June 2017: Typical Summertime WX To End Month

[Ptarmigan]

Regardless of tropical or not, I think we could see heavy rain.

[Andrew]

Even with this being 5+ days out, I think a southern track into Mexico is looking more and more likely if this develops at all. Ridging looks to build over Texas and the Central Gulf Coast pretty rapidly during the beginning of next week. Paired with a rather shallow system, as it stands right now I would imagine a storm that has trouble gaining latitude. Most of the models and associated ensembles are resembling a similar solution.

[srainhoutx]

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Tue Jun 13 2017 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. A broad area of low pressure is expected to form over the western Caribbean Sea or Central America late this week or this weekend. Some gradual development of this system is possible thereafter while it moves slowly northwestward. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 5 days...low...20 percent. Forecaster Cangialosi

[srainhoutx]

Looking at the overnight Multi Model Ensemble TC Genesis Probabilities, you can see that it was rather hard for the NHC to ignore and likely was the reason they tagged the area of interest heading into the weekend. Regardless of development, this has been a good practice run and also allowed us to shake off the cobwebs after several years of no real Tropical Troubles in our backyard.

[tireman4]

000
FXUS64 KHGX 131415
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
915 AM CDT Tue Jun 13 2017

.UPDATE...
Satellite derived PW values show values between 1.80 and 2.00
inches across the CWA. Convective temps are between 83 and 88
degrees so it its reasonable to expect to additional coverage this
afternoon with daytime heating. Current PoP/temp forecast looks
on track so other than a few minor tweaks, rest of the forecast
looks good to go. 43

&&

.PREV DISCUSSION... /ISSUED 645 AM CDT Tue Jun 13 2017/

AVIATION...
SHRA axis has shifted westward with just CLL in line for possible activity
this morning. With daytime heating, additional SHRA and possible TSRA
could form across the area this morning. Could see afternoon SHRA/TSRA
further inland. Lighter winds tonight could help to allow for possible
MVFR/IFR ceilings and/or fog to develop. 42

PREV DISCUSSION... /ISSUED 357 AM CDT Tue Jun 13 2017/

DISCUSSION...
The story of the week may be the heat. Upper ridging will build
in over the next several days, gradually choking off shower
potential and allowing for temperatures to drift up into the 90s,
along with heat indices up into the triple digits. We`re probably
not into heat advisory range just yet, but it is early in the
summer - like the first winter storm up north, sometimes people
are taken a little bit by that first slap of summer heat. It`s
worthwhile to remind everyone to not overdo it, look before you
lock, and put some extra emphasis on hydration.

SHORT TERM [Wednesday Through Friday]...

The mid to late week will continue to feature midlevel ridging,
but also look for a ridge axis/high pressure center at 700 mb and
850 mb to drift over the region. This looks to briefly disrupt the
vertical depth of onshore flow. These processes combined should
choke off potential for rain, and even the development of
overnight low clouds for the late week. Surface flow will remain
onshore, so dewpoints look to remain relatively high - but even
those should dip slightly in the afternoon as some drier air aloft
would mix down.

Anyway, with all of this going on, look for temperatures to drift
upwards into the lower to middle 90s. Heat indices would top out
at or above 100 across the area, and if current forecasts hold, a
couple solid patches in the 105-107 degree range. This stretch in
the late week is likely to have the highest apparent temperatures
as dewpoints are still relatively high while temperatures are able
to soar. As mentioned above, heat advisories are probably still
out of reach at this point, but that doesn`t mean it won`t be hot
out there. We`ve got several months of this to go, so it`s time to
start working in those summer adaptions to the typical heat of
summer in Southeast Texas.

LONG TERM [This Weekend and Beyond]...

The western ridge axis should continue in place, perhaps drifting
from Northwest Mexico towards the US Desert Southwest. Onshore
flow in the lower atmosphere does look to sync back up with the
surface, though this only seems to marginally increase moisture
levels. Still, it looks to be enough to temper high temperatures
and max heat indices slightly, and bring back potential for some
isolated diurnal showers and storms. It will be a subtle change in
the pattern, for sure.

Two things to keep an eye on as we steam towards mid-week - a
front-like feature that may backdoor in, and a low pressure center
hanging out around the Yucatan and southern Gulf. The front has a
better chance of directly impacting the area, but at more than a
week out, not ready to buy into the big PoPs some of the blends
are giving me right now. At the time the modeled front is backing
in from the northeast, flow from 850 mb up to 500 mb is also out
of the northeast, which would seemingly sap moisture from a
potential precip setup. Something to watch, as there`s plenty of
time.

As for that other feature, well, more on that in the tropical
section below (Spoiler Alert: it`s not very exciting...).

MARINE...

Elevated winds and seas early this morning (slightly higher
in and near area showers) are expected to decrease during
the day. Light to moderate south to southeast winds can be
expected for the remainder of the week and for much of the
upcoming weekend. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 93 75 94 75 95 / 40 10 20 10 10
Houston (IAH) 92 78 92 77 93 / 50 10 30 10 20
Galveston (GLS) 89 82 87 82 88 / 30 10 20 10 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 10 AM CDT this 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...43

[srainhoutx]

Upgrades are coming for the GFS and ECMWF in the not too distant future. Interestingly the 12Z Parallel GFS develops Hurricane Bret in about 8-10 days in the Western Gulf, ENE of Tampico. According to the Parallel GFS the TC is vertically stacked across all levels of the atmosphere and has a well structured anticyclonic Upper Ridge right over the surface low allowing for excellent ventilation.

[tireman4]

000
FXUS64 KHGX 131707
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1207 PM CDT Tue Jun 13 2017

.AVIATION...
Scattered afternoon showers with the chance for some of these TCU
to develop into a short-lived thunderstorm. Generally VFR
ceilings through the period with brief MVFR (isolated IFR) decks
advecting over more interior hubs after sunset. Winds stay up just
enough through sunrise Wednesday to exclude the mention of any
significant fog. Less precipitation coverage tomorrow with a mid
to late morning cumulus field...southeast winds around 10 mph. 31

&&

.PREV DISCUSSION... /ISSUED 915 AM CDT Tue Jun 13 2017/

UPDATE...
Satellite derived PW values show values between 1.80 and 2.00
inches across the CWA. Convective temps are between 83 and 88
degrees so it its reasonable to expect to additional coverage this
afternoon with daytime heating. Current PoP/temp forecast looks
on track so other than a few minor tweaks, rest of the forecast
looks good to go. 43


MARINE...
Elevated winds and seas early this morning (slightly higher in
and near area showers) are expected to decrease during the day.
Light to moderate south to southeast winds can be expected for the
remainder of the week and for much of the upcoming weekend. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 75 94 75 95 76 / 10 20 10 10 10
Houston (IAH) 78 92 77 93 77 / 10 30 10 20 10
Galveston (GLS) 82 87 82 88 81 / 10 20 10 10 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 10 PM CDT this evening for the
following zones: Brazoria...Chambers...Galveston.

GM...NONE.
&&

$$

Discussion...42
Aviation/Marine...31

[srainhoutx]

NWSCPC‏Verified account @NWSCPC · 1h1 hour ago
Moderate confidence continues regarding a possible tropical cyclone formation near the Yucatan over the next week. http://www.cpc.ncep.noaa.gov/products/p ... /index.php …

[DoctorMu]

Regardless of tropical or not, I think we could see heavy rain.

Something of the lemonade persuasion is exactly what I'm looking for...

Can we literally get over the hump/ridge? The longer we can delay the eventual Death Ridge, the better.

[DoctorMu]

Current GFS solution exhibits a more amorphous tropical open wave providing some area shower late next week.

Euro has the low heading into Mexico north of Tampico. GEM moves a tropical low towards Pensacola

[Katdaddy]

The Houston-Galveston, Corpus Christi, and Brownsville NWS summarize this area in their afternoon AFDs.

Houston-Galveston NWS

An area of disturbed weather approaching the Yucatan will emerge
into the southern Gulf early next week. As this wave moves west
into Mexico, it might bring a surge of deeper moisture into Texas
with a chance of showers returning next Monday or Tuesday.

Corpus Christi NWS:

NHC is outlooking an area of disturbed weather that has a low chance
of developing into a tropical cyclone over the next five days. That
area obviously bears watching but as of now is no threat to Texas.

Brownsville NWS:

Under scrutiny will be a tropical wave moving west from the Western
Caribbean Sea on Sunday to over the Yucatan Peninsula and then into
the Southwest Gulf on Monday. This development is seen quite well in
the ECMWF model, for example. A weak, broad surface low will then
develop over the Southwest Gulf on Tuesday, possibly causing winds
to back to east or northeast over the Northwest Gulf if any kind of
circulation is able to develop. The surface low should continue
moving west to the Mexican Coast and then inland, resulting in
enhanced rain chances for the County Warning Area, on the northern
periphery of the low`s influence, heading into the middle of next
week.

[srainhoutx]

Tuesday evening briefing from Jeff:

The National Hurricane Center (NHC) has placed a 20% chance of tropical cyclone formation across the western Caribbean Sea over the next 5 days.

As discussed previously, global forecast models remain consistent in the gradual formation of a large surface low pressure system across the extreme western Caribbean Sea, Yucatan Peninsula, or southern Gulf of Mexico this weekend into early next week. This surface low appears to develop from the tropical wave currently entering the eastern Caribbean Sea and the slight northward advancement of a monsoon trough across central America interacting over the western Caribbean Sea. There is also likely to be some lingering energy from the landfall of tropical storm Calvin yesterday along the southern MX coast in the general region. General agreement is that a surface low will form somewhere along the north or west coast of the Yucatan and track generally WNW to NW as deep layer ridging (high pressure) develops across the northern Gulf of Mexico and southern US. While the global forecast models and their ensemble members are in general agreement, there are some outstanding questions that could greatly affect the final outcome of this system.


1) Where exactly does a surface circulation develop
2) How much does any system interact with the landmass of central America and Mexico

One aspect that continues to be consistent in model runs is that the system will likely be very large in size with a large radius of at least 20-30kt winds across a large portion of the central and southern Gulf of Mexico by the middle of next week. It is not uncommon for such monsoon type surface lows (more common in the western Pacific) to have a fairly large envelope of moisture and winds. It is interesting to note that the ECWMF shows a favorable upper air pattern across the southern Gulf for intensification early next week, but maintains the system as a weak tropical storm…this could be in part due to the large size of the system which tend to not intensify as quickly as a smaller system…or maybe some other factor. In fact none of the global model guidance shows a strong system in the southern or southwestern Gulf of Mexico except for the GFS Para (which will be discounted) in favor of a weaker solution…a tropical depression or weak tropical storm.

East Atlantic:

While it would be very rare for any sort of tropical development in the deep tropical region between the African coast and the Caribbean Sea at this point in the season…a vigorous tropical wave as moved off the west coast of Africa and interestingly some of the global models show some development of this wave. While development is unlikely…this could be an early sign that conditions in the deep tropical Atlantic which have been less than ideal for the last several years are going to be more favorable this year. In fact the African wave train appears fairly active for June and the general dry stable conditions of the last few years appear to not be in place at least currently in the deep tropics of the Atlantic basin.

[Scott747]

Figured we would see at least one shift in the models. 18z gfs had a hint and the 0z Euro has a fairly sizable shift N and W into the lower/mid Texas coast as a weak system.

Could be a one off type of shift....

[srainhoutx]

Timing will be everything regarding just how far North the SW Heat Ridge actually evolves and the exact placement of a potential weakness situated along the Texas Coast between the Sub Tropical Ridge to our East and the building SW Heat Ridge to our North and West. Unfortunately, we cannot accurately determine beyond 3 to 5 days what our sensible weather may hold for the middle of next week. HGX does acknowledge that the possibility of a weak Tropical System attempting to organize this weekend does exist, but its eventual track is still fuzzy as of this morning.

.TROPICAL... Well, well, well...it appears the 00Z Euro has decided to try to make things interesting. But in the large scheme of things, not much has really changed. The guidance continues to spin up a tropical cyclone out of an easterly wave interacting with a broad Central American gyre - and we are now at a range where it`s really hard to dismiss it out of hand. That`s not to say there will be development, but it is not merely some fantasy of partial differential equations. The NHC gives a 20 percent chance of development in the next 5 days, which seems fair. Now, the "interesting" part. If you read the long term portion of the discussion, you`ll recall that the Southwest ridge looks to be positioned farther north than before. In the GFS, this is of little consequence - the steering flow continues to drive a low into Mexico, far south of us. The Euro, on the other hand, decides to have a little fun. The northern position of the ridge axis allows a low (that seems to have largely missed the Yucatan) to drive up into the Gulf. And though the ridge tries to build in, it`s too late. A tropical depression or weak tropical storm manages to sneak onshore around Matagorda Bay. So now you may be asking, "Is this what`s going to happen?". In a single word, doubtful. Even farther north, the ridge is pretty stout, and I tend to side with the GFS solution on this one. Additionally, it`s not the GFS alone on this one - GEFS is pretty clearly in support of its deterministic counterpart, and MSLP anomalies in the EPS implies the Euro ensemble is more in this camp as well, leaving the Euro Op on its own. I fully expect this Euro run to be more of a fluke - but it does serve as a reminder to ensure that all our hurricane plans and kits are refreshed and ready to go.

[cperk]

I can't wait until the next couple of Euro runs to see if our friend at the Houston/Galveston weather service is right.

[srainhoutx]

Wednesday morning briefing from Jeff:

The National Hurricane Center (NHC) is monitoring two areas of potential tropical development over the next 5 days. Both areas have a 20% chance of development.

Gulf of Mexico/Western Caribbean Sea:

A tropical wave axis moving into the eastern Caribbean Sea will arrive into the western Caribbean Sea this weekend where it will interact with a trough of lower pressure over central America. The major global models continue to show development of a broad area of low pressure over the extreme western Caribbean Sea or the western/northern coast of the Yucatan this weekend. There is growing support from the GFS and ECMWF ensemble members for development of at least a tropical depression and possibly a tropical storm.

General large scale ridging will be in place across much of the northern Gulf of Mexico, but subtle changes in the position of the ridge axis is resulting in some varying tracks of the surface low over the Gulf of Mexico. Additionally, models continue to forecast a very broad circulation with a large area of 25-35 kt winds over much of the central and southwestern Gulf of Mexico by the middle of next week. Until an actual surface circulation forms the expected track of any tropical system in the Gulf of Mexico will be uncertain. What appears to be differences in the tracks in the 00Z runs of the GFS and ECMWF appear to be related to the organization of the system and the development location.

Interest in the western Gulf of Mexico should closely monitor the progress of this system over the next several days.

Eastern Atlantic:

Visible satellite images this morning show a very well developed tropical wave axis several hundred miles SSW of the Cape Verde Islands with moderate to at times deep convection. While it would be extremely rare for a tropical depression to form this far east and south at this time of year (only two systems have ever formed east of the Caribbean Sea this early since 1850), but there is some model support at least in the near term as the wave tracks westward toward northern south America and the extreme SE Caribbean Sea. While water temperatures are currently marginal they will be warming along a westerly track, but overall favorable upper level winds currently will be increasing out of the SW and wind shear will likely hinder development as the system approaches the Islands. It is interesting that the global models are showing some development as the system nears the Windward Islands and then rapid dissipation across the eastern Caribbean Sea.

[Portastorm]

I mean no disrespect or throwing "shade" on HGX but I don't understand how they can continue to be so dismissive of the possibility of this potential system impacting South and Southeast Texas. Caution and patience are certainly the guidance key words here so that folks don't freak out about one model run. But that being said, there is a litany of tropical systems impacting this region in the month of June. It's not like it's unheard of.

With the GFS and Euro suffering beyond Day 5 in the skill scores, I'd be really concerned about any possibility beyond that range.

[cperk]

I mean no disrespect or throwing "shade" on HGX but I don't understand how they can continue to be so dismissive of the possibility of this potential system impacting South and Southeast Texas. Caution and patience are certainly the guidance key words here so that folks don't freak out about one model run. But that being said, there is a litany of tropical systems impacting this region in the month of June. It's not like it's unheard of.

With the GFS and Euro suffering beyond Day 5 in the skill scores, I'd be really concerned about any possibility beyond that range.

I totally agree Portastorm that forecaster has put himself out on a limb 5 days out.

[869MB]

I mean no disrespect or throwing "shade" on HGX but I don't understand how they can continue to be so dismissive of the possibility of this potential system impacting South and Southeast Texas. Caution and patience are certainly the guidance key words here so that folks don't freak out about one model run. But that being said, there is a litany of tropical systems impacting this region in the month of June. It's not like it's unheard of.

With the GFS and Euro suffering beyond Day 5 in the skill scores, I'd be really concerned about any possibility beyond that range.

I think it's really funny and ironic you say that because I was just thinking the exact same thing after I read what they had to say. My vibe is they may get away with it regarding this particular system, but they may want to be more careful going forward in regards to their verbiage and attitude with respect to possible future tropical systems this year because one of these disturbances may pull a surprise and their discussions may come back to haunt them.

[jasons2k]

Of all things, it's HAILING here at the Woodlands office....