August 2021: Major Hurricane Ida/SE Louisiana Landfall

[DoctorMu]

This has been a pleasant August. As much as I hate Summer, I have to admit, that I haven't seen scattered storms like this (in August) in quite a long time. I've tallied an inch over the last several days from rain that lasted 20-45 minutes a day.

Summer's last hurrah happens next week before we turn cooler and welcome Fall!

Back to reality for a week. But at least it's only a week before subsiding to the low 90s for highs.

[DoctorMu]

Predictions:

First legit cold front with lows in the 50s?

I'm going to continue our "cool" pattern and predict an early break on CLL: October 2nd.

[tireman4]

MontgomeryCoWx yeah ill be 21 in 11 days haha, but im majoring in environmental studies, weather is more of a personal hobby to me , and yup im attending every home game, never been to an aggie game but heard they are a lot of fun

You could double major..

[Stratton20]

Tireman4 I could, but the thing is meteorology requires some advanced math courses and I am not a math person

[DoctorMu]

Math's not for everyone...but math is the language of the Universe. It sets the rules, defines the gridiron. I will say the math involved in fluid systems, cyclone/vortices is really wicked stuff...not to mention the complexity/chaos involved in weather modeling iterations.

[Stratton20]

DoctorMu oh I imagine it is, the math involved is pretty tough stuff but its important, my brain would probably have a melt down when it comes to that haha but I can at least understand the importance or significance of calculations being done especially by the hurricane hunters when they are flying in a storm

[TxLady]

Good Evening All,

I have been watching Fred, and of course Grace. I had heard a few mentions of Henri; but, really wasn't paying attention to a system so far removed from us. This afternoon it suddenly hit me: my Daughter is leaving for Boston, tomorrow afternoon. This is a working trip, with a couple of days of personal time in Providence, RI. She doesn't return home until next Wednesday (8/25). If anyone has any opinions on the future track/intensity of Henri in reference to New England, I'd REALLY appreciate hearing them.

[Stratton20]

TxLady even though im not a weather expert, I would strongly advise your daughter to keep up to date with the forecast regarding Henri as it could Impact the NE Coast around that time, still uncertainty if it makes landfall or if Henri just passes uncomfortably close to the east

[srainhoutx]

Good Evening All,

I have been watching Fred, and of course Grace. I had heard a few mentions of Henri; but, really wasn't paying attention to a system so far removed from us. This afternoon it suddenly hit me: my Daughter is leaving for Boston, tomorrow afternoon. This is a working trip, with a couple of days of personal time in Providence, RI. She doesn't return home until next Wednesday (8/25). If anyone has any opinions on the future track/intensity of Henri in reference to New England, I'd REALLY appreciate hearing them.

Hi TxLady. Right now the NHC forecast track is offshore, as is typical there is some uncertainty in the 5 day forecast scheme. Fingers crossed that Henri remains offshore of New England and only brings increased tides, rip currents and rough Seas to the NE Coast.

Tropical Storm Henri Discussion Number 13
NWS National Hurricane Center Miami FL AL082021
1100 PM AST Wed Aug 18 2021

Henris appearance this evening is one of a tropical cyclone that is
battling vertical wind shear. The satellite structure has evolved
into a large convective plume with overshooting cold -70 to -75 C
cloud top temperatures near the center of the convective mass.
Underneath the cirrus, Henris structure has remained steady-state,
with a SSMIS pass at 2243Z showing a ragged mid-level eye on the 91
GHz channel that remains displaced a bit southeast of the low-level
signature on 37 GHz. The latest satellite intensity estimates have a
large spread in values ranging from 55-kt up to 80-kt. I have
elected to maintain Henris intensity at 60 kt for this advisory,
but there is a larger than normal uncertainty in this estimate.

The initial motion continues to be just south of due west at 265/8
kt. The short-term track guidance is in general agreement that Henri
will continue a general westward motion for the next day or so, as
the cyclone is caught to the south of a pronounced mid- to
upper-level ridge. However, the models disagree on how far westward
Henri is able to advance in the short-term, and these track
differences appear to be related to Henri's intensity and vertical
depth of the circulation. This track dependency is nicely
illustrated by the most recent ECMWF ensemble guidance, where
stronger members move further south and west in the short-term,
ending up on the left-side of the ensemble mean, while weaker
members move slower and more poleward. The deterministic guidance is
similar, with the weaker ECMWF and Canadian runs off to the
east/right while the stronger GFS and UKMET runs are further
left/west. These short-term track differences appear pivotal,
because the ridge over Henri is then expected to quickly erode as a
mid-latitude trough digs in over the Ohio Valley and becomes
negatively tilted over the Mid-Atlantic. The leftward track guidance
has Henri interacting with this trough leading to a track forecast
much closer to the northeastern US, while the rightward track
guidance is not captured by this feature, and stay further offshore
escaping out to sea. In general, the mean of the track guidance is
very similar, or just a shade to the right of the previous cycle. I
have elected to maintain a very similar track to the previous
advisory, splitting the difference between the previous forecast
just left, and the reliable HCCA consensus aid just right. As
mentioned previously, a NOAA Gulfstream IV aircraft has been
scheduled to investigate the synoptic environment of Henri tomorrow
and will hopefully provide more data ingested into the model
guidance to reduce the large track spread seen in the current cycle.

Henri is now under moderate northerly shear that is forecast to
increase to 25-30 knots over the next 24 hours. While this would
ordinarily weaken the tropical cyclone, the system also remains
under very warm 29-30 C sea-surface temperatures that are somewhat
above normal for this time of year. Due to these offsetting factors,
the latest NHC intensity forecast maintains Henri at 60-kt for the
next 24 hours. Afterwards, the shear is forecast to decrease as the
storm turns more poleward directly under the upper-level ridge axis.
This favorable synoptic pattern should allow Henri to intensify and
gradual intensification is shown up to a 80-kt peak in 72-h. The NHC
intensity forecast is more or less in the mean of the large guidance
spread, though it should be noted that the regional hurricane models
(HWRF, HMON, COAMPS-TC) have somewhat stronger peak intensities
later in the forecast period.

Key Messages:

1. The forecast track of Henri remains near the northeast coast of
the U.S. this weekend and early next week, and the risks of storm
surge, wind, and rain impacts in portions of the northeastern U.S.
and Atlantic Canada remains a distinct possibility. Interests in
these areas should closely follow the progress of Henri and check
for updates to the forecast.

2. Swells from Henri will begin to reach much of the east coast of
the U.S. and Atlantic Canada by the end of the week and continue
through the weekend. These swells could cause life-threatening surf
and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 29.8N 68.5W 60 KT 70 MPH
12H 19/1200Z 29.8N 69.9W 60 KT 70 MPH
24H 20/0000Z 30.0N 71.8W 60 KT 70 MPH
36H 20/1200Z 30.7N 72.7W 65 KT 75 MPH
48H 21/0000Z 32.3N 72.8W 70 KT 80 MPH
60H 21/1200Z 34.4N 71.8W 75 KT 85 MPH
72H 22/0000Z 36.9N 70.7W 80 KT 90 MPH
96H 23/0000Z 40.4N 69.4W 70 KT 80 MPH
120H 24/0000Z 41.8N 68.3W 60 KT 70 MPH

$$
Forecaster Papin/Beven

[DoctorMu]

Henri is going to be a summer Nor'easter (aka Hurricane) off the Massachusetts coast. It's not a large storm, but will have an impact on Boston (tropical storm conditions), and especially Cape Cod (possibly hurricane conditions).

[jasons2k]

Morning update from Jeff:

Hurricane Graces makes landfall over the eastern Yucatan

Discussion:
Grace made landfall this morning south of Cozumel with winds of 80mph. Prior to landfall a USAF mission recorded flight level winds around 75kts which equal surface winds near 65kts. While sea surface temperatures over the NW Caribbean are extremely warm, dropsonde data showed mid level dry air which helped to prevent any sort of rapid intensification with Grace.

Track:
Grace continues to move west along the south edge of a well defined and building mid to upper level ridge of high pressure over the northern Gulf of Mexico. This ridge of high pressure will force Grace W or WSW over the Bay of Campeche and into the eastern coast of MX over the next 48 hours. There is little spread in the track consensus aides and the official NHC forecast track is along and just north of the multi-model consensus. This is a high confidence forecast.

Intensity:
Grace will weaken some while crossing the Yucatan, but conditions over the Bay of Campeche are very favorable for intensification with warm sea state and little vertical wind shear. Once Grace is able to reform an inner core, intensification is likely and there could be a period of quick intensification as Grace nears the coast. The forecast calls for Grace to make landfall as an 80mph hurricane, but Grace could be stronger.

TX Impacts:
Direct impacts of Grace will remain well south of TX, however indirect coastal impacts will be likely starting tomorrow and lasting into the weekend. As the wind field spreads across the southern Gulf and Bay of Campeche, large long period swells will be generated and arrive along the TX coast late Friday into the weekend. Swells will reach 6-9 ft across out coastal waters over the weekend and combined with already higher than normal tides minor coastal flooding will be possible as early as Friday and then into the weekend especially on the Gulf facing beaches where wave run-up will be the greatest. Water levels of 3.0-3.5 MLLW (above the barnacle level) will be possible at high tides on Saturday. There will also be a significant rip current risk along the entire TX coast this weekend.

[Stratton20]

00z Euro now on board with a potential CAG system and 06z GFS continues to show this idea about 10 days or so from now

[Cpv17]

00z Euro now on board with a potential CAG system and 06z GFS continues to show this idea about 10 days or so from now

Yeah it’s going to be interesting to see where it starts consolidating because if it consolidates too far south and west then it could just go into Mexico. It’s also going to be interesting to see where the trough is going to be because a trough could pull it northward.

That’s saying if even anything develops or not. Could be nothing.

[tireman4]

000
FXUS64 KHGX 191037
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
537 AM CDT Thu Aug 19 2021

.AVIATION...

Deep tropical moisture will gradually decrease today but it looks
sufficient to generate another round of showers and thunderstorms
later this morning into the early afternoon. Coverage should be
less than yesterday as upper level ridging expands into the area.
Will only carry a vicinity for now and will TEMPO based on radar
trends. Generally VFR for the next 24 hours. 43

&&

.PREV DISCUSSION... /ISSUED 359 AM CDT Thu Aug 19 2021/

SHORT TERM [Tonight Through Saturday]...

Showers continue to develop and move inland overnight with the
highest concentration of showers over the eastern half of the CWA.
Moisture remains plenty deep early this morning with satellite
derived PW values between 2.20 and 2.30 inches. Moisture will remain
deep through 18z with drying expected in the afternoon as upper
level ridging over the north central Gulf expands westward. Fcst
soundings show convective temperatures in the upper 80`s but that is
mainly this morning as by afternoon the temperature profile shows
weak capping developing around 850 mb. Will go with chance PoPs
today with the higher rain chances over the east closer to the pool
of deeper moisture. MaxT values will warm a bit compared to
yesterday with MaxT values in the lower/middle 90`s.

Precipitation will end shortly after sunset if not earlier with the
loss of heating. It will remain warm overnight as winds don`t fully
decouple and fcst soundings show some potential for mid/high level
clouds. MinT values will only cool into the lower 80`s along the
coast and mid upper 70`s inland.

850 mb temperatures warm on Friday and it will feel like mid August
with MaxT values warming into the mid and upper 90`s. There could
still be some showers/storms with heating but convective
temperatures warm to 93-95 degrees so coverage will be isolated.
Fcst soundings show some dry air in the 850-500 mb layer and the
current thinking is that some of the dry air will mix to the surface
lowering sfc dew points just enough to keep heat index values below
advisory criteria. It is something that will need to be watched
closely as HI values are progged to reach 106 degrees so there is
not much room for error. Either way, it will be hot and the usual
heat safety rules apply,. Stay hydrated with water, find shade,
don`t overexert yourself if working outdoors etc... It will remain
warm Friday night with winds providing enough mixing to keep MinT
values in the lower 80`s near the coast and mid/upper 70`s inland.

43

LONG TERM [Saturday Through Thursday]...

A ridge of high pressure over Texas will be the dominating feature
through most of the long term period. This high pressure will
strongest over the weekend through Monday bringing minimal rain
chances and hot weather. Afternoon high temperatures will be in the
upper 90s through the weekend along and north of I-10 with slightly
lower temperatures down along the coast. The northern half of the
area, including the Houston Metro area, will approach triple digit
heat Sunday through Tuesday. There will be a relatively dry airmass
over Texas which will help keep heat indices from climbing to the
extremes, but still expecting them to climb to around 105 degrees
through Monday. The high pressure begin to weaken and slide north
Tuesday and Wednesday which will allow for higher PWATs to slide in
from the Gulf making the already hot conditions feel even hotter.
The increase in moisture will also bring higher precipitation
chances Tuesday through Thursday. Precipitation these days will be
mainly diurnally driven showers and thunderstorms that start out
near the coast and move inland through the day.

Fowler

MARINE...

Small craft should continue to exercise caution through at least the
morning as moderate onshore flow persists. Winds will decrease
slightly through the day, but expected to increase overnight tonight
to near SCEC criteria. Wave heights are expected to increase through
Saturday in response to Hurricane Grace moving through the Bay of
Campeche. Wave heights will be increasing to 4 to 6 feet by Friday
morning, then to 6 to 9 feet overnight Friday into Saturday morning.
Seas will then decrease through the day on Saturday, returning to 3
to 5 feet on Sunday. The increased wave heights will not be the only
impact from Grace churning to the south. The risk of rip currents
will be high through at least Saturday. There is also possibility of
some minor coastal flooding during times of high tide due to wave
run-up and elevated tides around 3.5 feet above MLLW. To include
both the threat of rip currents and the minor coastal flooding, a
Beach Hazard Statement has been issued. This may need to be upgraded
to a Coastal Flood Advisory for the high tide on Saturday. More
tranquil marine conditions are expected next week as high pressure
settles in.

Fowler

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 94 77 96 76 96 / 30 10 10 0 10
Houston (IAH) 95 79 97 77 97 / 40 20 30 0 20
Galveston (GLS) 91 84 91 84 91 / 40 10 10 0 20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Beach Hazards Statement through Saturday morning for the
following zones: Bolivar Peninsula...Brazoria Islands...
Galveston Island...Matagorda Islands.

GM...NONE.
&&

$$

Discussion...99
Aviation/Marine...99

[srainhoutx]

Look for a quiet period the next 10+ days or so as a big surge of African dust moves across the MDR into the Caribbean Sea. Typically SAL outbreaks end in mid August as we transition to the climatilogical peak of Hurricane season near mid September. I do see growing indications of a robust CCKW moving into the Atlantic Basin as the Calendar flips to September. That low riding tropical wave that Scott747 mentioned yesterday is still showing up and for some clarification, it's not a CAG the GFS is sniffing out. Keeping an eye on the SW Caribbean as September begins...

[captainbarbossa19]

Look for a quiet period the next 10+ days or so as a big surge of African dust moves across the MDR into the Caribbean Sea. Typically SAL outbreaks end in mid August as we transition to the climatilogical peak of Hurricane season near mid September. I do see growing indications of a robust CCKW moving into the Atlantic Basin as the Calendar flips to September. That low riding tropical wave that Scott747 mentioned yesterday is still showing up and for some clarification, it's not a CAG the GFS is sniffing out. Keeping an eye on the SW Caribbean as September begins...

Most of the dust is actually forecast to pass north of the Caribbean.

https://cyclonicwx.com/models/geos5/atl/uv10/

[tireman4]

Many thanks to our long range forecaster Srain for all he has done and continues to do for we on this board. A hearty thank you!

[Stratton20]

srainhoutx hope that dust stays away from the gulf, im already coughing and sneezing enough lol

[tireman4]

Another reason my runs have been brutal....dewpoints in the upper 70's/low 80's. The water is just "hanging in the air". Sigh.

[captainbarbossa19]

srainhoutx hope that dust stays away from the gulf, im already coughing and sneezing enough lol

I agree. There is something in the air that made my asthma horrible yesterday and Tuesday. Today, it is better but I do not need more dirty aerosols.