JUNE 2016: Showers/Storms Possible

[houstonia]

I am curious about air pressures and wind speeds. As a signal that a warm core is developing, would we notice a change in he air pressure? would wind speeds pick up?

thank you.

[srainhoutx]

I am curious about air pressures and wind speeds. As a signal that a warm core is developing, would we notice a change in he air pressure? would wind speeds pick up?

thank you.

There is a discussion on NWS chat regarding that. I will let Brooks answer if he has time. Meanwhile here is what NWS Corpus has to say and they do mention winds...

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
1059 AM CDT FRI JUN 3 2016

.DISCUSSION...Water vapor imagery shows the upper low near Austin
with vorticity lobe rotating south-southeast through the Hill
Country. A surface to 85h boundary had pushed through the area at
12z but has stalled over the near shore waters to south of Baffin
Bay. Expect sea breeze to develop early this afternoon and
converge with boundary that will be moving southeast through the
Brush Country. Less cloud cover over the southern Coastal Bend has
allowed air mass to become more unstable with LAPS/SPC analysis
showing surface base CAPE values around 2000 J/kg. Latest HRRR and
Texas Tech WRF models show convection should be on the increase
around 18z with threat for heavy rainfall greatest over the
coastal plains. But more vorticity lobes moving south out of the
Hill Country will provide better chances for convection over the
Brush Country this afternoon into this evening where POPs were
raised slightly. HRRR and Texas Tech WRF show low level southerly
flow will be increasing over the western Gulf of Mexico this
evening and maintain a low level convergence maximum from the
Mid-Coast region into the upper Texas coast. Abundant moisture
will be in this area with precipitable water values near or above
2 inches. The vertically stacked low is expected to drift south
tonight and be south of San Antonio by 12z Saturday maintain the
threat for locally heavy rainfall near and to the east of the low.
Current forecast shows categorical POPs for the Mid-Coast/Victoria
Crossroads area for overnight into Saturday. Looks good at this
time and current Flash Flood Watch for area until 00z Sunday will
remain unchanged.

[sau27]

My understanding of core rain events was that rain and storms concentrate around the center of the low pressure area. If the low is forecast to be down near San Antonio tonight isn't that where the greatest threat would be?

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1118 AM CDT FRI JUN 3 2016

JACKSON TX-
1118 AM CDT FRI JUN 3 2016

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
SOUTHEASTERN JACKSON COUNTY IN SOUTH CENTRAL TEXAS...

* UNTIL 115 PM CDT

* AT 1117 AM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY AREA.
UP TO TWO INCHES OF RAIN HAVE ALREADY FALLEN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
GANADO...LA WARD...LOLITA...LAKE TEXANA DAM AND VANDERBILT.

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0300
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1250 PM EDT FRI JUN 03 2016

AREAS AFFECTED...EASTERN TX...CENTRAL/WESTERN LA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 031640Z - 032100Z

SUMMARY...ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH
HEAVY RAINFALL RATES THIS AFTERNOON WHICH IS EXPECTED TO PRODUCE
MORE POTENTIAL FOR FLASH FLOODING.

DISCUSSION...A DEEP LAYER SOUTHERLY FETCH OF TROPICAL MOISTURE
CONTINUES TO FEED NORTH IN ACROSS THE WESTERN GULF COAST STATES
AND THE LOWER MS VALLEY. THIS IS ALL OUT AHEAD OF A DEEP CLOSED
LOW OVER CENTRAL TX WHICH IS ESSENTIALLY STATIONARY AT THIS TIME.

THE STRONGEST FOCUS THIS AFTERNOON FOR HEAVY SHOWERS AND
THUNDERSTORMS WILL BE MAINLY ACROSS CENTRAL/SOUTHERN LA AND
WRAPPING A BIT BACK TO THE NORTHWEST TOWARD NORTHWEST INTO FAR
EASTERN TX WHERE CONFLUENT LOW LEVEL FLOW WILL BE IN PLACE AS
SHORTWAVE ENERGY EJECTING GRADUALLY NORTHEAST AROUND THE EASTERN
FLANK OF THE UPPER LOW CROSSES THIS REGION. THE ENERGY WILL ALSO
BE INTERACTING WITH THE AFOREMENTIONED BAND OF DEEP MOISTURE...AND
GIVEN THE INCREASE IN SURFACE-BASED INSTABILITY VIA SOLAR
INSOLATION...THE OVERALL CONVECTIVE POTENTIAL SHOULD TEND TO
EXPAND A BIT IN COVERAGE.

PWATS ARE CLOSE TO 2 INCHES ACROSS THE LOWER MS VALLEY WITH SBCAPE
VALUES OVER SOUTHERN LA NOSING UP BETWEEN 2000 AND 3000 J/KG. THE
COMBINATION OF BOTH WILL RESULT IN VERY RAINFALL RATES THAT ARE
EXPECTED TO APPROACH 2.5 INCHES/HR. THERE HAVE ALREADY BEEN SOME
OVERSHOOTING TOPS WITHIN THE ONGOING CONVECTIVE BAND THAT HAS
IMPACTED SOUTHEAST LA TODAY...AND ADDITIONAL OVERSHOOTING TOPS ARE
EXPECTED WHICH COULD ENHANCE THE RAINFALL RATES FURTHER.

THE HIRES GUIDANCE SEEMS TO BE UNDERPLAYING THE CONVECTIVE THREAT
ACROSS CENTRAL/SOUTHERN LA BASED ON THE RADAR TRENDS...AND THE
DEGREE OF INSTABILITY POOLING IN OFF THE GULF OF MEXICO. EXPECT
RAINFALL AMOUNTS THROUGH 21Z TO BE AS HIGH AS 3 TO 6 INCHES WITHIN
THE MAIN AXIS OF CONVECTION CURRENTLY SHIFTING GRADUALLY EAST
ACROSS THE STATE. GIVEN SOME OF THE HEAVY RAINFALL SEEN
LATELY...EXPECT RUNOFF PROBLEMS AND SOME FLASH FLOODING TO BE
POSSIBLE THIS AFTERNOON.

ORRISON

ATTN...WFO...JAN...LCH...LIX...SHV...

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1218 PM CDT FRI JUN 3 2016

WALLER TX-GRIMES TX-
1218 PM CDT FRI JUN 3 2016

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
NORTHWESTERN WALLER COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN GRIMES COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 315 PM CDT

* AT 1217 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE MINOR FLOODING IN THE ADVISORY AREA.
UP TO ONE INCH OF RAIN HAS ALREADY FALLEN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
NAVASOTA...HEMPSTEAD...PRAIRIE VIEW...PINE ISLAND...ANDERSON...RICHARDS
AND ROANS PRAIRIE.

[unome]

from the tropical desk, but pertaining to TX in parts

Based on 1200 UTC surface analysis and satellite imagery through 1715 UTC.

GULF OF MEXICO...

A deep layer low is centered over central Texas near 33N98W. A quasi-stationary front extends south from the center to south Texas near Corpus Christi at 28N97W. A squall line is along the coast of Louisiana from 31N94W to 27N94W. Scattered moderate convection is within 60 nm of the squall line. SE surface flow is over the remainder of the Gulf of Mexico. Radar imagery shows scattered showers over the SE Gulf, Florida, the Straits of Florida, and w Cuba south of 28N east of 87W. In the upper levels, the upper level low over central Texas has diffluence SE of the center producing scattered moderate to isolated strong convection over the SW Gulf from 20N-25N between 94W-98W. Expect in 24 hours for the surface low to move to near Houston Texas with a cold front extending to S Texas with convection. Also expect the upper level low to drift south to S Texas.

[houstonia]

If the surface low is moving south into south Texas... does a surface low still have a circulation? And wouldn't that circulation still have the nasty northeast quadrant (the quadrant that, basically, right now is over LA)? If it moves south, doesn't that bring the bad section down over SE Texas again?

[djjordan]

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
NORTHEASTERN WHARTON COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN WALLER COUNTY IN SOUTHEASTERN TEXAS...
WEST CENTRAL HARRIS COUNTY IN SOUTHEASTERN TEXAS...
SOUTHEASTERN AUSTIN COUNTY IN SOUTHEASTERN TEXAS...
NORTHWESTERN FORT BEND COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 430 PM CDT

* AT 137 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
THUNDERSTORMS. THIS WILL CAUSE URBAN AND SMALL STREAM FLOODING IN
THE ADVISORY AREA. UP TO ONE INCH OF RAIN HAS ALREADY FALLEN AND
ADDITIONAL RAINFALL IS EXPECTED WITH THESE THUNDERSTORMS SLOWLY
MOVING NORTH ACROSS THE ADVISORY AREA.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
NORTHWESTERN ROSENBERG...KATY...BROOKSHIRE...EAST BERNARD...WALLIS...
FULSHEAR...SIMONTON...PATTISON...ORCHARD...WESTON LAKES AND CINCO
RANCH.

[Rip76]

If the surface low is moving south into south Texas... does a surface low still have a circulation? And wouldn't that circulation still have the nasty northeast quadrant (the quadrant that, basically, right now is over LA)? If it moves south, doesn't that bring the bad section down over SE Texas again?

I would tend to agree with this.

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0303...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 PM EDT FRI JUN 03 2016

CORRECTED FOR GRAPHIC

AREAS AFFECTED...SOUTHERN TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 031931Z - 040131Z

SUMMARY...THUNDERSTORMS ARE INCREASING IN COVERAGE AND INTENSITY
WITHIN AN UNSTABLE ENVIRONMENT. HOURLY RAIN RATES UP TO 2" COULD
LEAD TO FLASH FLOODING.

DISCUSSION...THUNDERSTORMS WITH COOLING CLOUD TOPS HAVE BEEN
DEVELOPING IN SOUTHERN TX DURING THE PAST HOUR NEAR A MESOSCALE
WAVE ALONG A THERMAL GRADIENT ACROSS SOUTH-CENTRAL TX AND ALONG A
DEW POINT GRADIENT TO ITS SOUTH IN DEEP SOUTH TX. PRECIPITABLE
WATER VALUES OF 1.5-1.9" EXIST ACROSS THE REGION PER GPS VALUES.
MLCAPES ARE UP TO 2500-3000 J/KG PER SPC MESOANALYSES. LOW-LEVEL
INFLOW IS CONVERGENT OUT OF THE SOUTHWEST AT 15 KTS WHILE 0-6 KM
BULK SHEAR VALUES ARE SUFFICIENT TO ORGANIZE CONVECTION.

THE CAM/MESOSCALE GUIDANCE SHOWS LOCAL AMOUNTS OF 2-4" IN THIS
AREA, WHICH COULD FALL QUICKLY. THE AVAILABLE MOISTURE AND
INSTABILITY IMPLY RAIN RATES WHICH COULD PEAK NEAR 2". THESE RAIN
AMOUNTS SHOULD CHALLENGE THE THREE HOURLY FLASH FLOOD GUIDANCE
VALUES, AND COULD CAUSE ISSUES IN URBAN AREAS. THE 12Z SSEO
NEIGHBORHOOD PROBABILITIES OF EXCEEDING THE THREE HOUR FLASH FLOOD
GUIDANCE IMPLY THE HEAVY RAINFALL WOULD PEAK IN THE 22-01Z TIME
FRAME.

ROTH

ATTN...WFO...BRO...CRP...EWX...HGX...

[srainhoutx]

I'll be away for awhile. Stay safe out there...

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
305 PM CDT FRI JUN 3 2016

HARRIS TX-
305 PM CDT FRI JUN 3 2016

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLOOD ADVISORY FOR...
NORTHWESTERN HARRIS COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 500 PM CDT

* AT 304 PM CDT...DOPPLER RADAR INDICATED HEAVY RAIN DUE TO
SLOW MOVING THUNDERSTORMS. THIS WILL CAUSE STREET FLOODING IN THE
ADVISORY AREA.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
TOMBALL...JERSEY VILLAGE...NORTHEASTERN ADDICKS PARK TEN AND CYPRESS.

[kayci]

It's so nice to see the sun and blue skies for a change!

[houstonia]

4 pm forecast discussion from the NWS. Good news; it looks like no warm core:

Area Forecast Discussion
National Weather Service Houston/Galveston TX
400 PM CDT FRI JUN 3 2016

.SHORT TERM (Tonight through Saturday Night)...
.Flash Flood Watch remains in effect through Saturday Evening...

Afternoon water vapor imagery shows the main upper low centered near Waco, with the surface circulation located just east near Goldthwaite. Scattered showers and thunderstorms continue to develop across the region this afternoon, with stronger activity dropping an isolated 1-2 inches of rainfall as it slowly drifts north. Expect continued development as mid/upper level impulses rotate around the main low, with a brief lull in activity possible later this evening with loss of daytime heating. The main upper low is expected to slowly drop south tonight, with another thunderstorm complex developing late tonight west/southwest of the region and spreading northeast along the coast as a result of low level speed convergence setting up along the coast (aided by whatever disturbances move overhead). Highlighting the greatest coverage (60-80 PoPs) along and south of Interstate 10 given consistency with the 00z SPC SSEO members/TTU WRF/HRRR. Anticipate widespread 1-2" rain totals in this area, tapering off north of Interstate 10. Given forecast soundings showing generally weak column winds overnight (850 to 300 MB mean winds less than 5 knots) locally higher amounts approaching 4 to 7" will be possible across the forecast area from any slow-moving or training activity that develops. Antecedent conditions are still ripe for any rainfall to produce flash flooding concerns (1 hour flash flood guidance values less than 3 inches) and have continued the flash flood watch for the entire area through 7 PM on Saturday.

Regarding the possibility for a core rain event overnight over the western counties as the upper low pushes south into South Texas, the upper low appears to be a cold core system as opposed to a warm core system based on analysis of upper air and aircraft data. 12z RAOBS sampled 500 MB temperatures of -8 to -9 degrees C across the state with 18Z aircraft soundings out of Austin (close to the center of the upper low) reporting 500 MB temperatures near -10 degrees C. Core rain events result from convection developing/consolidating near the center of a warm core low as cooling temperatures around the system result in increasing pressures, causing increasing low level convergence near the center of the system. This consolidating convective area can produce very heavy rains (a signal that the 12z NAM12 continued to advertise), with the rest of the models trending to an overnight convective pattern more consistent with a cold core upper low. However, will need to monitor trends for western areas if nocturnal convection does develop near the center of the upper low tonight.

Expect showers and thunderstorms to be ongoing Saturday morning as the thunderstorm complex south of Interstate 10 pushes along the coast with morning lows falling into the upper 60s to low 70s.

There`s lower confidence on how far inland rain will extend Saturday morning as whatever is developing along the coast may rob inflow/moisture and could see drier conditions during the morning hours on Saturday across the northern counties. As the complex shifts east of the region, expect another round of showers and thunderstorms to develop during the day Saturday from the combination of daytime heating (highs near 80s) and moisture wrapping around back the surface low into the region.

A brief lull in activity is expected Saturday night again with loss of heating and main lift from the upper low dropping south of the region with lows in the upper 60s to low 70s.

&&

.LONG TERM (Sunday through Thursday)...
The upper level disturbance over South Texas begins to shear out along the Texas coast on Sunday. Expect thunderstorm coverage to decrease significantly on Sunday as a weak frontal boundary pushes across the region, allowing drier air to filter into the area. The threat for locally heavy rain will exist at least along the coast ahead of the front with precipitable water values remaining above 1.7 inches and some weak lift provided by the shear axis.

A more typical summertime pattern begins to resume Monday and Tuesday with isolated to scattered thunderstorms developing along the sea breeze and afternoon temperatures warming back into the mid to upper 80s (with possibly the first 90 degree day this year for IAH next week). A building upper ridge mid to late week will result in a much needed dry period returning to the region.

Huffman

&&

.MARINE...
Periods of showers and thunderstorms can be expected the next few days as a series of upper level disturbances move overhead. Winds and seas will be higher in and near storms. Otherwise, onshore flow will persist into Saturday. A weak frontal boundary may push off the coast on Sunday. At this time, it appears that any affects from possible tropical development over the weekend and into early next week will remain well east of our area. 42

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 67 79 68 84 65 / 50 70 50 30 10
Houston (IAH) 69 81 68 85 68 / 70 70 50 40 30
Galveston (GLS) 75 81 75 83 74 / 70 70 50 30 30

[mckinne63]

Seeing some blue skies in Stafford. It was dark and gloomy just 5 minutes ago. Is this the calm before the storm?

[Rip76]

Looks as if we'll have less issues (tonight) than originally anticipated.

[mckinne63]

Looks as if we'll have less issues (tonight) than originally anticipated.

That is a good thing! Our neighbors and rivers need to dry out.

I am curious, what changed? I don't know anything about the weather, just what what I see here. It's been rain, rain, rain. rain for Friday thru Sunday.

[Ounce]

I'm beginning to wonder if that line of storms just south of Victoria is going to hold together as it makes the turn to the NE.

[jasons2k]

Looking at satellite and water vapor, maybe the center a little further north towards Waco has †aken over as the dominant circulation? Maybe?

[jasons2k]

Just caught-up on the thread.

I don't know if that's necessarily good news for us or now. A warm core system would tend to consolidate the rains near the core, or west of here. A cold-core convective system has the potential of setting-up training feeder bands off the Gulf. Pick your poison, either way.