Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/29/23
Area Forecast Discussion
National Weather Service La Crosse WI
1048 PM CDT Thu Sep 28 2023
.DISCUSSION...(This evening through Thursday)
Issued at 310 PM CDT Thu Sep 28 2023
Key Messages:
- Unusually warm, humid period ahead.
- Dry for most through the weekend despite 20-40% rain chances
north of Interstate 90 early Saturday morning.
WARMING UP INTO THE WEEKEND:
A synoptic pattern change is afoot with upper-level ridging building
into the Upper Midwest into the Weekend. Well above-average
temperatures are likely come Saturday and Sunday with most of the
area seeing afternoon highs in the 80s (>80% chance EPS). Global
deterministic models suggest upper-level ridging remains in place
until midway through next week. Unlike previous stretches of warmer
weather, an unusually moist airmass is progged to span across the
forecast area with NAEFS mean precipitable water values up to two
standard deviations above normal through Tuesday evening. This
translates to dew points in the mid to upper 60s in the current run
of the NBM. Combine the warm and humid conditions and heat indices
could approach 90 in river valley locations on Sunday. A summer
lover`s dream come true... but a fall-loving folk`s foe.
LOW-END RAIN CHANCES:
With the moist airmass present, any subtle perturbations in the mid-
level flow could produce enough lift to cause scattered
showers/storms. The best signal for this in the model guidance
occurs Friday night, but it`s unclear if precipitation will reach
our forecast area or remain to the northwest of the area in central
Minnesota and northwest Wisconsin. That`s certainly where the best
signal currently lies. The next chance for widespread rain chances
doesn`t occur until next week Wednesday when a low pressure system
approaches the Upper Mississippi Valley, but there`s too much spread
in the model guidance to dive into the details of that system at
this time.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1048 PM CDT Thu Sep 28 2023
VFR conditions are expected through the TAF period. Some potential
exists for fog through 12z along and east of the Mississippi River,
however it is uncertain if any patchy fog will get into KLSE with
increasing surface winds to the west and the 29.00z RAP soundings
showing strong winds up to 25 kts just off the deck which leads
to low confidence (10-20% chance) of patchy fog at KLSE.
Otherwise, expecting winds to increase into the afternoon at KRST
reaching around 15 kts and gusting to 20-25 kts from the south and
southeast. Winds will remain around 10-12 kts at KLSE through
most of the TAF period.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...KAA
AVIATION...Naylor
Area Forecast Discussion
National Weather Service Boston/Norton MA
1027 PM EDT Thu Sep 28 2023
.SYNOPSIS...
Slow moving low pressure moving off the mid Atlantic coast with
a boundary extending to the north will bring rain to portions
of southern New England late tonight into Saturday. The rain
will be focused across western CT/MA late tonight and Friday
shifting to SE New England late Friday night into Saturday.
Heavy rainfall is possible, especially across western CT. High
pressure builds into the region Sunday into next week, providing
a stretch of dry weather along with above normal temperatures.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Only minor tweaks to the forecast this evening. Still thinking
the focus for showers overnight will be mainly across portions
of CT, with some showers also possible towards the south coast
of RI and MA. Thought the last runs of the HRRR, RAP and
NationalBlend had a good timing for that idea. Adjusted
temperatures and dew points as well to reflect observed trends.
7 PM Update...
No major changes needed to the forecast. Clouds are starting to
spread into western CT and MA but no rain on the KBOX radar yet
and should hold off until after midnight. Given the clouds and
rather dry airmass, radiation fog isn`t looking likely, however
some models are hinting at the possibility for fog in NE MA
where clouds from the low are less likely to reach.
Previous Discussion...
Upper low moves east from the Gt Lakes as low pres emerges off
the Mid Atlc coast. An inverted trough extending north of the
low will provide a focus for developing rainfall, which appears
will be focused mostly to the SW of BOX CWA. This rainfall will
be enhanced by a developing SE low level jet focused into the
NYC area. While the heaviest rainfall is expected to set up to
the SW, rain chances will increase across western CT/MA,
including the Hartford- Springfield corridor which will be on
eastern edge of this rain area. We increased PoPs here but have
decreasing PoPs further E. In fact, there is considerable dry
air in the 925-700 mb layer across much of northern and eastern
MA tonight which should erode rainfall as it tries to move east,
so mainly dry conditions east of FIT-PVD. Lows range from upper
40s northern MA to low/mid 50s south of the Pike and near the
coast.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Highlights:
* Locally heavy rain Hartford-Springfield area Friday will shift to
SE New Eng late Friday night into Sat
The hi-res and global ensemble guidance are in good agreement on
focus for heaviest rainfall remaining mostly to the SW during
Fri as inverted trough and low level jet do not move much,
keeping a conveyor belt of moisture across this region. Western
CT/MA will be on the eastern edge of the best moisture and lift
with periods of heavy rain possible, especially in the Hartford-
Springfield corridor. We held off on Flood watches here as
consensus of the guidance keeps heaviest rainfall to the west
and SW. If axis of rainfall shifts east, watches will need to be
considered.
The drier air to the east will persist across much eastern and
NE MA where it may remain mostly dry Friday, other than a few
showers. Then Friday night, as the upper low approaches the
northern Mid Atlc coast, the surface low shifts eastward with
increasing easterly low level jet moistening the column and
increasing forcing for ascent. This will result in rain focus
gradually shifting to SE New Eng including RI and SE MA later
Fri night into Sat. The ECMWF is most aggressive with QPF for
this round of rain in SNE as it shows coastal low further N with
a stronger low level jet in New Eng than other global guidance.
However, we leaned toward HREF which is not as aggressive
through Fri night. We will have greater confidence in Sat
forecast with the 00z guidance suite as we get within the HREF
window.
Max rainfall in BOX CWA will be in Hartford-Springfield area
where 1.5-2.5 inches of rain is possible into Sat. However, it
is important to note that rainfall forecast is much higher to
the SW where hi-res guidance indicating high probs of over 5
inches of rain. If there is any eastward shift in the guidance,
flood watches will have to be considered. Rainfall amounts
expected to drop off to the NE and east of the lower CT valley
with the least amount of rainfall across NE MA where less than
0.5" is expected into Sat. But rainfall forecast in eastern MA
will be dependent on how the late Fri night/Sat period evolves
and there is uncertainty with this portion of the forecast.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Points:
* Rain exits Sat - mainly affecting south coastal areas
* Dry weather dominates much of next week with above normal
temps
Weekend looks to start off on a wet note, especially near South
Coast, Cape Cod, and Islands as offshore low and its inverted
trough head farther out to sea. From there, confidence is
increasing on trending toward drier and warmer weather for much
of next week. Multi-model ensemble shows ridging aloft works
across eastern third of country with 500 mb heights rising to
over 582 dm. This should bring highs well into 70s, if not some
lower 80s, by midweek. For now we stuck with NMB guidance but
it`s likely that highs will overperform a bit from what we have
forecast.
Late in week, closed upper low will start to work its way east
from northern Plains and could bring a return to an unsettled
pattern and colder temps, but this should occur after Thu.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Tonight...Moderate confidence.
Areas of stratus with MVFR/IFR cigs developing, but areas
coverage is uncertain. Rain developing and spreading across CT
and portions of western MA. Light E winds.
Friday...Moderate confidence.
MVFR persisting south of the Mass Pike, with mostly VFR to the
north. Rain will be focused across western CT/MA, with locally
heavy rainfall possible across western CT. More spotty showers
further E. E/NE wind 5-15 kt.
Friday night...Moderate confidence.
MVFR/IFR conditions across portions of CT, RI and SE MA with
mainly VFR to the north. Rain focus will shift east to RI and SE
MA.
KBOS Terminal...High confidence in TAF. Should remain VFR into
Fri, although some risk for patchy MVFR cigs later tonight. We
introduced a SCT025 layer to address this.
KBDL Terminal...Moderate confidence in TAF. Lowering cigs to
MVFR tonight with rain developing, mainly after midnight,
continuing Fri.
Outlook /Saturday through Tuesday/...
Saturday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA.
Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA.
Sunday through Monday: VFR. Breezy.
Monday Night through Tuesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Friday night...High confidence.
Generally easterly winds through the period. Gusts to 20 kt
tonight over southern waters, with 25 kt gusts possible over
the southern waters Fri and especially Fri night. SCA in effect
for southern/SE waters for combination of wind and seas.
Outlook /Saturday through Tuesday/...
Saturday: Low risk for Small Craft Advisory winds with local
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.
Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Slight chance of rain
showers.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft.
Sunday Night through Monday: Winds less than 25 kt. Seas up to
5 ft.
Monday Night through Tuesday: Winds less than 25 kt. Areas of
seas approaching 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 4 PM Friday to 8 PM EDT Saturday for
ANZ254.
Small Craft Advisory until 8 PM EDT Saturday for ANZ255-256.
&&
$$
SYNOPSIS...KJC/JWD
NEAR TERM...Belk/KJC/KP
SHORT TERM...KJC
LONG TERM...JWD
AVIATION...KJC/JWD
MARINE...KJC/JWD
Area Forecast Discussion
National Weather Service State College PA
1046 PM EDT Thu Sep 28 2023
.SYNOPSIS...
A cut-off upper low over the Great Lakes and Upper Ohio Valley
will drift east across Pennsylvania tonight through Friday. This
will allow showers to develop across the area tonight and
continue into Friday. Deeper Atlantic moisture may produce some
steadier rainfall over eastern portions of the Lower Susquehanna
River Valley late tonight through Friday afternoon. As the upper
low exits to the east, ridging at the surface and aloft will
build over the region this weekend and remain in place through
at least the first half of next week.
&&
.NEAR TERM /UNTIL 8 AM FRIDAY MORNING/...
All is well...with the forecast. Precip over wrn PA is breaking
up as the upper low gets closer. Will hold high PoPs there for
the next few hrs, but start tapering them after midnight. There
are even some breaks in the clouds over far SWrn PA which could
make a run for the Laurels. Fog is likely should the breaks move
in/materialize. Weak, spotty returns are starting to show up
over the SE where influx of ocean moisture has begun to thicken
up. Latest RAP has the lowest 7-8kft saturated over MDT. Cigs
remain AOA 1kft there thus far, but should drop a little more
and onto the hill tops. Temps will probably just dip 3-4F thru
the rest of the night.
Prev...
Precip closing on us from both sides. Upper vort max associated
with the main upper low very apparent on sat loop this evening.
A 40-50mi wide N-S band of light RA is covering wrn PA and has
been making precip over Warren Co for many hours. Expect the
rain to continue for the next 3-6 hrs as the vort max lifts NNE.
Amounts shouldn`t be of concern, and are totally beneficial to
one of the driest parts of the state.
Prev...
Sfc ridge axis extending from Quebec high center continues to
maintain dry conditions over central PA this afternoon. West of
the ridge axis, a few light showers have advanced ahead of the
approaching Ohio upper low, but have since lifted across the NW
Mountains and are exiting into southwest NY State. Mainly dry
conditions are expected for the balance of the afternoon before
more widespread showers associated with the upper low move
across the Alleghenies this evening.
The upper low tracks over Central PA tonight into Friday,
accompanied by just scattered coverage of showers for most, as
rain shield encounters the drier air and sfc ridge axis.
Eventually the moisture wins out, especially where easterly flow
is forced to ascend the Alleghenies, and areas of drizzle are
likely as well. The main area of focus will be the eastern edge
of the forecast area, which will be on the periphery of enhanced
onshore flow combined with tropical moisture off of the mid
Atlantic coast. Several hours of steady rainfall are likely to
bring a half inch or more of rainfall over eastern Lancaster
County, with lesser amounts over the remainder of the eastern
third of central PA.
&&
.SHORT TERM /8 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
High res CAMs and ensembles are in good consensus with a major
rainfall event targeting the northern mid Atlantic coastal
region and in particular portions of NJ, Long Island including
NYC. We are fortunate that the synoptic setup is just far enough
east for another beneficial rainfall to impact the southeast
part of PA, which is recovering from precipitation deficits for
much of the summer.
Ensemble mean qpf tonight through Friday night is low across
the entire region. However, a few outlier members continue to
indicate heavy rain can`t be completely ruled out for portions
of York and Lancaster Counties. However, overwhelming consensus
is for mean QPF of between a third and three quarters of an inch
over far eastern Lancaster County through Friday afternoon.
It will be cloudy throughout PA through most of Friday as
anomalous easterly flow and slow moving upper low combine.
Rich plume of tropical moisture offshore gets directed to
western Long Island and overruns cool/stable air over the
Northern Mid Atlantic region bringing a long period of moderate
to heavy rain Friday/Friday night there, with much lighter
amounts over central PA. Will continue to monitor the outliers
for any westward shift in heavy rain threat.
Drier, brighter and warmer conditions look likely by Saturday,
as the upper low shifts off the coast. However, lingering cool
temps aloft should promote a good deal of lingering cu/stratocu
per latest forecast soundings.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
An extended period of dry and warm weather is expected through
at least the first half of next week. An upper level ridge will
build over our area early next week and remain overhead for much
of the week. This ridge will set up with the appearance of an
omega block with the center of high pressure over the Ohio
Valley/Mid- Atlantic region. The 1024 high will be overhead on
Monday leading to a dry, sunny day and warm weather for this
time of year with highs reaching the mid to upper 70s. The
surface high will slowly drift to the east through Wednesday
leading to more warm, dry weather.
Toward the end of next week as the high moves farther east, some
southeasterly flow may develop. This could lead to an increase
in clouds east of the mountains and cooler weather, but there is
still a lot of uncertainty if that will unfold. Just something
to keep an eye on for now. A trough may move through next
weekend bringing a round of showers and a return to cooler
weather.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Expect conditions to deteriorate overnight tonight as
widespread clouds will move across the region, with some showers
possible this evening starting off in western PA. Resulting BR
over the western and central PA sites is likely. At the same
time, moist easterly flow will strengthen over the southeast
leading to more IFR cigs at MDT and LNS which will likely last
through at least Friday morning.
Friday morning and early afternoon will likely see mostly MVFR
cigs for most sites. Gradual improvement is possible later
Friday afternoon and into the evening hours, but guidance
suggest it will be a struggle to reach VFR conditions.
Outlook...
Sat-Tue...Areas of AM fog, with clearing by aftn each day.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Fitzgerald/Bauco
NEAR TERM...Dangelo/Bauco
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Travis/Bowen
AVIATION...Travis/Bowen
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
504 PM MDT Thu Sep 28 2023
...New AVIATION...
.SYNOPSIS...
Issued at 238 PM MDT Thu Sep 28 2023
Temperatures will continue to be rather warm through Friday with
record temperatures threatened. Starting Friday evening
thunderstorm chances return, peaking on Saturday. Heavy rain and
flash flooding are the main concerns for Saturday, but a strong
storm cannot be ruled out. By Sunday and Monday, storm chances
mainly confine to east of the Rio Grande before exiting completely
on Tuesday. Temperatures will not be as hot starting Saturday as
well.
&&
.DISCUSSION...
Issued at 238 PM MDT Thu Sep 28 2023
It`s a warm one as we wrap up our final days of September. UL
ridge axis is basically overhead and translating east. A weak s/w
does appear to be riding the front side of the ridge, but with a
lack of moisture, the most it`s producing is mid and high clouds.
Better surface moisture can be found across parts of Hudspeth
County and across Chihuahua. Isolated thunderstorms will be
possible in these locations. The storms across Chihuahua may try
and make a run for the international border, so although not
likely, a stray shower or storm cannot be ruled out this evening.
Moisture begins drawing northward into southern NM and far West TX
on Friday. For the most part, Friday will look similar to today
but with a degree or two of cooling. That is until later in the
afternoon into the evening and overnight hours. HRRR and even to a
lesser degree the global models have been trending more robust
with rain / storm chances. The GFS is probably the most excited
about our prospects, but the HRRR is showing isolated to scattered
activity. This appears to be round 1 of our rainfall with a
possible break or decrease in coverage Saturday morning. An UL
trough/low across the West Coast will continue to sharpen and
strengthen throughout the day Saturday with flow increasing aloft
over our area. Models are indicating a vort max will lift across
the area in the evening and overnight hours, which will combine
with fairly decent height falls to enhance convection. PW values
look to rise well over an inch, possible over 1.4" across eastern
areas, which would be well over the 90th percentile. Any storms
will be efficient rain-makers. This combined with deep southerly
flow will lead to the possibility of back-building and training,
especially along terrain. All this to say, flash flooding is a
concern, especially along and east of the Rio Grande. Therefore,
we have gone ahead with a flood watch for flash flooding in this
area valid Saturday afternoon through early Sunday morning.
500-1000 J/kg of CAPE combined with around 20 knots of bulk shear
also suggest a strong storm or two cannot be ruled out either with
gusty winds and marginally severe hail.
The large, deep UL trough will continue to shift east on Sunday
and Monday. Models have been progressively quicker with this
trough`s passage. As it approaches it will begin to push drier air
into the CWA, which will shove rain and storm chances to the east.
Grids still have POPs for Sunday and Monday along and east of the
Rio Grande, but I wouldn`t be surprised if those pops continue to
decrease and shift east given trends. Winds will also be breezy
during this time period as the H500 jet shifts overhead. The
trough will bring a Pacific front as well, which will drop highs a
bit closer to seasonal norms. Both the GFS and Euro show a s/w
dropping south along the back-side of the larger trough. As it
does so, it will drag Canadian air southward along with it at the
end of the period. Models do not agree on timing though.
&&
.AVIATION...
(00Z TAFS)
Issued at 454 PM MDT Thu Sep 28 2023
VFR conditions are expected through the period with FEW-
SCT110/250. Winds will continue from the W/SW with occasional
gusts 15-20KTS through 03Z. Scattered convection will be possible
to the SW of TAF sites towards the end of the TAF period.
&&
.FIRE WEATHER...
Issued at 238 PM MDT Thu Sep 28 2023
Moisture is expected to increase tomorrow, especially in the
afternoon and overnight hours. Min RH values will range 15-20
percent as a result. Thunderstorms will also be possible late
afternoon onward. Saturday looks to bring even higher rain and
storm chances along with the possibility of flash flooding. Drier
air begins to shift in from the west starting Sunday. Winds for
Friday will top out around 10 MPH but will increase for Saturday
and Sunday, especially along and west of the Divide. Sunday will
feature the strongest winds, but min RH values are expected to
remain in the upper teens and 20s.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 69 96 69 91 / 10 10 40 40
Sierra Blanca 60 89 62 85 / 0 10 40 50
Las Cruces 62 91 62 87 / 0 10 30 40
Alamogordo 62 90 62 86 / 0 10 20 50
Cloudcroft 49 68 48 65 / 0 30 20 80
Truth or Consequences 62 90 61 86 / 0 10 10 30
Silver City 59 83 57 81 / 0 10 10 40
Deming 60 92 60 88 / 0 10 30 40
Lordsburg 61 91 59 89 / 0 10 20 40
West El Paso Metro 67 94 67 90 / 10 10 40 50
Dell City 60 94 63 88 / 0 10 10 40
Fort Hancock 63 96 64 91 / 10 10 40 50
Loma Linda 63 88 62 83 / 10 10 30 70
Fabens 64 95 65 91 / 10 10 40 50
Santa Teresa 63 92 63 88 / 10 10 40 40
White Sands HQ 67 93 65 88 / 0 10 30 60
Jornada Range 62 91 62 86 / 0 10 30 50
Hatch 60 93 61 89 / 0 10 30 50
Columbus 65 91 63 87 / 10 10 30 40
Orogrande 61 90 62 86 / 0 10 20 60
Mayhill 54 80 52 76 / 0 30 10 80
Mescalero 52 79 52 76 / 0 30 20 80
Timberon 52 78 50 73 / 0 20 20 80
Winston 52 82 50 78 / 0 10 10 40
Hillsboro 59 89 57 85 / 0 10 20 50
Spaceport 58 90 59 85 / 0 10 20 50
Lake Roberts 51 82 50 79 / 0 10 20 50
Hurley 59 88 57 85 / 0 10 20 40
Cliff 54 91 53 89 / 0 0 10 30
Mule Creek 57 85 56 83 / 0 0 10 20
Faywood 60 87 59 83 / 0 10 20 50
Animas 60 91 58 89 / 0 10 20 30
Hachita 61 90 59 88 / 0 10 20 40
Antelope Wells 60 90 59 88 / 10 20 20 30
Cloverdale 60 85 58 83 / 0 10 10 20
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch from Saturday afternoon through late Saturday night
for TXZ418>424.
NM...Flood Watch from Saturday afternoon through late Saturday night
for NMZ409>411-414>417-427>429.
&&
$$
FORECASTER...27-Laney
Area Forecast Discussion
National Weather Service Houston/Galveston TX
554 PM CDT Thu Sep 28 2023
...New AVIATION...
.SHORT TERM...
(This evening through Friday Night)
Issued at 234 PM CDT Thu Sep 28 2023
Broadly speaking, the main surface weather feature over the region
is high pressure over the mid-south, and flow is east...ish. The
ish comes from a couple weak surface troughs over the Gulf. While
this has helped spur some isolated showers and storms over the
Gulf waters and immediate coast, this also has backed flow to
being a little more coast-parallel or even slightly offshore for
much of the area, and convection north of I-10, or even much in
front the coast looks increasingly unlikely. Some HREF members
and, pretty persistently, the HRRR are trying to spur isolated
showers in all parts of Southeast Texas. They may be a bit
overconvective, but in a nod to their insistence, I do have some
15-20 PoPs for most everywhere this afternoon into this evening.
Tomorrow...pretty much a lot of the same? One trough/weak low
pressure center should scrape more westward toward our area near
the northern Gulf coast, and that should boost coverage of showers
and storms over the Gulf waters for sure, and probably the very
immediate coast. But in general, I`d expect that low level ridging
in roughly the 850-700 mb layer to keep things under control,
especially the more you get inland and away from both a small vort
max in the mid-levels and the lower pressures over the Gulf.
Temperature-wise...not much change expected. Plentiful low-level
moisture should keep the temp floor high, with lows in the 60s in
the Pineywoods, low 70s elsewhere, and upper 70s to around 80 on
the Gulf coast both tonight and tomorrow night. For daytime highs,
continued expectation is for lower 90s closer to the Gulf,
increasing to the mid-90s inland. For those who manage to dodge
not only the low rain chances (not so hard) but also any of the
day`s fair weather cumulus (also not so hard, but a bit more
difficult), the hot spots may well push into the upper 90s. See,
College Station and its highs ranging from 97-102 the past week.
Change? When? Sorry, I don`t understand that question. Please ask
the long term forecaster.
&&
.LONG TERM...
(Saturday through next Wednesday)
Issued at 400 PM CDT Thu Sep 28 2023
The mid/upper air pattern amplifies during the Saturday-Monday time
frame, pushing 500 mb heights above 590 dam across southeast Texas.
In the low-levels, the orientation of high pressure well to our
northeast will enhance easterly flow from the Gulf. Global ensembles
show PWs averaging 1.25" to 1.75" (potentially higher near the
immediate coast). Other than a few vort maxes embedded in the
mid/upper flow, we do not see any systems capable of significant
lift during this time frame, especially considering the increased
ridging. However, relatively high PWs coupled with diurnal processes
and those pesky little vort maxes are expected to suffice for some
isolated to widely scattered shower and thunderstorm activity this
weekend into early next week, primarily over our southern counties.
Highs remain in the 90s with lows generally in the 70s. Conditions
will be muggy. However, some of that humidity is likely to mix out
during peak heating hours across the northern half of the CWA.
As we creep closer to mid-week, we do see some signs of a possible
pattern change. The aforementioned amplified pattern not only
suggests the presence of a ridge, but a trough as well. The pattern
may become progressive enough to allow these features to propagate
eastward, eventually placing the Lone Star State under the influence
of a deep mid/upper trough that is expected to build southward over
the western United States this weekend and early next week. For now,
global models and their ensembles suggest the bulk of this pattern
change doesn`t occur until the very end of the forecast period or
slightly beyond. Also worth mentioning is the PoPs uptick that
occurs at the end of the forecast period due to the potential
of.....do I dare say it.....an approaching cold front. The front
remains too far out into the long range to become too excited about.
But it is the most promising sign of a "real" cold front we have
seen in a while. Only time will tell!
Self
&&
.AVIATION...
(00Z TAF Issuance)
Issued at 554 PM CDT Thu Sep 28 2023
Could see more SHRA/TSRA development in the next hour or two as area
boundaries collide. Look for anything that does form to weaken and
dissipate this evening with the loss of heating. Some patchy MVFR fog
could form overnight (mainly in/around today`s rain areas), and we
could get SHRA/TSRA development near the coast and offshore before
or shortly after sunrise. TAF sites are expected to be VFR during
the day tomorrow (away from any storms). Going with VCSH once again
in the mid afternoon through early evening hours. Anything that does
develop should be gone by around or shortly after sunset. 42
&&
.MARINE...
Issued at 234 PM CDT Thu Sep 28 2023
Generally light to occasionally moderate winds and low seas will
prevail through Friday. A longer fetch of moderate east winds is
forecast to set up across the Gulf this weekend into Monday,
which will gradually increase seas. Caution flags may be warranted
at times. There will be a daily risk of isolated to scattered
showers and thunderstorms. Locally higher winds and seas are
possible in and near any thunderstorm.
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 73 97 72 95 / 10 0 0 10
Houston (IAH) 74 95 74 94 / 10 10 10 20
Galveston (GLS) 80 90 81 88 / 30 30 30 40
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
935 PM CDT Thu Sep 28 2023
.SYNOPSIS...
Issued at 926 PM CDT Thu Sep 28 2023
High pressure will be centered over the Great Lakes and Midwest
through the weekend into the middle of next week providing dry and
warm weather across central Illinois. Fog is possible again
tonight mainly along and north of I-74 and across portions of east
central Illinois. Temperatures will fall into the mid to upper
50s tonight, then warm into the 80s each day Friday through
Wednesday.
&&
.UPDATE...
Issued at 926 PM CDT Thu Sep 28 2023
Fog remains the main forecast concern overnight as dewpoint
depressions shrink beneath clear calm sky. Afternoon HREFv3
guidance supported 50-70% probabilities of 1/2 mile visibility
overnight in locations along and north of I-74. And while the
NBMv4.1 was less aggressive in its probability, it painted a
similar areal footprint with locations along and north of I-74
having the best chance for impactful fog.
Some uncertainty still remains as far as coverage and whether
dense fog will be widespread enough to warrant an advisory.
Despite the favorable radiation fog setup that we have in place,
overnight forecast lows are not exactly falling below the
crossover temperature -- at least not on a widespread enough
basis.
Some of our more recent guidance from the HRRR and GLAMP suggest
the axis of dense fog may develop just north of our cwa into
northern Illinois.
We will take a more reactive approach, for now, on a potential
advisory and let the observational trends dictate the product.
MJA
&&
.DISCUSSION...
Issued at 225 PM CDT Thu Sep 28 2023
---------- Key Messages ------------
1. Areas of dense fog will be possible across portions of the I-74
corridor and east central Illinois late tonight into Friday
morning.
2. A warm and dry stretch is likely Friday though Tuesday. High
temperatures could reach the mid to upper 80s in some locations
Saturday.
------------------------------------
This afternoon, high pressure is over the Great Lakes with
ridging extending back across the Upper Midwest. Northeast winds
in place today will veer to southeasterly Friday, but should
remain light, 5 to 10 mph or less. Main concern overnight will be
for fog development. Guidance is most bullish over NE IL into
Indiana closest to the surface ridge axis, and does bring some of
the densest fog potential to portions of the I-74 corridor and
east central Illinois, though at least patchy fog is possible area
wide. Upper Ridge will build across the mid and upper Mississippi
Valley Friday and should allow skies to become mostly sunny by
afternoon and allow warmer temperatures into the region. After
temperatures dip into the mid 50s overnight, temps will warm into
the upper 70s (north of I-74) to mid 80s Friday afternoon.
As upper ridge continues to amplify over the weekend into an Omega
Block, temps into the 80s will be in place area wide and are
expected to continue into Monday and Tuesday of next week.
Saturday looks to be the warmest day with temps in the mid to
upper 80s. NBM indicates that there is a chance (25-40 percent)
for temps to reach into the 90s across portions of the lower
Illinois River Valley. Daily temperature records are in the lower
90s Saturday (91 PIA / 92 SPI / 93 ILX), so we may be close but
those records appear to be safe for now.
Upper ridge will begin to buckle midweek while at the surface, a
cold front will push into the Midwest Wednesday and Thursday. This
will bring the next chance for showers and thunderstorms to the
region with more seasonable temperatures returning to central
Illinois in its wake the latter half of next week.
Deubelbeiss
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 549 PM CDT Thu Sep 28 2023
A lingering high pressure ridge will aid mostly clear skies
through 06z/1am with areas of dense fog then developing
overnight, particularly along the I-74 terminals (CMI/BMI/PIA).
Confidence is increasing that visibility will become reduced due
to fog, with overnight temperatures forecast to fall below the
crossover temperature and model guidance also showing a strong
signal for fog. Visibility may fall below 1 mile at times,
offering the potential for LIFR conditions around 12z/7am.
MJA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Paducah KY
648 PM CDT Thu Sep 28 2023
.UPDATE...
Issued at 648 PM CDT Thu Sep 28 2023
Updated aviation discussion for 00Z TAFs.
&&
.SHORT TERM...(Tonight through Saturday night)
Issued at 140 PM CDT Thu Sep 28 2023
An upper level low continues to work its way east over Michigan and
the eastern Great Lakes today. An attendant front is moving through
the area today propelled by the passage of the upper low. Storms we
were seeing this morning have moved out of the area off to the
southeast and although we could see another weak/spotty shower or
two pop up along the front, we should be mainly dry the rest of the
day. Highs today will warm into the 80s with the exception of areas
of the southeast that saw rain and cloud cover through this morning
(such as around the Hopkinsville area). Right now there is low
confidence regarding fog potential tonight due to the possibility of
scattered cloud cover. The HRRR and the SREF are indicating against
any significant fog formation, but given the amount of moisture near
the surface it can`t be entirely ruled out. Overnight lows will be
in the 50s out east and 60s out west.
Tomorrow an upper level ridge axis moves overhead and will help to
keep us dry and warm. While highs tomorrow look to be in the 80s,
just how far into the 80s is a little less certain with higher dew
points in the upper 60s to near 70 being a mitigating factor.
Ridging will continue to be in place for several days and we will
therefore be warmer than average again on Saturday. Expect highs in
the mid to upper 80s mostly, but a few places could see 90.
.LONG TERM...(Sunday through Thursday)
Issued at 140 PM CDT Thu Sep 28 2023
High pressure continues into Sunday with high temperatures in the
mid 80s. There is a consistent signal within the NBM and GEFS that
ridging will continue through the majority of the period from Sunday
onward as a trough amplifies over the Rockies. There is little
support for the trough to move until late in the period. Therefore,
the forecast through the week will likely mimic Sunday`s until the
pattern changes with the western trough translating east.
Ensemble guidance is in fairly good agreement with the
aforementioned trough arriving towards the end of the period
(Wed/Thur). However, the last several runs of both deterministic and
ensemble guidance have shown considerable variability in the many
facets of the structure of such a passage. Most of the variability
appears to be coming from the interaction with a strong polar trough
and the meandering low from the Rockies. The speed of the polar
trough has slowed down considerably to a point where its
amplification is also in question in the time frame that these
features would potentially phase. These effects are further
compounded by the influence of a blocking pattern setting up over
the north Atlantic during the week as well. In all, there is good
ensemble support for the passage of a new system sometime later
in the week with most fine details needing time to iron out.
&&
.AVIATION...
Issued at 648 PM CDT Thu Sep 28 2023
VFR conditions are forecast through the evening, then again
through much of tomorrow. After midnight tonight and early Friday
morning, the development of patchy fog is expected. Maintained
the mention of MVFR visibility at all forecast terminals during
that time frame for now. There is some potential for temporary
reductions to IFR, but confidence is low at this point, so will
reassess later this evening. Light easterly winds tonight will
gain a somewhat more northerly component tomorrow.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...RJP
SHORT TERM...SHAWKEY
LONG TERM...SHAWKEY/JAB
AVIATION...RJP
Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Thu Sep 28 2023
.Update...Updated Aviation
&&
.SYNOPSIS...
Dry conditions will continue through this weekend with near to
above normal temperatures continuing through Friday. A weather
system moving into the region will bring increasing winds and much
cooler temperatures heading into this weekend with the strongest
winds occurring on Saturday. Below normal temperatures settle
into the region by Sunday before gradually warming back up next
week.
&&
.DISCUSSION...
Dry conditions with above normal temperatures continue this
afternoon as dry westerly flow aloft continues across the region.
However, we are expected to shave a few degrees off our afternoon
highs compared to yesterday as the influence of the subtropical
ridge to our south continues to weaken and influence from the
strong trough centered near the Pacific Northwest increases. RAP
analysis this afternoon showed 500 mb heights around 584-586 dm
for our area indicating lowering heights compared to this time
yesterday, which were around 590 dm. Heights will continue to
gradually lower over the next couple of days as a shortwave
trough embedded in the overall large scale trough is set to dive
toward the south, reaching the northern part of California by
Friday evening. This will translate to temperatures continuing to
cool for tomorrow with near to slightly above normal temperatures
tomorrow afternoon. Daytime highs tomorrow will fall into the
upper 90s to around 100 degrees across the lower deserts.
As the trough digs south and approaches our region, it will allow
winds to increase over the next couple of days. Winds will initially
be strongest for southwest Imperial County, where gusts are expected
to climb in excess of 40 mph starting Friday afternoon. Elsewhere,
wind gusts Friday afternoon look to climb upwards of 15-25 mph in
most areas, but the strongest winds will come Saturday as the trough
deepens and moves into the Nevada and central/southern California
region. The will promote strong height falls across the region
Saturday and lead to widespread strong winds. Guidance continue to
indicate that peak wind gusts will climb upwards of 30-40 mph for
most areas Saturday afternoon with locally higher gusts expected
across Imperial County and the high terrain east of Phoenix. The
latest NBM continues to show high probabilities (>70%) of peak wind
gusts in excess of 40 mph across the aforementioned areas with
probabilities now in excess of 90% across Imperial County. Thus, a
Wind Advisory has been issued for much of Imperial County and
southern Gila County for Saturday afternoon and early evening. Winds
of this magnitude will have the potential to create some areas of
blowing dust, particularly in dust prone areas of southeast
California and Pinal County, which could lead to reduced
visibilities. Additionally, strong winds combined with dry
conditions across south-central Arizona will lead to elevated to
potentially critical fire weather conditions across Maricopa,
Pinal, and southern Gila Counties. Thus, a Fire Weather Watch
remains in effect for these areas. Out to the west, cooler
temperatures and higher moisture will help minimize greater fire
weather concerns.
Guidance continue to show a cold front pushing through the area
during the latter part of Saturday into Sunday. Ensembles show
increased moisture along and ahead of the front with PWATs generally
increasing into the 0.70-.090" range. However, even with this bump
in moisture rain chances are expected to remain very low across the
CWA with the best chances remaining across the northern Arizona high
terrain. Although we will be looking at minimal rain chances with
this weather system, a cooler air mass will lead to temperatures
dropping below normal by Sunday when daytime highs fall into the 80s
across the lower elevations. By Monday morning, low temperatures are
expected to dip into the upper 50s to low 60s. These will be the
coolest temperatures seen since early May.
Going into early next week, negative height anomalies will persist
across the Southwest CONUS as the trough slowly moves eastward.
Ensemble clusters currently favor ridging building back across the
West heading into the latter part of next week, which will allow for
temperatures to return back closer to near seasonal normal readings
by mid next week and potentially slightly above normal toward the
end of next week.
&&
.AVIATION...Updated at 2320Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected during the TAF period.
Winds will continue to follow diurnal trends, with speeds
generally remaining below 12 kts. Besides a FEW lingering mid-
level clouds this evening, skies are expected to be mostly clear
through tomorrow morning.
&&
.FIRE WEATHER...
Dry conditions will persist through the end of the week with near
to above normal high temperatures continuing through Friday.
Afternoon Min RHs Friday will be in the 10-20% range for most
areas before increasing to around 20-30% across the western
districts Saturday. Overnight Max RHs tonight will increase to
around 30-60% in most places with locally higher values around
70%, particularly in the Yuma and Imperial Valley areas. Winds
will increase over the next couple of days with the strongest
winds expected on Saturday. Gusts Saturday afternoon upwards of
30-40 mph are likely in many areas with locally higher gusts
across Imperial County and the southern Gila County high terrain.
Strong winds combined with low RHs Saturday will lead to elevated
to possibly critical fire weather conditions across south-central
and eastern Arizona. Starting Sunday, winds will begin diminishing
day to day with winds returning to normal by Tuesday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Fire Weather Watch from Saturday morning through Saturday
evening for AZZ132-133.
Wind Advisory from 11 AM to 7 PM MST Saturday for AZZ556>558-
560>563.
CA...Wind Advisory from 2 PM to 10 PM PDT Saturday for CAZ563>567.
Wind Advisory from 5 PM Friday to 5 AM PDT Sunday for CAZ562.
&&
$$
DISCUSSION...Smith
AVIATION...RW
FIRE WEATHER...Smith