precip potential through the end of the period to
hold on to token chance PoPs through the end of the period.
Regardless of the precip potential, conditions are expected to cool
substantially during the extended, with temps forecast at 5-10
degrees below climo Tue through Thu.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Convection should continue to wane across all
the TAF sites this evening with some debris cloudiness lingering
into the night. With more rainfall across the mountains today,
expect a better chance of mountain valley fog, but confidence at
KAVL remains marginal. Friday looks like an active day with PROB30
for TS warranted at all TAF sites. Winds will favor a S to SSW wind,
but will be light and variable or calm overnight.
Outlook: Diurnally active convective weather is expected each day
thru Monday. That means some brief restrictions around storms in
the afternoon/evening, then potential for fog development in the
early morning hours where it rained each day. Drier air may push in
from the north Tuesday, but some convective rain chances may linger.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JDL
NEAR TERM...ARK/PM
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...ARK
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1130 PM EDT Thu Aug 29 2024
.KEY MESSAGES...
- Record or near record high temperatures are forecast to continue into
Friday.
- A modest cool-down is expected for the weekend and beyond.
- While showers and thunderstorms are possible Friday through
Sunday, the greatest potential for rain is on Saturday.
&&
.UPDATE...
Issued at 1130 PM EDT THU AUG 29 2024
Made some minor edits to Sky grids to reflect latest trends,
mainly in reducing cloud cover. Otherwise, the forecast is on
track with no other substantive changes.
UPDATE Issued at 819 PM EDT THU AUG 29 2024
This afternoon`s convection and resulting outflows, along with the
loss of daytime heating, have resulted in the stabilization of
the atmosphere over eastern Kentucky. Only a few sprinkles or
light rain remain over far eastern parts of the forecast area,
and these will quickly diminish over the next 1 to 2 hours. PoPs
and Sky grids were updated to reflect these trends, with latest
observations used as the initialization for for the evening and
overnight temperature and humidity forecasts.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 514 PM EDT THU AUG 29 2024
Late this afternoon, to the north of an upper level ridge centered
in the southeast Conus, a weak frontal zone extended from coastal
VA northwest to southeastern OH and then west near the OH River
and eventually as a warm front associated with a low pressure
system over the Manitoba to the upper MS Valley region. An upper
level low associated with this low pressure system was centered
near the Saskatchewan/Manitoba to ND border region with an upper
level trough south across the northern to portions of the Central
Plains and an additional shortwave moving across portions of the
Rockies. Closer to home, a weak impulse/shortwave at 500 mb is
also moving across portions of the mid to Lower OH Valley region
around the southeastern U.S. ridge and likely contributing to
convective development across the region. With a frontal zone in
the vicinity of the OH Valley, isolated to scattered pulse showers
and thunderstorms have developed. These stronger pulse thunderstorms
especially those that have involved mergers have likely led to
gusty winds and perhaps some small hail and this potential will
continue this evening. MLCAPE is currently analyzed for areas
outside of convection in the 1000 to 2000 J/kg range, with mid
level lapse rates near 6C/km or less while low level lapse rate in
those areas in the 8 to 9C/km range.
This evening and tonight, the passing mid level disturbance will
move toward the mid Atlantic coast while the axis of the upper
level ridge centered in the southeast U.S. and extending into the
Great Lakes will approach eastern KY. Further west, the upper
level low is expected to track northeast toward far northwest
Ontario and Hudson Bay with the trailing trough nearing the
western Great Lakes to mid MS Valley region. At the same time, the
parent sfc low is expected to track toward northwest Ontario and
the Hudson Bay region as well. The frontal zone located in the OH
Valley region near the area should lift northeast as this occurs
into the Central Great Lakes region while the cold front nears the
western Great Lakes and drops into the Southern Plains. For
Friday and Friday night, the upper level low should continue
northeast into Hudson Bay while the trailing upper level trough
approaches and then moves into the Great Lakes to mid MS and Lower
OH Valley region. Head of this, the cold front will move to the
eastern Great Lakes and sag toward the OH River.
Convection should diminish by late evening, though a stray shower
or thunderstorm cannot be completely ruled out overnight per some
convective allowing model runs. Valley fog along the larger
creeks and area rivers should again develop by around midnight or
not long after in some cases and increase in coverage overnight.
This should affect some of the larger creeks, rivers, and area
lakes and should again lift and dissipate by the 9 to 10 AM EDT
timeframe. Cumulus develop on Friday as heating and mixing occur
likely around or not long after noon per forecast soundings.
Despite the surface frontal zone anticipated to have lifted north
and northeast of eastern KY on Friday, isolated to scattered
shower and thunderstorm activity may be focused in any leftover
outflow boundaries from convection that occurs through this
evening and in areas of differential heating. MLCAPE is forecast
per the 15Z RAP to reach the 1000 to 2000 J/kg range on average
Friday afternoon with shear again minimal. Pulse thunderstorms
should again occur and with DCAPE again forecast by some guidance
such as the RAP to be around 1100 J/kg on average if not higher in
some areas, strong wind gusts cannot be ruled out. Mid level
lapse rates 6C/km or lower may be a limiting factor again as far
as coverage while low level lapse rates should peak at 8 to 9C/km
and be favorable for gusty winds.
A relative lull in convection may occur from late evening into
Friday night. However, as the cold front nears and the upper level
trough approaches and height falls are noted at 500 mb convection
cannot be ruled out Friday night, especially further north and
west.
.LONG TERM...(Saturday through Thursday)
Issued at 531 PM EDT THU AUG 29 2024
A pattern change will unfold over the weekend as near to record-
setting August heat fades to a more seasonable early September
brand of warmth. The 29/12z model suite analysis beginning
Saturday morning shows a weakening ~591 dam high, centered over
Georgia/Alabama, being shunted to the south as a trough, extending
from the Central Plains/mid-Mississippi Valley northward to its
~533 dam parent low near/over far northern Quebec. At the
surface, a cold front extends from an ~980mb low over/near
northern Quebec southward to the Ottawa Valley and then
southwestward across the Central Great Lakes, Ozarks and beyond
into the Southern Plains.
The aforementioned cold front will continue to sag southeastward on
Saturday while a return flow advects and increasingly humid air mass
across the Commonwealth (mean PWATs flirt with 1.90 inches in the
LREF). Though spotty convection is possible early in the day,
more widespread convection (70 to 80 PoP) is forecast to develop
during the afternoon as the atmosphere destabilizes. With weak
shear, anticipate mainly ordinary pulse-type thunderstorms.
However, the NAM12/RAP13 suggest moderate SBCAPE values nearing
or exceeding 2,500 J/kg along with sufficient DCAPE to support a
few microburst/downburst events, thus isolated instances of
damaging winds are certainly possible. It will still be quite warm
with high temperatures forecast to range from the mid 80s to
around 90. Convection is expected to wane on Saturday night as the
cold front settles to along or just south of the Ohio River.
The cold front will continue to make slow southeastward progress on
Sunday, once again bringing the threat for widespread convection
(80-90 percent chance) for locations along and southeast of the
Hal Rogers/KY-80 corridor. Near and north of the boundary, maximum
rain chances wane to 30 percent over northern Fleming County.
High temperatures are forecast to range in the upper 70s to lower
80s, where rainfall will be most persistent, to the mid 80s north
of I-64, where better sunshine is anticipated. The increasingly
diffuse front will continue to sink south of the area on Sunday
night with waning rain chances. Theta-e analysis suggests that a
trailing secondary cold front will develop over the weekend and
sag into eastern Kentucky on Labor Day before hanging up over or
just south of the area. Drier air to oozes into northern Kentucky
during the afternoon on northeasterly flow as surface high
pressure passes through the Great Lakes. This will set the stage
for a mostly sunny and comfortable holiday with highs in the lower
80s north and lower to middle 80s south. Dew points fall through
the 50s and perhaps flirt near 50 north during the afternoon but
remain in the lower 60s south. This will set the stage for a
notable north-south temperature gradient on Monday night with
lows falling deep into the 50s north (possibly upper 40s in the
coolest valleys) but only in the upper 50s/lower 60s south.
As the high pressure slowly shifts east from the Great Lakes to
Northeast, weak surface lee troughing develops over the western
foothills of the Central Appalachians as moisture seeps back north
into the JKL forecast area. Consequently, weak disturbances
passing in the cyclonic flow aloft may spark a stray shower (10
to 20 PoP) on Tuesday over far southern Kentucky. Slight chance to
low chance PoPs are forecast across the CWA on Wednesday and
Thursday, as the trough lingers. Expect high temperatures in the
low to middle 80s on Monday/Tuesday and then upper 70s to lower
80s for most locations on Wednesday and Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 720 PM EDT THU AUG 29 2024
Shower and thunderstorm activity has diminished for the evening,
so will remove any mention of such from the 00z TAF package. Light
rain or sprinkles will continue until 00z or 01z toward KSJS, but
with VFR conditions will leave out of the TAF. Expect IFR valley
fog formation tonight, especially in areas that received
appreciable rain this afternoon as well as the typically larger
river valleys, but TAF sites are expected to remain fog-free as
of the 00z TAF package issuance. Isolated thunderstorms are
expected to develop Friday afternoon, but coverage is likely too
low to warrant anything besides VCTS mention.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...CMC
Area Forecast Discussion
National Weather Service Louisville KY
919 PM EDT Thu Aug 29 2024
.KEY MESSAGES...
* Likely the hottest days of the summer so far now through
Friday with near record heat each day.
* Isolated storms possible through evening. Locally gusty
winds possible from microbursts.
* Cold front will move through the region late this weekend,
bringing relief from hot temperatures and humidity.
&&
.UPDATE...
Issued at 919 PM EDT Thu Aug 29 2024
Convection has largely diminished across the region and skies are
beginning to clear out. Temperatures across the region varied from
the mid-upper 70s in areas that received rainfall this afternoon, to
the the lower 80s in the I-65 corridor and points west. The urban
heat island in Louisville metro is still around 90 this hour.
For the overnight period, quiet weather is expected. Temperatures
will drop into the 70s for lows. Could see some patchy fog over in
southern Indiana where dewpoints are a little higher. Also could
see some locally patchy fog over in the Bluegrass region where ample
rainfall fell this afternoon.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 320 PM EDT Thu Aug 29 2024
Diurnally driven storms have popped across the Bluegrass, with gusty
wind potential being noted in those areas. Will continue to see
microburst potential with any stronger core aloft given the steep
low level lapse rates, inverted V (dry low levels) signature on
soundings, and overall high DCAPE values (1100-1400 J/KG) as a
result of those features. Elsewhere, the cu field is more sporadic,
although agitated. Hi res HRRR continues to show isolated coverage
this afternoon over the whole CWA, so can`t rule out additional
coverage in those areas, although it may take remnant outflow from
upstream activity as a trigger. Given the lack of deep layer shear,
any storm this afternoon and early evening will be slow moving.
Locally heavy rainfall is possible for anywhere that a storm sits
for too long.
Outside of the PM storms, temperatures are hot with values peaking
in the 95 to 100 degree range. A few records have already been
broken today, including SDF at 100 degrees so far. See the Climate
Section of this AFD for more info.
Clear calm conditions expected overnight after diurnally driven
convection dies off. Could see some patchy fog in spots, especially
over southern IN where dew points will be a bit higher.
Friday brings one more hot day ahead of the approaching cool front.
As a result, looking for another day of mid to upper 90s, with
slightly higher dew points, especially along and west of I-65. Still
HI values should hold around 100 at max, shy of any needed headline
criteria. Expect to see isolated to widely scattered showers and
storms develop by afternoon into the evening, most notably along and
west of I-65 as the upper ridge begins to break down a bit.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 320 PM EDT Thu Aug 29 2024
Definite pattern change coming this weekend as a cool front stalls
out over the region with slow-moving upper trough crossing the
Great Lakes area Saturday. As that front washes out over the region,
the pool of moisture associated with it will be slow to scour out.
Thus, despite the current dry spell we`ve been in, we actually have
some good rain chances both Saturday and into Sunday...though the
more widespread higher amounts would look to be Saturday. Sunday`s
chances look better the farther south and east you go, as by
afternoon there should be a tight precipitable water gradient.
NAM/GFS both show around 2" in the Lake Cumberland region and around
1" along the Ohio River.
By Sunday night, the trough axis aloft will be shifting east of the
region and surface winds should have enough of a northerly push to
dry us out for the start of the next work week. Above normal low
temperatures for the weekend should down to near or just below
normal for the work week. High temperatures each day should be
around normal..first under weekend cloud cover then with the drier
air coming in.
By mid week, we start to see moisture increase with some weak
perturbations possibly allowing for pulse diurnal convection
Wed/Thu.
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 714 PM EDT Thu Aug 29 2024
VFR conditions will continue through the upcoming TAF period.
Afternoon convection has diminished in the last 30 minutes, but
there are quite a few mesoscale outflow boundaries moving across
north-central Kentucky (in particular the KSDF area). Mid-level
capping has kept convection across north-central KY in check this
afternoon and CINH will continue to increase as we go further into
the evening. Nonetheless, can`t rule out some additional convection
along the convergence of outflows near KSDF for the next hour or so.
Elsewhere, VFR conditions with light winds are expected this evening
and into the overnight. Some patchy fog may develop out toward KHNB
after 30/10Z. The outlook for Friday calls for VFR conditions with
southwesterly surface winds.
&&
.CLIMATE...
Issued at 320 PM EDT Thu Aug 29 2024
================== Near-Record Heat This Week ==================
Friday 8/30/2024
Max T Fcst/Record (Year)
Louisville: 99/98 (1953)
Bowling Green: 97/99 (1993)
Lexington: 98/97 (1953)
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Air Quality Alert until midnight EDT tonight for KYZ029>031.
IN...Air Quality Alert until midnight EDT /11 PM CDT/ tonight for
INZ076>079-083-084-089>092.
&&
$$
UPDATE.......MJ
SHORT TERM...BJS
LONG TERM....RJS
AVIATION.....MJ
CLIMATE......BJS/SRM
Area Forecast Discussion
National Weather Service Marquette MI
648 PM EDT Thu Aug 29 2024
.KEY MESSAGES...
- Quick round of showers and storms tonight into Friday. Low
chance (~5%) for damaging wind gusts over the far west.
- Breezy west winds, gusting up to 30 mph in the Keweenaw on Friday.
- Cold front brings a brief round of showers and storms with
gusty wind potential Saturday night, followed by breezy, cool
conditions on Sunday.
- Low end northwest gales expected late Saturday night and
Sunday morning across the east half of Lake Superior.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 411 PM EDT Thu Aug 29 2024
Current RAP analysis has mid level ridging centered over the western
Great Lakes with sfc high pressure situated over Quebec, extending
southwest into the Great Lakes Basin. This has, and will continue to
keep the UP dry through early this evening. Upslope southeast flow
off Lake Michigan has continued the broken low level cloud deck, but
this is expected to diminish into this evening. Temperatures the
rest of this afternoon should hold fairly steady in the upper 60s to
mid 70s, warmer over the west where there is clearer skies and
downsloping flow.
The main feature to focus on for the short term forecast is the trough
currently centered over the Saskatchewan/Manitoba province line with
it`s associated sfc trough and occluded/cold front draped south over
the Dakota/MN state line. Tonight through Friday, the mid level
trough lifts northeast through northern Ontario toward Hudson Bay.
This sends the sfc trough and cold front eastward across the UP,
forcing a round of showers and storms ahead of it. There is fairly
good agreement in the CAMs of this QLCS over northwest WI and
western Lake Superior this evening entering the west around 10-11pm
EDT as it begins to fall apart. From there the round of showers and
storms move into central Upper MI around 4am EDT and into the east
around 5-8am EDT. The timing of this front is not ideal for strong
to severe storms given the loss of diurnal heating. If the line is
able to make it into the UP before breaking apart, HREF mean MUCAPE
to ~1000 J/kg and bulk 0-6km bulk shear around 25-30 kts mean the
storms could be strong to severe storms. The main threat would be
some isolated damaging wind gusts. PWATs increasing up to around
1.8", the 99th percentile of the climatological NAEFS, and steep
warm cloud depths could support some heavier downpours up to 0.5-1".
Otherwise lows are expected in the low to mid 60s.
By Friday the cold front will be situated over the central UP with
showers and storms over the east half continuing eastward toward
Ontario. Instability will be minimal by this point so strong to
severe storms are not expected. Clearing skies follow behind the
cold front as drier air intrudes from the west. Friday then warms up
into the 70s with low 80s possible in the south central. Breezy
winds are expected in the Keweenaw, gusting up to 30 mph.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 446 PM EDT Thu Aug 29 2024
Medium range ensembles today are in excellent agreement on the large
scale flow changes that occur thru next week. Very well-defined mid-
level low that is currently centered over far sw Manitoba will lift
ne, reaching Hudson Bay Fri aftn. Ridging will then begin to build
modestly over western Canada, and this in turn will force the next
shortwave over s central Canada to drop se, modestly amplifying the
weak troffing that initially reaches the Great Lakes by the
preceding mid-level low. The trof amplification will occur over the
Great Lakes Sat night/Sun. This trof then quickly lifts out to the
ne early next week as positive height anomalies rapidly spread e
across the southern half of Canada, setting up temporary low
amplitude/nearly zonal flow across the southern half of Canada. Late
next week, at least some degree of flow amplification will likely
occur as western ridging builds, forcing troffing into the eastern
U.S. For Upper MI, this evolution of the flow will bring a warm day
on Sat ahead of the cold front associated with the shortwave
dropping toward the northern Great Lakes. A much cooler day will
follow on Sun. Slight moderation will occur on Labor day, then
warming more firmly gets underway as low amplitude/nearly zonal flow
quickly spreads across southern Canada. Temps should rise to 5 to
10F above normal by midweek. Some cooling should be favored late
week or over the Sep 7/8 weekend, depending on degree of potential
pattern amplification. As for pcpn, passage of the cold front Sat
night will bring a quick round of shra/some tsra to Upper MI Sat
night. Following shot of cool air may support a few lake effect
-shra during Sun morning under breezy nw low-level flow. Dry weather
will then overall prevail next week. There remains a weak signal
that the onset of waa early next week as eastern trof lifts out may
offer a less than 20pct chc of some shra around Tue. Next better chc
of shra should hold off until late week when pattern potentially
begins to amplify.
Beginning Fri night/Sat, nothing more than sct to perhaps bkn at
times high clouds are anticipated during this time. A seasonable
night with lows from around 50 to the lower 60s Fri night will be
followed by a warm day on Sat under w to sw winds ahead of next cold
front approaching from the nw. Expect highs mostly in the upper 70s
to lwr 80s F with dwpts comfortable in roughly the 50-55F range for
much of the area. Will be on the breezy side Sat under deep mixing
that could tap 30kt winds, particularly across western Upper MI.
Vigorous shortwave dropping se into the northern Great Lakes will
send associated cold front across Lake Superior and Upper MI Sat
night. Decent forcing with sharp cold front will likely support a
narrow band of shra/some tsra along the front despite rather limited
moisture. Dry subcloud layer and 850mb winds ramping up to 40-50kt
just ahead of front suggest gusty winds in excess of 45mph may
accompany some of the shra. Given the holiday weekend and nice
weather preceding thru Sat aftn, will be something to monitor as the
shra arrive over nw Upper MI around 00z and then quickly spread se.
850mb temps tumble from 15 to 16C ahead of the front early Sat
evening to 4-6C Sun morning. With buoys indicating water temps
ranging generally from 16 to 20C, isold post-frontal nw flow lake
effect shra will be possible Sunday morning. Incoming dry air mass
and anticyclonic flow associated with high pres building se into the
northern Plains/Upper Mississippi Valley will limit coverage and
potential, but still worthy of schc (~20pct) mention. The cooler air
mass will setup a breezy day across the fcst area. Fcst soundings
suggest gusts 25-35 mph near Lake Superior/Keweenaw and 20-25 mph
elsewhere. Even if -shra don`t occur, should see quite a bit of
cloud cover blossom for a time under incoming 850mb thermal trof.
Expect highs in the 60s, but the s central should reach 70F.
If sfc high pres ends up over Upper MI Sun night or Mon night, would
expect a chilly night with frost potential in the interior. For now,
it doesn`t look like we`ll get a perfect radiational cooling night,
but some patchy frost is a possibility. Sun night may end up as the
coolest night. High temps will moderate on Labor Day and temps will
return to well into the 70s for Wed/Thu under dry weather.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 648 PM EDT Thu Aug 29 2024
Generally VFR conditions prevail through this evening. A quick round
of showers and some storms makes their way through tonight into
Friday morning, bringing MVFR restrictions to IWD and CMX first and
to SAW a hour or two later. Cigs at SAW look to drop down to IFR
late tonight/early Friday morning. Best window for showers is
between 2-6Z at IWD, 4-9Z at CMX, and 6-12Z at SAW. Expect
conditions to improve into Friday morning as skies clear behind the
cold front. Otherwise, gusts approaching 30 kts are possible on
Friday at CMX.
&&
.MARINE...
Issued at 446 PM EDT Thu Aug 29 2024
Approaching cold front will cross Lake Superior overnight thru Fri
morning. Ahead of the front, E to SE winds will gust 20-30kt tonight
with the strongest winds probably in a zone from around Stannard
Rock to Passage Island. Internal probabilistic guidance suggests a
10-30% chance of peak gusts reaching low end gales with the highest
of these values along the International Border. Showers and
thunderstorms will also move across the lake and may add to the
gustiness of the ongoing winds, particularly over the western lake.
Winds shift WSW to W with frontal passage, and the stronger winds
shift to western Lake Superior for Fri. Internal probabilistic
guidance indicates a 10-30pct chc of peak gusts reaching gale force
btwn Isle Royale and nw Upper MI. Winds across eastern Lake Superior
will settle back to around 20kt on Fri.
Winds diminish Fri night and Sat morning to around 20-25kt between
Isle Royale and the Keweenaw and remain 20kt or less elsewhere. Next
cold front approaches from the nw on Sat. Ahead of the front, expect
sw winds to again gust to 25-30kt over western Lake Superior in the
aftn. Winds across eastern Lake Superior will be under 20kt. The
cold front will sweep se across Lake Superior Sat night. A cool air
mass following the front will lead to better mixing of higher winds
down to the lake sfc for Sun. Incoming pres rises will also aid
stronger winds. Probabilistic guidance continues to indicate a 60-
80% chc of low end NW gale force gusts across the e half of Lake
Superior late Sat night/Sun morning. Winds begin to diminish from w
to e Sun aftn and will fall to under 20kt for Mon/Tue as sfc high
pres arrives over the western Great Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...Rolfson
AVIATION...07
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
627 PM CDT Thu Aug 29 2024
.KEY MESSAGES...
- Near record heat this afternoon with high temperatures around
100 degrees. While temperatures will be a few degrees cooler
on Friday, an increase in moisture will cause heat index
values to be hotter near 105 degrees.
- A slow moving cold front will bring the chance of showers and
storms on Friday. More numerous scattered activity arrives
Friday night with rain chances continuing through Saturday,
and possibly Sunday.
- Much cooler air arrives over the weekend, with less humid
conditions in time for Labor Day. The next chance of rain
arrives by the middle of the week.
&&
.UPDATE...
Issued at 626 PM CDT Thu Aug 29 2024
Updated Aviation discussion for 00Z TAF Issuance.
&&
.DISCUSSION...
Issued at 228 PM CDT Thu Aug 29 2024
Today is certainly turning out to be quite the hot day as the PAH
ASOS is 101/61 at this hour! WPC sfc analysis currently shows a
frontal boundary lifting north of the FA as a warm sector
regime is now setting up with upper level ridging. A stray
shower or storm still remains possible this afternoon, but any
pcpn will quickly diminish with the loss of differential
heating.
An influx of moisture will advect north across the lower Ohio Valley
on Friday causing dewpoints to rise into the low to mid 70s. Did lean
closer to the NBM 90th percentile as model soundings are more
saturated compared to today inhibiting the mixing potential. MaxTs
will also be a bit cooler in the lower 90s due to the increase in
moisture. This will still translate to higher heat index values
between 100-105 degrees across much of the FA. It is probable
that a few locations will briefly reach Heat Advisory criteria,
but due to the short duration and limited spatial coverage,
will hold off on issuing any headlines.
As a cold front slowly moves southeast across Missouri in the
afternoon, a 500 mb shortwave will transverse towards the FA by
Friday evening providing forcing for ascent. Many of the 12z
CAMs including the HRRR do not support much in the way of CI
until Friday evening while a few outliers such as the ARW has CI
occurring in the afternoon. Given the lack of upper level
forcing, meager effective bulk shear below 20 kts, and
potential inability to reach the convT in the upper 90s, have
trended PoPs downward through the day compared to the NBM.
Should a few isolated pulse storms develop, a brief gusty
stronger storm would not be out of the question given MLCAPE
between 1500-2500 J/kg and steep low-level lapse rates around
7.5-8.0 C/km.
In the wake of fropa associated with the aformentioned cold
front, more scattered convection is likely Friday night into
Saturday as sfc convergence increases. While stronger storms
will not be a concern with these due to waning instability,
localized excessive rainfall cannot be ruled out due to a slow
storm motion around 15-20 kts. FFG in the 3-4 inch range should
limit the flash flooding potential on a synoptic scale, but the
drier soil conditions will favor typical run off and poor
drainage issues on roadways. Overall, QPF is only progged in the
0.50 to 1.50 inch range for most locations.
With that said, a few lingering showers remain possible on Sunday,
especially across southern portions of the FA. Drier air will then
begin to advect in from the north as a trough digs across the Great
Lakes region with a ~1026 mb sfc high pressure building south
from Canada. This means more comfortable conditions are store by
Sunday night into Labor Day as dewpoints will return to the
lower 60s and even upper 50s. Temps will be slightly below
normal with maxTs progged in the low to mid 80s and lows
ranging from the upper 50s to lower 60s. As sfc high pressure
slides east, there is some uncertainty in how quickly moisture
returns from the south towards the middle of the week. Most of
the deterministic models keep the FA dry, but some of the
ensembles including the GEFS are a bit more aggressive in
bringing in low pcpn chances by Tuesday.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 626 PM CDT Thu Aug 29 2024
Other than some patchy fog offering the possibility for vsby
restrictions pre dawn, it`ll be another Visual Flight Rules
forecast with mainly high based diurnal cu again tmrw.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...Air Quality Alert until 11 PM CDT /midnight EDT/ this evening
for INZ081-082-085>088.
KY...None.
&&
$$
Area Forecast Discussion
National Weather Service Pocatello ID
203 PM MDT Thu Aug 29 2024
.SHORT TERM...Tonight and Friday. Dry and calm conditions will
remain in place across central and eastern Idaho. With decent
inversions in place, we do expect colder valleys to be in the 20s
to lower 30s...just a bit warmer than last night. We will continue
to see 40s and even some 50s tonight within the inversion layer.
Highs Friday should finally push back to around or just above
average for the end of August. Expect another wash, rinse, repeat
night for Friday night...warming up a few more degrees vs tonight.
Keyes
.LONG TERM....SATURDAY THROUGH NEXT THURSDAY...
A ridge of high pressure will remain in control through at least
Sunday morning...if not Monday morning...slowly drifting east with
time. This will support quiet, clear to mostly clear conditions
across SE Idaho with very light winds and no precipitation, although
varying degrees of wildfire smoke/haze will likely continue to be
noticeable. Outside of the smoke and any attendant air quality
impacts, nice late-summer days are expected! While some model
guidance hints at a very low chance of a shower or t-storm Sunday
afternoon, Monday is the more likely day where we`ll begin to feel
the effects of our next approaching low pressure system in the form
of a modest wind increase and daily chances of showers/t-storms,
lasting at least through Tuesday evening everywhere if not lingering
Wednesday in eastern portions of the CWA. Overall impacts (wind, QPF
amounts, etc.) seem relatively modest with this next system so
far...a look at 500mb height cluster analysis shows good agreement
in the evolution of this feature with very weak EOF patterns, only 1
ensemble QPF cluster (15% of the ensemble space) advertises
noticeably heavier QPF, and no organized response is evident in the
ECMWF Extreme Forecast Index (EFI) for any weather element. All of
this points to overall good forecast agreement at this juncture with
no strong alternate forecast scenarios/concerns really emerging at
this time. High temps will continue to top out in the 80s to low 90s
leading into this system, before we see a modestly noticeable drop
into the upper 70s and low 80s on Tuesday and Wednesday (although
with continued precip chances as the through works through). Long-
term model solutions diverge by late next week with anything from a
ridge of high pressure (63% cluster support) to another low pressure
storm system (36% cluster support) possible. - KSmith
&&
.AVIATION...A ridge of high pressure will build into the Great Basin and
northern Rockies over the next several days, supporting clear skies,
very light winds, and no precipitation through at least Sunday
morning, if not Monday morning. The only aviation impact we`ll be
monitoring is smoke and haze, especially from the Wapiti Fire west
of Stanley. Varying degrees of mid-level smoke/haze are evident on
satellite and being observed visually today, but so far this has not
resulted in any deviations from SKC and P6SM at TAF sites outside of
KSUN, and we have no confidence that any significant degradations
will occur over the next 24 hours, thus places like KBYI and KPIH
remain VFR for now. Vsbys dropped as low as 1 1/2SM this morning at
KSUN with smoke manifesting as a "cloud deck" up near 4,000 feet AGL
as well, but vsbys have improved rapidly coincident with the diurnal
wind shift at 17z/11am...quicker than originally advertised in the
18z TAF. Confidence is very low in how impacts from smoke will
evolve over the next 24-36 hours, but for the TAF, we have mimicked
what happened today with slight improvements but continued HZ
through the afternoon/evening, another vsby drop overnight with NW
down-valley flow drawing more smoke southward from the fire region,
and then fairly quick improvement again between 17-19z/11am-1pm
Friday when winds shift into the SE. This general concept has
perhaps a hint of broad support from the HRRR smoke model, but again
confidence is low and we`ll have to monitor trends closely. KBYI is
perhaps the next best candidate for some slightly reductions in
vsby at the sfc, but confidence is too low to add any impacts to
their TAF at this time. By either Sunday afternoon or Monday
afternoon, winds and shower/thunderstorm chances will start to
increase again ahead of our next low pressure system. - KSmith
&&
.FIRE WEATHER...Dry conditions will persist until we get to the
back end of the Labor Day weekend. Dry air will keep poor
overnight recovery in place. We are even expecting some valley
locations, where we might see downslope/downvalley flow help keep
the air from settling too much, only recovering to the 20-40%
range. Single digit and teen relative humidity values will remain
the norm as well. We should see enough monsoon moisture for
isolated dry storms by Sunday afternoon. The better chance of rain
and thunderstorms arrive for Labor Day and Tuesday. Keyes
&&
.AIR QUALITY...A large area of smoke mainly due to the Wapiti Fire
continues to encompass portions of central and eastern Idaho. The
smoke has been thinning and shifting south and west due to flow in
between the low over south-central Canada and high pressure to
southwest. It does appear the thicker smoke will eventually pivot
west and eventually to north based on the flow in the next 24-48
hours. This would keep the worst over the central mountains and
shift it toward Lemhi County and southwest Montana. Other areas
will likely some amount of smoke, but the to a lesser extent. We
currently have AIR QUALITY ADVISORIES for Custer and Blaine
Counties, and both are in effect through tomorrow. Keyes
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Salt Lake City UT
259 PM MDT Thu Aug 29 2024
.SYNOPSIS...Dry air will lead to clear skies through Friday
with light and variable winds, along with wildfire smoke across
northern Utah and SW Wyoming into Saturday. Moisture increases
slightly across southern Utah by the weekend with isolated high-
based convection possible during the afternoon Saturday and
Sunday. Temperatures will gradually warm through the weekend and
rise to 5-15 degrees above normal for Labor Day Weekend.
&&
.SHORT TERM (Through 12Z/6AM Saturday)...Early afternoon Thursday,
a strong area of low pressure was located over southern Manitoba,
while a ridge of high pressure was building into the Western Great
Basin. Cool early morning temperatures across northern Utah and SW
Wyoming were giving way to high temperatures near to slightly
below normal across the north, to near to slightly above normal
across the south for late August. Behind the front, west to
northwest winds will allow for central Idaho wildfire smoke to
gradually drift southward into northern Utah and southwest Wyoming
through this evening, with increasing haze and decreasing
visibility and air quality. HRRR smoke model suggests this smoke
will continue advecting southward into portions of central Utah on
Friday, while gradually becoming more diffuse as we head through
the weekend. See Utah DEQ for the latest air quality forecasts.
Heading through the remainder of the period, the above-mentioned
Western Great Basin ridge will build across Utah by Saturday
morning. This will favor gradually increasing temperatures through
the weekend with a return to above normal temperatures. Moisture
will begin to gradually increase across southern Utah as well
through the period, with afternoon terrain-based cumulus today
giving way to a high-based shower or thunderstorm or two by Friday
afternoon. This coverage will gradually increase through the
weekend.
.LONG TERM (After 12Z/6AM Saturday), Issued 305AM MDT...
By the weekend, the center of the ridge of high pressure over the
Intermountain West will begin to shift east of our area, allowing
for mean southerly flow aloft (particularly over southern Utah).
This will bring increased moisture into the area, although much
less significant than recent monsoon surges. Global ensemble PWATs
range from 0.4 to 0.6" across the area for the 25th-75th
percentile by Sunday. For comparison, recent monsoon events
featured PWATs of 1-1.3". Model soundings also show meager
instability and with thin CAPE profiles high above the surface and
dry low levels, suggestive of high-based showers and perhaps
thunderstorms. Thus, the main threat with any convective
development will be gusty winds. Such convection will initially be
limited to southern Utah mountains Saturday, spreading northward
and eventually including all higher terrain areas by Monday, with
isolated to scattered coverage of weak storms.
Meanwhile, a warming air mass will result in temperatures climbing
through the weekend, peaking Sunday/Monday at 5-10 degrees above
normal for most locations. HeatRisk for the Labor Day holiday shows
a few pockets of orange, or moderate risk, but mostly limited to
unpopulated West Desert locations.
Looking ahead to next week, ensembles are in fair agreement with a
closed low moving onshore somewhere between NorCal and the Pacific
NW and (temporarily at least) flattening the ridge overhead of our
area. Depending on how close the low is to our area, we could see
elevated winds and perhaps a convective threat, though the most
favored solution in ensembles (around 70% of the solution space)
holds the low too far to our northwest to have much impact. At the
very least, temperatures will subside by a few degrees as the ridge
flattens. Thereafter for the remainder of the week, ensembles are in
high agreement with mean ridging over the entire Western US and thus
continued above normal temperatures.
&&
.AVIATION...KSLC...North to northwest winds to remain in place
until 04-05Z when typical southerly drainage flow is most likely
to develop. This is slightly delayed compared to a normal evening
thanks to a northerly pressure gradient. Increasing haze beginning
this evening due to wildfire smoke from Idaho, resulting in
potentially minor VIS reductions through Friday morning.
.REST OF UTAH AND SOUTHWEST WYOMING...Wildfire smoke will
gradually overspread northern Utah and SW Wyoming through this
evening while spreading further southward into portions of
central Utah during the daylight hours Friday. Greatest potential
for VIS reductions is forecast to be generally along/north of a
ENV-OGD- EVW line, with a few pockets of horizontal visibility
reductions down to as low as 4-5SM along with a thin, opaque layer
of smoke. Otherwise, expect mainly light, terrain-driven winds.
&&
.FIRE WEATHER...A cold front has grazed across northern Utah
on Thursday, bringing a cooldown while maintaining low humidity.
Some smoke will drift into northern Utah from central Idaho fires
as well, and persist across the north into Saturday. Overall
though, conditions remain tranquil Thursday. Meanwhile, a ridge of
high pressure will gradually build into the area through the
weekend, bringing a gradual warming trend and a return to hot
temperatures by the end of the weekend, when temperatures will
reach 5F to 15F above normal for early September. Just enough
moisture will return to southern Utah this weekend to support
isolated, mainly high-based showers and thunderstorms. Winds will
be primarily terrain-driven except near shower and thunderstorm
outflow. Early next week, mainly in the Monday and Tuesday
timeframe, an area of low pressure will move from northern
California through Idaho. This will draw increased moisture
northward across the state by Monday thanks to increasing
southwest winds, bringing both some RH recovery along with a
statewide chance of high-based showers and thunderstorms. As the
low moves eastward by the middle of next week, it will force the
flow to turn more westerly while dragging a weak cold front across
northern Utah, resulting in a modest cooling trend while
simultaneously scouring moisture out of the area.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&
$$
ADeSmet/Van Cleave
For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
745 PM EDT Thu Aug 29 2024
...New UPDATE, AVIATION...
.UPDATE...
Issued at 745 PM EDT Thu Aug 29 2024
No changes made to existing forecast package. Somewhat less active
overall this afternoon and evening, however a few areas saw heavy
rainfall and gusty winds that prompted a few statements. Remaining
convection largely limited to offshore waters, with a low chance
of a stray shower lingering through the evening before mostly
clear to partly cloudy skies tonight. Repeat evolution likely on
Friday, with afternoon and early evening showers and storms and
highs in the lower to mid 90s.
&&
.DISCUSSION...
Issued at 204 PM EDT Thu Aug 29 2024
Broad surface high pressure centered between Bermuda and the Bahamas
continues to ridge west-southwest across Florida and into the Gulf
of Mexico. This synoptic pattern will keep Florida in a predominant
easterly wind flow through the week and into the weekend. This will
favor late afternoon/evening showers and storms forming along both
the east and west coast sea breeze boundaries. Abundant moisture
with PWAT values ranging between 1.6-2.1 inches will support
scattered to numerous showers and storms each day with the highest
chances over southwest Florida. Latest radar is showing these storms
currently over the central and southwest part of the state and will
continue moving westward through the day. The latest HRRR guidance
has the bulk of these showers and storms over the west coast of
Florida between 2-5 pm later today moving from east to west. Some of
the stronger storms could produce gusty winds and localized flooding
in low lying areas. Seasonal temps are also expected with highs in
the low to mid 90`s and overnight lows in the 70`s. Heat indices
will reach 102-107 each afternoon. The National Hurricane Center is
keeping a close eye on an area in the central Atlantic that has a 40
percent chance of development through 7 days. We will be closely
monitoring this system over the next week for further development.
&&
.AVIATION...
(00Z TAFS)
Issued at 725 PM EDT Thu Aug 29 2024
Similar evening underway with diminishing convection, therefore
held VCSH to open the cycle although that may be generous,
however VFR expected into Friday afternoon when convection with
the E FL sea breeze initiates and pushes west within the easterly
flow over the peninsula, bringing a window of MVFR/IFR chances
mid-late afternoon into the evening before returning to VFR
evening into overnight.
&&
.MARINE...
Issued at 204 PM EDT Thu Aug 29 2024
Easterly winds around 10-15 knots will be in place across the waters
through the period, with a weak sea breeze possible near the coast
each afternoon. Showers and storms will be most likely in the late
afternoon and evening pushing offshore from land. No headlines are
expected.
&&
.FIRE WEATHER...
Issued at 204 PM EDT Thu Aug 29 2024
High pressure to the north ridges across Florida keeping a
predominant easterly wind flow across the region. Scattered to
numerous showers and storms can be expected each day through the
week and into the weekend. No fire weather concerns are expected.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 76 92 76 92 / 40 50 10 70
FMY 76 94 76 91 / 30 70 30 90
GIF 75 93 75 93 / 30 60 10 80
SRQ 75 94 75 92 / 40 50 20 70
BKV 73 94 73 93 / 40 50 10 60
SPG 80 93 79 93 / 40 50 20 70
&&
Sea Breeze Thunderstorm Regime For Friday: 2
Sea Breeze Thunderstorm Regime For Saturday: 2
For additional information on sea breeze regimes, go to:
https://www.weather.gov/tbw/ThunderstormClimatology
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Hurt
DISCUSSION/MARINE/FIRE WEATHER...Wynn
DECISION SUPPORT/UPPER AIR/CLIMATE...Delerme