July 2018: Weekend/Early Next Week Rain Chances

[DoctorMu]

TWC took most of the rain out of the forecast, except Sunday. Fortunately. NOAA retains 50% chance over the next 3 days.


This was a repeat of Wednesday in that showers fell apart as they neared with the sun setting...then reformed SW of us.

[srainhoutx]

TWC took most of the rain out of the forecast, except Sunday. Fortunately. NOAA retains 50% chance over the next 3 days.


This was a repeat of Wednesday in that showers fell apart as they neared with the sun setting...then reformed SW of us.

Still hopeful that the stalled frontal boundary just to your N and E can give you folks in B/CS a good chance at some rainfall on Sunday.

[tireman4]

Weekend Forecast

[tireman4]

Jeff's AFD (sorta) for the late afternoon and evening..

[Rip76]

Staring to see those towers...

[jasons2k]

Just not much out there today, so far.

[DoctorMu]

Just not much out there today, so far.

That's changed a bit. The statewide radar is something to see! We're getting into the action a little. Just 60-90 earlier in the day with a cell makes a significant difference. A nice 10-15 min shower.

[srainhoutx]

Keep those umbrellas handy and remember when thunder roars, head indoors. High moisture levels and effective dynamics could lead to heavy rainfall rates wherever the heaviest storms develop today through Monday.

[srainhoutx]

NWS Houston‏Verified account @NWSHouston · 20m20 minutes ago
We are getting several reports of tropical funnels and waterspouts over Galveston Bay. These are typically short-lived weak circulations. Please stay weather aware! #glswx #txwx

[DoctorMu]

Fast moving showers are lined up across old outflow boundaries. Drink up, northern counties!





Area Forecast Discussion
National Weather Service Houston/Galveston TX
1244 PM CDT Sat Jul 7 2018

.AVIATION...
Current radar imagery has a splattering of showers and
thunderstorms streaming across the northern TAF sites CLL/UTS/CXO
and over our coastal terminals. Coverage should expand this
afternoon across all SE TX sites as convection continues to
blossom off of old outflow boundaries, and along the sea and bay
breezes. Short term guidance such as the HRRR and Texas Tech WRF
carry the precipitation into the evening hours dissipating mostly
before midnight. Overall, winds will be veering more onshore
through the day and remain between 5-10 kts. Gusty winds will be
possible beneath stronger storms that develop. MVFR ceilings will
build back in along the coast tomorrow, and showers will likely
develop by early morning Sunday. Have gone ahead and included VCSH
in for LBX/GLS by 09Z, with precipitation beginning a few hours
later for the inland terminals.

Hathaway

&&

.PREV DISCUSSION... /ISSUED 1056 AM CDT Sat Jul 7 2018/

DISCUSSION...
We are starting to see activity perk up across SE TX this morning,
especially near the coast. With generally uniform 2" PWs over the
area and daytime heating, scattered showers/thunderstorms will be
possible through the rest of the day today, with the best chances
likely with the seabreeze as it moves inland. Did tweak POP grids
in the short-term to match up with current trends. Otherwise, not
too many changes with temps this afternoon/evening. 41

PREV DISCUSSION... /ISSUED 430 AM CDT Sat Jul 7 2018/

A small cluster of thunderstorms that have moved across the
central western forecast area early this morning have exited
Colorado County this past hour. Today`s convective activity will
be very similar to yesterday`s as weak disturbances pass across
within the dominant northeasterly steering flow. Festering showers
and thunderstorms over the western Gulf this morning are possibly
a sign that, with inland warming into the middle to upper 80s,
northwestern Gulf evolving towering cumulus-producing-showers will
begin to develop closer to the coast with some of these
strengthening into thunderstorms. A weak land breeze boundary
along with land-sea frictional elements will assist in better
lower level convergence over the coastal counties. Nearshore
clustering cells will likely work their way onshore through the
late morning hours and put down a quick few hundredths to a
quarter of an inch upon their westward trek. There should be
enough early day sun to heat interior temperatures up into the
lower 90s. This will provide enough instability/lift to allow for
the development of more central CWA widely scattered showers and
storms. A lifting sea breeze front will also aid in providing the
additional focus, or low level convergence, required for further
downstream initiation of future discrete storm cells. Greater than
2 inch pwats will exist within a channel of lower heights as
eastern Texas stays under the weaker underbelly of a Four Corners-
centered upper ridge. Considering that a weak circulation over the
Florida Panhandle will be moving into the northeastern Gulf later
today, POPs are weighted more towards areal (precipitation)
coverage as confidence remains high on occurrence. Partially
cloudy becoming overcast skies will regulate many interior maximum
temperatures in the upper 80s to lower 90s, middle 90s further
north where there is no or delayed rain. High moisture and weak
winds will stick minimum temperatures in the average inland middle
70s with coastal lower 80s. Heat indices will typically top out
in the average upper 90s.

A weak inverted trough will be moving into the western Gulf Sunday.
As this wave approaches east Texas, Sunday`s precipitation chances
will climb into the likely category as the region falls along and
east of its axis. All of the key ingredients are in place such as
high unseasonable moisture and an unstable background environment
(progged ~7-8 deg C lapse rates produce ample strong to marginal
severe thermodynamic indices) indicate that there is a high
probability of widespread shower and thunderstorm activity tomorrow.
Once this wave passes, relatively lower heights and an unchanged
thermo profile suggests that there will be another round of daily
convection; less coverage than Sunday but still a decent amount of
clustering convection that impact at least 40-50% of the forecast
area by sunset. Late period, or from Tuesday on through the work
week, increasing heights will commence a drying pattern with any
daytime shower/storm behavior forming along the regional (sea/bay)
mesobreezes. Less precipitation and drier ground will lift maximum
temperatures by a few degrees in subsequent days. Average lower to
middle 90 ambient temperatures with the typical lower to middle 70
dew points will produce slightly higher heat indices closer to 105 F
than 100 F. 31

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0416
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 PM EDT SAT JUL 07 2018

AREAS AFFECTED...SERN TX...SRN LA...SRN MS...FAR SW AL

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

VALID 071830Z - 080030Z

SUMMARY...NUMEROUS THUNDERSTORMS WILL DEVELOP THIS AFTERNOON ALONG
THE WEST-CENTRAL GULF COAST AND MOVE SLOWLY ACROSS THE REGION.
RAIN RATES OF UP TO 2-3 IN/HR WILL BE POSSIBLE WHICH COULD LEAD TO
FLASH FLOODING.

DISCUSSION...GOES-16 DAY CONVECTION RGB IS SHOWING A BLOSSOMING OF
INCREASINGLY VIGOROUS CONVECTION IN THE VICINITY OF A DISSIPATING
STALLED FRONT ALONG THE GULF COAST. ADDITIONAL CONVECTION WAS
DEVELOPING ALONG SOME SEA BREEZE BOUNDARIES THAT WERE SLOWLY
ADVANCING INLAND. GOES-16 IR SATELLITE CHANNELS ALSO SHOW A
GENERAL COOLING OF THE CLOUD TOPS...AND REGIONAL RADARS HAVE SHOWN
A SIGNIFICANT EXPANSION IN THE COVERAGE OF CONVECTION OVER THE
PAST COUPLE HOURS (16-18Z). THIS TREND IS EXPECTED TO CONTINUE FOR
THE NEXT HOUR OR TWO WITH AN INCREASING TREND FOR CONSOLIDATION OF
CONVECTION INTO LARGER CLUSTERS...PARTICULARLY NEAR COLLISIONS IN
OUTFLOW BOUNDARIES...SEA BREEZES...AND THE STALLED FRONT. THIS
SHOULD LEAD TO A RELATIVELY HIGH COVERAGE OF RAIN IN THE NEXT SIX
HOURS...WITH POCKETS OF HEAVY RAINFALL IN EXCESS OF 2-3 INCHES.

THE ENVIRONMENT IN THE OUTLINED AREA IS VERY MOIST...WITH NUMEROUS
GPS-PW OBSERVATIONS IN THE 1.9 TO 2.1 INCH RANGE SUPPORTIVE OF
HEAVY RAIN RATES AND EFFICIENT RAINFALL PRODUCTION. THE DEEP LAYER
(0-6KM) MEAN WINDS WERE ONLY AROUND 5-10 KNOTS...INDICATING THE
POTENTIAL FOR VERY SLOW STORM MOTIONS. COLLIDING BOUNDARIES MAY
FURTHER INCREASE RESIDENCE TIME OF HEAVY RAIN IN CERTAIN
LOCATIONS. THESE TWO FACTORS SHOULD BE AMONG THE MOST FAVORABLE
FOR FLASH FLOOD POTENTIAL THIS AFTERNOON AND EARLY THIS EVENING
ACROSS THE REGION.

FLASH FLOOD GUIDANCE IS NOT ESPECIALLY LOW IN THE REGION...WITH
3-HR FFG AROUND 3-4 INCHES. RAINFALL APPROXIMATELY THAT HIGH IS
POSSIBLE GIVEN THE ENVIRONMENT AND STORM MOTIONS...BUT GIVEN THE
LACK OF STRONG LOW-LEVEL FOCUSING MECHANISMS...THE COVERAGE OF
SUCH RAINFALL MAY BE LIMITED IN AREAL EXTENT. THEREFORE...WHILE
FLASH FLOODING IS POSSIBLE IT SHOULD BE LOCALIZED. THE 12Z HREF
SHOWS THE HIGHEST MEAN QPF AND GREATEST PROBABILITIES OF FFG
EXCEEDANCE IN SOUTHWEST AND SOUTH-CENTRAL LOUISIANA. A DECREASING
TREND IN CONVECTIVE COVERAGE AND THE FLASH FLOOD THREAT IS
EXPECTED AROUND SUNSET.

LAMERS

ATTN...WFO...EWX...FWD...HGX...JAN...LCH...LIX...MOB...SHV...

[srainhoutx]

Looks like training along and just S of the frontal boundary across our Northern CWA is producing some 2 to 3 inch rainfall amounts. HGX is monitoring in case Flood Advisories become necessary.

[jasons2k]

Storms all day missed me to the north and spit out an outflow. Now all the new storms are forming along the outflow / sea breeze collision to my south. I’m stuck in the middle, not a drop.

[srainhoutx]

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
507 PM CDT SAT JUL 7 2018

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
WESTERN HARRIS COUNTY IN SOUTHEASTERN TEXAS...

* UNTIL 600 PM CDT.

* AT 505 PM CDT, DOPPLER RADAR AND AUTOMATED RAIN GAUGES INDICATED
THUNDERSTORMS PRODUCING HEAVY RAIN ACROSS THE WARNED AREA. COUNTY
GAUGES HAVE REPORTED TWO TO THREE INCHES OF RAIN HAVE FALLEN IN
THE PAST HOUR. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
JERSEY VILLAGE AND NORTHERN ADDICKS PARK TEN.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND, DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS, URBAN AREAS, HIGHWAYS, STREETS AND UNDERPASSES AS
WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

[Texaspirate11]

SOME waterspouts reported today off the bay

Threatening clouds and some rumble, but no rain though in my area

[DoctorMu]

Storms all day missed me to the north and spit out an outflow. Now all the new storms are forming along the outflow / sea breeze collision to my south. I’m stuck in the middle, not a drop.

There's a fairly large cell on its way toward you from the ENE. Maybe 20-25 min out.

[jasons2k]

Storms all day missed me to the north and spit out an outflow. Now all the new storms are forming along the outflow / sea breeze collision to my south. I’m stuck in the middle, not a drop.

here's a fairly large cell on its way toward you from the ENE. Maybe 20-25 min out.

Well, that one is quickly falling apart, but I am watching what is going on Liberty County with interest though. But it's 5:45 already - I might be grasping at straws.

[srainhoutx]

Looks like we will see a bit more areal coverage earlier in the day. Reports recently of tropical funnels and a water spout or two near East Beach/Galveston Bay.

07082018 mcd0419.gif

MESOSCALE PRECIPITATION DISCUSSION 0419
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
716 AM EDT SUN JUL 08 2018

AREAS AFFECTED...UPPER TX AND LA COASTAL PLAIN

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

VALID 081116Z - 081616Z

SUMMARY...SHOWERS AND THUNDERSTORMS ARE SLOWLY INCREASING IN
COVERAGE. HOURLY RAIN TOTALS TO 2.5" WITH LOCAL AMOUNTS TO 4" ARE
POSSIBLE WITHIN THE PULSE CONVECTION.

DISCUSSION...AN UPPER LOW WITH A TRAILING UPPER TROUGH/SHORTWAVE
EXTEND FROM EASTERN AR SOUTHWEST THROUGH NORTHERN LA INTO EASTERN
TX PER GOES-16 WATER VAPOR IMAGERY. SINCE 08Z, ML CAPE IN THE
REGION HAS BEEN COMING UP UNDER ITS BASE NEAR AND SOUTH OF I-10
PER SPC MESOANALYSES NEAR AND SOUTH OF A SURFACE
TROUGH/CONVERGENCE ZONE, WITH AN UPTICK IN EFFECTIVE BULK SHEAR
OFFSHORE. PRECIPITABLE WATER VALUES OF 2.1-2.3" EXIST HERE PER
GPS DATA. INFLOW IS WEAK BUT CONVERGENT OUT OF THE SOUTHWEST AT
5-10 KTS PER VAD WIND PROFILES.

WHILE CONVECTION IN SOUTHEAST LA SHOULD PEAK WITHIN THE NEXT
COUPLE HOURS, BOTH THE 06Z GFS-BASED GALVEZ-DAVISON INDEX AND 06Z
HREF PROBABILITIES OF 1"+ IN AN HOUR IMPLY/ADVERTISE A FURTHER
INCREASE IN CELL COVERAGE THROUGH ROUGHLY 16Z FOR SOUTHWEST LA AND
SOUTHEAST TX. AFTER THAT TIME, SEA BREEZE CIRCULATIONS ARE
EXPECTED TO TAKE OVER WHICH WOULD SPREAD THE THUNDERSTORM ACTIVITY
MORE INLAND. BELIEVE THE 06Z CANADIAN REGIONAL MODEL, 00Z NMMB,
00Z NSSL WRF, AND 06Z NAM CONEST HAVE A BETTER GRASP OF WHAT IS
EXPECTED OVER THE NEXT SEVERAL HOURS. TWO WEEK PRECIPITATION
ANOMALIES ARE POSITIVE IN PATCHES NEAR THE LA COAST, WITH AREAS OF
SOUTHEAST TX 200-400% OF NORMAL. WITHIN THIS ENVIRONMENT, MOSTLY
PULSE CONVECTION SHOULD LEAD TO HOURLY PRECIPITATION TOTALS TO
2.5" WITH LOCAL AMOUNTS TO 4". THIS RAINFALL WOULD BE MOST
PROBLEMATIC IN URBAN AREAS.

ROTH

ATTN...WFO...HGX...LCH...LIX...

[srainhoutx]

07082018 mcd0420.gif

MESOSCALE PRECIPITATION DISCUSSION 0420
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1203 PM EDT SUN JUL 08 2018

AREAS AFFECTED...SC AND SE TEXAS...SW LOUISIANA

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

VALID 081602Z - 082200Z

SUMMARY...VERY SLOW-MOVING STORMS ARE EXPECTED TODAY. THEY WILL
BECOME MORE NUMEROUS AROUND MIDDAY AND MEANDER AROUND THE REGION
THROUGH THE AFTERNOON. RAIN RATES MAY REACH 2-3 IN/HR WHICH COULD
PRODUCE LOCALIZED FLASH FLOODING... ESPECIALLY IN URBANIZED AREAS.

DISCUSSION...CIRA BLENDED TOTAL PW PRODUCT SHOWS PW VALUES AROUND
1.9 TO 2.3 INCHES OVER MOST OF THE OUTLINED REGION FROM
SOUTH-CENTRAL TEXAS INTO SOUTHWEST LOUISIANA. THIS CLOSELY MATCHES
BOTH 12Z SOUNDINGS FROM THE AREA...AND NUMEROUS GPS-PW
OBSERVATIONS WITH THE HIGHEST OBSERVATIONS FROM HOUSTON METRO TO
NEAR LAKE CHARLES LOUISIANA (AROUND 2.2 INCHES). DESPITE THE
TYPICAL HUMID CLIMATE ALONG THE GULF COAST IN THE SUMMER
MONTHS...2.2 INCH PW VALUES WOULD BE AROUND OR JUST ABOVE THE 90TH
PERCENTILE FOR MID JULY ON THE LAKE CHARLES SOUNDING CLIMATOLOGY.
THUS ANOMALOUSLY HIGH LEVELS OF ATMOSPHERIC MOISTURE ARE IN
PLACE...AND SHOULD PROMOTE EFFICIENT RAINFALL PRODUCTION IN
STORMS.

FURTHER EXACERBATING THE THREAT OF LOCALLY HEAVY RAINFALL ARE THE
VERY WEAK WINDS THROUGH MUCH OF THE DEPTH OF THE TROPOSPHERE. A
LOW-LEVEL TROUGH (SFC-850MB) STRETCHED IN A BROAD ARC FROM NEAR
LAREDO TO NEAR BATON ROUGE...AND THIS WAS COINCIDENT WITH A
WEAKNESS IN THE MID-UPPER LEVEL FLOW. FORECAST MEAN WIND
(850-200MB) ACROSS THE REGION WAS GENERALLY AROUND OR LESS THAN 5
KNOTS. FLOW THIS WEAK SHOULD ALLOW STORMS TO BE NEARLY STATIONARY
UPON INITIAL DEVELOPMENT...WITH PERHAPS SOME SLOW PROPAGATION AS
CELL MERGERS FORCE DEVELOPMENT OF SMALL CLUSTERS AND LOCALIZED
COLD POOLS. THERE IS NOT A STRONG LOW-LEVEL BOUNDARY FOR
CONVECTION TO FOCUS ON...SO THE CONVECTION MAY NOT PERSIST IN THE
SAME AREA FOR MANY HOURS. HOWEVER...THE SLOW DRIFT AND POTENTIAL
FOR CELL MERGERS AND INTERACTIONS SUGGESTS THAT HEAVY RAIN CAN
PROBABLY BE SUSTAINED AT SOME LOCATIONS FOR A COUPLE HOURS...WHICH
MAY LEAD TO A FLASH FLOOD THREAT. RAIN RATES OF 2-3 IN/HR SEEM
ACHIEVABLE GIVEN THE DEEP SATURATED PROFILES...MODERATE TO STRONG
INSTABILITY...AND VERY SLOW STORM MOTIONS.

ONE MESOSCALE FEATURE OF INTEREST IS A NNE PROPAGATING OUTFLOW
BOUNDARY...EVIDENT ON GOES-16 VISIBLE SATELLITE LOOPS AND KHGX
RADAR. AT 16Z IT STRETCHED FROM ABOUT 40W OF VCT TO NEAR BYY TO
NEAR 25ESE OF SGNT2. EXTRAPOLATING CURRENT TRENDS WOULD PUSH THE
OUTFLOW BOUNDARY INTO THE VICINITY OF HARRIS COUNTY AND HOUSTON
METRO BETWEEN 19Z AND 21Z. THIS MAY PROVIDE ADDITIONAL FOCUS FOR
CONVECTIVE ORGANIZATION AND DEVELOPMENT JUST DOWNSTREAM FOR AN
HOUR OR TWO...AND THUS BRIEFLY ENHANCE RAIN RATES. SOME SCATTERED
CONVECTION WAS ALREADY DEVELOPING ACROSS HOUSTON METRO...BUT THIS
MAY ENHANCE RAIN RATES ALONG THE I-10 CORRIDOR EARLY THIS
AFTERNOON.

LAMERS

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...

[srainhoutx]

FLOOD ADVISORY
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1107 AM CDT SUN JUL 8 2018

CHAMBERS TX-HARRIS TX-
1107 AM CDT SUN JUL 8 2018

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

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

* UNTIL 100 PM CDT.

* AT 1107 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 IN THE PAST 30
MINUTES OVER BAYTOWN.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
EASTERN PASADENA, BAYTOWN, LA PORTE, DEER PARK, SEABROOK, BEACH
CITY, CLOVERLEAF, HIGHLANDS, CLEAR LAKE, CHANNELVIEW, BARRETT,
EASTERN SOUTH BELT / ELLINGTON, SOUTHWESTERN MONT BELVIEU, TAYLOR
LAKE VILLAGE, EL LAGO, SHOREACRES, COVE, MORGAN'S POINT, ELLINGTON
FIELD AND EASTERN HOUSTON SHIP CHANNEL.