March-2017: Active Spring WX Pattern Ahead

[DoctorMu]

Traditional Ag Spring Break cold front on its way early next week. How it becomes here depends upon how far the cold air slides east. Potential snowstorm in TN and east, maybe upper MS. Could be a frost around here Monday night.

[srainhoutx]

The afternoon computer guidance suggests that the combination of a couple of upper air disturbances rippling along the sub tropical jet from the Eastern Pacific, a developing coastal trough/low along the Texas Coast and a backdoor cold front could all come together making for a very wet and potentially stormy Friday into early Sunday.

[tireman4]

HGX NWS alluding to Steve's forecast...

000
FXUS64 KHGX 091807
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
Issued by National Weather Service Lake Charles LA
1207 PM CST Thu Mar 9 2017

.DISCUSSION...
For the 03/09/17 1800 UTC TAF package.

&&

.AVIATION...
Continued influx of moist Gulf air resulting in widespread cloud
cover across SE TX late this morning. CIGS are generally MVFR at
the southern/coastal terminals with VFR farther inland, though
there has been some variability noted in Obs. Light shower
activity remaining largely west of the terminals, though expected
to get close to KCLL later this afternoon. Some continued slight
improvement to CIGS is possible through the afternoon hours, but
low clouds and/or reduced VSBYS are expected to return areawide
tonight. KGLS continues to contend with sea fog pushing WWD from
the nearshore coastal waters. Satellite imagery suggests there may
be some improvement here in a few hours or so, especially in terms
of a CIG, but at least some restriction to VSBY is expected to
continue through the forecast period.

13

&&

.PREV DISCUSSION... /ISSUED Issued by National Weather Service Lake Charles LA/

DISCUSSION...Satellite imagery/surface obs depicting widespread
stratocu across the area. Despite considerable cloud cover,
afternoon high temperatures will reach well above above the norm
on a warming southeast low level flow. Radar currently absent of
precip, but could see some isolated showers and possibly a
thunderstorm this afternoon with sufficient moisture now in place.
Forecast looks on track and no morning update will be required.

PREV DISCUSSION... /ISSUED 1018 AM CST Thu Mar 9 2017/

DISCUSSION...Satellite imagery/surface obs depicting widespread
stratocu across the area. Despite considerable cloud cover,
afternoon high temperatures will reach well above above the norm
on a warming southeast low level flow. Radar currently absent of
precip, but could see some isolated showers and possibly a
thunderstorm this afternoon with sufficient moisture now in place.
Forecast looks on track and no morning update will be required.

PREV DISCUSSION... /ISSUED 906 AM CST Thu Mar 9 2017/

UPDATE...
Very little change to the forecast in this morning`s update.
Tweaked the temperatures by a degree or two to account for the
trends based off the latest observations. High temperatures should
reach into the mid to upper 70s today. Still expecting to see
those overcast skies hold tight through the remainder of the day, with
some lower visibilites slowly on the rise across much of the
inland areas this morning. Carrying a 20 to 30% PoP today, as the
forecast soundings are still showing saturation in the lower
levels. Therefore, expecting a few showers and possibly an
isolated thunderstorm as we move into the afternoon hours and
into the early evening. Should see conditions begin to dry out,
dampening the chance for precip overnight. Still looking like a
wet Friday, as the atmosphere remains fairly unstable out ahead of
the next cold front pushing through SE TX late Saturday into
Sunday. Models are triggering on a few shortwaves propagating
across the region Friday and Saturday, which would help aid in the
shower and thunderstorm development.
Hathaway

Marine...
Sea fog ongoing but satellite and models showing some drier air
mixing in late this morning/afternoon. Have extended the marine
dense fog advisory to 11 for any lingering fog. ESE-SE winds near 10
to 10-15 knots the prevailing wind today becoming more solidly
southeasterly. Sea fog will likely return again late this
afternoon/evening.
45

PREV DISCUSSION... /ISSUED 507 AM CST Thu Mar 9 2017/

DISCUSSION...
A typical early winter morning for us here in southeastern
Texas...mainly overcast with areas of fog limiting inland and
maritime visibilities to as low 1 or 2 miles. High overcast and a
near surface 10 knot wind likely keeping areawide dense fog at
bay. There may be a few sites that drop down to below a mile a
few hours past sunrise requiring a very short fuse inland Dense
Fog Advisory. Unsettled would be the appropriate adjective to
describe the weather pattern these next few days. Moisture has
returned and models are predicting a fairly unstable environment
for any passing shortwave disturbance to initialize strong to
possibly severe thunderstorms from this afternoon through a cold
frontal passage early Sunday morning. A quick inspection of the
satellite depicts a very active weather scenario over Mexico and a
strengthening subtropical jet that may move up into lower Rio
Grande going into the weekend. Weak shortwave ripples passing through
this high wind corridor will likely skirt the region and kick off
periods of heavier weather from today through Saturday. Afternoon
T readings approaching 80 F will be more than enough to steepen
low to mid level lapse rates in producing (what is modeled to be)
1 to ~2k J/kg afternoon CAPE values and -3 to -6 Lifted Indices.
K Indices of greater than 30 are indicative of more numerous
thunderstorm activity/coverage. Overall bulk shear is not overly
impressive but...if these thermodynamics come to fruition...then
this alone should carry the weight of supporting possible strong
storms evolving to severe as early as this afternoon but more
likely on Friday and Saturday.

The approach and passage of a shortwave trough Saturday will
place high to likely chance POPS in place beginning tomorrow as
the region falls into the warm sector. Upper level support isn`t
very supportive of the severe argument although run-to-run model
behavior favors an emergence of the STJ. The area may fall under a
favorable quadrant by Saturday as the STJ merges with the Polar
Branch over the southeastern U.S. Saturday. A cold frontal passage
either late Saturday night or overnight Sunday morning will generate
moderate inland northerly breezes...strong offshore flow over the
local waters. Albeit delayed by a day or so...a continental cold
air mass will slip down over the MS River Valley and clip eastern
Texas. Single digit 85H temps will regulate warmth and actually
have early next week falling to `below` normal in relation to the
mid March diurnal T curve. Slow cloud erosion going through
Sunday morning will aid in keeping the afternoon in the 50s to
lower 60s for many interior county communities. A reinforcing cold
front Monday will maintain an offshore flow pattern through late
Tuesday. Thus...sluggish subsequent day warming into the lower 70s
Monday and Tuesday/min Ts in the 40s/low 50s. Dry weather will
persist through mid week. The next western storm system brews
Thursday and has increased late week rain/storm chances. 31

Aviation...
IFR/LIFR conditions expected to slowly improve toward mid/late
morning...though most locations might not see higher end MVFR
observations until after lunch. Do anticipate some iso/sct really
light precip between 17-23z, they shouldn`t be long lasting nor have
much of an impact to mention in the TAFs. Ceilings will likely begin
falling again quickly after sunset and expect another night of 200-
1000ft cloud decks. Areas of sea fog...will likely start making it
back inland during the evening hours as well. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 65 79 63 76 50 / 10 50 50 70 60
Houston (IAH) 66 79 64 75 52 / 10 50 50 70 60
Galveston (GLS) 67 74 67 73 60 / 10 50 40 60 60

&&

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

&&

$$

[srainhoutx]

Friday morning briefing from Jeff:

Interesting forecast for the next 48 hours as several features could produce showers and thunderstorms or nearby convective development could locally reduce chances for storms.

Weak short wave over Matagorda Bay this morning has moved little since 300am with widespread showers extending ESE/SE well over 100 miles into the Gulf of Mexico and a large explosion of thunderstorms over the coastal bend from Corpus extending well SE out over the Gulf. Additionally a weak cool front is sliding SW from deep E TX ahead of a surge of high pressure along the US east coast. A look at local dewpoints show little difference over SE TX, with lower dewpoints over E TX behind this front. Air mass is generally moist and unstable with low convective temperatures in the mid to upper 70’s. Surface temperatures should warm into the mid 70’s by early afternoon and expect to see a fairly marked increase in showers and thunderstorms between late morning and early afternoon. Think both the stalled short wave over Matagorda Bay and the weak boundary approaching from the NE will provide focuses for thunderstorms today. It is possible that the short range models are focusing the activity too far north today when compared against the current radar coverage and storms out over the Gulf could “rob” moist inflow resulting in little inland activity.

Main threats will be isolated severe storms as seen yesterday over Montgomery County and locally heavy rainfall. HRRR and even the TX TECH WRF show some almost feeder banding type structures on the NE flank of the disturbance near Matagorda Bay and rotate these features across Fort Bend into Waller and western Harris County this afternoon. Storms yesterday over SC TX produced upwards of 3-4 inches of rainfall in 2 hours or less and would not be surprised to see similar rates today under the stronger cells.

Forecast for Saturday is challenging as much will depend on how activity evolves today, how far SW the weak frontal boundary moves, and if the local air mass can destabilize. General model trend has been for the formation of a coastal low near Matagorda Bay early Saturday along the weak frontal boundary and then this feature moves more eastward out over the Gulf of Mexico instead of previously advertised ENE/NE motion inland over SE TX. This latest development and track would focus the greatest rain chances and QPF along the coast or offshore. There is still enough guidance that suggest storms could develop inland and these storms would present a heavy rainfall threat.

Strong cold front will push across SE TX early Sunday morning. Latest guidance shows the coastal low tending to rob much of the inland moisture by Saturday night with most of the activity focused across C/SC TX and only a thin line of showers or thunderstorms over SE TX. Strong cold air advection will onset early Sunday and drive temperatures into the 50’s. Clouds look to linger into the afternoon hours and this will hold temperatures in the 50’s for much of the day with gusty N winds. It will certainly feel cold on Sunday.

Skies clear Sunday evening and winds relax resulting in a cold night across the area. Surface temperatures could bottom out in the upper 30’s north of I-10 on Monday AM…maybe even mid 30’s. Currently not expecting freezing conditions but some frost will be possible. Cool weather continues into the middle of next week with lows in the 40’s and highs in the 60’s followed by a late week warming trend ahead of the next storm system due into the area toward the end of next week.

[DoctorMu]

Backdoor cold front sneaking over LA border early. May over perform.


Yep - Temp and dew point starting to drop. We won't see 70°F again until Tuesday or Wednesday.

[srainhoutx]

The combination of a Coastal trough, a couple of embedded disturbances in the mid levels around 16K FT tracking ENE in a noisy sub tropical jet and a backdoor frontal boundary all combine to make for a wet Saturday into early Sunday with the possibility of a couple of stronger storms mainly along and S of HWY 105 toward the Coast and offshore waters. The Weather Prediction Center has outlined a Marginal Risk of Excessive Rainfall for today through tomorrow morning mainly along and S of I-10 from Matagorda Bay toward Metro Houston and Beaumont.

[srainhoutx]

Saturday morning briefing from Jeff:

Slowly intensifying coastal low around Matagorda Bay will begin to shift ENE up the coast this afternoon into the evening hours.

While short range guidance continues to struggle with the formation and movement of the coastal low forming around Matagorda Bay, radar trends seem to indicate that the bulk of the activity associated with this system will remain over the Gulf of Mexico waters or along and S of US 59 this afternoon with generally light to maybe moderate rainfall inland of US 59. Additionally, radar from Houston and Corpus shows fairly intense convection over the Gulf waters well S of Freeport which is helping to prevent moisture from freely flowing inland which should also help to keep rain chances reduced north of I-10 this afternoon.

Heavy rainfall today into this evening should remain generally south of US 59 and more likely remain off the TX coast or out across the nearshore Gulf waters. Still steady light to moderate rainfall for the next 6-10 hours will likely result in storm totals today of 1-2 inches S of US 59 with amounts less than .50 of an inch inland of US 59.

A strong cold front will sweep across the area tonight ushering in a cold modified arctic air mass. Temperatures on Sunday will remain in the 50’s under cold air advection and cloudy skies…so compared to late…it will feel cold. Still looking at lows on Monday morning to fall into the upper 30’s for many locations and sheltered areas could see a frost on Monday morning. GFS is holding on to clouds longer keeping low temperatures on Monday in the 40’s instead of the 30’s. Even the usually cold CXO (Conroe) GFS output is only 42 for Monday morning. Typically this would not be of much concern this time of year…but the incredible warmth this winter has led to widespread early leaf out that could be damaged by a late season frost.

[DoctorMu]

A lot more energy and rain than expected north of I-10. I had hope for clearing. Cool and very wet.

[DoctorMu]

Cold advection over performing in CLL as expected. We'll be lucky to make it past 50°F today. NOAA has downgraded temps for the week as a reinforcing cold front approaches on Monday. I think the NOAA forecast for Tuesday and Wednesday may still be optimistic. Naturally Spring Break weather was last month. That's Texas + maybe a climate change noodge.

[DoctorMu]

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1216 PM CDT Sun Mar 12 2017

.AVIATION...
MVFR ceilings are expected to slowly improve some time over the next
24-36 hours. Seeing some breaks developing to the NE of UTS and also
to the SW of LBX. If this trend continues, we might see improving conditions
at some of our northern TAF sites as well as near the coast in the next
couple of hours. 18Z TAFs might be a little too optimistic with VFR
ceilings by tomorrow morning, but latest HRRR has this happening almost
area wide this evening. N to NE winds will be decreasing this afternoon
and into the overnight hours. 42
&&

.PREV DISCUSSION... /ISSUED 1022 AM CDT Sun Mar 12 2017/

UPDATE...
A cold front has moved well off the Upper Texas Coast this
morning with breezy and cool conditions in place across Southeast
Texas behind it. The main updates to the forecast reflect
decreasing rain chances for the marine areas and lower high
temperatures today in the wake of the front. Forecast soundings
show moisture remaining trapped beneath a post-frontal inversion
for most of the day (located between 900-970 MB per morning
soundings from Fort Worth, Lake Charles, and Shreveport) and this
persistent cloud cover combined with ongoing cold air advection
will mean that temperatures will struggle to climb out of the 50s
today. Have lowered high temperatures in response. Will need to
keep an eye on northeastern counties where visible satellite
imagery shows a few breaks in the cloud cover, which may provide
enough heating to help temperatures reach the 60 degree mark.

Huffman

PREV DISCUSSION... /ISSUED 442 AM CDT Sun Mar 12 2017/

DISCUSSION...
Front and associated shra are in the process of pushing off the
coast early this morning. Any lingering precip should gradually
taper off in the next several hours. Although the mid and upper
parts of the atmosphere will continue drying out thru the day,
cloudiness trapped under the llvl inversion will likely limit much
of a warm-up today.

Another reinforcing front will make its way into the region late
Monday as Canadian high pressure migrates south and eastward.
Onshore flow should resume by midweek as the high moves far enough
to the east, but rain chances will be limited (at least until
late in the week) as it`ll take a while for the atmosphere to
modify. GFS/ECMWF are still flip-flopping in regards to which one
wants to bring a front into the region next weekend. Will maintain
lowish POPs already advertised in the extended until we see some
better agreement & forecast confidence. 47

[BlueJay]

It is still chilly outside but the sun has moved out the clouds and it's beautiful. I will be enjoying this "extra" hour of light on the first night of daylight saving time! Supper on the patio anyone?

[BlueJay]

Brrrr! It's chilly. Is everyone on spring break?

[srainhoutx]

Gorgeous Mid March afternoon with full sunshine. Areas N of I-10 may drop to the mid/upper 30's by tomorrow morning. Should be a great evening to view the full "worm" moon. Temperatures look to moderate by mid week making for a good Spring Break!

[DoctorMu]

Spectacular afternoon. I'd be OK with DST if the weather were like this in the evening until October!

Cold March tonight with potential for frost. Conroe could see mid-30s and test freezing?

[BlueJay]

Happy St. Patrick's Day to all! It may be a good day to wear a little green. ;-D

[Katdaddy]

The calm and warm weather continues. Caught a cirrus dolphin this evening.

[srainhoutx]

After a quiet spell and Spring Break for many across our Region, there are indications of changes brewing in the medium and longer range as a potent Spring Storm system ejects out of the Southern Rockies into portions of the Southern Plains. Typically we see the potential for severe weather in such a pattern. At this time the main focus will be well North of SE Texas, but it serves as a reminder that we are in Severe Weather Season.

[BlueJay]

Great photo Katdaddy! Nice catch!

[DoctorMu]

GFS. Euro, and NOAA have upped the chance of rain for Friday to 80%...with greatest accumulation north and east.

Maybe 0.75-1.25 in from N Harris Co to CLL

[Katdaddy]

Spring 2017 has officially arrived. Expect highs in the mid 80s except upper 70s along the immediate coast with partly to mostly sunny skies through mid week across SE TX.

The severe weather potential remains across the S Plains on Friday. Perhaps a few strong storms for SE TX.