October 2017 - Halloween Forecast/Rain Chances

[tireman4]

Halloween Discussion....I think changes will be made to this forecast as we get closer.




000
FXUS64 KHGX 261120
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
620 AM CDT Thu Oct 26 2017

.AVIATION.../12Z TAF/
Surface low pressure in the Plains will allow for gusty SW to S
winds this afternoon across the area with VFR conditions. Winds
decrease overnight as a cold front approaches the area. The front
could reach KCLL/KUTS before 12Z Friday. Front expected to reach
IAH 12-15Z Friday for the 30 hour TAF time frame. A few showers
may be possible along the front. Showers may develop ahead of the
front for KHOU/KSGR/KLBX and KGLS with VFR ceilings as moisture
from the Gulf increases. Front expected to push off the coast by
18Z Friday and support gusty northerly winds Friday afternoon for
upcoming TAF updates.

Overpeck


&&

.PREV DISCUSSION... /ISSUED 415 AM CDT Thu Oct 26 2017/

DISCUSSION...
A northwesterly flow aloft will transition to southwesterly
tonight as an upper level trough develops over the state. This
approaching upper trough has already helped to kick the surface
high pressure ridge east of the state. Weak Gulf moisture return
has already begun. A cold front will move into Southeast Texas
Thursday night and Friday morning. There is some disagreement on
the timing of the frontal passage amongst the model runs. A
general consensus has the front at College Station around 7:00 AM
Friday, the Houston area down to Matagorda Bay around mid
morning, and then off of the coast of Galveston around midday.
Rainfall may be limited at first but do expect the development of
showers and possibly isolated thunderstorms as the morning
progresses. Model soundings showed the best potential for
thunderstorms to be over the central and coastal areas Friday
afternoon.

Main impacts will be post-frontal winds on Friday and Friday
night, and then low temperatures over the weekend. Some of the
guidance is suggesting that a wind advisory may be needed at
least over the western and southwestern counties during Friday
afternoon, and then along the coast late Friday afternoon through
the evening. Regarding temperatures, model blends and guidance
continue to indicate freezing temperatures may be possible at
least over the far northern counties mainly early Sunday morning.
Some isolated locations may experience a morning low around
freezing as early as Saturday morning. Coldest temperatures over
the weekend will likely be north of a line from Somerville to
Groveton. Needless to say, it will be a rather chilly weekend over
the entire area.

Onshore winds return quickly on Monday. A rather active
southwesterly flow aloft should then develop beginning on Tuesday.
Both the GFS and ECMWF show the possibility of an inverted coastal
surface trough will develop on Tuesday and Tuesday night. With the
subtropical jet overhead, better chances for thunderstorms can be
expected both Tuesday and Wednesday.

40

MARINE...
Southwest to south winds will increase this afternoon and tonight
across the Upper Texas Coast. Small craft exercise caution or even
advisories may be needed tonight as winds increase to around 20 knots
in the offshore waters. Seas may reach 5-7 feet by Friday morning.

A strong cold front should push off the Upper Texas Coast Friday
afternoon with winds increasing to around 25 knots behind the front.
Winds should peak around midnight going into Saturday morning with
the chance of gale force wind gusts. Seas may reach close to 8 to 10
feet in the offshore waters with the strong winds. Winds should
decrease Saturday morning into the afternoon allowing seas to slowly
subside. Small craft advisories will likely be needed Friday
afternoon through at least Saturday morning.

High pressure moves over the area on Sunday allowing for light winds
and low seas. Winds increase from the south as high pressure moves
over the northern Gulf on Monday.

Overpeck

FIRE WEATHER...
While there has been some recovery in relative humidity this
morning, southwest to south winds today will support strong mixing
by the afternoon with sustained winds around 15 mph and a few wind
gusts to around 20-25 mph. Relative humidity may drop to 25 to 35
percent north and west of the US 59/I-69 corridor through SE Texas.
Gulf moisture will be returning ahead of the next front which will
push through Friday. Conditions Saturday will support borderline
hazardous fire conditions with northerly winds around 10-15 mph and
relative humidity back down close to 20 percent. Sunday will still
be dry but with lower winds.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 83 54 66 34 66 / 0 10 20 10 10
Houston (IAH) 83 62 70 41 61 / 0 10 40 20 10
Galveston (GLS) 81 70 76 49 63 / 0 10 60 40 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...40
Aviation/Marine...39

[tireman4]

00
FXUS64 KHGX 261659
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1159 AM CDT Thu Oct 26 2017

.DISCUSSION...

18Z Aviation...The main feature of interest is late in the TAF
period with the strong cold front that should reach CLL around
10Z, IAH around 14Z, and near the coast 16Z tomorrow. Expect
scattered showers to develop ahead of the front near and south of
a SGR-IAH line in the 10Z-16Z window. Small chance of TSRA near
the coast right along the boundary. 33

&&

.PREV DISCUSSION... /ISSUED 1118 AM CDT Thu Oct 26 2017/

UPDATE...
Another beautiful day with a more moderate southwest wind backing
around the dial to onshore by the end of the day. As onshore winds
will only exist for roughly 12 hours...this will limit moisture
return ahead of tomorrow`s cold frontal passage. This should
focus Friday`s higher POPs closer to the coast/southeastern CWA
during the day as the front marches through the northern and
central forecast area. Mainly overcast becoming partly cloudy
Friday with gusty north winds...daytime temperatures reaching
their peak in the mid to late morning and falling through the
afternoon in the post-frontal. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 83 54 66 34 66 / 0 10 20 10 10
Houston (IAH) 83 61 70 41 61 / 0 20 40 20 10
Galveston (GLS) 81 70 75 49 63 / 0 20 60 40 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION from 4 PM CDT this afternoon
through Friday morning for the following zones: Coastal
waters from Freeport to the Matagorda Ship Channel out 20
NM...Coastal waters from High Island to Freeport out 20
NM...Galveston Bay...Matagorda Bay...Waters from Freeport
to the Matagorda Ship Channel from 20 to 60 NM...Waters
from High Island to Freeport from 20 to 60 NM.

&&

$$

Discussion...33

[srainhoutx]

Looks like a great Fall weekend ahead filled with watching the Astros playing at home in the World Series and feasting on cold weather comfort food. Seeing a lot of reports from our Neighbors in N Texas receiving sleet mixed with rain near the Metroplex. Enjoy the weekend and Go Astros!!

[mckinne63]

What a beautiful fall day! Go Astros!

[srainhoutx]

Light Frost in NW Harris County and daily record low smashed at IAH this morning dating back to 1993. The official low is 36F with a lot of freezing or below freezing temperatures across our Northern/NE and Western Counties. It was 35F at the airport in Corpus Christi as well.

[Katdaddy]

Light frost also down here in League City this morning. Temps approaching 70F under sunny skies will feel nice this afternoon.

[cperk]

Light frost here in Richmond also.Woke up to 34.5 degrees.Keep it coming.

[Katdaddy]

Way to go Houston Astros!

Warm temps and unsettled weather with be the theme across SE TX for Halloween into the first weekend of November. Hopefully the showers will hold off trick or treating.

[srainhoutx]

Monday morning briefing from Jeff:

Record lows were achieved Sunday morning over the region with an early season cold air outbreak.

BUSH fell to 35 on Sunday morning surpassing the previous record of 39 from 1910.

In fact temperature fell into the upper 20’s over Trinity, Houston, and Polk Counties.

Cold Canadian surface high pressure is moving east of the area and the return of southerly winds is in progress. Low temperatures this morning have ranged from 10-20 degrees warmed than yesterday morning. Deep Gulf moisture will begin its return to the area this afternoon and will be marked by an increase in cloud cover and humidity. A weak cold front over the southern plains will move southward and approach the region early Tuesday before stalling somewhere over SE TX Tuesday night. Do not think this front will make it much into the area, and will likely stall somewhere NW of the US 59 corridor. Strong warm air advection on Tuesday will result in scattered showers developing especially in the afternoon hours. Texas Tech WRF shows development along the coast tomorrow morning which then spreads slowly inland during the day.

Main rainfall event should hold off until Tuesday night, but there could certainly be some showers or even a thunderstorms on Tuesday evening. Moisture levels really ramp up Tuesday night with PWS rising to near 1.9 inches by Wednesday morning. Will have to keep a very close eye on the stalled frontal boundary over the region with those types of moisture levels. A couple models are screaming heavy rainfall for Wednesday morning and 1.9 inch PWS are certainly something to be aware of in the event of any training cells. For the moment will go with widespread rain and thunderstorms late Tuesday night into the first part of Wednesday.

Rainfall totals of 1-2 inches appears likely over much of the region with much higher totals where cells anchor or train for any period of time. Similar to Friday the 20th where nearly 7 inches of rain fell in a few hours along Clear Creek, some isolated significantly higher totals will be possible on Wednesday.

Frontal boundary washes out on Wednesday evening and continued onshore flow will result in a moist and warm air mass into the weekend. Will cap rain chances through the Wed-Sat period at 30%, but a few periods could see higher rain chances given disturbances in the flow aloft.

Halloween Forecast:
Showers and thunderstorms will be possible Tuesday evening…increasing through the evening. Will start with 40% chances near sunset and increase to near 60% by 1000pm. Temperatures will remain warm in the 70’s through the evening with high humidity.

[tireman4]

00
FXUS64 KHGX 301707
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1207 PM CDT Mon Oct 30 2017

.DISCUSSION...

18Z Aviation...Scattered CU expected across southeast areas this
afternoon as 10-15 KT southerly winds bring moisture back to the
area. Expect ceilings overnight, generally just above MVFR. Also,
expect scattered showers to develop in the vicinity of a stalling
front across the area Tuesday morning. Wind direction will be a
little tricky on Tuesday because of the slow moving front.
Directions look to vary from NE to SE across the area. 33

&&

.PREV DISCUSSION... /ISSUED 1019 AM CDT Mon Oct 30 2017/

UPDATE...
The last clear and cool morning for several upcoming days as
higher moisture returns today. Moisture creeping back upon onshore
winds as higher southern Gulf moisture advects its way into the
coastal bend...a trend that will continue through the day.
Increasing cloud cover and rain chances will move in from the west
southwest tomorrow with the western 2/3rds of the forecast area
facing high chances of showers and a possible thunderstorm during
the Halloween evening hours. A cold front now working its way
south out of the Texas Panhandle will slowly approach the region
through tonight and hang up somewhere across eastern Texas. With
moisture forecast to increase from current 0.5 inch column (pw)
values to well over an inch a day from now...precipitation chances
(mainly rain/showers) will become more widespread from west-to-east
from mid-Tuesday onward. Early Tuesday afternoon prog profiles show
mainly inland rain or showery weather with lapse rates falling back
enough latter in the day to mention isolated thunderstorms. Higher
rez modeling depicting precipitation beginning across the local
waters and coastal counties from as early as sunrise tomorrow
morning. While the better lower level focus will reside further
north...higher instability remains south. Thus...there is a
moderate chance of morning thunder to commence those communities`
last day of October/Halloween. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 79 55 69 58 78 / 0 20 40 80 60
Houston (IAH) 78 60 74 62 78 / 0 20 30 60 80
Galveston (GLS) 77 69 76 71 79 / 0 20 40 70 80

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...33

[Katdaddy]

A few showers over the NW GOM and along the coastal areas this morning as rain and thunderstorm chances increase thanks to a stalling cool front across SE TX. Expect showers and possibly a few thunderstorms for trick or treating this evening.

An portion of this morning’s Houston-Galveston Area Forecast Discussion regarding this evening:

It would be a good idea to be prepared for showers and storms while getting your Halloween activities out of the way earlier. Once done, settle in for some (potentially historic) TV at night.

Locally heavy rains will be possible later tonight near the stalled front. In addition, a few strong storms will be possible Wednesday if additional thunderstorms develop. The SPC has SE TX in a marginal risk area for severe thunderstorms. After some active weather days we will begin to dry out at the end of week.

[BlueJay]

Thunder on Halloween! Sounds scary.
Happy Halloween everyone!
Go Astros!

[tireman4]

I believe his is alluding to the Astros in the World Series...



000
FXUS64 KHGX 311147
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
647 AM CDT Tue Oct 31 2017

.AVIATION...
Area will be seeing increasing SHRA/TSRA coverage today through
tomorrow morning with a weak frontal boundary in the vicinity.
Ceilings will be lowering to mainly MVFR levels. Anticipate
improving conditions tomorrow as the day progresses. 42
&&

.PREV DISCUSSION... /ISSUED 433 AM CDT Tue Oct 31 2017/

DISCUSSION...
Showers over the Gulf are hinting at wetter weather to come. The
character of this rain will initially be more showery and closer
to the coast, before transitioning to being more widespread and
tied to a cold front expected to stall over Southeast Texas
tonight. It would be a good idea to be prepared for showers and
storms while getting your Halloween activities out of the way
earlier. Once done, settle in for some (potentially historic) TV
at night. While activity should generally be winding down
Wednesday, a marginal threat for severe weather exists as the
environment will become more supportive of stronger storms (should
any storms exist). Beyond Wednesday, some off-and-on potential
for showers will continue, but the trend will be towards drier
weather as we head towards the weekend. Along with this, we can
also look for a return of temperatures in the 80s.

NEAR TERM [Through Today]...

Regional observations show a cold front right on the doorstep of
Southeast Texas. Winds at Bryan/College Station and Caldwell have
gone light and northerly, but their dewpoints remain near 60
degrees at 3am. That said, the front should sag a little more
south through the morning, before stalling out and even retreating
back north a little this afternoon.

So far, the only rain over the region is mainly over the Gulf
waters, though a shower over Galveston has racked up just over
half an inch of rain. Any showers pushing onshore have so far have
largely fizzled beyond the immediate coast - GOES-16`s
precipitable water product shows just over an inch across the
area, verifying models soundings that show a column that is still
pretty dry. However, as the column moistens today, we should look
for greater shower activity over land. Expect a greater flourish
of showers and even some lightning towards mid-afternoon as HRRR
soundings show the column moistening rapidly in conjunction with
an increase in instability.

Temperatures today should have a pretty decent gradient. Just on
the cool side of the front for most of the day, temperatures in
the far north will likely fail to reach 70 degrees. However, near
the coast, temperatures in the upper half of the 70s can be
expected in locations that don`t become rain cooled.

SHORT TERM [Tonight Through Thursday]...

At some point tonight, the atmosphere should become more
saturated, with more widespread rain tied more to convergence
along the stalled front. Midlevel heights look to drop slightly -
enough to give us a "skinny CAPE" profile that can be associated
with heavy rainfall. On the plus side, strong winds aloft should
make individual cell motion relatively speedy, so no one cell is
likely to drop a ton of rain over any one spot. Also, even though
instability looks to rise, it only does so modestly, which will
likely limit updraft strength. On the downside, the mean steering
wind looks to be fairly front- parallel, meaning that training of
cells can occur as long as onshore flow from the Gulf continues
to fuel development along the front.

So rather than getting downpour from one particular storm, rains
may add up over time. It`s hard to pinpoint a specific time for
this to occur right now, but examination of multi-model soundings
seem to suggest a window between the late evening and sunrise
Wednesday for this setup to occur. Another source of uncertainty
is location. The heaviest rains should occur along and near the
stalled frontal feature. In the current forecast, this would be
along a line roughly parallel to the coast, but over the
relatively rural area between the Houston metro and College
Station. However, any change in the push of the front would impact
where this focus area occurs.

There seems to be pretty good agreement among the models for a
rainfall max near the front. However, there`s a pretty decent
spread in how much rain falls. The GFS is driest of the major
deterministic models, with rain totals around an inch. The Euro is
in the 2-3 inch range, while the NAM and GEM push towards 4
inches. We are beginning to come into the range of the CAM suite
of guidance, as well. The TTU WRF is also relatively dry with
totals peaking around 2-3 inches, and its ensemble showing less
than a 10 percent change of exceeding 3 inches. On the wet end,
though, the NCAR ensemble shows a 50-70 percent chance of
exceeding three inches near the front, and a 10-30 percent chance
of exceeding 6 inches. Those numbers may sound low, but a 1 in 3
chance of getting more than 6 inches of rainfall is a fairly
significant potential.

Ultimately, think the placement of the front, relatively modest
amount of instability, and quick cell motion will keep things from
getting too out of control. The GFS is probably a little too
optimistic, but something in the middle of the envelope seen by
the Euro and TTU-WRF seems entirely reasonable. But, the setup of
having a stalled front over Southeast Texas, inflow from the Gulf,
and potential for training makes me leery of writing off at least
locally heavier rainfall entirely. So, after coordination with
WPC, a marginal risk for excessive rainfall exists in the area.
If there are indications through the day that things are
overperforming and trending towards the higher end of the
guidance, the severity of that threat will have to be stepped up.

On Wednesday, we should generally be looking for things to be
winding down. As winds become more unidirectionally southwesterly,
look for the column aloft to dry up and become capped. However,
before things are totally shut off, this setup will create some
potential for severe weather. MLCAPEs will begin to approach 2000
j/kg, with deep layer shear remaining above 30 kts. With DCAPE
approaching 1000 j/kg and a fair amount of shear and curvature in
the lowest km, there will be a nonzero potential for damaging wind
gusts and even a quick tornado should any storms manage to get
going. That "should any storms manage to get going" will be the
operative phrase, though. Because of that, we are also in a
marginal risk area for severe weather in SPC`s Day 2 outlook.

Potential for rain comes down on Thursday - but with an upper
trough moving along the Red River Valley though and with continued
inflow from the Gulf, we may see some isolated updrafts to
overcome the cap. There`s a decent amount of instability to tap
into if the cap can be overcome, so thunderstorms are a
conditional risk. However, whether anything can overcome the cap
is a very big question here.

LONG TERM [Thursday Night Through Tuesday]...

Ridging aloft will begin to develop over the Rio Grande Valley or
northeastern Mexico through the weekend, which should trend our
weather towards the dry side. With onshore winds at low levels and
a location towards the fringe of the ridge, can`t totally rule out
some rain, but there`s enough confidence to put in a dry forecast
for this weekend and early next week. With the midlevel high
building heights over Southeast Texas, we can also look for
temperatures to trend towards above normal values, currently
forecast to be in the lower 80s. Another front looks to approach
the area later next week, but there is significant differences in
the guidance at this time, and is fortunately for this forecaster
beyond the scope of this forecast.

MARINE...

Increasing onshore winds and building seas can be expected into
the middle of this week under a tightening pressure gradient.
Caution flags are anticipated, and advisories might be needed.
Look for rising shower and thunderstorm chances through Wednesday.
Lighter onshore winds and lower seas will develop toward the end
of the week and will persist into the upcoming weekend. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 68 58 76 66 87 / 60 80 40 10 10
Houston (IAH) 75 68 79 69 86 / 70 90 80 20 30
Galveston (GLS) 77 73 79 74 82 / 50 60 80 30 30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

25/42

[unome]

poor kiddos - hope this doesn't ruin their trick-or-treating

[DoctorMu]

Things have begun to saturate up and down trop column. Light rains erupting and beginning more stead.

WAs hoping it would hold off until trick or treating has concluded in the BCS area...but then we've been pretty dry since Harvey.

Intermittent Showers are the operative phrase.

[DoctorMu]

Trick and Treat:

PREV DISCUSSION... /ISSUED 1121 AM CDT Tue Oct 31 2017/
UPDATE...
This shift wishes it had better weather news for all of
those across southeastern Texas that want to spend time outdoors
this All Hallow`s Eve. High to likely chances for periods of rain
and isolated thunderstorms from this afternoon on through
Wednesday afternoon hours. So, the question has been answered as
to precipitation occurrence but question marks still linger for
the amounts of rain we will receive through tomorrow. Of
course...when looking over the model du jour menu there are a
couple of solutions that peg 3 to 4 inch storm total rain amounts
over the coastal regions. These solutions develop a surface
low/trough off to the southwest and provide better mid-level
inflow into this current lower level boundary currently positioned
roughly from a Matagorda Bay to city of Houston to south of a
Lake Livingston line. Tale of two regions across the CWA this
morning...lower 60s north of boundary and lower 70s south of
stalled front. The focus is there...as is the moisture (1.6
pwats)...so it is just a matter of time before we will begin to
experience inland convective development. This forecast update has
an areal average 1 to 2 inches falling between this afternoon and
late Wednesday...locally 3 to 4 inches in the vicinity of the
front is certainly not out of the question. As the earlier shift
mentioned...there is a 30-40% chance of counties south and west of
metro to pick up 3 inches or greater by the end of the day.

Tomorrow remains unsettled...high chance for showers/storms earlier
in the day and...if you split the CWA with a southwest-to-northeast
orientated line...the higher TSRA chances would reside east of that
line. Progged sounding (indices) not showing anything super impressive
within the resident environment that would suggest severe but there
is enough instability for any cell to briefly exhibit strong draft
structure. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 68 56 76 66 87 / 50 80 30 10 10
Houston (IAH) 75 65 79 69 86 / 70 80 80 30 30
Galveston (GLS) 76 69 79 74 82 / 50 50 70 30 30

[BlueJay]

We are getting a nice shower now. Hmmm. I also hope that the kids aren't rained out.

[BlueJay]

It's raining.
It's pouring.
I think our little trick or treaters have been thwarted.

On to November 2017.

[tireman4]

00
FXUS64 KHGX 011511
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1011 AM CDT Wed Nov 1 2017

.DISCUSSION...
Surface analysis has stalled frontal boundary basically from
Victoria to Tomball to Lufkin this morning. Temperatures south of
the front are in the low 70s with temperatures north of the front
in the 50s/60s. Front should dissipate today and with cloud cover
gradually decreasing, high temperatures still look on track for
the upper 70s. Main forecast update was to adjust rain chances for
ongoing trends. Radar shows some shower and thunderstorm activity
along the coast but all of this activity is moving east. Latest
model trends with the HRRR support this so look for drying
conditions the rest of the day.

Overpeck

&&

.PREV DISCUSSION... /ISSUED 651 AM CDT Wed Nov 1 2017/

AVIATION...
The NE to SW oriented line of SHRA/TSRA will continue moving eastward
and out of the HOU-LBX-GLS area TAF sites over the next several hours.
Low ceilings will begin to slowly improve after sunrise, and TAF sites
are anticipated to become mostly VFR later this morning or this afternoon.
S to SSW winds will be increasing to 10 to 15 knots, and some locations
could see some gusts around 20 knots this afternoon. The S to SSW winds
are expected to be around 8-10 knots overnight, and this should help
to keep the potential for significant fog development on the low side.