January 2020: Unsettled WX Week Ahead

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don
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I agree ,Canadian is also onboard now fwiw. Main difference from the GFS is that it shows a more localized event with most precip confined to the coastal bend and southeast Texas.
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Cpv17
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The Euro for late next week isn’t making any sense to me.
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Katdaddy
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Temps mostly in the 30s across SE TX this morning with some high clouds. One more nice mild day before it begins to feel like Spring Thursday with warming temps and increasing clouds and moisture.

Everyone in SE TX needs to remain weather aware Friday afternoon through early Saturday morning. The SPC now has a enhanced risk area across most of SE TX with all modes of severe weather possible including tornadoes. In addition, this looks to be more of a night time event.
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srainhoutx
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Wednesday morning weather briefing from Jeff:

Severe thunderstorms will be possible over portions of SE TX Friday evening into early Saturday morning.

All severe weather modes will be possible.

A powerful upper level storm system will dig into the SW US and then sweep across TX Friday and Friday night. Ahead of this system a robust and highly sheared warm sector air mass will develop Thursday into Friday. Air mass will undergo rapid modification from the current dry and cold to warm and moist by late Friday. As the upper level trough begins to move toward TX late this week, a surface cold front and associated surface low pressure system will develop over the southern plains. Moisture transport on a powerful low level jet by Friday morning is impressive over SET X with 40-60kts at 850mb and PWS rising into the 1.5 inch range. High temperatures warming into the mid to maybe upper 70’s along with the influx of a “Gulf” air mass will support modest instability for this time of year with CAPE values of 1000-1500J/kg across the region by late afternoon. It should be noted that “cool” season severe weather outbreaks along the Gulf coast tend to not need as much instability as similar systems in the Spring and significant severe weather and tornadoes have occurred with similar setups in the past (especially over LA, MS, AL). Elevated mixed layer (cap) will advect ENE across SE TX from northern MX during the day Friday and this should prevent much activity across the developing warm sector for much of the morning into the early afternoon hours. Warm sector air mass will become highly sheared by Friday afternoon with a strong low level jet in place over SE TX with winds turning with height into the 700mb and 500mb levels.

Main question for Friday afternoon is does the cap waken enough to allow discrete cells to develop across the warm sector…and this potential looks possible along and north of I-10 and more likely north of HWY 105. Any discrete cells that can develop and break the capping inversion Friday afternoon will have plenty of low level wind shear in place for damaging winds and tornadoes. Strong surface winds of 25-35mph will be in place across the region Friday afternoon and evening with the strong low level jet overhead…and some of this stronger wind energy will mix down in any showers or storms that form.

Cap looks to erode fairly quickly Friday evening as strong linear forcing approaches from the WNW along an advancing cold front. Squall line is likely to develop and sweep across much of the region. Main threat will likely be the potential for wind damage as strong winds aloft may be transported to the surface in the line. Additionally bowing segments along the line could produce wind damage and isolated tornadoes. All severe modes will be possible, but wind damage is looking the most likely with the profiles in place.

SPC has outlooked most areas north of I-10 for an enhanced risk of severe weather for late Friday.

Storm system will be progressive and will quickly sweep across the region. Rainfall amounts look to average 1-2 inches with the greatest amounts toward Lake Livingston and lesser amounts toward Matagorda Bay.

Next Week:

Unsettle weather pattern will remain in place with a weak system moving across the area early in the week with more showers and maybe a thunderstorm. Of more interest is the potential for a very cold air mass to move into the northern plains early next week. This cold air mass has been lurking in western Canada since around Christmas and appears to dislodge some early next week. Models are showing -30’s over eastern Montana and North Dakota by next Tuesday and Wednesday. While the upper level pattern is not overly favorable for the delivery of this cold air mass southward, will need to watch for the air mass to “bleed” southward under its heavy density (such cold air is very heavy and spread across the surface like water on a table) and possibly reach TX by late next week in the form of a shallow, but very cold arctic front.

Severe Weather Outlook (Friday):
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MontgomeryCoWx
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Jeff does a fantastic job describing complex events in simple terms.
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MontgomeryCoWx
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Cpv17 wrote: Tue Jan 07, 2020 11:15 pm
don wrote: Tue Jan 07, 2020 10:41 pm 0z GFS is still showing a ice storm next Thursday/Friday fwiw
Yeah, but I would like to see the strength of the hp a few mb stronger.
1050 in January is nothing to write off. That's a nice High.

Canadian has a 1041 all the way into the Southern Plains. I believe it is 1053 when it enters the States.
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tireman4
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773
FXUS64 KHGX 081130
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
530 AM CST Wed Jan 8 2020

.AVIATION [12Z TAF Issuance]...

VFR conditions are expected for the next 12-18 hours and then
ceilings should begin to develop. MVFR ceilings will be possible
06Z to 12Z for KCLL/KUTS/KCXO and then developing south towards
KIAH for the morning hours. SE winds will be gusty this afternoon
and hang around 7-10kts overnight. Winds pick back up tomorrow
with a stronger LLJ developing.

Overpeck

&&

.PREV DISCUSSION /Issued 420 AM CST Wed Jan 8 2020/...

.DISCUSSION...

The main forecast concern is the severe weather potential Friday
afternoon and night over much of SE Texas. SPC has the area under
an enhanced risk for severe weather on Friday. Primary weather
hazards will be tornadoes, damaging winds, and hail. Locally heavy
rainfall will be possible as a line of storms moves across the
area but flash flooding is not expected to be a concern. We need
to pay close attention to weather conditions on Friday and Friday
night. With a night time threat of severe weather, people need to
have multiple ways to get warnings and back up plans.

Overpeck




.SHORT TERM [Today Through Thursday]...

Like yesterday, today should be another day to get outside and
enjoy, at least until the Gulf moisture begins to return. High
temperatures should reach the mid/upper 60s again with southeast
winds increasing.

Return flow sets up in earnest tonight into Thursday. Temperatures
overnight may drop to the 50s/60s before midnight but then begin
to hold steady or increase through the morning hours. Temperatures
should reach the mid/upper 70s with dewpoints climbing into the
60s for much of the area. There may be some sea fog that forms
Thursday night but depends upon how strong winds will be and any
resulting mixing. We will certainly see an increase in cloud cover
and a few showers during the day Thursday.

Overpeck


.LONG TERM [Friday Through Wednesday]...

Warm southerly flow combined with PWATs nearing 1.3 to 1.5 inches
across the area will lead to a possible foggy night along the coast
Thursday night. Low temperatures will get down into the mid to upper
60s, so near normal highs for this time of year. Meanwhile, an upper
level trough will be digging into the Desert Southwest tightening
the gradient over Texas through the day on Friday. This will lead to
a pretty windy day across the area with winds 15-20 kts at the
surface, and models are indicating a strong 850mb of 40 to 50+ kts
over the area beginning around noon. That digging trough to the west
is also what will bring the potential for severe weather later in
the day on Friday.

The moist atmosphere on Friday will lead to mostly cloudy skies
with some isolated showers and thunderstorms popping up in the
afternoon. Higher PWATs in the EC does bringing higher coverage in
the showers and thunderstorms during the day on Friday, but have
trended more towards the NAM/GFS PoPs and QPF totals for this event.
While the cap looks to remain in place during the day on Friday,
which will inhibit strengthening of any storms that develop, it is
possible that some of those storms could become strong to severe if
they break that cap. Then, the second threat of the event comes with
the associated cold front as a strong line of thunderstorms develops
along the boundary and pushes through the region Friday evening into
the overnight hours. Timing right now is that it will reach the
northwestern parts of the region around 00 and 03z on Saturday, then
into Houston Metro around 03 to 06z, and then off the coast by
around 9z. Damaging winds, hail, and tornadoes will be possible with
the QLCS that accompanies the front. We also cannot rule out
discrete supercells that form ahead of this line. The Storm
Prediction Center has most of the area under an Enhanced Risk for
severe thunderstorms for most of the region on Friday (Day 3),
including Brazos and Harris counties, with a Slight Risk extending
all the way to Matagorda Bay.

There are still some inconsistencies in the guidance, and with the
severe weather threat still three days out, do not focus on the
specifics of the threat. Just make sure that you have taken the
appropriate preparations in case severe weather threatens your
location and continue to monitor the forecast in the coming days.
This will be a potential nocturnal severe weather event on a Friday,
which can make severe weather even more dangerous as it can be
harder to receive warnings about severe weather. So, make plans now
on how you will receive warnings, which can be from a NOAA weather
radio, your phone (but make sure you have the option to receive
emergency alerts turned on), the internet, or through local media.

After the frontal passage on Friday, high pressure settles in over
the region. So, expect much drier and cooler weather resulting in a
pretty nice weekend for Southeast Texas. Moisture increases from the
southeast on Monday through midweek bringing a return to possible
showers and thunderstorms.

Fowler


.MARINE...

Southerly winds increase tonight into Thursday with strong
southerly winds continuing through friday. A long fetch will
support building seas so caution, perhaps advisory, flags will be
needed as soon as tonight and Thursday. A cold front with a line
of thunderstorms will be possible Friday night and may need
advisories for strong northerly winds behind the front on
Saturday. Some of the storms Friday night could be strong to
severe with gusty winds. Strong northerly winds should decrease
Saturday afternoon and night.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL) 68 57 76 64 77 / 0 10 30 20 70
Houston (IAH) 67 59 76 66 79 / 0 10 30 30 50
Galveston (GLS) 66 62 71 68 74 / 0 10 20 20 30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...None.

&&

$$


AVIATION...Overpeck
mcheer23
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Massive flip by 12z GFS, cold air thrown off to the east.
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don
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12z GFS has backed away from the ice storm solution as the cold air gets shunted off to the east similar to the Euro,of course theirs plenty of time for things to flip back.
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snowman65
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mcheer23 wrote: Wed Jan 08, 2020 10:34 am Massive flip by 12z GFS, cold air thrown off to the east.
As expected.....
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