June: Onshore Flow Returns With Increasing Gulf Moisture

[srainhoutx]

Morning e-mail from Jeff:

Some impressive records fell yesterday across the region as the heat wave moved into its 3rd day.



Heat Advisory in effect from noon to 800pm today.



Sprawling upper level ridge centered over the plains continues to provide extremely warm late June weather. The weak short wave which combined with early afternoon temperatures in the 102-106 range yesterday to produce a few severe thunderstorms has moved SW of the area in the ENE upper air flow. Morning low temperatures have only fallen to 86 at Galveston (GLS was still 88 at 300am) and in the low to mid 80’s across the urban metro areas. These very warm morning readings combined with afternoon heat index values at or above 108 requires the heat advisory to be issues. Residents should limit their outdoor activity to less than 30 minutes between the hours of 200pm and 600pm when heat index values will be the highest. Highs today will again reach the low 100’s at most locations. With trigger temperatures in the upper 90’s to near 100 and afternoon highs expected to meet or exceed these values, cannot rule out a few very isolated strong late afternoon thunderstorms. Drier air moving in from the ENE should keep development less than yesterday.



As is usual under such strong high pressure and weak wind fields, visible satellite images have shown a large mass of haze over the western and northwestern Gulf of Mexico and inland over much of TX. This is due to the fairly stagnant conditions that are common under large domes of high pressure in the summer months. This haze when combined with the daily pollution across the metro area will support high readings of ground level ozone this afternoon.



The mammoth upper level ridge will begin to break down and back off to the north and west starting Thursday and this will allow afternoon temperatures across the coastal areas of TX to fall back into the upper 90’s. Inverted trough/upper level low off the TX coast will begin to retrograde (move westward) into the coast and then inland on Friday and this feature will help to moisten a fairly dry air mass. Combination of increasing moisture, cooler convective/trigger temperatures in the lower 90’s and a more favorable seabreeze setup will support at least a chance of rainfall this weekend (20-40%). Best chances will be south of HWY 105 where moisture will be the greatest, the seabreeze will serve as a focus, and the influence of the central US high will be weakest. Increased moisture, rain chances, and cloud cover will help return temperatures to near normal for late June (low to mid 90’s) helping to end the current heat wave. Hopefully we will see some rainfall to help wet the ground not allowing the ridge to strongly re-establish over the region early next week. The ridge will not back off over N TX during this period and that is of some concern as soil moisture will continue to decline and the intense heat will help build on itself (helping to pump up the ridge and keep it locked in place…much like last summer.)



Record Highs for Tuesday June 26:

College Station: 106 (broke record of 105 in 2009)

Galveston: 97 (broke record of 95 in 1875)

BUSH IAH: 105 (broke record of 104 in 2009)

Hobby: 102 (broke record of 99 in 2009)

Brownsville: 103 (broke record of 100 in 1900)

Waco: 107 (tied record of 107 in 1980)

Austin Mabry: 109 (broke record of 105 in 2009, set new all-time June record high, previous record was 108 on June 14, 1998)

Corpus Christi: 106 (broke record of 100 in 1980)

Victoria: 108 (broke record of 102 in 2009)

San Antonio: 106 (broke record of 103 in 2009)



The low temperature of 85 yesterday at Galveston is the hottest low temperature ever recorded during the month of June. It should also be noted that the 100 degree high at Galveston on Monday was the first time the city has ever hit 100 degrees during the month of June.



Tuesday Storm Reports:

A few isolated storms developed in the intense afternoon and as suspected they produced some severe weather.



7S Tomball, Harris: .75 inch hail at Louetta and Grant Rd



Jersey Village, Harris: Dime size hail at West Rd and Telge



Addicks, Harris: 4 hangers damaged at the West Houston Airport



Columbus, Colorado: .50 hail and trees/power lines blown down.

[texoz]

Morning e-mail from Jeff:

Some impressive records fell yesterday across the region as the heat wave moved into its 3rd day.

Heat Advisory in effect from noon to 800pm today.

Sprawling upper level ridge centered over the plains continues to provide extremely warm late June weather. The weak short wave which combined with early afternoon temperatures in the 102-106 range yesterday to produce a few severe thunderstorms has moved SW of the area in the ENE upper air flow. Morning low temperatures have only fallen to 86 at Galveston (GLS was still 88 at 300am) and in the low to mid 80’s across the urban metro areas. These very warm morning readings combined with afternoon heat index values at or above 108 requires the heat advisory to be issues. Residents should limit their outdoor activity to less than 30 minutes between the hours of 200pm and 600pm when heat index values will be the highest. Highs today will again reach the low 100’s at most locations. With trigger temperatures in the upper 90’s to near 100 and afternoon highs expected to meet or exceed these values, cannot rule out a few very isolated strong late afternoon thunderstorms. Drier air moving in from the ENE should keep development less than yesterday.

As is usual under such strong high pressure and weak wind fields, visible satellite images have shown a large mass of haze over the western and northwestern Gulf of Mexico and inland over much of TX. This is due to the fairly stagnant conditions that are common under large domes of high pressure in the summer months. This haze when combined with the daily pollution across the metro area will support high readings of ground level ozone this afternoon.

The mammoth upper level ridge will begin to break down and back off to the north and west starting Thursday and this will allow afternoon temperatures across the coastal areas of TX to fall back into the upper 90’s. Inverted trough/upper level low off the TX coast will begin to retrograde (move westward) into the coast and then inland on Friday and this feature will help to moisten a fairly dry air mass. Combination of increasing moisture, cooler convective/trigger temperatures in the lower 90’s and a more favorable seabreeze setup will support at least a chance of rainfall this weekend (20-40%). Best chances will be south of HWY 105 where moisture will be the greatest, the seabreeze will serve as a focus, and the influence of the central US high will be weakest. Increased moisture, rain chances, and cloud cover will help return temperatures to near normal for late June (low to mid 90’s) helping to end the current heat wave. Hopefully we will see some rainfall to help wet the ground not allowing the ridge to strongly re-establish over the region early next week. The ridge will not back off over N TX during this period and that is of some concern as soil moisture will continue to decline and the intense heat will help build on itself (helping to pump up the ridge and keep it locked in place…much like last summer.)

Record Highs for Tuesday June 26:

College Station: 106 (broke record of 105 in 2009)

Galveston: 97 (broke record of 95 in 1875)

BUSH IAH: 105 (broke record of 104 in 2009)

Hobby: 102 (broke record of 99 in 2009)

Brownsville: 103 (broke record of 100 in 1900)

Waco: 107 (tied record of 107 in 1980)

Austin Mabry: 109 (broke record of 105 in 2009, set new all-time June record high, previous record was 108 on June 14, 1998)

Corpus Christi: 106 (broke record of 100 in 1980)

Victoria: 108 (broke record of 102 in 2009)

San Antonio: 106 (broke record of 103 in 2009)

The low temperature of 85 yesterday at Galveston is the hottest low temperature ever recorded during the month of June. It should also be noted that the 100 degree high at Galveston on Monday was the first time the city has ever hit 100 degrees during the month of June.

Tuesday Storm Reports:

A few isolated storms developed in the intense afternoon and as suspected they produced some severe weather.

7S Tomball, Harris: .75 inch hail at Louetta and Grant Rd

Jersey Village, Harris: Dime size hail at West Rd and Telge

Addicks, Harris: 4 hangers damaged at the West Houston Airport

Columbus, Colorado: .50 hail and trees/power lines blown down.

Two "wow" items from that.
1) the note about Galveston hitting 100 for first time on record in June
2) the fact that even with a semi-wet spring this heat wave was able to generate substantial & widespread heat in Texas. Hard to imagine the results with the same dry conditions as last year. Would the temps yesterday been even hotter, by a couple degrees?

FYI, 22 out of a possible 30 record high days for June in Austin have occurred since 2008.
For Houston it's 13 of 30.

Since January 1st, 2012, approx 38,000 record highs vs 5,500 record lows across the US.
In the last 365 days, approx 70,000 record highs vs 15,500 record lows.
The 50yr average was 1:1 ratio.
http://www.ncdc.noaa.gov/extremes/records/

[srainhoutx]

The onshore flow has returned as Gulf moisture begins to lift N with SE breezes. PW's will slowly increase to the 2.0 range as we end the month of June. The High Pressure Ridge that has plagued us since last weekend is shifting further E and daily sea breeze will develop and increase daily into Saturday. Temps will 'cool' somewhat with highs in the upper 80's along Coastal Counties and mid to upper 90's inland. With the daily sea breeze pushing further inland each day and convective temps in the lower 90's, I would not be surprised to see isolated showers/storms slowly begin to increase today into Friday. On Saturday, an inverted trough becomes more developed as a 500mb upper low over S Central Texas putting SE Texas in a more favorable position to the E of that feature. We will see. More widespread rain chance will increase by Saturday and Sunday, the first day of July, should offer the best chance of area wide scattered rainfall. More on that in the July Topic.

06282012 SPC day1otlk_1200.gif

06282012 HGX image_full3.gif

[srainhoutx]

Morning e-mail from Jeff:

Record heat of the last few days will end as increasing moisture brings better rain chances and cloud cover to the area keeping temperatures closer to late June averages.

Visible satellite images and radar shows a few shower developing along the coast this morning suggesting moisture is increasing over the area from south to north as the upper ridge that has been in control of late has begun to weaken and back off to the NW. Upper level trough along he TX coast will slowly move WNW over the weekend placing the area under increasingly deeper tropical moisture and favorable lift side of the trough axis. Given the look of things this morning on both satellite and radar, feel rain chances may be slightly higher than 20% for today and could see better coverage on Friday into the weekend as it appears the deeper moisture is already arriving into the area. Seabreeze boundary will be active each day over the weekend and expect to see showers and thunderstorms develop and move northward from the coast Fri-Sun. Best chances will be across the southern 2/3rds of the area closer to the deepest moisture and away from the influences of the plains ridge. Should see a good 40-50% coverage each day with a few locations getting a good soaking. Increased rain chances and cloud cover will keep temperatures in the low 90’s for highs over the weekend or near late June normals.

High pressure looks to built back into the region by early next week ending rain chances and pushing temperatures back into the mid to upper 90’s but not the 100’s like this week as a cooling onshore flow will be present.

[weatherguy425]

Models don't seem to have the best handle on the moisture plume an developing ULL. NAM keeps all rain well to our southwest (near corpus) while the GFS has hefty totals along along the Texas and Louisiana coasts, with very little of it actually making it ashore. Though the presence of showers already in our coastal counties, an already rapidly moistening atmosphere, and the habit of models to underestimate these synoptic players leads me to believe ( or hope ) that we'll end up on the wetter side of possibilities.

[jasons2k]

Yep, and the models tend to be a step behind reality on these situations - they seem to start/initiate faster and then also end sooner/faster than the models forecast.

[jasons2k]

Decent little line along the sea breeze today Hear some thunder here downtown.

[srainhoutx]

For what it's worth, the 12Z Euro has come in 'wetter'...

HPC:

UPPER LOW/INVERTED TROUGH MOVING ACROSS NORTHEAST MEXICO/SOUTHERN
TEXAS...
PREFERENCE: 12Z NAM/12Z GFS/12Z ECMWF COMPROMISE WITH ABOVE
AVERAGE CONFIDENCE

DIFFERENCES WITH THIS SYSTEM ARE SMALL...THOUGH THE 12Z UKMET/12Z
CANADIAN ARE WEAKER WHILE THE 12Z ECMWF/12Z NAM/12Z GFS ARE
STRONGER. BOTH ENSEMBLE MEANS SUPPORT SOLUTIONS ON THE STRONGER
SIDE OF THE GUIDANCE ENVELOPE SUCH AS THE 12Z NAM/12Z GFS/12Z
ECMWF. THE PREFERENCE IS FOR A 12Z NAM/12Z GFS/12Z ECMWF
COMPROMISE HERE WITH ABOVE AVERAGE CONFIDENCE CONSIDERING ITS SLOW
MOVEMENT.




SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
138 PM CDT THU JUN 28 2012

TXZ199-213-281945-
HARRIS-MONTGOMERY-
138 PM CDT THU JUN 28 2012

...SPECIAL WEATHER STATEMENT...

AT 134 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
RAPIDLY DEVELOPING THUNDERSTORM NEAR ALDINE...MOVING NORTHWEST AT 15
MPH.

PEA SIZE HAIL...FREQUENT CLOUD TO GROUND LIGHTNING...BRIEF HEAVY
DOWNPOURS...ARE POSSIBLE WITH THIS STORM.

LOCATIONS IN THE PATH OF THIS STORM INCLUDE...TOMBALL...THE
WOODLANDS...SPRING...JERSEY VILLAGE...JACINTO
CITY...HUMBLE...HOUSTON...HILSHIRE VILLAGE...CHATEAU WOODS AND
ALDINE AND THE BUSH INTERCONTINENTAL AIRPORT AREA.

[jasons2k]

......and it evaporated *just* as it approached the house.......

[srainhoutx]

Thunder is rumbling up here in NW Harris County. It just goes to show that things don't always work out as expected. All the showers/storms were suppose to be to our SW near Matagorda Bay.

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
426 PM CDT THU JUN 28 2012

TXC201-282230-
/O.NEW.KHGX.FA.Y.0062.120628T2126Z-120628T2230Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
HARRIS TX-
426 PM CDT THU JUN 28 2012

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
WESTERN HARRIS COUNTY IN SOUTHEAST TEXAS...

* UNTIL 530 PM CDT

* AT 425 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
VERY HEAVY RAIN WAS FALLING NEAR ADDICKS. 1 TO 2 INCHES OF RAIN HAS
FALLEN IN THE LAST HOUR AND ANOTHER HALF INCH TO AN INCH WILL BE
POSSIBLE.

[srainhoutx]

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
443 PM CDT THU JUN 28 2012

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
EASTERN FORT BEND COUNTY IN SOUTHEAST TEXAS...
SOUTHERN HARRIS COUNTY IN SOUTHEAST TEXAS...

* UNTIL 515 PM CDT

* AT 436 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL. THIS
STORM WAS LOCATED NEAR BELLAIRE...AND DRIFTING SOUTHWEST AT 5 MPH.

* LOCATIONS IN THE SEVERE THUNDERSTORM WARNING INCLUDE BUT ARE NOT
LIMITED TO STAFFORD...MISSOURI CITY AND MEADOWS.

[srainhoutx]

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
548 PM CDT THU JUN 28 2012

TXZ227-282330-
FORT BEND-
548 PM CDT THU JUN 28 2012

...SIGNIFICANT WEATHER ADVISORY...

AT 544 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR ROSENBERG...MOVING WEST AT 10 MPH.

WINDS GREATER THAN 35 MPH AND BRIEF MODERATE DOWNPOURS ARE POSSIBLE
WITH THIS STORM.

LOCATIONS IN THE PATH OF THIS STORM INCLUDE...ROSENBERG...RICHMOND...
KENDLETON...AND BEASLEY. HIGHWAY 59 BETWEEN RICHMOND AND BEASLEY IS
IN THE PATH OF THE STORM...ALSO.

[srainhoutx]

There is little doubt moisture is on the increase this evening down in the Western Gulf. The upper trough is currently spinning NW of the Hill Country and drawing that Gulf moisture N and W. The HPC has slowly increased the QPF forecast along the Texas Coast the past couple of days. As we have seen many times, these upper low/troughs can throw a curveball or two and are very difficult to forecast. Regardless, we will be 'cooler' and chances of scattered showers and storms are increasing. The fly in the ointment will be just how quickly that upper air disturbance shifts W into Old Mexico.

[srainhoutx]

The overnight guidance suggest a bit less chance in the rainfall department today, but as we saw yesterday the computer models do not perform well with subtle meso features and upper trough/lows. The developing 500mb trough/upper low is beginning to wrap up over Central Texas and guidance suggests that feature will slowly drop WSW to the Lower Rio Grande Valley by Sunday. Scattered showers and storms are developing offshore this morning along the Middle/Upper Texas Coast and moving NW. Rain chances look to increase to area wide on Saturday as the upper air disturbance becomes a bit better organized and continues to draw deep tropical moisture inland. PW's near 2.0 and low convection temps in the 80's should produce sufficient conditions for those that are under the stronger storms to pick up a quick inch or two of rain. While it appears areas to the SW of the Houston Metro have the better chance of seeing heavier rainfall totals, I would be cautious as like we saw yesterday the exact placement of those stronger storms cannot be determined and are often modeled incorrectly. The further NE you are from Houston, the lesser the rain chance it would appear.

HPC

ELSEWHERE...WEAK ENERGY ALOFT COMBINED WITH ONSHORE FLOW OFF THE
WESTERN GULF WILL SUPPORT AN INCREASING AMOUNT OF PRECIPITATION
ALONG THE TEXAS COAST FRIDAY AND SATURDAY.

HPC QPF Forecast:

Day 1

LOWER TO MIDDLE TX COAST...

A MID TO UPR LEVEL CLOSED LOW WL REMAIN IN THE MEAN ACRS CNTRL TX
DAY 1. THIS WL HELP MAINTAIN MOIST SELY LOW LEVEL FLOW INTO THE
LOWER TO MIDDLE TX COAST...SUPPORTING SHOWER ACTIVITY ACRS THESE
AREAS. MODEL CONSENSUS IS FOR MDT TO LOCALLY HVY PCPN AMTS ALONG
THE LOWER TO MID TX COAST

Day 2-3

...SOUTH TEXAS...

THE MODELS ARE ALMOST IN UNANIMOUS SHAPE ON DEVELOPING A MID TO
UPPER LOW ACROSS SOUTH TX AND THIS CIRCULATION/INVERTED TROUGH
AXIS TRACKING WESTWARD OR UP THE RIO GRANDE ON THE SOUTHERN
PERIPHERY OF THE IMPRESSIVE UPPER HIGH TO THE NORTH. IT APPEARS A
SOLID VORT MAX SWEEPS INTO SOUTH TX FROM THE WRN GULF ON SAT...
WHICH COULD FUEL ENHANCED SEA-BREEZE SHOWERS/STORMS... BEFORE THE
SYSTEM BEGINS TO TRACK DOWNSTREAM ON SUN. HPC GENERALLY FOLLOWED
THE LAST TWO ECMWF RUNS AS A BASE FOR QPF... DUE TO ITS SOLID
CONTINUITY.

[srainhoutx]

The 12Z WRF and RAP suggest the best rain chances today will be W of the I-45 Corridor, while the 09Z SREF is suggesting rains will spread a bit further E. It is noteworthy that the radar and visible imagery trends suggest a bit more Eastward spread of the heavier storms along the Middle Texas Coast as the upper low meanders over N Central Texas. Tropical funnels have already been reported near and just W of Matagorda Bay as well.

[srainhoutx]

HGX Hazardous Weather Outlook recently updated:

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1117 AM CDT FRI JUN 29 2012

TXZ163-164-176>179-195>200-210>214-226-227-235>238-301630-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
1117 AM CDT FRI JUN 29 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CONTINUE
THROUGH THE EVENING HOURS TONIGHT WITH BRIEF HEAVY
RAINFALL...GUSTY WINDS...AND FREQUENT CLOUD TO GROUND LIGHTNING.

THE BULK OF THIS ACTIVITY IS EXPECTED TO REMAIN BELOW SEVERE LIMITS
ALTHOUGH THERE IS A POSSIBILITY OF AN ISOLATED SEVERE THUNDERSTORM
LATE THIS AFTERNOON...PARTICULARLY ACROSS OUR NORTHWESTERN
COUNTIES. THE PRIMARY SEVERE THREAT WOULD BE FROM DAMAGING
STRAIGHT LINE WINDS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

AN UPPER LEVEL DISTURBANCE ACROSS SOUTH TEXAS WILL CONTINUE TO
SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND
ACROSS SOUTHEAST TEXAS. HEAVY DOWNPOURS AND FREQUENT CLOUD TO
GROUND LIGHTNING WILL BE THE MAIN CONCERNS WITH THIS ACTIVITY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

[Portastorm]

JB tweet over the lunch hour:

"Tropical wave western gulf increasing, but will run out of room. Rainmaker, heat breaker for deep south Texas."

[jasons2k]

Now we just need some of the rain a bit more North and East. I see the mosture plume in water vaopr is here, just not the rain coverage we see offshore and to the W/SW. Come on.....please....so close...

[srainhoutx]

HPC Model Diagnostic Discussion:

SRN PLAINS/ERN MX UPR LOW CNTR...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE

THE 12Z NAM IS CURRENTLY INDICATING AN UPR CIRCULATION ACRS CNTRL
TX ALONG WITH ANOTHER REGION OF DISTURBED WX OVER THE WRN GULF.
UNDERNEATH THE UPR LOW...THESE FEATURES SHOULD SPIRAL CYCLONICALLY
WITH A MEAN POSN ANYWHERE FROM THE RIO GRANDE UP TO NEARBY
GALVESTON BAY BY 01/0000Z DEPENDING UPON THE SELECTED MODEL. ONE
LOBE OF ENERGY IS FCST TO MIGRATE WWRD ACRS MX WHILE THE SYSTEM
CURRENTLY OVER THE GULF WILL SHIFT NWRD INTO CNTRL TX. THE NAM/GFS
REMAINS CONSISTENT IN RETROGRADING THE TROF AXIS AS THE ENERGY
SPREADS WWRD TOWARD THE SIERRA MADRES WHILE THE DISTURBANCE ACRS
TX SHEARS OUT AS IT SHIFTS TOWARD THE UPR RIDGE TO THE NORTH. THE
GUIDANCE AS A WHOLE PAINT A SIMILAR PICTURE WHICH LEADS TO A
GENERAL MODEL COMPROMISE BEING PREFERRED. THIS IS A SWITCH FROM
THE EARLIER ISSUANCE AS THE 12Z CMC HAS BETTER RESOLVED THE ENERGY
IN THE GULF OF MX.


FCST CONFIDENCE: HIGH