October: Chilly Halloween Outlook

General Weather Discussions and Analysis
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jasons2k
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Massive core dump at my house...
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MontgomeryCoWx
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2 inches in magnolia!
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tireman4
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226
FXUS64 KHGX 291537
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1037 AM CDT Tue Oct 29 2019

.SHORT TERM [Today Through Tonight]...
Cluster of storms in Colorado/Austin county moving slowly
northeastward along the intersection of the warm front and cold
front. Good deal cooler today near College Station/Caldwell today
than Houston/Galveston separated by the boundary. Cold front
should stall with some slight east to west wobbles then very
slowly shift back west this evening but will probably be short
lived as speed max evident around 200 mb tracks into the area and
exit region impinges on the area with an increase in development
of showers and isolated thunderstorms.
45


&&

.MARINE...
Updated to add another SCEC for the Bolivar nearshore waters and
for Galveston Bay where corridor of tighter gradient winds has
returned. Seas in the nearshore building and rough with elevated
tide levels. Winds may relax a little this evening.
45

&&

.PREV DISCUSSION /Issued 655 AM CDT Tue Oct 29 2019/...





.LONG TERM [Thursday Morning Through Tuesday]...
By Thursday morning, the cold front should have pushed through the
upper Texas Gulf waters, but we could see some lingering showers and
thunderstorms. There remains some strong signals in the mid layer
frontogenesis parameters along what looks to be the 850 mb frontal
boundary. The chance for precipitation looks to linger until early
afternoon Thursday across our coast from Matagorda to Chambers
counties and over the bays and Gulf waters. That said, Thursday
morning will likely start of gloomy and gusty, with lingering cloud
cover across much of the region and sustained northerly winds
between 15 to 25 mph, with the stronger winds more focused along the
coast. By the early evening hours, and just in time for Halloween
festivities, conditions should be on the dry side with clouds
clearing, partly cloudy becoming mostly clear, along with gusty
conditions to compete with. Temperatures will also be on the chilly
side, as by late afternoon temperatures are expected to be in the
upper 40s to 50s dropping in the evening hours into the low 40s to
50s. Overnight low temperatures will eventually bottom out close to
freezing (across Houston and Madison counties) to the upper 40s
along the coast. Therefore, an isolated Freeze Warning may be needed
for Houston and Madison counties Thursday night into Friday morning.

Friday will definitely feel like a Fall-like day, with high
temperatures only reaching into the mid 50s to low 60s across SE TX,
with clear skies overhead and breezy conditions. 850 mb temperatures
are still showing a secondary surge of colder air on Saturday as
indicated in previous runs, with the ECMWF remaining the most
aggressive of the global models. Upper-level ridging and breezy
conditions should prevail through the weekend. Dew points remain in
the 30s to 40s through essentially early Monday when onshore flow
eventually returns along with the return of better moisture.

Hathaway


&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 71 60 66 39 53 / 90 60 90 70 10
Houston (IAH) 78 69 79 45 56 / 40 20 80 90 20
Galveston (GLS) 75 72 77 50 59 / 30 10 70 70 40

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...Gale Watch from late Wednesday night through Thursday evening
for the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM...Galveston
Bay...Matagorda Bay...Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.

SMALL CRAFT SHOULD EXERCISE CAUTION until 7 PM CDT this evening
for the following zones: Coastal waters from High Island to
Freeport TX out 20 NM...Galveston Bay...Waters from High
Island to Freeport TX from 20 to 60 NM.


&&

$$

SHORT TERM/AVIATION/MARINE...45
DSS...LUCHS/46
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srainhoutx
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Tuesday afternoon weather briefing from Jeff:

A strong cold front will move across the area on Wednesday resulting in the coldest Halloween in recent memory of the region.

Heavy rainfall will remain a threat tonight into Wednesday with rainfall ending early Thursday morning.

Area of thunderstorms has tracked from near Columbus to near Lake Livingston at the moment with this cluster having produced some impressive rainfall rates. A fairly large swath of 2-3 inches of rainfall occurred from southern Austin County ENE across portions of Waller, northern Harris, southern Montgomery and now into northern Liberty and San Jacinto Counties. Isolated totals of 3-4 inches fell with this cluster. This cluster was produced at the leading edge of a much colder air mass which is located from west of Huntsville to near Columbus and north of a warm front located along the coast. An upper level disturbance helped to spark this heavy rainfall along the leading edge of returning deeper moisture on surging low level jet. Activity should scatter out for the next few hours as the disturbance moves ENE of the region.

Overnight the cold front just to our west will begin to move eastward and across the region by early Wednesday morning. Upper level dynamics increase and expect numerous showers and thunderstorms to develop both along and then behind the frontal boundary. Temperatures will cool into the 60’s on Wednesday behind the front and then into the 50’s on Wednesday night. An additional 1-2 inches of rainfall is likely over much of the area through early Thursday morning.

850mb boundary will move across the are early Thursday morning ending the rainfall, but strong cold air advection and trapped low level moisture will likely keep a low level stratus deck in place by at least the first part of the day. Temperatures will go almost nowhere on Thursday with gusty NW winds of 15-25mph helping to transport cold air into the region and most places will remain in the low to mid 50’s. Still expecting some heavy rainfall bot tonight and again on Wednesday, and isolated totals of 2-3 inches will be possible. Heaviest rains today fell over areas that needed rainfall and are in drought, but will need to keep an eye on overall storm totals and any higher short duration rainfall rates over the next 24 hours for mainly street ponding.

Skies will begin to clear on Thursday evening, but NW winds will continue and this will result in a cold Halloween evening for all of the area with temperatures in the 40’s and gusty NW winds. Could see the surface freezing lien get close to northern Houston and Madison Counties early Friday morning where guidance is hitting 33, so these areas may require a very early season freeze warning. All other areas will fall into the upper 30’s and low 40’s on Friday morning. Large cold high pressure cell will be slow to move eastward and maintain a fairly “cold” air mass in place through the weekend with lows in the 40’s and highs in the 60’s under clear skies.

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jasons2k
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So far today, I have measured 2.27" with light rain continuing. That storm cluster from earlier has moved into SW Louisiana with some Severe Thunderstorm warnings over there.

Go Astros!!
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srainhoutx
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Wednesday morning weather briefing from Jeff:

A powerful cold front will sweep across SE TX today into this evening.

A cold front is currently along a lien from Victoria to west of Huntsville this morning with Columbus at 50 and Galveston at 75. This shallow, yet cold air mass is already running ahead of what models were thinking as is usual in these situations and the front will likely move into the I-45 corridor from the west later this morning. Upper level speed max noted on water vapor images is moving toward SE TX and within the last hour showers and thunderstorms have begun to develop across the western and northwestern counties. Expect this trend to continue this morning into the early afternoon hours. Some of these storms could become strong with heavy rainfall of 1-2 inches. Will likely see a break in the rainfall from mid afternoon into late afternoon before the arrival of the 850mb front this evening. Lift along this feature will promote additional showers and thunderstorms over the region through about 300-500am Thursday morning. Additional rainfall today and tonight will likely average 1-2 inches over much of the area.

Powerful cold front will blast off the TX coast later this afternoon with very strong cold air advection in place tonight. Upstream air mass is very cold for late October and this air mass will usher into the region overnight. Temperatures will fall into the 50’s by late this afternoon and then into the 40’s and 30’s tonight into Thursday morning. North winds of 15-25mph will drive wind chills to near 30 by Thursday morning over areas along and north of I-10. Clouds will clear on Thursday, but cold air advection will continue and highs will not reach much above 50. Houston and Madison Counties continue to look to flirt with near freezing temperatures on Thursday morning and a freeze warning may be required for these areas.

Cold air mass will remain in place into Friday with lows falling into the 30’s over much of the area Friday morning, except for the coast. Once again near freezing temperatures will be possible across Houston, Madison, Grimes, and Brazos Counties on Friday morning.

Latest models show another front incoming over the weekend which keeps a cold air mass in place through the weekend with lows in the 40’s and highs in the 60’s.

Gale Warning is in effect for all coastal waters from late today through Thursday. Impressive pressure gradient and cold air striking the warm Gulf waters will support sustained winds of 30-40mph across the Gulf waters and even into the bays tonight into Thursday with frequent gusts of 40-50mph. Wind advisory may be required for areas SW of Houston later today, will have to see how winds respond around the Matagorda Bay area…most areas will be 15-25mph with gusts of 30-35mph into Thursday.

Halloween Evening:
Rain will be over by Thursday morning and clouds will clear Thursday midday, but strong cold air advection will continue into Thursday night. Temperatures will likely be in the 40’s across much of the area Thursday evening with N winds of 10-20mph and wind chills in the 30’s and 40’s. Halloween 2019 may end up being one of the coldest Halloween’s since 1925 for this area.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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tireman4
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172
FXUS64 KHGX 301206
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
706 AM CDT Wed Oct 30 2019

.AVIATION [12Z TAF Issuance]...

Watching a cluster of TSRA SW of KCLL and moving towards KCLL.
This activity seems to be forming within lift from a weak jet
streak that has been hard to define on water vapor imagery. It
seems to be showing up better on the 6.9 micron water vapor
imagery and this convection is on the nose of the jet based on
this imagery. HRRR has a hint of this activity but not close at
all with intensity of the convection. We may need to amend KCLL
TAF for this activity shortly. It is also hard to tell if we will
need to amend any other TAFs as this activity has formed sooner
than most model guidance. This will probably be the case over the
next 12 hours. There will be several changes to the TAFs to stay
ahead of any trends in convection as well as the LIFR conditions.

Most areas will have LIFR conditions behind the front and slowly
improving overnight into tomorrow morning. There may be a second
band of precip around 06Z Thursday to monitor. GFS/NAM still
resolving this band as well as the Tx Tech WRF but other hi-res
guidance are not. Since this activity will most likely be
associated with the 850mb front, will keep mention of precip going
in TAFs until the 06-09Z Thursday time frame. There may be some
enhancement of rainfall with an remaining instability aloft but
something future TAF cycles can address with new guidance.

Overpeck

&&

.PREV DISCUSSION /Issued 430 AM CDT Wed Oct 30 2019/...

.DISCUSSION...

.SHORT TERM [Today Through Thursday]...
Cold front this morning at 4AM/9Z has already made more progress
south than expected. The front has pushed through Victoria to
Wharton then just at the doorstep of Sugar Land and Tomball. The
front has not quite made it to Conroe yet but through Huntsville.
HRRR 06Z run seems to have a the best handle on the front with a
realistic temperature gradient. Short term forecast leans heavily on
the HRRR and WRF model guidance for timing of the front and
temperatures for the next 24 to 36 hours. Airmass behind the front
is looking to be colder than the last couple of forecast cycles
showed so we could very well have low temperatures Thursday in the
30s for the northern half of the area and high temperatures in the
low 50s for much of the area. Temperatures will likely be in the 40s
for trick or treat activities and given the gusty winds, wind chills
could be in the upper 30s to low 40s.

There seems to be two main periods today and tonight when
precipitation chances will be the highest. First it looks like WRF
and HRRR guidance are highlighting a cluster of elevated convection
from Brenham/College Station over to Huntsville/Crockett in the 16Z
to 20Z time frame (11AM to 3PM). It is quite possible for this
cluster of convection to focus farther south depending upon the
movement of a jet streak approaching the area. There still should be
some elevated convection and increased lift as the cold front begins
to make a stronger push south. Like yesterday, if storms get
organized there could be an isolated wind/hail threat but likely
remain below severe levels. This also means that there could be some
brief heavy rainfall with some isolated totals in the 1-3 inch range.

The other concern for higher rain chances will be close to 06Z
Thursday as the 850mb front pushes into the region. Strong
frontogenesis should support lift and post frontal banded
precipitation. Any remaining instability will enhanced rainfall
amounts with this band. The GFS/NAM support banded precip along a
line from Columbus to Conroe to Lufkin. This very well could shift
south into the Houston area before weakening with dry air moving
into the region. HRRR trends only show a broken line of activity
during this time frame with the WRF/HREF members focusing this area
of higher rainfall more along the coast. The lone exception is the
Tx Tech WRF ARW which is more in line with the NAM/GFS. Granted
rainfall amounts look to be around a half inch tops with this band
Regardless this should be the last push of rainfall with the front
and really dependent upon the movement of the 850mb front.

Overpeck


.LONG TERM [Thursday Night Through Wednesday]...
A much colder airmass will continue to filter in across Southeast
Texas tomorrow night into Friday. Therefore, a Freeze Warning
will likely be needed early Friday morning across our northern
counties from Burleson to Grimes to Houston. Low temperatures
should drop into the low 30s across our northern zones to mid 40s
along the coast. Could this be the earliest first freeze of the
season for some sites? Potentially Huntsville, but for College
Station and Crockett, they have seen earlier first freezes looking
back through climatology (table below).

First Freeze Dates: Earliest Ever On Average
College Station 10-28 (1957) 11-27
Huntsville 11-03 (1999) 11-03
Crockett 10-21 (1989) 11-15

Regardless, this will definitely be a much earlier than normal first
freeze for many locations. With gusty winds anticipated overnight,
wind chills could dip down into the mid 20s to low 30s across much
of the region, especially north of I-10. A chilly day should
continue through the afternoon hours Friday, with high temperatures
forecast to be approximately 15 to 20 degrees below seasonal
normals. That said, expect high temperatures to top out in the upper
50s to low 60s. Mostly clear skies should prevail with light
northeasterly winds.

A secondary push of colder air is expected on Saturday to
reinforce the already cold conditions. Therefore, average
temperatures should remain below normal through much of the
weekend. 850 mb temperatures will take a tumble once again,
dropping from the low teens down to 5 to 8 degrees C. The GFS now
looks to be the most aggressive out of the global models with
this reinforcing shot of cold air. Very weak upper-level ridging
is still expected over the southwestern Gulf of Mexico through the
weekend, with rather zonal flow over Southeast Texas. Drier air
should also remain in place, with dew points in the 30s to 40s.

Onshore flow returns early Monday and with that, so does the
moisture. Dewpoints should climb back up into the 50s to 60s by
Monday afternoon, and more widespread cloud cover can also be
expected. A slight chance for showers and thunderstorms returns
across the southern half of the forecast area. More widespread
precipitation is anticipated for Tuesday, as precipitable water
values reach up to 1.2 to 1.5 inches once again.

Hathaway


.MARINE...
The main change from the previous forecast was to upgrade the gale
watch to a gale warning for the Upper Texas Coast. The cold front is
still on track to push off the coast this evening with strong
northerly winds behind it tonight into Thursday. We adjusted the
gale warning timing to start around 03Z Thursday and go until 21Z
Thursday. Small craft advisory conditions are expected then going
from 21Z Thursday to roughly 06Z Friday. It looks like we get
another increase in NE winds on Saturday as another front pushes off
the coast with high pressure building into Texas.

Overpeck


&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 54 35 52 32 60 / 100 80 10 0 0
Houston (IAH) 69 40 53 35 59 / 90 90 10 0 0
Galveston (GLS) 75 46 55 46 61 / 90 90 10 0 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...Gale Warning from 10 PM this evening to 4 PM CDT Thursday for
the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM...Galveston
Bay...Matagorda Bay...Waters from Freeport to Matagorda
Ship Channel TX from 20 to 60 NM...Waters from High Island
to Freeport TX from 20 to 60 NM.


&&

$$


AVIATION...Overpeck
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snowman65
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With this incoming very cold air so early in the season, could there be any impacts on the overall temps for the remainder of the winter season? I know the earlier forecasts called for warmer or much warmer than average for pretty much the entire US.....??
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jasons2k
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It felt great outside earlier this morning. Starting to cool off now. I’m not looking forward to this next cold front. Might be too cold to run in the morning. 40 is about my cutoff.
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srainhoutx
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The 12Z NAM suggest we will struggle to reach a high in the low/mid 40's tomorrow with a freeze possible across our Western and Northern Regions tomorrow morning. Light winds and clear skies Friday morning may well bring 30's into Metro Houston. Gardner's be aware!
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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