August:Hot & Dry To End The Month/SE TX

[Katdaddy]

Hey Canebo we missed yesterday's isolated sea breeze storm on the other side of Magnolia Creeks. Let hope the weak front and tropical mositure give us decent rain chances later this week.

[Canebo]

Hey Canebo we missed yesterday's isolated sea breeze storm on the other side of Magnolia Creeks. Let hope the weak front and tropical mositure give us decent rain chances later this week.

Katdaddy:
We are in Brittany Lakes and just missed it too. Thunder and wind, but no rain. I am hoping for it this weekend too,
but don't have high hopes.

[biggerbyte]

I hear you, Canebo. Hopefully we will not get caught in the middle. That is a possibility if everything tropical stays south. There are two schools of thought as of today. We will see.

[srainhoutx]

Morning e-mail from Jeff:

Changes from hot and dry to wet and cooler on the way.



High pressure over the SW US will gradually shift further west and combine with building high pressure over the NW US to carve out a deep downstream eastern US trough. This pattern will unlock so fairly cool air by August standards and send it southward over the northern plains and then SE toward the Ohio Valley and east coast this weekend. Across TX the cold front will arrive into the state Thursday and slowly sag southward over the weekend. Main brunt of the cold air advection will be to our NE, but the front or its associated outflow boundaries from thunderstorms will likely sag into central TX and our northern counties by late Saturday.



The combination of the frontal boundary, increasing moisture from both the Pacific and the Gulf, and short wave riding down the backside of the trough and across the frontal boundary will support much better rain chances starting Friday and continuing into the weekend. Should see some decent organization of the storms both along the frontal boundary and the inland moving seabreeze front, so most locations should see some rainfall. Pattern does favor heavy rainfall and will need to keep an eye on this aspect as the boundary will linger into early next week providing several days of wet weather.



Big wild card is whether or not some sort of tropical system will try and spin up over the western Gulf of Mexico late this weekend into early next week. GFS has been consistent on moving the remains of TD #7 across central America and the Yucatan then into the Bay of Campeche where it slows the wave and closes it off into a weak surface low. The EURO and CMC continue the wave axis westward and into mainland Mexico with no development. The GFS has performed very well this year in the tropics with both Debby and Ernesto and TD #7, so it could be on the right track. With that said, shear looks to be increasing over the western Gulf in response to the tail end of the trough over the eastern US and I think the GFS is too strong with any surface low that may develop. That pattern fits a classic western Gulf of Mexico surface trough that may close off into a weak low, but is highly sheared and all the weather is N and NE of its surface center. If the EURO is correct the frontal boundary would stall across the northern Gulf and this would also help increase the surface gradient with lowering pressures to the south.



For now will keep the frontal boundary stalled near/over our area inland of the coast and any tropical development weak. Combination of these features will keep rain chances high into early next week and if low pressure does form in the western Gulf, rain chances would likely increase into the middle of next week.

[srainhoutx]

As Jeff stated and as the GFS has clearly shown for days, the tropical disturbance that has been suggested would never fully vertically stack and could be a potential heavy rainfall maker for the southern half of Texas. The latest HPC QPF Forecast reflects this potential and is only good through day 5. Should the GFS solution be correct with a slow meandering weak surface low and a stalled boundary across the region, those forecasted rainfall totals may well be too little. We will see.

[Kludge]

W/ NAM suggesting some rain for the Northern parts of the HGX CWA this afternoon, I figured I'd post a radar hotlink or two. Meager lapse rates, long/skinny CAPE and unimpressive LIs on NAM, but not much CINH and maybe enough difference between temp and dewpoint near peak heating for some gusty wind action up Hunstsville/Lufkin way.

Thanks for the research and heads-up, Ed. Today marks one month here with now measurable precip. Sure hope this pans out.

[srainhoutx]

The 12Z guidance continues advertise a stalling boundary and the HPC Final Afternoon Update includes a spot low pressure system just S of Brownsville and mentioning of potential tropical development and enhanced rainfall.

[MontgomeryCoWx]

Bring me another 9 inches in a week!

[SusieinLP]

Nice dark cloud stayed around for awhile but no rain...I see Baytown is getting a nice shower.....Hopefully there are more showers to come this weekend...

[michmich]

So a pool party/outdoor bbq on Saturday afternoon in Cypress is probably not a good idea?

UGH.

[JackCruz]

Yes, agreed. I would LOVE another week of non stop rain...too bad the consequence of such and event will be flooding

[srainhoutx]

The overnight guidance continues to paint a very wet weekend and cooler weather with all the cloud cover. PW's increase to the 2 inch range by Sunday and 1-3 inches of rainfall are possible with isolated higher amounts under heavy thunderstorms. The frontal boundary will begin to drop into our area late Saturday into Sunday and slow down or stall just to our N. This boundary will set the stage for a focal point of heavy storm development and a heavy rainfall concern. On Sunday, deep tropical moisture will surge N from the Gulf as the remnants of TD 7 heads toward the NE Mexican Gulf Coast. With a deep mid latitude trough becoming established to our E across the Eastern half of the country and unseasonably cool air well off to our N and E, moisture pools across the Western Gulf and begins to pull N and NE. The $64,000 question remains will a weak tropical system form near S Texas. The GFS backed off developing a 'stronger' system overnight while the Euro suggested a tad stronger system than it had been suggesting all week. The fly in the ointment then becomes just how far the frontal boundary sags S. If that boundary remains to the N of Metro Houston, a significant flood potential could be in the cards. A further S boundary would mean less of a flood threat. It does appear that a short wave will drop SE on Monday and could provide some additional push to the frontal boundary. That said the main energy for this frontal boundary will be well to our E. Still more questions than answers, but we certainly will see a change from the hot and dry pattern of late and chances of everyone seeing some beneficial rains look likely. Let's just hope we don't get more than we bargained for because there is a potential that things could turn out much 'wetter' than some expect early next week. Stay Tuned. This is one of those very difficult and changeable forecasts that will need to be monitored rather closely...

[srainhoutx]

Morning e-mail from Jeff:

One more day of dry and hot before the pattern begins to change.



Large ridge of high pressure that has been anchored over W TX and NM for weeks has weakened and shifted westward allowing a downstream trough to develop over the central and eastern US. This unusually deep trough for mid August will allow a rare cold front to move into TX later today and approach SE TX over the weekend. Gulf moisture begins to increase later today and really on Friday with PW values increasing to 2.0 inches by Friday afternoon. With weakening low level winds and building moisture, expect the seabreeze to become active on Friday while thunderstorms from the north move southward during the afternoon and may clip our N and NE counties.



Saturday-Sunday:

Slow moving/stalling frontal boundary arrives into/near the area as moisture increases even more off the western Gulf. Expect a good round of thunderstorms on Saturday with heating both from the seabreeze and the stalling front. GFS and EURO are really hammering away at Sunday as being the wettest day. Once again widespread storms are likely at really any point from late Saturday night into Sunday evening. Weak short waves in the NW flow aloft could develop storms in a highly moist air mass and nearly anytime during that period. Starting to get slightly concerned on the rainfall totals with the potential for a surface boundary in the area and deep tropical moisture in place. Both of those factors point to a locally heavy rainfall threat.



Early Next Week:

Decent agreement in the model guidance through Sunday begins to diverge early next week. Tropical wave (old TD 7 remains) currently over the southern Yucatan and central America will lift WNW into the Bay of Campeche this weekend. GFS has backed away from its tropical cyclone development and has fallen in line closer to the EURO and CMC and keeping the system a tropical wave. Two main questions focus on early next week: 1) how much moisture is pulled northward from this tropical wave along the western Gulf coast and 2) how far south does the frontal boundary move. EURO and CMC try and push the front offshore early next week allowing a drier air mass the move into the region, while the GFS keeps the boundary over the area with deep tropical moisture in place. Convective outflows could push the front southward into the Gulf, but then again it is mid August. Will take a blend of the GFS and other guidance and show the front making slow progress toward the coast early next week. With several days of a stalling boundary and deep tropical moisture in place, many rounds of heavy rainfall appear likely. As the ground saturates over time with daily rains, will start to see increased run-off and the threat for flooding may increase especially if the boundary lingers into the middle of next week.

[Katdaddy]

This will be a welcome pattern with slightly cooler temps and decent coverage of rainfall however as Srain indicates it possible we get more than we want. Joe B tweeted about Gulf mischief next week earlier this morning. I will be curious if has additional tweets with his concern. Lots of moisture looks to pool in the GOM next and its that time of year where homebrew becomes a concern

[srainhoutx]

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
938 AM EDT THU AUG 16 2012

VALID 12Z MON AUG 20 2012 - 12Z THU AUG 23 2012


PRELIMINARY UPDATE...

USED THE 00Z/16 DETERMINISTIC ECMWF TO UPDATE THE PRELIMINARY
FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7. THE ECMWF IS STRONGLY
CORRELATED WITH THE 00Z/16 ECENS MEAN...GEFS MEAN...AND
DETERMINISTIC GEM GLOBAL THROUGH THE PERIOD. THE 00Z/16 GFS IS OUT
OF SYNC WITH THE OTHER GUIDANCE LATE IN THE PERIOD...SHOWING ITS
BIAS OF WARMING TOO QUICKLY AND TOO SHARPLY IN THE WAKE OF THE
EASTERN TROUGH. SOUTH TEXAS CONTINUES TO BE AN AREA OF INTEREST
FOR POTENTIALLY HEAVY RAINFALL. WHETHER AN ORGANIZED TROPICAL
CYCLONE IS ABLE TO FORM OVER THE FAR WESTERN GULF OF MEXICO MAY BE
IMMATERIAL TO THE RAINFALL THREAT...WITH THE MOIST PLUME FROM THE
SOUTH INTERSECTING THE SOUTHERN EDGE OF THE WESTERLIES OVER THE
REGION. THE BIGGEST SENSIBLE WEATHER UPSHOT OF USING THE ECMWF
VERSUS THE GFS OVER THE NORTH CENTRAL STATES IS THE TENACITY OF
COOLER AIR TO THE EAST...WITH AN ENHANCEMENT TO THE BAROCLINICITY
VIA OVERRUNNING PRECIPITATION.


CISCO

[djmike]

Question: I am reading a lot about this weekends weather and potential of flooding rains, but every graphic I see that shows QPF/Precip totals shows nowhere near flooding rains from this whole combining mess this weekend. I think the most totals I've seen for ALL of TX the next 5 days is 2" at most. GFS and Euro don't show all that much either...just curious if there is another qpf map out there that shows something more and why everything else isn't showing all that much. Is it possible Texas really won't see a LOT? ...Thanks!

[srainhoutx]

Question: I am reading a lot about this weekends weather and potential of flooding rains, but every graphic I see that shows QPF/Precip totals shows nowhere near flooding rains from this whole combining mess this weekend. I think the most totals I've seen for ALL of TX the next 5 days is 2" at most. GFS and Euro don't show all that much either...just curious if there is another qpf map out there that shows something more and why everything else isn't showing all that much. Is it possible Texas really won't see a LOT? ...Thanks!

Everything hinges on what becomes of the Western Gulf moisture (development ~vs~ no development) and just how far S the boundary pushes and where it stalls. No one can forecast with any certainty exactly how this will play out at this time. It's just something to monitor and be aware of. The HPC and NWS have clearly stated it is a challenging forecast at best.

[srainhoutx]

Not a whole lot of changes via the 12Z operational GFS regarding a developing tropical system in or near the Western Gulf. What is a tad different is the rainfall and a slow creep inland with each run of that model. Some of the totals suggested by the GFS are nearing the 15 inch mark along the NE Mexico/S Texas Gulf Coastal waters and 5-10 inches along the Middle Texas Coast offshore. Inland totals are less as suggested by the GFS, but that model has shifted some better moisture inland and a robust 700mb level along the US 59 Corridor. That said there appears to be abundant deep tropical moisture available and various meso features that cannot be identified or model at this range will be the major fly in the ointment. As we know, tropical downpours are capable of dumping a lot of rainfall very quickly and that may well be the theme as we head toward the late weekend/early to mid next week timeframe. We will see.

[rnmm]

With all this talk of rain (which is wonderful by the way ) I am glad I chose today to get the mowing done...how much rain can our coastal and inland areas expect? Time will tell, I guess

[srainhoutx]

The 12Z Euro has come rather similar to what the 00Z run suggested. That model tries to develop a weak surface low near Tampico and slowly moves the 850mb vorticity N along the Mexican Gulf Coast. It is also note worthy that the Euro remains rather aggressive suggesting the frontal boundary will move offshore before stalling and retreating back N near hour 168 as a weak broad surface reflection meanders near Brownsville.