Thursday, March23, 2017 L-36.com


Marine Weather and Tides
Bolivar Peninsula, TX

Version 3.4
What's New / NOTES
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 7:16AMSunset 7:34PM Thursday March 23, 2017 11:19 AM CDT (16:19 UTC) Moonrise 3:15AMMoonset 2:19PM Illumination 16% Phase: Waning Crescent; Moon at 26 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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GMZ335 Matagorda Bay-galveston Bay- 1009 Am Cdt Thu Mar 23 2017
This afternoon..Southeast winds 10 to 15 knots. Bay waters slightly choppy.
Tonight..Southeast winds 15 to 20 knots. Bay waters choppy.
Friday..South winds 15 to 20 knots. Bay waters choppy. A slight chance of showers and Thunderstorms in the morning, then a chance of showers and Thunderstorms in the afternoon.
Friday night..South winds 15 to 20 knots becoming southwest 10 to 15 knots after midnight. Bay waters choppy becoming slightly choppy after midnight. A chance of showers and Thunderstorms.
Saturday..West winds 10 to 15 knots becoming southwest 5 to 10 knots in the afternoon. Bay waters slightly choppy becoming smooth in the afternoon. A slight chance of showers and Thunderstorms.
Saturday night..South winds 5 to 10 knots. Bay waters smooth.
Sunday..South winds 10 to 15 knots. Bay waters slightly choppy.
Sunday night..South winds 10 to 15 knots. Bay waters slightly choppy. A slight chance of showers and Thunderstorms.
Monday..South winds 10 to 15 knots. Bay waters slightly choppy. A chance of showers and Thunderstorms.
Monday night..South winds 5 to 10 knots. Bay waters smooth.
GMZ300 Synopsis For High Island To The Matagorda Ship Channel Out 60 Nautical Miles Including Galveston And Matagorda Bays 1009 Am Cdt Thu Mar 23 2017
Synopsis for high island to matagorda ship channel out 60 nm.. A light to moderate onshore flow will prevail this afternoon but are expected to strengthen significantly tonight and Friday in response to an intensifying area of low pressure over the plains. A cold front will approach the coastal waters on Saturday but the front is forecast to stall inland. Onshore winds are expected to prevail through the weekend.

7 Day Forecast for Marine Location Near Bolivar Peninsula, TX
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location: 29.49, -94.56     debug


Area Discussion for - Houston/Galveston, TX
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Fxus64 khgx 231523
afdhgx
area forecast discussion
national weather service houston/galveston tx
1023 am cdt Thu mar 23 2017

Discussion
Morning surface analysis shows dewpoints back in the low/mid 60s
and temperatures in the low/mid 70s. Temperatures should increase
back into the mid 80s like the last couple of days. Water vapor
imagery shows upper low over the 4 corners region which will be
the main system supporting the severe weather potential for
tomorrow. Hi-res mesoscale models showing a line of storms moving
through the area tomorrow afternoon. Afternoon forecast package
will focus on those forecast details. Only changes this morning to
the forecast will be for keeping up with ongoing t/td trends.

Overpeck

Prev discussion /issued 608 am cdt Thu mar 23 2017/
aviation...

MVFR CIGS a little slow to develop this morning but potential is
still there for low ceilings through 15z or so. Drier air aloft
will mix to the sfc later this morning and skies will become
mostly clear. Stronger winds aloft will mix to the sfc and gusty
south winds are expected this aftn/evening. MVFR CIGS possible
again tonight and fcst soundings show CIGS developing as early as
03z. Leaned a bit more toward persistence. Fcst soundings also
show low level saturation increasing Fri morning beneath a 40 kt
low level jet. Might get some streamer showers Fri am but did not
mention in the tafs at this time. 43
prev discussion... /issued 413 am cdt Thu mar 23 2017/
discussion...

upper ridging sliding east across texas today will promote
another day of dry and warm conditions across southeast texas.

Surface observations as of 4 am show temperatures in the mid 60s
to low 70s, with a few locations reporting patchy fog.

Additionally, split channel IR satellite imagery shows stratus
gradually expanding northward from the interstate 10 corridor.

Similar to the past few mornings, fog (some locally dense
possible) and low clouds will lift or dissipate by mid-morning
with mostly sunny skies this afternoon allowing temperatures to
rise into the upper 70s to mid 80s. Near record high temperatures
are again expected along the coast today.

Early morning water vapor imagery shows an upper trough
translating across the great basin, with this feature expected to
reach the southern plains tonight. Vorticity advection ahead of
this upper trough has already resulted in the development of a lee
surface trough over the high plains, with surface cyclogenesis
expected to commence by this evening as the upper trough continues
to translate east. In response, southerly surface winds will
increase to 10 to 20 mph tonight and through the day tomorrow with
stronger gusts around 25 mph possible. Elevated winds overnight
will preclude a fog threat for the region and also allow for
temperatures a few degrees above what we observe this morning,
with overnight lows in the upper 60s to low 70s.

As the upper trough crosses the southern plains on Friday, it
will drag the surface cyclone east with it. Showers and
thunderstorms are expected to develop along an associated
prefrontal trough or dryline across central texas on Friday
(possibly leftover convection from west texas today), with strong
lift (100-110 knot 250 mb jet streak) allowing the storms to grow
upscale into a line through the morning hours as the system moves
east. Daytime heating may encourage enough destabilization across
parts of the brazos valley to promote SBCAPE values around
1500-2000 j/kg, allowing rapid thunderstorm development as the
line reaches our western counties. While guidance offers slightly
different solutions with the timing for the system, this
thunderstorm line looks to reach the western counties around
midday, the interstate 45 corridor during the afternoon to early
evening hours, and the eastern counties late Friday evening to
early Saturday morning. Depending on the strength of the cold
pool(s) associated with this line, it may end up propagating
faster than currently anticipated.

Regarding the severe weather threat for Friday, environmental
conditions still remain favorable to produce at least a few strong
to severe storms within the larger thunderstorm line. The
aforementioned instability combined with 0-6 km bulk shear values
around 50-60 knots will promote organized thunderstorms capable of
producing damaging winds, especially from any kind of downward
momentum transfer of near surface winds as a 35-45 knot low level
jet sets up across the region. This low level jet will also draw
deeper gulf moisture back into the region, with precipitable water
values rising into the 1.2-1.5 inch range by Friday afternoon.

While locally heavy rain will be possible given the amount of
atmospheric moisture present, the overall speed of the line should
mitigate against any widespread flooding threat (mean winds in
the cloud bearing layer of 850-300 mb around 40-50 knots). Another
threat will include an isolated tornado or two along the leading
edge of the thunderstorm line as the strength of the near surface
winds will also result in 0-1 km bulk shear values 15-25 knots.

Could also see large hail given mid-level lapse rates in excess of
6.5 c/km, but have lower confidence in this hazard materializing
as forecast soundings are advertising relatively skinny cape
profiles (indicating the potential for updrafts to become water
loaded and not as efficient for producing hail).

The main question with Friday's severe weather threat will
largely be where it actually materializes. While both NAM and gfs
bufr soundings continue to erode/lift a capping inversion through
the day Friday, the strength of their mid-level southwest flow
(30-35 knots) raises concerns for enough warm air advection to
occur to limit the southern extent of the thunderstorm line as it
moves into southeast texas. Given how forecast parameters are
lining up across the forecast area (including lift from upper
level system and corridor of strongest 0-6 km bulk shear values),
areas north of a brenham to cleveland line will need to be
monitored for the greatest severe weather threat... But again
cannot rule out anywhere north of the interstate 10 corridor.

Interestingly, inspection of the 400 mb relative humidity fields
from the arw, nmm, nam, and GFS (which can serve as a proxy for
stronger convection as it indicates thunderstorm tops greater than
roughly 24,000 ft agl) shows fairly good consensus in strongest
convection remaining north of interstate 10... With a few that
only show convection north of the aforementioned brenham to
cleveland line.

A weak cold front will push into the region behind the main
thunderstorm line early Saturday morning as the system exits the
region, possibly stalling near or pushing just off the upper texas
coast. No impact on temperatures is expected from this front as
deepening westerly flow behind Friday's system will encourage
temperatures to again rise back into the upper 70s to mid 80s on
both Saturday and Sunday with dry conditions prevailing across the
region.

The next disturbance to affect rain chances for the region lifts
across the southern and central plains on Sunday night, sending a
weak cold front into the area on Monday. Daytime heating and weak
convergence along the front may be enough to produce a few showers
and thunderstorms along the front, with best chances along the
upper texas coast where deeper moisture is forecast to reside. Dry
conditions Tuesday in the wake of the front will be short-lived
as the next storm system to affect the region arrives during the
middle of next week. Considerable timing difference exist between
medium range guidance regarding this system, but widespread
showers and thunderstorms appear possible for the region during
this time.

Huffman
marine...

high pressure over the northern gulf and lower pressures in the
lee of the rockies will maintain an onshore flow today. The
pressure gradient will tighten significantly Thursday evening into
Friday as the high moves east and low pressure over the western
plains intensifies. A small craft advisory will probably be
required tonight over the gulf waters and a scec will be needed
for the bays. The low will move toward the mid mississippi valley
on Saturday and drag a cold front into texas. It is unclear how
far the front will travel before stalling on Saturday. There are
some indications that a wind shift to the west could briefly
develop Saturday morning before winds back to the south by
Saturday evening. The gradient will weaken as the front nears the
coast and wind speeds will decrease on Saturday. Another area of
low pressure will develop over eastern new mexico on Sunday and
the gradient is expected to tighten once again. Winds will back to
the s-se and increase in response to the deepening low. More
caution flags possible Sunday and Sunday night. The low over nm
will move east but the associated cold front with this feature
will also stall before reaching the coast. Moderate to
occasionally strong onshore winds are expected next week with more
caution flags Tuesday night and SCA conds Wednesday night. 43

Preliminary point temps/pops
College station (cll) 85 66 79 58 81 / 0 10 80 30 10
houston (iah) 84 68 80 66 83 / 0 10 40 60 20
galveston (gls) 79 70 78 70 80 / 0 10 20 50 20

Hgx watches/warnings/advisories
Tx... None.

Gm... Small craft should exercise caution until 10 pm cdt this evening
for the following zones: 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... 39


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
RLOT2 - 8770971 - Rollover Pass, TX 3 mi50 min S 8 G 12 74°F1022.3 hPa
HIST2 12 mi50 min SSE 6 G 9.9 73°F 75°F1022.5 hPa
GNJT2 - 8771341 - Galveston Bay (North Jetty), TX 13 mi50 min SSE 8.9 G 11 76°F 72°F
GTOT2 17 mi50 min 73°F 70°F
42035 - GALVESTON 22NM East of Galveston, TX 19 mi90 min S 9.7 G 12 71°F 72°F2 ft1021.9 hPa (+1.6)67°F
EPTT2 - 8771013 - Eagle Point, TX 19 mi50 min S 13 G 15 72°F 74°F1021.9 hPa
KXIH 22 mi45 min S 6 G 12 75°F 66°F
GRRT2 22 mi50 min S 8 G 11 72°F 74°F1022.1 hPa
MGPT2 - 8770613 - Morgans Point, TX 26 mi50 min SSE 8.9 G 13 74°F 72°F1021.9 hPa
SRST2 - Sabine Pass, TX 31 mi80 min S 8 G 9.9 71°F 1022.6 hPa (+1.3)66°F
LYBT2 33 mi50 min SSE 8 G 9.9 73°F 72°F1020.9 hPa
SBPT2 - 8770570 - Sabine Pass North, TX 40 mi50 min S 8 G 12 73°F 74°F1023.8 hPa
TXPT2 40 mi50 min S 9.9 G 12 71°F 71°F1022.6 hPa
LUIT2 41 mi50 min SSE 8 G 11 74°F
NCHT2 - 8770777 - Manchester, TX 41 mi50 min S 9.9 G 12 74°F 72°F1021.7 hPa
PORT2 - 8770475 - Port Arthur, TX 42 mi50 min S 6 G 8.9 70°F1022.5 hPa
KVBS 49 mi45 min Calm 73°F 68°F

Wind History for Rollover Pass, TX
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Galveston, Scholes Field, TX22 mi28 minSSE 1010.00 miFair76°F68°F77%1022.3 hPa
High Island 179A (Apache Corp), LA22 mi45 minS 6 G 1210.00 miFair75°F66°F74%1022 hPa

Wind History from XIH (wind in knots)
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Last 24hr4CalmS4Calm456S8S11S11S10S6
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1 day agoW8W9W8W7W9SW7SW7SW7SW7SW9SW9SW10SW9SW11SW10SW11SW8
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2 days agoSW9W10W9W11W10SW9SW8SW9SW9SW9SW9SW9SW8SW10SW7SW10SW9SW8SW9W10W12W13SW12SW9

Tide / Current Tables for Rollover Pass, Texas
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Rollover Pass
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Thu -- 02:29 AM CDT     1.00 feet High Tide
Thu -- 04:14 AM CDT     Moonrise
Thu -- 07:17 AM CDT     Sunrise
Thu -- 11:24 AM CDT     -0.02 feet Low Tide
Thu -- 03:19 PM CDT     Moonset
Thu -- 07:31 PM CDT     Sunset
Thu -- 07:39 PM CDT     1.07 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.91110.90.80.70.50.30.20.1-0-00.10.30.50.70.911.11.1110.9

Tide / Current Tables for Galveston Bay Entrance, Texas Current
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Galveston Bay Entrance
Click for Map
Thu -- 12:53 AM CDT     -0.11 knots Min Ebb
Thu -- 04:15 AM CDT     Moonrise
Thu -- 07:18 AM CDT     -2.18 knots Max Ebb
Thu -- 07:18 AM CDT     Sunrise
Thu -- 11:27 AM CDT     0.00 knots Slack
Thu -- 02:29 PM CDT     1.86 knots Max Flood
Thu -- 03:20 PM CDT     Moonset
Thu -- 07:16 PM CDT     -0.00 knots Slack
Thu -- 07:32 PM CDT     Sunset
Thu -- 09:59 PM CDT     -0.59 knots Max Ebb
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
-0.2-0.1-0.3-0.7-1.1-1.5-1.9-2.2-2.1-1.8-1.2-0.40.51.41.81.81.61.20.70.1-0.3-0.5-0.6-0.5

Weather Map and Satellite Images
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Weather Map
wmap_A
IR Satellite Image from GEOS
east_satellite

GOES Local Image of SouthCentralPlains    EDIT
Geos

Wind Forecast for Houston/Galveston, TX (12,3,4,5)
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Ground Weather Radar Station Houston/Galveston, TX
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Gulf Stream Current


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Disclaimer:
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.