August 2014 - Showers/Storms Possible To End The Month

[JamieP]

For what its worth the 12Z GFS brings that mess N of the Yucatan NNW and develops a 850 vort max that pushes inland between Matagorda and Galveston. It also looks like a good surge of deep tropical moisture surges into the Western Gulf with a tropical wave nearing the Yucatan in the NW Caribbean. Further E in the Caribbean SSW of Greater Antilles, another sheared tropical wave is moving W and pressures are beginning to fall across the Western Caribbean.

Srain, what does "850 vort max" mean in layman's terms? Forgive me, I'm still learning - but I can gather from the rest of your post that "landfall between Matagorda and Galveston" is never a good scenario for our area. Are we possibly looking at a hurricane here?

[tireman4]

Morning AFD:

FXUS64 KHGX 281628
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1128 AM CDT THU AUG 28 2014

.DISCUSSION...
SEE AVIATION FOR 18Z TAF ISSUANCE.

&&

.AVIATION...
ANOTHER DAY OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS
THE TAF SITES THIS AFTERNOON. MOSTLY VFR CONDITIONS SHOULD PREVAIL EXCEPT
INSIDE SHOWERS AND THUNDERSTORMS WHERE VISIBILITIES COULD BE
SIGNIFICANTLY REDUCED. TOMORROW THERE APPEARS TO BE ANOTHER CHANCE
OF SHOWERS AND THUNDERSTORMS THANKS TO REMAINING UPPER LEVEL
ENERGY. HIGH RES TEXAS TECH WRF MODEL SHOWING PRETTY GOOD AREAL
COVERAGE TOMORROW THANKS TO HIGH PWAT AIR. FOR NOW VICINITY
SHOWERS AND THUNDERSTORMS APPEARS TO HAVE THIS COVERED. 23

&&

.PREV DISCUSSION... /ISSUED 1028 AM CDT THU AUG 28 2014/

DISCUSSION...
THANKS TO THE WEAK LOW OFF THE SOUTHERN TEXAS COAST AREAS OF
SHOWERS AND THUNDERSTORMS HAVE DEVELOPED IN PLACES ALONG THE UPPER
TEXAS COAST AND ACROSS THE COASTAL WATERS. SOME TRAINING HAS BEEN
OBSERVED RESULTING IN RADAR RAIN TOTALS OF 2 TO 4 INCHES IN SOME
PLACES. SO FAR RAINS HAVE BEEN CONFINED MAINLY NEAR THE COAST
WHERE THE COLDEST CLOUD TOPS ARE. UNLIKE YESTERDAY THERE`S A
HIGHER CHANCE TODAY OF INLAND STORMS...HOWEVER NOT REAL CONFIDENT
HOW FAR INLAND THE STORMS WILL GO. FOR THE MORNING UPDATE...WENT
AHEAD AND RAISED RAIN CHANCES A LITTLE BIT BASED ON RADAR TRENDS.
ALSO LOWERED AFTERNOON TEMPS A COUPLE DEGREES FOR AREAS ALONG THE
COAST WHERE CLOUD COVER AND RAIN WILL KEEP IT COOLER. FURTHER TO
THE NORTH CURRENT THINKING IS THAT AFTERNOON HIGHS WILL STILL
REACH THE MID 90`S AS LONG AS COASTAL CLOUD COVER STAYS SOUTH.
42/99






http://forecast.weather.gov/product.php ... glossary=1

[srainhoutx]

Not a 'cane JamieP. That is a mid level vorticity maximum around 5000 ft up. What it does mean is it could offer is a bit better lift or better chances of rising air with a deep tropical airmass inplace. Think of it as a 'trigger' that enables better chances of heavy storms to develop.

[ticka1]

Looking at radar - the rain just can't make any headway inland - it dissipates as it tries to move north. I don't see this scenario changing much so it looks like Galveston and along the coast westward are getting the benefical rains that they so need.

Onward to Friday and see what mother natures brings for us

[JamieP]

great, thanks Srain!

[srainhoutx]

Looks like Kludge may getting some storms shortly...or close by. That's fairly far inland.

[Kludge]

Looks like Kludge may getting some storms shortly...or close by. That's fairly far inland.

I wish. Unfortunately I still appear to be on the wrong side of the >poof!< barrier.

[davidiowx]

Showers and thunderstorms along the coast of South Texas are
associated with a weak area of low pressure. This system is
forecast to move inland over southern Texas and northern
Mexico later today and development is not expected.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...near 0 percent.

[jasons2k]

You can clearly see the Coc on the Brownsville radar, spinning offshore the coast slowly headed west.

I've seen many a TD with a worse-looking radar presentation than that. Just sayin'

[jasons2k]

LF on SPI....still slowly moving SW

[srainhoutx]

From Nesdis:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 08/28/14 1949Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES-13 1930Z HANNA
.
LOCATION...TEXAS...
.
ATTN WFOS...CRP...BRO...
ATTN RFCS...WGRFC...
.
EVENT...SATELLITE FEATURES FOR LOCALIZED HEAVY RAIN THREAT TONIGHT
.
SATELLITE ANALYSIS AND TRENDS...TROPICAL LOW PRESSURE/MCV THAT HAS
PRODUCED SEVERAL CONVECTIVE BLOW UPS DURING FAVORED DIURNAL CYCLES
OVER THE LAST FEW NIGHTS HAS CONTINUED TO SLOWLY DROP WSW THROUGH THE
AFTERNOON. MOST RECENT VIS IMAGERY SHOWS THAT A MORE WELL DEFINED MCV
HAS DEVELOPED JUST S OF OPM AND OVER THE LAST FEW HOURS HAS BEEN MOVING
STEADILY TO THE WSW AND SHOULD MOVE ONSHORE IN THE NEXT HOUR OR TWO.
SCATTERED CONVECTIVE ACTIVITY HAS BEEN DEVELOPING JUST ESE OF THE CENTER
AND ALONG OUTFLOW/GULF BREEZE BOUNDARIES THAT WERE SLOWLY PROGRESSING
INLAND. BLENDED PW ANALYSIS WAS SHOWING VERY DEEP MOISTURE OF AROUND
2.4" NEAR THE CENTER OF SYSTEM WHILE 2.10-2.40" PWS EXTENDED UP THE
COAST TOWARDS THE VIC OF LCH.
.
AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION
THREAT AREA SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED
BELOW IN APPROXIMATELY 10-15 MINUTES.
.
SHORT TERM OUTLOOK VALID 1930-0130Z...MEDIUM CONFIDENCE FACTOR
IN SHORT TERM OUTLOOK...ASSUMING OBSERVED CIRCULATION JUST S OF OPM
REMAINS THE DOMINANT ONE, GOES MID TO LOW LEVEL WINDS WOULD SUGGEST THAT
A CONTINUED SLOW WSW MOTION SHOULD CONTINUE ON THE SHORT TERM AND THIS
SHOULD BRING IT INTO PORTIONS OF S TX AND PERHAPS FAR N MEXICO BY LATER
THIS EVENING. BEYOND THIS TIME PERIOD AS UPPER LEVEL TROF PUSHES E INTO
THE PLAINS, OBSERVED NE/SW ORIENTED COL OVER CNTRL TX SHOULD REORIENT
ITSELF E/W PERHAPS ALLOWING FOR A SLOW W MOVEMENT TO MID AND LOW LEVEL
CIRCULATION. THIS WOULD TEND TO SUGGEST THAT MCV SHOULD BE VERY CLOSE
TO THE TX/MEXICO BORDER OR PERHAPS OVER FAR N MEXICO DURING FAVORED
CONVECTIVE DIURNAL CYCLE OVERNIGHT. COMBINATION OF UPSTREAM SOUNDINGS AND
GOES SOUNDER SUGGEST LITTLE CLOUD LAYER SHEAR WITH SUFFICIENT CONDITIONAL
INSTABILITY TO SUGGEST ANOTHER CONVECTIVE DEVELOPMENT NEAR AND DOWNSHEAR
OF MID LEVEL CENTER OVERNIGHT. WEAK N/NE SHEAR PROFILES WOULD TEND TO
SUGGEST THAT THE HEAVIEST CONVECTION SHOULD BE NEAR AND JUST S OF CNTR
OF MCV WHILE STILL LOCALIZED HEAVY RAINFALL SHOULD FALL FURTHER NORTH
TO THE CNTRL TX COAST WITHIN DEEP MOISTURE AND MAXIMUM INFLOW ALONG ANY
COASTAL FRONT/TROF THAT IS ABLE TO DEVELOP. CONFIDENCE IS MEDIUM AT BEST
TO OVERALL PLACEMENT OF LOW TO MID LEVEL CIRCULATION BUT DO FEEL CONFIDENT
THAT ANOTHER CONVECTIVE DEVELOPMENT SHOULD OCCUR NEAR CENTER OVERNIGHT
TONIGHT BRINGING LOCALLY VERY HEAVY RAINFALL VERY NEAR THE TX/MX BORDER
WITH LOCALLY HEAVY RAINFALL EXTENDING FURTHER NE TO THE CNTRL TX COAST.

[srainhoutx]

The WPC/HPC issues Day 2 Slight Risk Excessive Heavy Rainfall for portions of SE Texas and SW Louisiana tomorrow evening into Saturday evening.

[srainhoutx]

1 km Rapid Scan visible imagery suggests a weak low level circulation may be developing N of the Yucatan along the tail end of the trough.

The image below is not 1 km Rapid Scan.

[jasons2k]

HRRR nailed it today. Unfortunately, that means another dry day here....still sitting at 1.34" for August

[BlueJay]

Count your blessings, jasons. We gained 0.09 inches thus far in August 2014. : - (

[jasons2k]

yeah, most of that was on the 18th when I got .90, but it just missed you.

[Ptarmigan]

1 km Rapid Scan visible imagery suggests a weak low level circulation may be developing N of the Yucatan along the tail end of the trough.

The image below is not 1 km Rapid Scan.

http://www.ssd.noaa.gov/goes/east/gmex/rgb-animated.gif

The tropics are heating up. I would not be surprised if something spun up the Gulf of Mexico. Many storms tend to spin up right before Texas is hit.

Tropical Cyclones That Intensified Before Hitting Texas
Hurricane #1 1929
Freeport Hurricane 1932
Hurricane #3 1936
Surprise Hurricane 1943
Hurricane #5 1945
Hurricane #11 1949
Celia 1970
Chantal 1989
Jerry 1989
Charley 1998
Bret 1999
Allison 2001
Fay 2002
Claudette 2003
Humberto 2007

[srainhoutx]

We will need to monitor the convection S of Galveston moving NW. The oil rigs have reported wind of 40 to 50 kts with those storms. Rains chances look to increase tonight into tomorrow mainly along and E of I-45 as a surge of higher PW's (2.5) Surge inland from the Gulf and the S Texas mess spreads NE towards the Upper Texas Coast and the trough across the Panhandle slowly advance E across N Texas and Oklahoma.

[ticka1]

Email from Jeff Lindner - Friday Morning 8-29-2014

Heavy Rainfall possible next 36 hours.

Tropical cyclone formation possible this weekend/early next week W Caribbean Sea/southern Gulf of Mexico

A plume of extremely deep tropical moisture with PWS of 2.3-2.5 inches is heading for the upper TX coast and SW LA coast this morning. A complicated surface pattern has developed with the old surface low we have been tracking now for days located midday between Corpus Christi and Brownsville this morning resulting in ongoing flooding in that region. A secondary weak circulation has now developed over the central Gulf of Mexico and is moving quickly toward the upper TX/SW LA coast at this time. The leading edge of this system is clearly seen on Houston radar across the offshore waters with a strong leading squall (ie note all the marine warnings in effect). This initial squall in racing NNW at over 45mph and producing frequent wind gust to over 50mph (Note: Apache Oil Platform KXIH just gusted to 30kts just SE of Galveston) . It should reach the coast within the next hour and then begin to spread inland.

Additionally, a trough axis is slowly approaching the area from the WNW with ongoing thunderstorms over NW and NC TX and outflow boundaries moving SE toward SE TX which will act to add another mechanism for lift on this very moist air mass needing little trigger.

Meso and global models are in decent agreement that the current central Gulf activity will move inland this morning with a break in the action likely this afternoon. Gulf “re-loads” early this evening and models really ping the nearshore and SE counties for sustained heavy to excessive rainfall overnight into Saturday morning. Looks like the best threat would be along and SE of a line from Palacios to Houston to Liberty. This pattern is showing up in several of the meso models so the confidence that excessive rainfall is going to happen is fairly high especially given the copious moisture in place…but the location is slightly different in each model and it is very possible that the heaviest rains remain right along the coast or just offshore.

Rainfall Amounts:
Given the saturated and tropical air column in place warm rain production is likely with little evaporation. PWS are over +2SD for late August which is always cause for concern when moist levels reach this high. Galveston picked up over 3.0 inches yesterday in a little over an hour, so this air mass is very much capable of some big short term rainfall rates. Current thinking is that amounts of 2-4 inches will be likely SE of a line from Palacios to Liberty with lesser amounts inland. Could see isolated totals greater than 6 inches near the coast and offshore. Hourly rainfall rates will be on the high side and could easily exceed 3.0 inches.

Caribbean Tropical Wave:
A tropical wave currently located over the central Caribbean Sea is moving westward and will move into the western Caribbean Sea over the weekend. Currently upper level winds are not favorable for development, but are forecast to become more favorable this weekend into early next week. Global model guidance and various ensemble members continue to support tropical cyclone formation in the western Caribbean Sea or southern Gulf of Mexico late this weekend/early next week. Current thinking is that while weak, enough ridging will be present over the US Gulf coast to keep anything that develops moving generally WNW toward the Mexican coastline. Will need to keep a close eye on this feature over the holiday weekend.

Tides:
Still seeing higher than normal tides along the coast…in fact the current high tide this morning has been the highest water level rise yet. This appears to be a function of tidal pile-up over the last few days. Hard pressed to blame the wave action as the buoy 20 E of Galveston is 3.9 ft with 5 second periods this morning. Should start to see tides subside some as winds veer to the SE today, but it will be a slow fall and they will remain elevated through the weekend. Additionally, slightly higher than normal wave action is resulting in high rip-current danger along the middle and upper TX coast.

Current Water Levels:

Galveston Bay North Jetty: 2.73 ft
Galveston Pier 21: 2.43 ft
Eagle Point: 2.25 ft
Morgan’s Point: 1.86 ft
Lynchburg Ferry Landing: 1.75 ft
Freeport: 2.33 ft
Sargent: 1.34 ft
Rollover Pass: 1.84 ft
Sabine Pass: 2.51 ft

I have attached a NWS briefing that helps graphically explain most of the above text.

[JamieP]

We had an inch in our rain gauge from yesterday morning's storms (I'm south of Alvin). The clouds moving in from the south looked very tropical this morning, almost band like, similar to what you see when a tropical system moves in. My husband also pointed out the red sky at sunrise - reminded me of the saying "red skies at morning, sailors take warning".