May 2017: Memorial Day/End Of May Outlook

[ticka1]

Will we see more active weather or slowdow going into 2017 Atlantic Hutricane Season!

[CarlCobb]

Great!

[Katdaddy]

A chilly morning across SE TX mostly in the 50s. The potential for active weather returns Late Tuesday night and again Wednesday evening and night. The SPC has a Marginal Risk area for SE TX both days.

[srainhoutx]

Monday morning briefing from Jeff:

One day of bad weather is in the forecast for the next 7 days…Wednesday.

Next storm system will rapidly approach TX late Tuesday into Wednesday with a potential for strong he severe thunderstorms and heavy rainfall. Overnight model guidance has come into better agreement on convective evolution on Wednesday yielding higher confidence on how things will evolve during the day.

Moisture return will begin later today and transport of deep moisture from the southern Gulf of Mexico will arrive into the area by Tuesday evening with PWS rising to 1.6 inches and then 1.9 inches by Wednesday morning. Air mass becomes very unstable by early Wednesday morning with CAPE values pushing 2500-3000 J/kg with steepen lapse rates. A weak short wave is forecast to arrive across the region between roughly 300am and 900am or near the same time a surface warm front is moving northward across the region. Short range models are just at the end of this period currently and show deep convection developing along the northward moving warm front in support with the NAM and GFS models. Good instability and shear suggest strong to severe thunderstorms will be possible early Wednesday morning with the main threat being large hail. Low level shear could become maximized near the surface warm front yielding a tornado threat.

Looks like a break during the late morning into the early afternoon hours and even some clearing which will only serve to greatly destabilize and already very unstable air mass. CAPE values soar toward extreme levels of around 4000 J/kg by early afternoon and a surface cold front will be approaching the region during this time along with another incoming short wave. Expect explosive deep convection to form along the frontal boundary from mid afternoon into the evening hours with severe thunderstorms possible. Main threats appear to be damaging winds and large hail with a squall line moving across the area. While weak capping may develop in the wake of the morning activity, this cap is weaker than the recent systems and appears breakable with lift or trigger temperatures in the lower 80’s.

Post Wednesday will onset several days of very nice weather with lows in the 50’s and highs in the 80’s under clear skies.

[tireman4]

00
FXUS64 KHGX 011434
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
934 AM CDT Mon May 1 2017

.UPDATE...
Surface observations show that we got just a little bit chillier
than forecast overnight, but also that temperatures have rebounded
very quickly after sunrise, and so the forecast of temperatures
in the lower to middle 80s under sunny skies looks on track. Made
cosmetic tweaks to temperature and dewpoint to better match
trends this morning.

&&

.PREV DISCUSSION... /ISSUED 607 AM CDT Mon May 1 2017/

AVIATION...
VFR conditions expected. Winds will pick up later this morning and
this afternoon as the surface high moves off the coast.

40

PREV DISCUSSION... /ISSUED 317 AM CDT Mon May 1 2017/

DISCUSSION...
Weak high pressure just off the Texas coast will continue to drift
slowly east today. Light west to southwest winds this morning will
gradually increase and become SSE this evening. The high will
bring sunny skies today. The dry air in place should allow for a
large diurnal range in temps today and a 30 degree range looks
possible. A return of low level moisture should keep min temps
tonight a bit warmer. 850 temps warm on Tuesday and high temps on
Tuesday should warm into the upper 80s. Fcst soundings not showing
much in the way of cloud cover to hinder the temperature rise.

Tuesday night gets a bit more interesting. A weak upper level
disturbance will approach SE TX after 06z. Moisture return really
gets going around 09z and fcst soundings show PW values climbing
to 1.90 inches by 12z. Instability also increases and SE TX will
lie in a weak 70 kt RRQ. Still expecting elevated convection to
develop in the warm air advection regime. Mid level lapse rates
are steep so would expect some of the stronger storms to produce
hail. Bumped PoPs upward for coastal regions late Tuesday night.
The storms will continue for part of the morning before ending as
the disturbance pushes east. Think there will be a break late
Wednesday morning through the early afternoon before another
upper level disturbance and a surface cold front approaches. Fcst
soundings show clouds eroding for a time in the early afternoon
with a bit of heating helping to destabilize things ahead of the
front. Fcst soundings show CAPE values 4000, PW values near 1.90
inches, LI`s around -11 and lapse rates remain steep. NAM fcst
soundings show a weak capping inversion in the 850-700 layer while
the GFS shows no capping in place. At this time, feel the front,
the second disturbance coupled with a weak splitting jet structure
and a strengthening RRQ will foster a second round of convection
that will move through SE TX late Wed afternoon or evening. This
area of convection will have the potential to produce damaging
winds. The ECMWF and GFS are on the same page with things
including the timing which has conditions clearing out after 06z
Thursday. Will hold onto PoPs for a bit longer (into Thurs AM)
because the Canadian model is slower and this model has been
rather consistent with timing.

The upper trough moves east on Thursday and SE TX will lie in a
dry northwest flow as ridging tries to amplify over Texas. Dry
conditions expected through next weekend with mild spring
temperatures through Friday and a gentle warm up next weekend. 43

MARINE...
Onshore winds will return later today and tonight as high pressure
moves overhead and east of the area. Moderate to strong onshore
winds are expected Tuesday night and Wednesday as the surface
pressure gradient tightens over the area. Conditions may approach
advisory levels late Tuesday night into Wednesday. A cold front is
expected to make its way off of the coast Wednesday night or early
Thursday morning.

A few marine impacts are possible with the mid week event:
- Long-period swells will help contribute to higher than normal tide
levels. Water levels are forecast to be highest during the time of
high tide Wednesday morning. These could approach 1 foot above
normal.
- Isolated strong to severe storms are possible Tuesday night and
Wednesday morning, and then again Wednesday night ahead of
the front.
- A small craft advisory is likely following the frontal passage
Wednesday night and Thursday.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 84 58 89 66 82 / 0 0 0 50 80
Houston (IAH) 86 62 88 69 82 / 0 0 0 50 80
Galveston (GLS) 81 73 84 75 80 / 0 0 0 60 80

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...25

[DoctorMu]

41°F in Conroe this morning. Impressive for May!

[Ptarmigan]

May is the wettest month on average.

[DoctorMu]

May is the wettest month on average.

June just edges out May in CLL. Most of that is in the first half of the month before the spigot is turned off for the summer.

[Katdaddy]

The potential remains for active weather early Wednesday morning and again Wednesday evening and night across SE TX. The SPC has a Slight Risk area from SE TX across Central and S LA and S MS.

Mostly sunny dry days and cooler temps to follow tomorrow night's cool front through the rest of the week with continued sunny skies and warming temps through the weekend.

[tireman4]

000
FXUS64 KHGX 021122
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
622 AM CDT Tue May 2 2017

.AVIATION.../12Z TAF/
Latest satellite imagery shows clear skies over SE Texas and
overall expect VFR conditions for the next 12 to 18 hours. Winds
should increase from the SE today in response to low pressure
forming in west Texas.

Gulf moisture should return after 03-06Z allowing at least MVFR
ceilings to form, perhaps some IFR ceilings. Showers should
develop after 06Z with deep convection possible after 09Z through
15-18z Wednesday. This will likely be the first round of
convection with a short wave trough moving across the area with
higher moisture/instability. TAF will carry VCSH/VCTS for now with
future TAF updates refining timing. A second round of convection
will be possible Wednesday evening as a cold front pushes into the
region.

Overpeck


&&

.PREV DISCUSSION... /ISSUED 348 AM CDT Tue May 2 2017/

DISCUSSION...
A strong storm system expected to move across the plains will
bring thunderstorm chances back to SE TExas with the potential
for strong and possibly severe storms Wednesday and Wednesday
evening. High pressure will then build over the state and bring a
period of dry weather through the remainder of the week and into
early next week.

Another dry and warm day is expected today. Above normal high
temperatures are expected today as warm air and moist air
advection increases across the area.

The main time frame of concern will be tonight through Wednesday
evening. A warm front moving up the coast will enter into the
Matagorda Bay area by late this evening. Isolated showers ahead
of the warm front should become more widespread by daybreak. Model
forecast soundings show increasing CAPE values and helicity
values on Wednesday, indicating at least a slight chance for
isolated severe storms. Both the NAMbufr and GFSbufr soundings do
show a bit of warming aloft Wednesday afternoon around 700 to 750
mb as southwesterly winds develop. If so, this may help hinder
thunderstorm development in the afternoon. A plausible scenario
is that there will be an initial period of showers and isolated
thunderstorms moving northward ahead of the warm front in the
morning with a brief break over portions of the area in the
afternoon until the cold front arrives in the evening. The 00Z
run of the Texas Tech 3km WRF shows this scenario over the
southwestern counties of the forecast area and keeps storm chances
over the eastern counties throughout the afternoon. Like how SPC
summarizes the threat in their day 2 discussion--isolated hail and
wind threat with a possible tornado threat in the day; then a
more organized threat associated with a possible squall line ahead
of the cold front in the late afternoon and the evening. This in
line with the 00Z Texas Tech, GFS and ECMWF.

By the way, cannot rule out locally heavy rainfall with the
system. Model PWs do reach from 1.8 to 2 inches ahead of the
front. However, felt that storm motion will be fast enough to keep
amounts down. This is reflected in the accumulated model QPF which
shows only about one quarter to one half inch west of the I-45
corridor and 0.5 to 1 inch to the east. A couple of models had
0.5 to 1 inch along the coast as well.

After the frontal passage, drier conditions will persist into
Monday of next week. Do expect cooler than normal temperatures on
Thursday with a warming trend into the 80s starting on Friday
into Monday.

40

MARINE...
Low pressure is expected to form in the Texas Panhandle today
allowing for southerly winds to increase this afternoon and tonight.
Small craft exercise caution may be needed for the Upper Texas Coast
tonight. There is expected to be a surge in moisture with a weak
vorticity maximum moving over the Upper Texas Coast by Wednesday
morning. This may increase shower and thunderstorm activity
Wednesday morning. A cold front should push off the coast Wednesday
night bringing another chance of thunderstorms for the coastal
waters. Strong offshore winds should develop behind the front early
Thursday morning. Small craft advisories may be needed through the
morning hours with winds gradually decreasing through the afternoon.
Offshore winds continue for the end of the week and seas should drop
to low levels.

Tide levels may reach about 1 foot above normal in Galveston Bay
during high tide Wednesday afternoon. Gulf facing beaches may have
tides about 0.5 to 1.0 feet above normal during high tide near noon
time Wednesday. This will put most areas about 2.6 to 3.0 feet above
MLLW causing minimal impacts if any. Strong rip currents will be
possible Wednesday as well. We may need to monitor Thursday and
Friday for low water issues with offshore winds persisting. This may
cause tides to be about 1 foot below normal.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 89 68 85 56 76 / 0 30 70 30 0
Houston (IAH) 88 69 84 58 78 / 0 40 70 50 0
Galveston (GLS) 82 74 81 62 75 / 0 50 70 60 10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...40
Aviation/Marine...39

[javakah]

2nd day updated, with an enhanced area to our northeast.

[don]

The euro show's 2-3 inches of rain tomorrow across most of Harris,Chambers, Liberty and Galveston Counties fwiw

[srainhoutx]

The afternoon updated QPF for the next 48 hours suggest possibly 1 + inches of rain across Metro Houston. That said the European solution being a bit more bullish does raise an eyebrow enough to reschedule some roofing we had scheduled tomorrow until later this week.

[Cromagnum]

Incoming 0.10 inches of rain again.

[jojotheidiotclown]

When is the heat coming?

[javakah]

Woah. Quite the expansion of the Enhanced area. Also, things just starting to pop around Corpus.

[Katdaddy]

The quick atmospheric turn around has occurred overnight. Isolated showers and thunderstorms have quickly developed across SE TX this morning. Some of these could become strong to severe this morning as they push further inland. An active afternoon and evening is still on track for E and SE TX extending across all of LA into MS overnight. Most of E and SE TX are in an Enhanced Risk area. Remain weather aware through this evening. This morning's Houston-Galveston NWS Hazardous Weather Outlook:

This hazardous weather outlook is for portions of Southeast Texas..

.DAY ONE...Today and Tonight

There is an enhanced risk for severe storms today along and east of a line from Madisonville to Houston to High Island with a slight risk over areas to the west of this line. A slight risk for excessive rainfall exists generally along and east of a line from near Madisonville to Katy to San Luis Pass. Showers and thunderstorms will become more widespread later this morning especially along and east of the Interstate 45 corridor. More storms are expected ahead of a cold front late this afternoon through the early evening. Hazards include large hail, damaging wind gusts, locally heavy rainfall and isolated tornadoes.

Spotter activation will likely be required today and early this
evening.

[Ounce]

Severe Thunderstorm Warning
TXC199-241-457-031230-
/O.NEW.KLCH.SV.W.0080.170503T1126Z-170503T1230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Lake Charles LA
626 AM CDT WED MAY 3 2017

The National Weather Service in Lake Charles has issued a

* Severe Thunderstorm Warning for...
Tyler County in southeastern Texas...
Hardin County in southeastern Texas...
Central Jasper County in southeastern Texas...

* Until 730 AM CDT

* At 625 AM CDT, severe thunderstorms were located along a line
extending from near Thicket to near Kountze, moving north at 40
mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage
to roofs, siding, and trees.

* Locations impacted include...
Beaumont, Silsbee, Woodville, Kountze, Colmesneil, Chester,
Saratoga, Fred, Wildwood, Warren, Town Bluff, Thicket, Caney Head,
Votaw, Honey Island, Mt. Union, Spurger, Village Mills, Ivanhoe and
Hillister.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3049 9469 3049 9454 3102 9465 3071 9401
3012 9429 3013 9430 3029 9466 3038 9469
TIME...MOT...LOC 1125Z 188DEG 35KT 3039 9454 3031 9434

HAIL...1.00IN
WIND...60MPH

$$

Landreneau

[srainhoutx]

05032017 mcd0635.gif

Mesoscale Discussion 0635
NWS Storm Prediction Center Norman OK
0704 AM CDT Wed May 03 2017

Areas affected...Southeast TX and southern LA

Concerning...Severe potential...Tornado Watch likely

Valid 031204Z - 031330Z

Probability of Watch Issuance...80 percent

SUMMARY...WW issuance is likely within the hour. Storms will
continue to increase in intensity (as observed with ongoing activity
north of HOU and across southwest LA at 12Z) and coverage this
morning.

DISCUSSION...A couple of storms have developed and intensified
across southeast TX (near and north of the Houston metro), and
moving onshore the southwest LA coastal region from the northwest
Gulf of Mexico per trends in mosaic radar imagery. Although overall
storm coverage is limited at this time, observational data indicated
the storms that have formed have developed strong updrafts (some
with weak low- to mid-level rotation and rapidly cooling cloud tops
to 50,000+ ft.).

Early morning surface analyses showed a warm front advancing north
across southeast TX and approaching the LA coast with storms thus
far developing near this front. Rich low-level moisture was located
across the warm sector (dew points into the lower 70s). This
combined with the presence of steep midlevel lapse rates (exceeding
8 C/km) per objective analyses and 12Z soundings will continue to
contribute to a destabilizing air mass from south to north and
MLCAPE ranging from 1500-2500 J/kg this morning.

Meanwhile, water-vapor imagery showed an eastward-moving midlevel
shortwave trough in south-central to southeast TX as 700-mb winds
have veered to westerly at SJT/DRT and EWX with the passage of this
trough. Forcing for ascent with this trough and within the exit
region of an accompanying 50-55 kt westerly 500-mb jet will support
further thunderstorm development this morning across southeast TX
into southwest LA. The favorable thermodynamics and strong
low-level (increasing SRH values) and deep-layer shear (vertically
veering winds) will favor organized storms, with hail as the initial
threat. However, the ongoing reduction of inhibition will allow for
storms to become surface based this morning with additional
severe-weather hazards (including damaging winds and a tornado
threat).

..Peters/Guyer.. 05/03/2017

...Please see www.spc.noaa.gov for graphic product...

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

[srainhoutx]

MESOSCALE PRECIPITATION DISCUSSION 0181
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
833 AM EDT WED MAY 03 2017

AREAS AFFECTED...SOUTHEASTERN TX/SOUTHWESTERN LA...

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

VALID 031232Z - 031702Z

SUMMARY...A WAVY BOUNDARY FEATURING A SHARP DEW POINT GRADIENT
WILL REMAIN A FOCUS FOR ACTIVE CONVECTION THIS MORNING. MULTIPLE
CELLS HAVE ALREADY ERUPTED ACROSS SOUTHEAST TX AND INTO THE
ADJACENT GULF COAST WATERS. RECENT CAMS SUGGEST AN INCREASINGLY
MORE ORGANIZED EVENT UNFOLDING DURING THE NEXT FEW HOURS WHICH
SUPPORTS AN INHERENT FLASH FLOOD RISK.

DISCUSSION...GPS SOUNDER DATA INDICATED A FAIRLY SHARP
PRECIPITABLE WATER GRADIENT BOUNDING TX/LA. 10Z DATA SHOWED PWAT
VALUES IN THE 1.50 TO 1.75 INCH RANGE EXTENDING FROM SOUTHEAST TX
DOWN THE COASTLINE WHILE VALUES ROUGHLY AN INCH LESS WERE MORE
COMMONPLACE OVER A VAST MAJORITY OF LA. WITHIN AN UNCAPPED
ENVIRONMENT...PER THE 11Z RAP OBJECTIVE ANALYSIS...EARLY MORNING
THUNDERSTORMS HAVE DEVELOPED ALONG THE UPPER TX GULF COAST AND
MOVED INLAND AT A FAIRLY HEFTY CLIP. THERE ARE PLENTY OF VARIABLES
SUPPORTING AN EXPANSION OF THE PRECIPITATION SHIELD. THIS INCLUDES
AMPLE MOISTURE (PWATS OF 1.75 INCHES AND SURFACE DEW POINTS NEAR
75 DEGREES)...SUFFICIENT UPPER DIFFLUENCE...ABUNDANT
INSTABILITY...AND A WAVY EAST/WEST LOW-LEVEL BOUNDARY IN PLACE.

BASED ON THE FORECAST OF SURFACE-BASED INSTABILITY PARAMETERS THE
NEXT SEVERAL HOURS...THE REGION REMAINS FOR THE MOST UNCAPPED
WHICH SHOULD SUPPORT ADDITIONAL CONVECTIVE DEVELOPMENT THROUGH THE
MORNING AND INTO THE EARLY AFTERNOON. THE IDEA IS FOR MUCH OF THIS
ACTIVITY TO LATCH ONTO THE AFOREMENTIONED EAST/WEST BOUNDARY WHICH
MAY LEAD TO AN EXTENSIVE PERIOD OF TRAINING/BACKBUILDING. THE
HIGH-RESOLUTION MODEL SUITE FAVORS SUCH AN
EVOLUTION...PARTICULARLY THE 00Z HRW-ARW/NSSL-WRF AND RECENT RUNS
OF THE HRRR. FOR THE MOST PART...THE REGION HAS BEEN ON THE DRIER
SIDE THE PAST COUPLE OF WEEKS WHICH SHOULD INITIALLY MITIGATE ANY
EXTENSIVE FLASH FLOOD RISK. AN EXCEPTION IS ON THE FAR EASTERN
SIDE OF THE MPD WHERE A FEW PARISHES ACROSS SOUTHWESTERN LA
(JEFFERSON DAVIS...ALLEN...AND EVANGELINE) HAVE SEEN HEAVY
PRECIPITATION SINCE LATE APRIL.

RUBIN-OSTER

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