July - Hot & Muggy To End The Month

[srainhoutx]

The reliable global and ensemble guidance is suggesting a back door frontal boundary will approach from the NE as a very unseasonably deep trough develops across the East Central/Eastern US. The guidance appears to be struggling from run to run as to just how far S that boundary will move before pulling up stationary. Previous days had suggested the boundary would be near the I-10 Corridor. Today, the GFS and Euro are suggesting that boundary may be a bit further to the N across E Texas and Central Louisiana. There are some indications that a wave of low pressure/inverted trough may develop somewhere near S Central Texas. Meanwhile in the Bay of Campeche there are some indications that a tropical disturbance may fester for several days. Deep tropical moisture should surge from the Western Caribbean into the Western/Central Gulf near the 4th of July timeframe. The upper ridge that is bringing our SW wind flow from old Mexico should change to a more southerly flow allowing that increased tropical moisture to move toward the Mexican/Texas and Louisiana Gulf Coast. We will need to monitor any strong storms dropping S from the Plains in a northerly flow aloft as pressure fall across the Lone Star State early next week into the July 4th long Holiday weekend.

[srainhoutx]

As mentioned yesterday, the reliable global and ensemble guidance are suggesting a very unsettled pattern develop around the 4th of July and extending into the long Holiday Weekend. A rather potent upper low/trough will develop near the Ohio Valley and slowly retrograde WSW as the upper ridge that will bring us our 100F heat sill shift NW into the Pacific NW and Western Canada. There continues to be indications that a trough of low pressure will develop near S Central Texas/Middle Texas Coast along a stalled boundary. Copious deep tropical moisture will stream in from the NW Caribbean with precipitable water values (PW’s) exceeding the 2+ inch mark. This deep rich moisture from the tropics sets the stage for a multi day rainfall event that will benefit locations across most of the Western and Central Gulf extending E. Those with outdoor plans over the 4th of July may want to monitor future weather forecasts as the rain and storm chances may need to be increased during the Holiday period. MIMIC does show a rather impressive tropical wave moving W near 45W. We may need to watch that feature as the timing for arrival in the NW Caribbean coincides with a favorable MJO pulse/Kelvin Wave entering the Western Atlantic Basin during the second week of July. We will see.




EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
129 AM EDT THU JUN 27 2013

VALID 12Z SUN JUN 30 2013 - 12Z THU JUL 04 2013

...PATTERN OVERVIEW...

SOLID AGREEMENT IN THE MEDIUM RANGE FOR A RIDGE IN THE WEST AND IN
THE CANADIAN/US ROCKIES. AND IN THE EAST AND CENTRAL
US...ALONG/DOWNSTREAM OF 100W LONGITUDE...A 'REX BLOCK'
CONFIGURATION TO THE UPPER-LEVEL FLOW BY THE END OF DAY 7...WITH
NORTHERN STREAM TROUGH MIGRATING THROUGH SOUTHEAST CANADA.

...GUIDANCE AND UNCERTAINTY ASSESSMENT...

FOR THE PAST 7 MID SHIFTS...THE PATTERN HAS BEEN A RATHER
PREDICTABLE ONE...WITH A WARM/STABLE SUBTROPICAL RIDGE IN THE FOUR
CORNERS (A MORE SUMMER LIKE PATTERN)...SANDWICHED BETWEEN
TROUGHS/CUTOFF LOWS IN THE EASTERN PACIFIC AND EASTERN US (AN
ANOMALOUS ONE). THE RATHER SLOW WESTWARD PROPAGATION OF THE FLOW
PATTERN HAS BEEN THE ONE SUBTLE CHALLENGE OF THE MEDIUM RANGE
FORECAST.

A COMBINED EC ENSEMBLE MEAN/GEFS MEAN APPROACH (THE 26/12Z CYCLE
TONIGHT) CONTINUES TO BE THE PREFERENCE ON THE OVERNIGHT DESK.
THIS MAINTAINS SOME WESTWARD PROPAGATION OF THE FLOW PATTERN EAST
OF THE CONTINENTAL DIVIDE AND KEEPS GOOD CONTINUITY WITH THE
PREVIOUS GRAPHICS THROUGH DAY 5 (TUESDAY). BEYOND DAY 5...LIKED
THE 26/12Z EC MEAN (70%) AND DETERMINISTIC ECMWF (30%) ALOFT FOR
THE CYCLONIC FLOW DEVELOPING TO THE SOUTH OF THE UPPER-LEVEL RIDGE
(REX BLOCK LIKE FEATURE ALONG 100W BETWEEN 40N-55N LATITUDE).

WITH THE H5 HEIGHT ANOMALIES...A GOOD 3 TO 4 STANDARD DEVIATIONS
(SDs) BELOW NORMAL IN THE SOUTHERN MISSISSIPPI VALLEY AND A GOOD
3-4 SDs ABOVE NORMAL OVER NORTHERN ALBERTA (BY DAY 6)...THE
FORECAST CONTINUES TO HOLD ON TO THIS UNUSUAL FLOW PATTERN WITH
THE 26/12Z DETERMINISTIC ECMWF AND 27/00Z DETERMINISTIC GFS IN
REASONABLE AGREEMENT THROUGH THE MIDDLE OF DAY 5. AM MUCH MORE
CONFIDENT IN THE DETAILS (EVEN BEYOND DAY 5) BENEATH THE
UPPER-LEVEL RIDGE FOR PLACES LIKE SEATTLE...PORTLAND...BOISE AND
SAN FRANCISCO...THAN I AM WITH THE DETAILS OF THE UPPER-LEVEL
TROUGH AND EMBEDDED SHORTWAVE ENERGY OVER THE NORTH CENTRAL STATES
SUBJECT TO VERIFYING A 'REX BLOCK' LIKE FLOW PATTERN ON THE FOURTH
OF JULY.

THOUGHT THE 27/00Z GFS IS NO CLOSER TO A STABLE SOLUTION BY THE
END OF DAY 5 (3/00Z) THAN ITS 26/12Z CYCLE RUN WITH EMBEDDED
ENERGY MOVING ATOP THE UPPER-LEVEL RIDGE AXIS (IN CENTRAL CANADA)
AND INTO THE NORTH CENTRAL STATES AND MID MISSOURI VALLEY. AM A
BIT SURPRISED WITH THE H5 HEIGHT ANOMALIES BEING SO "BELOW NORMAL"
AT THE BASE OF THIS TROUGH AXIS OVER THE LOWER AND MIDDLE MS
VALLEY...THERE REMAINS LITTLE TO NO MODEL PRECIPITATION OUTPUT
BENEATH THIS UPPER-LEVEL FEATURE.

...SENSIBLE WEATHER HIGHLIGHTS...

THE HEAT IN THE WEST AND PACIFIC NORTHWEST WILL EVENTUALLY MOVE
INTO SOUTHWEST CANADA AT THE END OF THE PERIOD...WITH THE GEFS/EC
ENSEMBLES CONTINUING TO CARRY AN UPPER-LEVEL TROUGH OVER THE GREAT
LAKES...EAST COAST AND MISSISSIPPI VALLEY INTO DAY 7.

PROLONGED PERIOD OF LOCALLY HEAVY RAINFALL CONTINUES TO BE A
SENSIBLE WEATHER THREAT FOR MUCH OF THE GULF COAST AND EASTERN
SEABOARD...WITH THE UPPER-LEVEL TROUGH ANCHORED OVER THE MS
VALLEY...AT LEAST THROUGH DAY 6 (NEXT WEDNESDAY).

VOJTESAK

[jasons2k]

This is what Jeff Lindner had to say about the long-term. I will gladly take rain any day I can get it, but it just figures the period hinted at is July 4-7 -- the 4 days most of us working people are looking forward to spending some time outdoors by a pool/lake/beach & watching fireworks.

4th of July and beyond:
Models are coming into agreement that the unusually deep trough over the eastern portion of the nation early next week will begin to back westward and could be over or just west of E TX by next Thursday. Tremendous tropical moisture over the Gulf of Mexico at this point (PWS at or above 2.0 inches) looks to advance on the coast by the afternoon of the 4th suggesting a fairly active seabreeze. With this trough axis possibly getting just west of the area by the 5th, moisture levels soar and rain chances will be on the rise. In fact the period from the 4th -7th of July is starting to look fairly wet.

[Texas Pirate]

Houston Galveston NWS:

WATCHING TROPICAL
MOISTURE SURGE FOR THE MIDDLE/END OF NEXT WEEK FOR INDEPENDENCE
DAY. MODELS HAVING A TOUGH TIME WITH THIS FEATURE SO WILL KEEP 20
POPS AS PRECIP WATER VALUES APPROACH 1.8-2 INCHES ACROSS THE AREA.
THIS MAY BE NEXT BEST CHANCE FOR RAIN ACROSS THE AREA. 39



We're doomed. And its only June.

[srainhoutx]

The 12Z GFS is indicating a surge of deep tropical moisture from the NW Caribbean streaming into the Western Gulf early to mid next week. The Eastern trough relaxes a bit and the frontal boundary begins to wash out or retreat N on Tuesday/Wednesday bringing a return flow off the Gulf. As we head toward the 4th of July long Holiday period, PW’s increase to the 2+ range and a weak disturbance begins to form in a broad area of lower pressures in the Bay of Campeche. Increased showers and storms appear to begin in earnest a week for today (July 5th) and move inland adding to the inland coverage of rain chances. It is interesting to note that the Bermuda Ridge begins to build back into the Eastern Gulf mid next week and upper level winds become slightly more favorable for a weak tropical disturbance to fester in the Western Gulf. We will see.

[srainhoutx]

One thing we will need to monitor is some form of low pressure system developing along the tail end of the frontal boundary S of Louisiana. The reliable models (GFS/Euro) and their ensembles are suggesting lower pressures across the Western Gulf as well as a bit of ridging from the Bermuda High back into the Eastern Gulf. Past experience tells us that any stalled frontal boundary near the Gulf Coast with advancing tropical waves/moisture from the NW Caribbean is worth watching later next week. Stay Tuned, as they say...

[srainhoutx]

The operational GFS and Euro are suggesting a broad area of low pressure developing in the Bay of Campeche near the July 4th timeframe. While those reliable models do not develop any significant tropical system, both of those models are suggesting a surge of deep tropical moisture exiting the NW Caribbean associated with a couple of tropical waves with increasing PW’s over the 2 inch mark pooling in the Western Gulf. Enhanced rain and storm chances should begin in earnest late in the day of the 4th and continue into the long Holiday weekend.

[srainhoutx]

The overnight global and ensemble guidance are advertising a couple of cool mornings with low temps in the 60’s for Monday and Tuesday N of 1-10. The deep trough to our N and E should begin to retrograde or move W as the Upper Heat Ridge shifts NW into the Pacific NW and the Canadian Providences of British Columbia/Alberta. Deep tropical moisture that is building across the Caribbean Sea will enter the Western Gulf by mid week. PW’s of 2+ inches and a return flow off the Gulf with SE breezes will likely set the stage for increasing rainfall chances late on Thursday (July4th) and extend into the long Holiday weekend. The NCEP ensembles as well as the Euro ensemble mean suggests that an area of tropical disturbed weather may fester in the Bay of Campeche as the upper air pattern becomes a bit more supportive as TS Dalila moves along the Mexican Pacific Coast and the northerly flow aloft transitions to a more southerly flow as the upper trough axis shifts W late next week.

[TexasBreeze]

This sounds like something you would post srain! Snippet from HGX disco update...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1047 AM CDT SUN JUN 30 2013

.MARINE... OUTFLOW HAS SHIFTED SOME WINDS TO THE WEST AND SE WINDS IN THE EASTERN ZONES. FRONTAL BOUNDARY CRAWLING SOUTHWARD BUT WITH HEATING SHOULD PICK UP SPEED AND LEAPFROG SOUTHWARD. WIND SHIFT SHOULD MAKE IT INTO THE UPPER TEXAS COASTAL WATERS THEN WAFFLE AROUND FOR A FEW DAYS. WILL HAVE TO KEEP AN EYE ON THE GULF AS FRONT STALLS IN THE GULF AND SHEAR RELAXES.

[Katdaddy]

Currently 98F in League City and we some beautiful skies this morning as a result of the storm complex off to the W and NW of SE TX.

[srainhoutx]

TC genesis probabilities continue to increase in the Bay of Campeche during the long 4th of July Holiday period. Increasing chances of tropical downpours appear to be in the cards for the Mexico, Texas and Louisiana Gulf Coastal areas into next weekend.

[Rip76]

Since the title says, "thoughts" I wanted to add mine.
Something I've been thinking about "our" weather the last couple of years.

It seems (or feels) to me, like our seasons have shifted a bit. Almost right after Hurricane Ike, and that cool front right after it.
And the horrible drought of 2011.

I get the feeling that our seasons are shifting to the "left" a bit. Whereas, the old weather of February and March is now April and May.
June and July temps are now "Augusty." (If that's a word).

It also seems that we have more of an, Arizona/New Mexico feel to our weather now as well, where we didn't have that before.
Maybe it's an axis shift?
June bugs are called that for a reason I assume, but are showing themselves as early as March.

Maybe it's jet stream positioning.


Anyway, my .02.

[srainhoutx]

Morning e-mail from Jeff:

After record heat on Saturday, a weak cool front has in fact moved off the coast ushering in an usually dry and “cool” air mass for the first week of July.

Dry air continues to settle southward this morning with dewpoints falling into the 50’s and 60’s across the region which is rare for July. Mid level temperatures are also cooling and while the surface dry air will heat up quickly only looking at the mid 90’s today and likely a little cooler on Tuesday. With dry air in place, overnight lows will fall toward those dry dewpoints or into the 60’s across the area. While it will still be warm during the day, the lack of significant humidity will make it feel near the actual temperature or similar to a “dry heat.

Main part of this forecast will focus on a major upcoming pattern change that promises a significant increase in rain chances toward the end of the week and next weekend. Large upper level trough over the MS valley this morning will be forced westward (retro-grade) due to building Atlantic ridging over the western Atlantic. This trough axis will only slowly move westward taking nearly the entire week to reach eastern TX. While there is some significant difference in the model guidance on where this axis resides by the end of the week and where a possible mid or upper level low develops over the southern plains…the overall trend is toward a very wet pattern. At the same time as this trough axis drifts westward, a strong tropical wave will move west out of the Caribbean Sea and into the Gulf of Mexico with a pool of deep tropical moisture (PWS 2.2-2.4 inches) flooding much of the central and eastern Gulf by late this week. This moisture will be drawn northward on the eastern side of the trough axis bringing potentially significant rainfall.

Current thinking is that the area will salvage a decent 4th of July as the trough axis will likely be just east (near the TX/LA state line) on Thursday with dry air still in place over our region. Tropical air mass will be lurking not far away and expect it to arrive into the coastal waters late Thursday and on the coast Friday with rain chances increasing south of I-10 on Friday. Brunt of tropical surge arrives Saturday into Sunday with PWS climbing to well over 2.0 inches and trough axis/mid level low developing/moving into central TX placing our region under very favorable upper air divergence and lift. Patterns such as these can produce some incredible rainfall in short periods of time and while rain chances will be increasing and peaking over the weekend and a flood threat may also develop. Mid and upper level low pressure systems can at times begin to act like tropical cyclones when embedded within a tropical air mass…this usually results in very heavy concentrated rainfall near the core of the system overnight and in the early morning hours and then banding of rainfall on the fringes during the afternoon hours. Rainfall rates in such a moist nearly saturated air mass will approach or exceed 2-3 inches per hour.

Models have also been bouncing around with attempting to close off the trough wave/trough axis over the western Gulf and this would not be out of the question given the likely extensive amounts of thunderstorms that will be ongoing off the TX coast Friday-Sunday. Regardless if a surface low did form, the impacts would be nearly the same with copious rainfall across SE TX into the coastal bend.



[jasons2k]

Saw this in today's NWS discussion:

RAINFALL DEFICITS FOR THE YEAR (THRU THE END OF JUNE) STAND AT...

3.18 INCHES FOR CLL
5.01 INCHES FOR GLS
5.56 INCHES FOR HOU
10.54 INCHES FOR IAH

I'm very close to IAH and the 11" deficit. For only 6 months, that's a pretty steep deficit - reminiscent of 2011.

Also, Didn't HOU break a record or two for daily rainfall this year? Pretty amazing even with that they're still over 5" behind. I guess it shows how much or our rain has come mostly in a couple of major events, not spread out, so the drought is affecting the plants a lot worse than the numbers indicate.

[jasons2k]

I get the feeling that our seasons are shifting to the "left" a bit. Whereas, the old weather of February and March is now April and May.

FWIW I have noticed, and commented to friends quite frequently this spring that the season was a month behind. Everything was like clockwork, just a month behind schedule.

[kayci]

Guess I need to start doing the rain dance again.

[Ptarmigan]

Hopefully it will be a wet this week.

[Paul Robison]

I personally believe that, if it develops at all, it will probably be a central or eastern Gulf affair (Louisiana, Mississippi, Alabama, Georgia, Florida). Both the CMC and GFS are in agreement that at least weak troughing will be present over the Great Lakes as the system (TC? Weak low?) enters the Gulf, with high pressure to the northwest over the Southwest and northeast off the coast of North Carolina. The GFS advertises a stronger Southwest ridge, with influence farther east, and it sends the storm into the Florida Panhandle. On the other hand, the CMC has a weaker ridge; this would allow for a more westward track, but it's also depicting a deeper trough able to pull the storm (probably will be one) into southeastern Louisiana.

Do I have a point?

[Ptarmigan]

Has a major hurricane ever made landfall on Southeast Texas in July? Yes, it has happened on July 21, 1909. It was dubbed the Velasco Hurricane. It made landfall on what is now present day Freeport. It made landfall as a Category 3 hurricane with 115 mph winds and central pressure of 959 millibars.

Many areas saw 5 to 7 inches of rain with the highest total being 8.5 inches near Hallettsville. Houston Weather Bureau Office in Downtown Houston recorded less than 1 inch of rain.

http://en.wikipedia.org/wiki/1909_Velasco_hurricane
http://www.rootsweb.ancestry.com/~txmat ... e_1909.htm

[Paul Robison]

Has a major hurricane ever made landfall on Southeast Texas in July? Yes, it has happened on July 21, 1909. It was dubbed the Velasco Hurricane. It made landfall on what is now present day Freeport. It made landfall as a Category 3 hurricane with 115 mph winds and central pressure of 959 millibars.

Many areas saw 5 to 7 inches of rain with the highest total being 8.5 inches near Hallettsville. Houston Weather Bureau Office in Downtown Houston recorded less than 1 inch of rain.

http://en.wikipedia.org/wiki/1909_Velasco_hurricane
http://www.rootsweb.ancestry.com/~txmat ... e_1909.htm

Yes, I read that too. Why do you mention it? What does it have to do with this coming weekend's weather?