JUNE 2016: Showers/Storms Possible

[Ptarmigan]

The afternoon Global guidance continues to advertise a rather unusual pattern developing during the coming work week. Another Western trough swings through the Southern Rockies while further North along the Polar jetstream a very potent storm system organizes and sends a Canadian front into the Southern Plains. Ahead and along the front, the models suggest showers and thunderstorms may develop with a very moist airmass in place ahead of the rather slow moving frontal boundary. There are indications that a Coastal trough/low may attempt to organize near Brownsville that further raises an eyebrow. While we are several days away from knowing exactly what the sensible weather will be, due to all the recent flooding and our neighbors are suffering from flooded homes, it is worth monitoring the weather trends particularly early next week. Stay tuned and check back for more updates.

Looks more like a fall setup than late spring or early summer. Those setups can lead to extremely heavy rain.

I have seen upper level lows over the Four Corners and that kind of setup leads to flooding like in June 1973, May 1989, October 1994, and Tax Day 2016.

[srainhoutx]

I am becoming increasingly concerned that potions of our Region may see yet another heavy rainfall potential. The overnight guidance continues to advertise a combination of features that point to a very unsettled pattern. A potent upper trough will eject out of the Great Basin Tuesday with embedded disturbances rotating beneath the trough as well as the sub tropical jet. Another feature is something we have not seen lately and that is a very wet phase of the Madden Julian Oscillation progressing E from the Eastern Pacific into the Western Caribbean Sea and the Gulf. The blues and purples on the MJO charts below suggest rising air and very deep tropical moisture being entrained into an slow moving frontal boundary that will approach Tuesday into the rest of the upcoming work week. This Canadian front is expected to be rather strong, but likely will not make much progress of the Coast as the Upper Air dynamics are well to our NE in the Great Lakes. An Upper Ridge attempts to build to our West in California that may allow additional disturbance to ride S later in the work week toward Texas. All in all, the pesky and stormy pattern looks to persist into the coming week as we begin June. Stay Tuned folks, we are all tired of this very wet and flooding pattern that we just cannot seem to shake.

[unome]

http://www.cpc.ncep.noaa.gov/
http://www.cpcpara.ncep.noaa.gov/

CPC's days 8-14 (Jun 5-11 currently) shows below-normal precip, but other time periods are all very wet - that time period also has scorching temps out west

http://www.cpc.ncep.noaa.gov/products/p ... cp.new.gif

[srainhoutx]

The 12Z GFS has been rather insistent on developing a Coastal low/trough along the tail end of the frontal boundary that appears to be stalled along the Coast next weekend. Such a scenario raises an eyebrow as we sometimes see a bit of a spin up in June along the tail end of these stalled boundaries that can create problems of extended rainfall and the possibility of Coastal flooding if they become stronger than the models at this range can resolve.

[DoctorMu]

Yeah, I've been concerned about tropical development along the boundary.


The high CAPE and southern jet predictions are out in West Texas this week though...so we have that going for us. The GFS is sticking to prediction of rainfall exceeding 1 inch from the Hill Country west...but we'll see how this plays out in the next few days.

[DoctorMu]

[srainhoutx]

We are starting to see some ensemble support from the American Ensembles (GEFS) suggesting an area of low pressure at the surface, mid and the upper levels may well be possible at the tail end of that stalled boundary next weekend.

Edit to add:
The European model seems to agree on the potential of a Coastal low/trough as well and the Update WPC Day 3 to 7 Surface Charts suggests the potential as well.

[srainhoutx]

Afternoon updated quantitative precipitation forecast continues to increase. If a Coastal low does develop, except these totals to go up further particularly along the Coastal tier of Counties.

[DoctorMu]

GFS is also picking up the coastal low at 132 hours out (Saturday)...waiting on the 18z run.

[Katdaddy]

A beautiful satellite this evening across the Plains as an active pattern continues.

[DoctorMu]

18z GFS has a broader coastal low, but 3-5 inches of rain over 72 hours with a bullseye near Brenham.

[srainhoutx]

For what it's worth, the 18Z GEFS suggests multiple areas of 1004 mb to 1008mb low pressure spinning up from the NW Caribbean to the NW Gulf late next week. We will continue to monitor for potential development and suggest folks monitor the future updates.

[srainhoutx]

Once again we are seeing a complex and complicated sensible weather forecast challenge developing this week into the weekend. An upper low over Southern California is expected to move ESE toward Texas by mid week and become cut off from the mean upper flow across the United States as a wavy stalled frontal boundary becomes draped across Texas. PW's are expected to increase to above 2+ inches as deep tropical moisture pools across S Central, Central and SE Texas Tuesday into at least Friday. A pesky SW flow aloft brings embedded disturbances across the Region and rounds of showers and thunderstorms increase Wednesday as the meandering upper low sets up over S Central Texas. There continues to be some indications that a coastal trough of low pressure attempts to develop along the Lower/Middle Texas Coast pumping copious amounts of moisture over the stalled boundary. We may see rounds of strong to possibly severe thunderstorm develop Wednesday into Friday with daytime heating. Once again we just cannot accurately forecast exactly where, which neighborhoods or when the heaviest rainfall may occur due to mesoscale processes that cannot be determined beyond about 6 or so hours ahead of time. If the quantitative precipitation forecast continue to increase, except Flash Flood Watches to be hoisted during the coming work week. Again, this is a low confidence forecast as of this morning so expect changes as the week unfolds. This unsettled pattern looks to linger throughout the coming work week and possibly into next weekend.

[srainhoutx]

Memorial Day briefing from Jeff:

Ingredients coming together to produce yet another significant rainfall event across TX this week

Upper level low currently across southern CA will move slowly eastward and then slow down and completely cut-off from the main upper level flow by the end of the week over MX into the western Gulf of Mexico. Upper level disturbances will eject out of this feature starting on Wednesday with many additional disturbances passing over the region Thursday-Saturday. Slow motion of the entire system and of individual disturbances is very concerning when combined with PWS of 1.8-2.0 inches and a weak steering pattern aloft. Overall setup is favorable for large thunderstorm complexes with excessive rainfall and severe weather.

As with all the events we have faced over the last six weeks…it is the smaller scale features that determine where the greatest rainfall sets up. A surface cool front will accompany this large upper level system and may stall across SE TX and SC TX Thursday into Friday leading to a surface focusing mechanism.

With the grounds across this state saturated and rivers running well into flood along with lakes and reservoirs well above normal…there is just no room for additional water. Rains of the recent weeks have been pushing area rivers and lakes to their breaking point and we are now there. Additional heavy rainfall is going to result in fast responses on area watersheds and additional flooding. Significant releases from area lakes may be required with widespread heavy rainfall leading to downstream flooding. Many rivers including the Brazos and Trinity, Colorado, San Jacinto, San Bernard, and Navasota will still be flooding…and flooding significantly as this next system moves into the area.

Will go with widespread rainfall amounts of 1-3 inches with much higher isolated totals possible as we have seen now twice in the last six weeks these very moist air masses coupled with favorable dynamics can produce some incredible rainfall amounts.

Residents across the area should remain alert to the forecast this week and to changes to current river forecasts for the area.

7 Day Forecasted Rainfall Amounts

[Andrew]

GFS is coming around to look more similar to the ECMWF which isn't positive news. Looks like instead of having the front move all the way through, both of these models indicate we could have it stall over parts of SE Texas and a lot of moisture from the gulf. The key here is how favorable will the dynamics be for sustained heavy rain. Obviously we won't know that until later this week when rain start happening.

[srainhoutx]

The afternoon updated quantitative precipitation forecast continues to increase. Will need to monitor for severe thunderstorms/squall lines moving out of the Hill Country Tuesday and Wednesday then the focus shifts to the potential of about 48 to 60 hours of very heavy rainfall rates as the Western upper low stalls NW of Corpus Christi and a frontal boundary hangs up somewhere along or N of the I-10 Corridor Thursday, Friday and possibly into Saturday. It is also a bit worrisome to see the processes that may be involved with this cutoff upper low. NWS Fort Worth/Dallas mentions the potential of a transition from a cold core vertically stacked upper low to that of a warm core. If in fact that is what the guidance is indicating, a warm core system can take on characteristics that can bring very heavy nocturnal storms capable of dropping tremendous amounts of rainfall. We will need to monitor the trends to see if in fact that is what this potential late week weather maker may bring.

Area Forecast Discussion
National Weather Service Fort Worth TX
345 PM CDT MON MAY 30 2016

.DISCUSSION...
The airmass over the region is pretty worked over from the
overnight and morning convective episode, but afternoon sunshine
has returned and some pockets of enhanced instability have
developed primarily across the far western zones and also eastern
zones. Some isolated slow moving diurnal convection with locally
heavy rainfall will be possible in these areas through early
evening, but would expect this activity to diminish or dissipate
by mid evening with the loss of heating. Otherwise, the synoptic
environment over the region tonight is suggesting that a repeat
round of West Texas storms moving into the region is unlikely.
This is because the mid-upper level westerly winds have weakened
which means cell motions will be much slower, but also the low-mid
level flow has become more westerly which limits the deep layer
shear and ability for convective complexes to organize and track
easterly as well. Most of North and Central Texas will experience
a tranquil evening with temperatures not unpleasant for the time
of the year. However increasing low clouds and low level moisture
by morning will keep lows from falling beyond the upper 60s.

The next upper level shortwave trough will arrive into the Texas
Panhandle and West Texas by midday Tuesday and southerly flow over
our region will once again organize. This will bring rich Gulf
moisture northward and again set the stage for a convectively
active evening and overnight period. While a few showers and
storms may pop up right over the area during the day Tuesday in
the moist and unstable airmass, the main show will develop
northwest of the CWA in the afternoon hours and head southeast
into North Texas during the evening and overnight hours. Instability
will be plentiful and deep layer shear is sufficient for organized
convective modes -- primarily multicell complexes but brief
supercellular structures during the evening hours will be possible
over the NW zones. So a low severe weather threat will occur with
this round of convection, but perhaps more of a concern is the
locally heavy rainfall potential. The topsoils are saturated from
the recent rounds of rain (especially over most of the NW CWA) and
any additional rainfall will be more prone to run off. Average QPF
of 1 to 2 inches appears likely for the northwestern zones and we
may consider a flash flood watch for this area in subsequent
forecast packages. The convection Tuesday night will likely
continue to track southeastward across the region into Wednesday
morning so will continue to show likely PoPs. We may see a
respite in the activity by the afternoon hours, but generally
cloudy conditions will prevail and help to keep high temps around
80 degrees for the first day of June.

The weather pattern will get interesting by Wednesday night as a
cut off upper level low moves into the state from the west. This
low will be vertically stacked, meaning that there will be a low
pressure/height center from the surface to the tropopause in the
same general area. This means the region will be in a persistent
area of upper level lift coincident with a continuous
east/southeast low level feed which will keep precipitable water
values up around 1.9 inches. Meanwhile the temperature gradients
associated with the upper low will weaken which is a sign of a
system transitioning from cold-core to warm-core. These warm-core
lows can sometimes set up a convective feedback loop where
convective episodes serve to enhance the upper level dynamics for
lift which results in more convection...and then more lift...and
so on. This can result in localized regions of very heavy rainfall
particularly during the late night and morning hours. So on the
synoptic scale there is the concern that all of the ingredients
are in place for some excessive rainfall totals somewhere across
Texas for the latter half of the week. Obviously we can`t say
exactly where these areas of heavy rain will set up at this time.
We can say that the due to the lack of baroclinic energy the
severe weather threat will be almost zero, since instability will
be limited and winds will also be fairly light through the
tropospheric column.

For the particulars of the forecast, have indicated good chances
of rain both day and night Wednesday night through Saturday
morning. The cyclone drops southeast into the Gulf during the day
Saturday and allows northerly winds to bring in some drier air
behind a cold front into our region which should gradually end
the rain chances. High temperatures will be below normal -- with
forecast values in the upper 70s to low 80s to start out the first
few days of June.

TR.92

[Katdaddy]

Not the best weather news but after a beautiful Memorial Day and mostly dry Tuesday; we begin the transition to an extended period of rainfall that looks to last through next weekend. Some strong to severe storms will be possible but localize heavy rains adding to the ongoing flooding will be the main threat. Expect Flash Flood Watches to go into effect across a large portion of TX including SE TX Wednesday afternoon. From the Houston-Galveston morning Area Forecast Discussion:

Thus...all of the above is evidence to this ongoing message of an early June high rainfall event that will likely exacerbate flooding somewhere in our forecast area.

[srainhoutx]

Morning briefing from Jeff:

Major flooding continues on parts of the San Jacinto and Brazos Rivers

San Jacinto River:

West Fork at Humble:

Water is falling, but the river remains above flood stage. The river continues to fall slightly faster than the forecast and expect the river to be back within banks likely late Wednesday.

East Fork at FM 1485:

River continues a very rapid fall and has fallen back within banks.

San Jacinto At Sheldon:

River is falling quickly and will fall below major flood stage this morning and back within banks Wednesday into Thursday.

Upper Cypress Creek:

Flooding continues along upper Cypress Creek west of US 290, but is receeding. Overflow into Bear Creek has ended and the water is falling back toward bankfull at the FM 529 bridge crossing.

Brazos River at Richmond:

Record flooding is in progress and will continue into Wednesday.

Large areas of Fort Bend County have been inundated with flow overtopping FM 723 and FM 359 north of the river and FM 2759 at Thompsons. Water has inundated portions of Rosenberg near the river Water is several feet against multiple levees across Fort Bend County and is spilling across the river basin divide into Oyster Creek threatening portions of the Quail Valley and Lake Olympia subdivisions. Flow is surrounding portions of Sienna Plantation

Massive flooding of the floodplain will progress downstream into Brazoria County where any last minute preparations for this flood should be completed this morning.

This is a very significant flood for Fort Bend County.

Weather Outlook:

A significant storm system will approach the area mid week into the weekend with all ingredients coming together to produce another significant rainfall events over the region. The upper level low will slow and cut-off over SC TX late week placing SE TX in a favorable upper air pattern and this combined with high moisture levels and strong low level convergence are all point toward significant rounds of heavy rainfall that will only worsen the ongoing flooding issues.

Will go with a solid 2-4 inches of rainfall Wed-Sat, but think this may need to be increased and certainly isolated amounts will be higher.

Residents across the region should remain aware of the weather forecast and the potential for additional or new flooding on area watersheds.

[/i]

[srainhoutx]

Start spreading the word folks. Our Texas NWS offices are attempting to get the word out early since our Rivers, watersheds and grounds just cannot handle much more rainfall. Expect Flash Flood Watches will be hoisted across the Region tomorrow into Thursday depending on what the future trends hold and If the approach upper low transitions from cold winter like core to warm tropical like core as some of the models are suggesting.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
730 AM CDT TUE MAY 31 2016

LA SALLE-MCMULLEN-LIVE OAK-BEE-GOLIAD-VICTORIA-WEBB-DUVAL-
JIM WELLS-KLEBERG-NUECES-SAN PATRICIO-ARANSAS-REFUGIO-CALHOUN-
INCLUDING THE CITIES OF...COTULLA...CALLIHAM...CROSS...
LOMA ALTA...TILDEN...GEORGE WEST...THREE RIVERS...BEEVILLE...
GOLIAD...VICTORIA...LAREDO...FREER...BENAVIDES...SAN DIEGO...
ALICE...ORANGE GROVE...KINGSVILLE...CORPUS CHRISTI...PORTLAND...
INGLESIDE...ARANSAS PASS...SINTON...MATHIS...ROCKPORT...REFUGIO...
WOODSBORO...PORT LAVACA
730 AM CDT TUE MAY 31 2016

...HEAVY RAINFALL EVENT WEDNESDAY NIGHT THROUGH FRIDAY...

AN UPPER LEVEL DISTURBANCE WILL ENTER THE REGION FROM THE WEST
WEDNESDAY NIGHT AND THURSDAY...THEN MEANDER OVER THE AREA FRIDAY.
MOISTURE WILL INCREASE TO COPIOUS AMOUNTS OVER SOUTH TEXAS BY
WEDNESDAY. THE COMBINATION OF THE UPPER DISTURBANCE...ATMOSPHERIC
MOISTURE AND INSTABILITY WILL CONTRIBUTE TO SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS OVER SOUTH TEXAS WEDNESDAY NIGHT THROUGH
FRIDAY.

TOTAL RAINFALL AMOUNTS OVER SOUTH TEXAS WEDNESDAY NIGHT THROUGH
FRIDAY IS EXPECTED TO RANGE FROM 2 TO 3 INCHES WITH LOCALLY HIGHER
AMOUNTS. LOCALIZED FLOODING MAY OCCUR OVER SOUTH TEXAS DURING
THIS EVENT. THERE IS SIGNIFICANT UNCERTAINTY AS TO WHETHER
WIDESPREAD FLOODING WILL OCCUR. IF THE CONFIDENCE IN WIDESPREAD
FLOODING INCREASES...A FLASH FLOOD WATCH MAY BE ISSUED.

STAY TUNED TO NOAA WEATHER RADIO...COMMERCIAL RADIO...TELEVISION...
OR OTHER MEANS OF COMMUNICATION...FOR THE LATEST WEATHER INFORMATION
REGARDING THIS UPCOMING EVENT.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT TUE MAY 31 2016

VALID 12Z FRI JUN 03 2016 - 12Z TUE JUN 07 2016


...PATTERN OVERVIEW...

THE PATTERN OVER THE LOWER 48 WILL TRANSITION BACK TO A RIDGE IN
THE WEST AND TROUGH IN THE EAST THIS WEEKEND AND INTO EARLY NEXT
WEEK. WITHIN THE MEAN FLOW...THE REMNANTS OF BONNIE SHOULD
FINALLY LIFT AWAY FROM THE CAROLINA COAST ON FRIDAY...AHEAD OF A
COLD FRONT PRESSING TOWARDS THE EASTERN SEABOARD. AN UPSTREAM
SHORTWAVE DIGGING INTO THE UPPER MIDWEST AND GREAT LAKES SATURDAY
AND SUNDAY SHOULD HELP REINFORCE A BROAD TROUGH IN THE EAST.
MEANWHILE...AN UPPER LOW OVER TEXAS WILL GRADUALLY WEAKEN AND
MEANDER EASTWARD...AND AN AMPLIFYING UPPER RIDGE AND POTENTIAL
UPPER TROUGH LIFTING INTO CALIFORNIA WILL BE THE MAIN FEATURES IN
THE WESTERN U.S..


...MODEL EVALUATION/PREFERENCES...

MODELS ARE IN UNUSUALLY GOOD AGREEMENT WITH THE GENERAL FLOW
PATTERN EVOLVING OVER THE CONUS THIS FRIDAY THROUGH NEXT
TUESDAY...AND THE COMBINATION OF RELATIVELY STEADY DETERMINISTIC
RUNS AND MINIMAL SPREAD IN ENSEMBLE MEMBERS GIVES EVEN EXTRA
CONFIDENCE IN THE LARGE SCALE FORECAST. THERE IS STILL SOME
UNCERTAINTY WITH THE EXACT TIMING AND AMPLITUDE OF THE SHORTWAVE
DIGGING INTO THE UPPER MIDWEST/GREAT LAKES THIS WEEKEND AND THE
UPPER TROUGH LIFTING INTO CALIFORNIA SUNDAY INTO MONDAY.
ALSO...DETAILS OF THE REMNANTS OF BONNIE LIFTING AWAY FROM THE
CAROLINA COAST AND THE WEAKENING UPPER LOW OVER TEXAS HAVE YET TO
BE RESOLVED. THE WPC FORECAST STARTED WITH THE ECMWF ENSEMBLE
MEAN SINCE IT APPEARED TO BEST REPRESENT THE MIDDLE OF THE SUBTLE
MODEL SPREAD WITH SOME OF THE SMALLER SCALE FEATURES OF THE
FORECAST.


...SENSIBLE WEATHER HIGHLIGHTS...

CONDITIONS WILL REMAIN WARM AND DRY BENEATH AN UPPER RIDGE IN THE
WEST...WITH DAYTIME TEMPERATURES APPROACHING RECORD HIGHS ACROSS
THE PACIFIC NORTHWEST AND NORTHERN ROCKIES THIS WEEKEND.
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ALONG A
FRONTAL BOUNDARY LINGERING FROM THE WESTERN GULF COAST TO THE
CAROLINAS FRIDAY THROUGH SUNDAY. THE GREATEST THREAT FOR HEAVY
RAINS SHOULD BE ACROSS TEXAS AND THE LOWER MISSISSIPPI
VALLEY...WHERE ANOMALOUS GULF MOISTURE SURGING NORTHWARD AHEAD OF
THE CLOSED LOW OVER TEXAS COULD FEED INTO DEVELOPING STORMS.


GERHARDT

[BiggieSmalls]

After this week, is this pattern finally going to shift to normal sunny Summer weather? Two springs in a row that have been absolutely awful