MAY 2019: Wednesday Storm Complex/Scattered Showers To End May

[sau27]

Mesoscale models still cant make up their mind on what happens tonight into tomorrow. They look to show some additional descrete cell development for the next few hours but we'll see if the atmosphere can turn that out. The cap looks to be gone for now, but we will have to see if it starts to build back in before the next round gets here.

[unome]

Updated SPC May 3, 2019 2000Z Thunderstorm Outlook https://www.spc.noaa.gov/products/exper/enhtstm/

graphic is the current 04Z-12Z

4z-12z.gif

have a way to get weather warnings

[DoctorMu]

This is looking pretty bad - where is the darn watch??? Geez.

Classic Nowcast situation. The tell was in the radar loops.

[mckinne63]

Mesoscale models still cant make up their mind on what happens tonight into tomorrow. They look to show some additional descrete cell development for the next few hours but we'll see if the atmosphere can turn that out. The cap looks to be gone for now, but we will have to see if it starts to build back in before the next round gets here.

Cap was holding over the SW area of Houston. A few raindrops, but that was it.

[DoctorMu]

Update from Jeff:

Flash Flood Watch is being issued for SE TX for tonight along and N of I-10.

Heavy rainfall over the last few days and again this afternoon has resulted in saturating ground conditions. Air mass will begin to recover from the current round of storms and as another strong disturbance approaches tonight a new complex of thunderstorms with heavy rainfall will likely develop over SW/SC TX and move toward the area.

Additional rainfall amounts of 1-2 inches with isolated totals of 3-4 inches will be possible with this next round or storms. Most Harris County watersheds will be able to handle this amount of rainfall. However, increasing run-off from both rainfall today and yesterday into the San Jacinto River (west and east forks) as well as Spring Creek and Willow Creeks in N Harris County needs to be monitored.

Main threat from high rainfall rates both this afternoon and tonight will be street flooding.

Update:
Spring Creek at Hegar Rd has risen to 3ft below bankfull and will continue to rise. Minor low land flooding on rural lands near the creek from the headwaters to Hegar Rd is possible this evening. Additionally, low bridges crossing the creek could be impacted.

3.8+ inches on top of 1.8 inches from last last week. IMBY.

[DoctorMu]

Mesoscale models still cant make up their mind on what happens tonight into tomorrow. They look to show some additional descrete cell development for the next few hours but we'll see if the atmosphere can turn that out. The cap looks to be gone for now, but we will have to see if it starts to build back in before the next round gets here.

Instability yields instability, folks. Let's keep a wary Eye out. Thanks to all here who reported the Three Amigos Supercell activity realtime.

[unome]

Instability yields instability, folks. Let's keep a wary Eye out. Thanks to all here who reported the Three Amigos Supercell activity realtime.

Tres Amigos ! I got body-searched for wearing a t-shirt with that on along with my 2 gf's when returning to Houston one year !

[unome]

Area Forecast Discussion
National Weather Service Houston/Galveston TX
359 PM CDT Fri May 3 2019

.DISCUSSION...
Stalled outflow boundaries have allowed for backed E/SE surface
flow resulting in enough turning and low level shear to support
rotating updrafts today. There is also ample moisture with PWAT
over 1.6-1.7 inches and increasing 925mb flow to support higher
rain rates with these strong/severe storms. This has led to
advisory level flooding where storms moved over areas that already
had rainfall last night and yesterday. A few bayous and creeks
have reached bankfull or are forecast to exceed banks. Water vapor
imagery shows one short wave trough about the exit the region
which has been the trigger for today's storms. Upstream there is
another jet streak coming into the Rio Grande Valley and is
already causing deep convection over west central Texas. Large
scale ascent with this jet streak should spread over SE Texas
tonight into tomorrow morning. Given conditions already in place
and better upper level support tonight, we decided to go with a
flash flood watch since another 1-2 inches really quickly could
cause at least advisory level flooding and isolated 3-4 inches
could push for flash flood warnings. Flash flood watch covers
areas basically along I-10 northward since these areas have seen
the most rainfall. Harris County is included mainly because the
northern half of the county has had quite a bit of rainfall while
areas to the south and southeast of Harris County have had very
little. Still quite possible some of the higher amounts could
occur over Houston and impact bayous, underpasses and other low
lying urban areas. As for a severe threat, it should be more
isolated overnight and if lines of storms form, then damaging
winds will be the main concern. This is all secondary to the
potential for heavy rainfall. Storms should be leaving the area
Saturday afternoon so have rain chances decreasing after 18Z
Saturday.

Overpeck

.MARINE...
East to southeasterly winds have been diminishing this afternoon,
with seas following behind them. While Freeport buoy is reporting 4
foot seas, have gone ahead and let the SCEC fall off as winds are
down to 4 kts and season should dip below 4 feet. Showers and
thunderstorms have mainly been over land today, but potential will
continue tonight into Saturday. A weak boundary will stall out north
of the coast Saturday, and winds will be out of the southwest
Saturday morning before turning more easterly as high pressure
settles in Saturday night. Easterly flow will continue through much
of the day Sunday, and onshore flow returns by the beginning of next
week. Tides are forecast to remain about a foot above normal through
the weekend, and could potentially cause issues by early next week.

Luchs

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 66 82 63 85 65 / 90 60 0 10 0
Houston (IAH) 69 83 66 86 67 / 90 80 0 10 0
Galveston (GLS) 72 79 72 81 73 / 80 70 10 10 0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch through Saturday afternoon for the following
zones: Austin...Brazos...Burleson...Coastal Harris...
Colorado...Grimes...Houston...Inland Harris...Madison...
Montgomery...Northern Liberty...Polk...San Jacinto...
Southern Liberty...Trinity...Walker...Waller...Washington.

GM...NONE.
&&

$$

Discussion...39

[unome]

Mesoscale Discussion 0518
NWS Storm Prediction Center Norman OK
0423 PM CDT Fri May 03 2019

Areas affected...south central Texas

Concerning...Severe potential...Watch likely

Valid 032123Z - 032230Z

Probability of Watch Issuance...80 percent

SUMMARY...Storms including a few supercells are expected to persist
much of the evening over south central Texas. Large hail and
damaging wind are the main threats. A WW will likely be needed soon.

DISCUSSION...Numerous storms continue developing in the weakly
capped and moderately to strongly unstable warm sector (2000-3000
J/kg MLCAPE) across south central TX. Wind profiles with 40-45 kt
effective shear will support some organized structures including
supercells. Activity will likely persist through much of the
evening.

..Dial/Grams.. 05/03/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CRP...EWX...SJT...

LAT...LON 31160082 30359835 29369788 28619827 28179898 28199975
29220050 29900118 31160082

[unome]

Meso 2 currently over TX

http://rammb-slider.cira.colostate.edu/ ... 000&y=1000

[unome]

this, from Matt Lanza https://twitter.com/mattlanza/status/11 ... 1918954510

Matt Lanza
‏Verified account @mattlanza

The last real remaining storm for today is exiting northeast of Atascocita, but the next round is already getting its act together in Hill Country and between Austin and San Antonio. That’s tonight’s story.

[srainhoutx]

Heavy Rainfall possibilities may be increasing...

05032019 mcd0189.gif

Mesoscale Precipitation Discussion 0189
NWS Weather Prediction Center College Park MD
641 PM EDT Fri May 03 2019

Areas affected...central to south-central TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 032240Z - 040405Z

Summary...Scattered areas of flash flooding are expected across
portions of central to south-central TX through 04Z. The
congealing of multiple cells into the evening should allow for a
few locations of very heavy rain with rainfall rates of 2-3 in/hr
and storm total as high as 4-6 inches.

Discussion...The combination of forcing ahead of a mid-upper level
shortwave approaching from west-central TX (seen on water vapor
imagery), diffluent flow aloft and plentiful instability has
allowed for the development of scattered to numerous thunderstorms
across central TX. The latest GPS derived precipitable water
values ranged from 1.4 to 1.7 inches across the region at 22Z and
MLCAPE was 1500-3000 J/kg per the latest SPC mesoanalysis.

As the shortwave over west-central TX continues toward the east
early tonight, convective coverage will continue to expand but as
the number of cells increases, the eventual congealing into an MCS
appears likely. Southerly 850 mb flow from the RAP is currently
forecast to range between 10-20 kt over southern/south-central TX,
but these values may be too weak if MCS development becomes robust
inducing stronger inflow, certainly in a storm-relative sense into
the complex. As a sufficient cold pool develops, movement of the
forecast MCS should be off toward the ESE and perhaps become less
of a flash flood threat as forward speed increases.

There has been decent support for this idea from recent runs of
the HRRR, the Texas Tech WRF and experimental NSSL WoF System.
Much of TX from the middle Rio Grande to locations near I-45 have
been rather wet over the past 24 hours and over the previous
couple of weeks. This has lowered Flash Flood Guidance and
increased susceptibility to runoff. The forecast models apparently
handling tonight's event well show support for maximum totals of
4-6+ inches of rain by roughly 04Z, which would lead to flash
flooding.

Otto

ATTN...WFO...CRP...EWX...FWD...HGX...SJT...

[unome]

https://origin.wpc.ncep.noaa.gov/metwat ... 89&yr=2019

[srainhoutx]

Seeing reports out of the Austin area of rainfall rates exceeding 4 inches per hour. Going to take a break. Keep up the great work all!

[Cpv17]

2-4” over the next week? I have a hard time believing that with this setup. I’ve yet to get any measurable rainfall though. Last real good rain we got here was at the end of February when we got 5” in 2 hours. Since then we’ve gotten about 4” so things are pretty dry around here.

[unome]

2-4” over the next week? I have a hard time believing that with this setup. I’ve yet to get any measurable rainfall though. Last real good rain we got here was at the end of February when we got 5” in 2 hours. Since then we’ve gotten about 4” so things are pretty dry around here.

where is "here" ?

[Cpv17]

Wow

[Cpv17]

2-4” over the next week? I have a hard time believing that with this setup. I’ve yet to get any measurable rainfall though. Last real good rain we got here was at the end of February when we got 5” in 2 hours. Since then we’ve gotten about 4” so things are pretty dry around here.

where is "here" ?

In between Wharton and El Campo. Rain keeps missing us to the north.

[unome]

2-4” over the next week? I have a hard time believing that with this setup. I’ve yet to get any measurable rainfall though. Last real good rain we got here was at the end of February when we got 5” in 2 hours. Since then we’ve gotten about 4” so things are pretty dry around here.

where is "here" ?

In between Wharton and El Campo. Rain keeps missing us to the north.

you should put your location in your profile, so that when you talk about your weather conditions, ppl who are reading the board can tell where you are speaking of

[Cpv17]

where is "here" ?

In between Wharton and El Campo. Rain keeps missing us to the north.

you should put your location in your profile, so that when you talk about your weather conditions, ppl who are reading the board can tell where you are speaking of

Will do.