March-2017: Active Spring WX Pattern Ahead

[Katdaddy]

Severe Thunderstorm Warning
TXC039-051900-
/O.NEW.KHGX.SV.W.0030.170305T1815Z-170305T1900Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Houston/Galveston TX
1215 PM CST SUN MAR 5 2017

The National Weather Service in League City has issued a

* Severe Thunderstorm Warning for...
South central Brazoria County in southeastern Texas...

* Until 100 PM CST.

* At 1214 PM CST, a severe thunderstorm was located near Lake
Jackson, moving northeast at 15 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage
to roofs, siding, and trees.

* Locations impacted include...
Lake Jackson, Angleton, Richwood, Brazoria, Jones Creek and
Bailey`s Prairie.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

For your protection move to an interior room on the lowest floor of a
building.

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature`s leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

[mckinne63]

And it just keeps raining here in Stafford. Light, than heavier, than light again. It has been raining most of the day since I got up at 6:30am this morning. I don't think it's actually ever stopped.

[srainhoutx]

I received .70 of an inch in the old rain bucket since yesterday afternoon. The heaviest rainfall came this morning as the upper low neared SE Texas and even heard a rumble or two of thunder. This rainfall was perfect for washing down the Oak and Pine pollen and providing the yard with a nice drink of water. I see that areas across Southern Harris and Brazoria Counties received near or above 6 inches of rainfall. Matagorda and Wharton Counties did have severe thunderstorms and a couple of tornadoes recorded on cell phones along HWY 35 with some low topped (25K) rotating super cells. Perhaps a bit more rainfall with some isolated strong storms before the next frontal boundary crosses the area Tuesday evening. Will look at that potential tomorrow as we get a bit more information.

[srainhoutx]

Early morning Water Vapor imagery suggest a potent shortwave upper trough advancing East across the Great Basin and Intermountain West which is expected to fire off strong to severe storms across portions of Arkansas, Missouri, Iowa and Western Illinois late this afternoon into the overnight hours. Will need to monitor the trends across the Ozarks for a potential tornado threat with strong damaging winds and severe hail. That serves as a reminder to have some sort of weather alert capability, particularly at night while sleeping.

The attachment 03062017 day1otlk_1300.gif is no longer available

Also noted via MIMIC that an increasing surge of deeper tropical moisture with its origin from the Western Caribbean head toward the Middle/Upper Texas Coast and SW Louisiana. Currently the Storm Prediction Center has outlined a Marginal Risk for Severe Storms tomorrow mainly along and East of the US 290 Corridor and N of I-10. We will need to monitor for break in the clouds tomorrow that could increase daytime heat and destabilize the atmosphere further as a frontal boundary slowly approaches the SE Texas Area.

[srainhoutx]

Monday morning briefing from Jeff:

Active weather will continue into the week as mainly zonal to SW flow will be in place.

Fairly impressive rainfall event over SE TX yesterday with amounts averaging over 4-5 inches over portions of Wharton and Fort Bend Counties and up to 6.5 inches over southern Harris County. Rainfall was clearly more than expected…possibly a function of the very warm Gulf of Mexico helping to produce ample moisture into the region. Even had a few weak tornadoes in both Brazoria and Matagorda Counties.

Warm air advection pattern is well established across the region this morning with 25-30kt low level jet in place. Gentle lift from the low level jet and convergence is producing isolated to scattered showers moving quickly northward across the region. This pattern will continue for much of the last with the best coverage likely from now through mid morning as a weak short wave moves across the region.

Next item of interest will be a cold front which will move into the region on Tuesday. Showers and thunderstorms will be possible with the front with ample moisture in place. Current frontal timing is early to mid morning on some of the short range models and later in the day on the GFS. Will lean toward the faster frontal passage which should help to keep instability limited and think the SPC marginal risk area will be for a for isolated strong storms. Could see some brief heavy rainfall with the frontal passage, but not expecting anything like yesterday and most totals should average less than an inch. Only concern would be if the frontal passage is slowed and does arrive in the afternoon hours which will result in better instability from low level heating.

Front looks like it will stall somewhere near the coast or just offshore and winds quickly swing back to onshore late Wednesday. Could see some warm air advection showers on Thursday as the front lifts back northward.

Showers and thunderstorms will be back in the forecast Friday-next weekend as another storm system approaches from the west. Frontal passage at some point on Saturday looks to likely produce the greatest rain chances and possibly some thunderstorms. Will keep an eye on this system in the coming model guidance as systems of recent have been tending to over-produce weather wise over the region.

[DoctorMu]

Just OBLITERATED the warmest February ever.

[DoctorMu]

Marginal Severe Risk tomorrow (not slight or enhanced):





Area Forecast Discussion
National Weather Service Houston/Galveston TX
601 PM CST Mon Mar 6 2017

.AVIATION...
MVFR cigs are expected to return early this evening and gradually
lower overnight toward IFR. Winds will not relax until between
06-09z as a cold front nears the area. Once the winds decouple,
would expect some patchy fog to develop. Sfc dew pts near KGLS are
near 70 so can`t rule out some sea fog developing near the coast.
The RAP and TT WRF also begin to produce some light streamer
showers between 08-10z so added a VCSH for inland TAF sites but
could really get a shower just about anywhere. The front will
approach KCLL between 13-15z, Houston between 17-21z and Galveston
between 20-23z. PW values ahead of the rise to between 1.5 and 1.6
inches with CAPE values between 1500-2500 J/kg. LI values are
progged between -4 and -7 so can`t rule out getting some strong to
possibly severe storms along the front. Have tempo for the fropa
and associated convection and might need to beef up the wind gusts
with the front. Fcst soundings keep some cloudiness behind the
front so will slow clearing until after this TAF package ends. 43

&&

.PREV DISCUSSION... /ISSUED 356 PM CST Mon Mar 6 2017/

DISCUSSION...
Coverage beginning to decrease this afternoon and expecting most
of this activity to be gone by this evening. However, this break
should be short lived as the strong onshore winds help to gin up
more WAA-type showers along/near the coast toward sunrise. Further
north, we will be seeing development along/just ahead of the cold
front moving down from the Southern Plains. While the upper
dynamics look more favorable for strong storms NE of the CWA, we
should still see a fairly healthy line of SHRA/TSRAs develop and
begin moving into the area Tues morning. Still a bit concerned
with locations in/around SE TX that received some good rainfall
Sun and with the rains/clouds today, not really getting much
drying. However, do think that the storms we do get will be moving
and not likely to train.

A brief break in the weather expected behind this front for most
of Weds as a flat upper ridge builds in from the west. Returning
onshore winds on Thurs will begin setting the stage for increasing
POPS through the latter part of the week. Models are still a tad
disparate with the upcoming pattern but starting to see some
consensus with the GFS idea of a more active southern stream jet
by late Thur on through Sat. The next cold front is currently on
track for a Sat night FROPA across SE TX. 41

Marine...
SCEC across the Upper Texas Coast tonight and into Tuesday
morning, as winds will remain between 15 to 20 knots. Seas
will also remain elevated in the offshore waters, remaining between
6 to 7 feet with the occasional 8 foot seas. Expecting south
southeast winds out ahead of the next cold front that is passing
through SE Texas Tuesday afternoon. Showers and scattered
thunderstorms will begin Tuesday morning and continue through the
afternoon out ahead of the front. The front should push offshore
late Tuesday, and winds will shift out of the east northeast for
much of the day Wednesday. Winds will quickly return to onshore flow
overnight Wednesday and into Thursday. Still expecting moderate seas
for the rest of the week.

[Katdaddy]

An active weather pattern will continue through the weekend across SE TX. Today's cold front will move across the area this afternoon with a line of scattered thunderstorms with some that could be strong however the main risk area for severe weather will be NE of Houston metro. The front slows down and moves off the coast this evening. Our next storm system and front looks to arrive over the weekend bring the possibility of more strong thunderstorms

[srainhoutx]

Tuesday morning briefing from Jeff:

Cold front will move into SE TX today with a chance for strong thunderstorms…a few may become severe.

Unsettled and active pattern remains in place through next week.

Cold front just crossing the Red River with a well defined pre frontal trough south of this boundary approaching the northern sections of SE TX this morning. Air mass over SE TX is moist with PWS running 1.4-1.5 inches and instability will be building after some modest morning heating. Short range models show scattered showers and thunderstorms developing by mid morning with the warm air advection regime near the coast and spreading inland while additional activity develops along the southward moving frontal trough. While instability is generally on the low side along with wind shear, the mid levels do cool some late this morning helping to increase lapse rates. Think the main severe threat is NE of our area across LA, but cannot rule out an isolated severe storms along and east of I-45 today…main threats would be hail and gusty winds with an isolated tornado possible.

Heavy rainfall may become a concern toward the early to mid afternoon hours depending on how the mesoscale processes evolve today. Activity in the pre frontal warm sector may become widespread and organized enough to produce a few hours of heavy rainfall prior to the arrival of a line of storms with the pre frontal trough. Models are also suggesting the pre frontal trough slows after crossing I-10 and limps to the coast this evening. Not sure I agree 100% with the model guidance as think with the cooling mid level temperatures and fairly robust convection storms will likely generate a cold pool which will maintain good forward motions and hopefully push the activity through the area. Main concern is for those areas hit hard with heavy rainfall on Sunday as grounds are saturated and run-off will be maximized in those locations. A quick 1-3 inches of rainfall will be possible today.

Front stalls off the coast on Wednesday with low level moisture trapped under the frontal inversion so look for cloudy and cool conditions. Upglide of warm moist air across S TX and the Rio Grande plains will likely keep showers and even elevated storms going in those regions. Front will activate as a short wave approaches Thursday and Friday and will return northward as a warm front. Lift and moisture increases especially on Friday and will likely need to go with high rain chances for this period. May need to bring heavy rainfall into the forecast for Friday at some point.

Next front is due into the region late Saturday with another line of thunderstorms…this system should be similar to today…only at night with less instability.

Yet another storm system will rapidly approach the area early next week with additional chances for thunderstorms and heavy rainfall.

[tireman4]

000
FXUS64 KHGX 071057
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
453 AM CST Tue Mar 7 2017

.DISCUSSION...
The morning approach and afternoon passage of a cold frontal
boundary...along with a possible leading pre-frontal trough...
will increase the probabilities of areawide rain (showers) with
embedded thunderstorms to likely during the daytime hours. There
appears to be enough afternoon wind energy and a brief window of
steep enough lapse rates/mid-level cold air intrusion just ahead (or
along) the front to mention a marginal risk for any strong storm to
produce gusty winds to over 30 knots...penny to quarter size
hail...a brief tornado...and/or locally heavy rainfall if the front
stalls close to the coastline latter today.

An early day stout 20-30 knot low level southwesterly wind will
maintain this unseasonably moist 1.4 to 1.5 inch pwat air mass.
The main cold front that will pass cross the region today is
currently located just south of a Lubbock to Abilene to Oklahoma
City line...or passing across the Red River Valley through the 4
AM hour. A pre-frontal trough will likely lead this boundary and
reach the far northern counties of the forecast area around 9 or
10 AM...with the cold front across the northern third of the CWA
between 10 AM and 1 PM. The cold front should clear the city
between 1 and 4 PM...slowing as it nears the coast during the
late afternoon into early evening hours. Possible QLCS cold pool
could outrace the synoptic front and blow off the coast around
sunset. Due to the shallow nature of the frontal boundary itself...
lower level (sub 3km) shear and SRH are not overly impressive at
around 20 knots and 30-50 m2/s2...respectively. Nevertheless...there
may be just enough spin right along the pre-frontal trough or any
storm gust front to spin up a quick weak tornado or put down a
near 30 knot wind gust. Relatively lower WBZ heights are indicative
of small hail...possibly to quarter size...within stronger storm
downdrafts. A possible slowing of a relatively-thin broken convective
line over the southern third of the CWA could equate to a few hours
of 1-2 inch per hour rainfall rates with little to no movement. This
could cause some minor flooding concerns during the late afternoon
into early evening hours. Again...a minor concern as these storms
may spit out a downstream cold pool that races off the coastline
and scour out any linger precipitation by 5 or 6 PM.

Breezy northeast flow Wednesday under mainly overcast skies as
mid-level moisture gets trapped within the frontal inversion.
Backing surface high pressure will quickly scoot east into the
southeastern U.S. by tomorrow night and have return flow in play
by Wednesday evening. A relatively zonal upper flow pattern will
set up through mid week as 588 dam ridging remains located over
the Bay of Campeche. Weak disturbances riding on through within
the westerlies will keep low POPs (mainly showers) in Thursday`s
forecast. A shortwave trough passage/higher PVA Friday within a
near 1.5 pwat air mass will increase areawide daytime rain chances
back up into the moderate to high category.

The next storm system/cold frontal passage will occur next weekend.
Current model timing has the front passing through either late
Saturday night or overnight Sunday morning. This system is forecast
to be fairly progressive...most active weather to occur overnight
Sunday morning with the front well off the coast by sunrise. A
quick hitter with average 0.25-0.50 inch amounts...similar
thermodynamic indices as today`s system translating to similar
threats...but with the disadvantage of occurring during the
overnight hours.

Despite the weekly cloud cover and dominant onshore flow...the
weekly diurnal temperature curve will generally follow a slightly
above normal trend...middle to upper 60 F minimum temperatures
with upper 70 to lower 80 F afternoon maximums. 31


&&

.Marine...
Looks like winds are starting to diminish as frontal boundary in
north Tx makes southward progress. That being said...4-8 ft/10sec
swell will take a while to go down so have extended the small craft
advisory beyond 20 nm until noon. Otherwise...the front mentioned
above will probably slow as it nears the coast later in the
afternoon and likely won`t move off the coastline until 5-8pm with a
thin band of shra/tstms a possibility. Patchy 3-6sm fog will
probably linger in the nearshore Gulf waters until the windshift. NE
flow in the wake of the front will strengthen during the overnight
hours and suspect we`ll need another advisory...at least in the Gulf
waters.

Onshore flow will resume late Wed and persist until the next front
(and associated precip) pushes off the coast late Saturday night. 47

&&

AVIATION...
Wide range of ceilings across the area this morning ranging from
VFR well inland to MVFR/IFR conditions south of CXO. Seeing an
increase of weak streamer shra on radar as well. Expect very few
changes to the 06z TAFs which seem to have a good handle on things
in regards to incoming cool front today. Will likely see an
increase in sct shra activity into the mid morning hours...esp
northwest of Highway 59...as a weak frontal boundary moves into
the region. Vast majority of models indicate this boundary will
slow down as it makes its way toward the coast. Atmosphere becomes
more unstable w/ time as well and suspect we`ll start seeing some
embedded tstms emerge during the late morning and afternoon. Due
to the slow movement and a sfc focusing mechanism...some cells
will be capable of producing some localized heavy rain. Tough to
pinpoint an exact location(s), but may be an issue for some
Houston area terminals 18-22z. Fcst soundings keep some cloudiness
behind the front so will carry some mid level clouds through the
end of the TAF period. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 72 53 74 62 78 / 60 0 10 10 30
Houston (IAH) 76 55 72 63 77 / 80 10 20 10 30
Galveston (GLS) 73 62 68 66 73 / 80 30 30 10 20

&&

[srainhoutx]

Update from Jeff:

Air mass over SE TX is becoming unstable with morning heating leading to rapid buildup of instability. Latest SPC meso analysis shows 2500-300 J/kg of CAPE now across Fort Bend into Harris Counties with 1500 J/kg across a larger portion of SE TX. PWS are pooling along and ahead of the surface boundary which is starting to entering SE TX. AM CRP sounding continues to show warm air advection below 700mbthen .5 to 1.5 C of cooling in the mid levels with steepening lapse rates above the morning low level inversion. Expect the remaining inversion to erode over the next few hours and rapid increase in both storm organization and intensity across SE TX and the coastal bend.

Convection allowing guidance from SPC is showing greater storm organization in the next few hours and severe parameters appear to be increasing to warrant a slightly higher chance of all severe modes. Additionally, better storm organization will support higher rainfall rates and overall totals and the current most unstable air mass appears very near/over the areas that saw excessive rainfall on Sunday…this will need to be watched as the activity unfolds over the next several hours.

[jasons2k]

There were some storms/a line near DW Hooks moving this way, and it just fell apart. Looking to the NW now...

[srainhoutx]

Special Weather Statement
National Weather Service Houston/Galveston TX
111 PM CST TUE MAR 7 2017

Waller TX-Harris TX-
111 PM CST TUE MAR 7 2017

...STRONG THUNDERSTORMS ACROSS SOUTHWESTERN MONTGOMERY...NORTHEASTERN
WALLER AND NORTHWESTERN HARRIS COUNTIES THROUGH 200 PM CST...

At 110 PM CST, Doppler radar was tracking a strong thunderstorm over
Waller, or near Prairie View, moving southeast at 15 mph. Funnel
clouds have been spotted with this storm. A brief touchdown may be
possible.

Winds in excess of 30 mph will be possible with this storm.

Locations impacted include...
Prairie View, Hockley, Waller and Pine Island.

[jasons2k]

The next line split too as it apporached...

[tireman4]

00
FXUS64 KHGX 071744
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1144 AM CST Tue Mar 7 2017

.AVIATION.../18Z TAF/
Visible satellite imagery and radar show convection along the
front. Surface analysis has front just reaching KCLL to just north
of KUTS. This is a bit slower than forecast from previous runs of
the HRRR. Overall the HRRR continues to have the best timing of
the front over the next 6 hours so will rely on it and timing
tools to better pinpoint frontal passage for Houston terminals.
Right now it looks like the front should reach Houston area 20-22Z
this afternoon and then the coast 23-01Z this evening. TAF will
continue a mix of VFR/MVFR ceilings and mention TSRA. TSRA will be
isolated but could become more numerous closer to Houston. SPC
mesoanalysis indicates 2000-3000 J/kg CAPE. Recent sounding from
UofH has a moist but unstable profile. Very little shear for storm
organization so expect multicellular convection. This means a
microburst threat but likely see just TSRA wind gusts of 30 to 35
knots with most storms.

Ceilings should improve behind the front but the front will be
shallow. Expect moisture to be in place in 925-850mb layers so
will keep VFR ceilings in place tonight into tomorrow. Return flow
increases late Wednesday so may see MVFR ceilings again Wednesday
night into Thursday morning.

Overpeck

&&

.PREV DISCUSSION... /ISSUED 1001 AM CST Tue Mar 7 2017/

DISCUSSION...
Cold front beginning to move into the CWA this morning but the
majority of the activity appears to be just ahead of the boun-
dary (with the pre-frontal trof). Only made a few minor tweaks
to the going POP/WX grids for this update. Estimated/extrapol-
ated FROPA at IAH 19-20Z and GLS 22-23Z. 41

[Katdaddy]

Its a cloudy cooler morning across SE TX with upper 50s inland N of Houston and low 60s across the rest of the area. Clouds but no rain today however showers will be back in the forecast for Thursday. Expect rain and thunderstorms Friday through Saturday night before another cool front pushes offshore bring clearing skies for Sunday.

41 year's ago an E-F3 tornado moved across N Central and NW Galveston County. This tornado passed about a quarter of a mile from my current location. It would be more than a little intense should this happen in the modern day as I would see it approaching from the WNW and then moved just to the NNE. It would have been close enough to hear the deep roar, see power flashes, and see flying debris.

[BlueJay]

WoW Katdaddy! Talk about March coming in like a lion!

[srainhoutx]

The afternoon updated Quantitative Precipitation Forecast through next Monday suggests more unsettled weather is ahead. It appears there are at least a couple of disturbances embedded in the noisy sub tropical jet from the Eastern Pacific heading our way with an active storm track to our N and E

[Katdaddy]

A cloudy and foggy morning across much of SE TX. An unsettled weather pattern is expected through early Sunday morning with an active subtropical jet. Thunderstorm chances ramp up Friday through early Sunday morning with some strong storms possible as well as heavy rain. The current satellite shows the first of several disturbances approaching TX from MX.

[srainhoutx]

Thursday morning briefing from Jeff:

Several upper air disturbances will bring chances of showers and thunderstorms this afternoon through Sunday morning.

Air mass over the region has moistened as the frontal boundary from Tuesday has washed out allowing Gulf moisture to return. This has resulted in coastal sea fog lifting into a fairly widespread thick deck of inland stratus clouds. IR images show a well defined short wave over NC MX this morning with several disturbances prepared to move ENE across SC into SE TX starting this afternoon and continuing into Saturday. Air mass is generally forecasted to be moderately unstable for the next 48 hours which may result in strong to isolated severe thunderstorm formation although wind shear is generally on the weak side.

Think any showers and thunderstorms that develop this afternoon will be isolated to widely scattered and mainly driven by warm air advection and any surface heating. TX TECH WRF shows an almost seabreeze like pattern this afternoon with a few showers spreading inland from the coastal counties.

A fairly strong disturbance will approach SE TX Friday with widespread showers and thunderstorms possible. Global model guidance is fairly bullish on rain chances during this period while the more course meso scale models show much of the activity across SC TX. Overall air mass will be moist and unstable, but beside the lift from upper air dynamics, there does not appears to be any sort of low level boundary over the region. Will cap rain chances around 50-60% for Friday and think any severe threat will be isolated at best.

Showers and thunderstorms will continue Friday night into Saturday night ahead or an approaching cold front. Little change in air mass or instability should continue to support isolated severe storms with the threat becoming heavy rainfall on Saturday and Saturday night as totals begin to pile up. Rainfall today-early Sunday will average 1-2 inches over the area with isolated totals up to 4 inches. I am wary of the rainfall potential given the last several setups over the area have produced much larger amounts than forecasted especially this past Sunday, but at this time there is nothing suggesting a significant flood signal. Strong March cold front will blast across the area early Sunday morning with modified arctic air mass spilling into TX. Strong cold air advection on Sunday will cap high temperatures in the 50’s under slowly clearing skies.

Secondary surge of cold air will arrive on Monday which will keep temperatures below normal for the early and middle part of next week (lows in the 40’s and highs in the 60’s). Monday morning may feature lows into the upper 30’s across the region if skies clear out late Sunday and could see some frost in the more sheltered locations.