don wrote:The "real" cold air (low 40's 30's) doesn't usually start until the middle to end of November.
Like December 9th! haha
Last year we went from a DP of 70° to 4 inches of snow in less than 48 hours!
don wrote:The "real" cold air (low 40's 30's) doesn't usually start until the middle to end of November.
Those are the ones you have to watch out for rotation on the southwestern flank of the storm. Hopefully we won’t see any hooks forming.don wrote:We really need to be weather aware tomorrow, the HRRR shows what looks to be discrete supercells tomorrow afternoon ahead of the main line of storms.
don wrote:We really need to be weather aware tomorrow, the HRRR shows what looks to be discrete supercells tomorrow afternoon ahead of the main line of storms.
Code: Select all
Mesoscale Discussion 1599
NWS Storm Prediction Center Norman OK
0720 AM CDT Wed Oct 31 2018
Areas affected...Portions of western into central TX
Concerning...Severe potential...Watch possible
Valid 311220Z - 311445Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated hail will be possible as storms continue to
develop and increase in coverage from west to east across western
into central Texas this morning. While watch issuance is not
warranted for these elevated storms, areas downstream across central
Texas will be monitored for potential watch issuance later this
morning or early afternoon.
DISCUSSION...Deep forcing for ascent is evident and emerging from NM
into west TX this morning, given the presence of ongoing nocturnal
thunderstorms continuing to develop and spread eastward ahead of a
progressive shortwave trough. The combination of this ascent and
cooling 500-mb temperatures/steepening midlevel lapse rates
spreading east atop low-level warm advection/moistening, given
southerly low-level winds, suggests storms will continue to form
east this morning across western into central TX.
The western extent of a cold front has moved very little the last
several hours, and at 12Z extended from near KDAL to between KMWL
and KACT to just south of KSJT and KFST, and west-northwest to KGDP.
Short-term trends and guidance suggest most of the storms this
morning should remain elevated north of this front, where forcing
for ascent will be maximized within the nose of the southerly
low-level jet. The presence of steepening midlevel lapse rates,
effective bulk shear around 40 kt and MUCAPE of 1000-1500 J/kg
should support a few strong to severe storms with isolated large
hail being the primary severe threat this morning.
Meanwhile, objective analyses indicated the likelihood for
convection that forms near the cold front from north of KACT into
Hamilton to San Saba Counties would be surface based, given the lack
of inhibition, currently. Given stronger forcing for ascent with
the southwest trough and a transient northeastward-moving impulse
from Mexico is expected to arrive across central TX later this
morning or early afternoon, in concert with stronger
destabilization, a watch issuance is not warranted in the short
term. However, convective trends will be monitored for an increase
in storm development/intensities that would result in watch
issuance.
..Peters/Edwards.. 10/31/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...EWX...SJT...LUB...MAF...
Code: Select all
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0815 AM CDT Wed Oct 31 2018
Valid 311300Z - 011200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM
EAST-CENTRAL AND SOUTHEAST TEXAS TO SOUTHWESTERN MISSISSIPPI...
...SUMMARY...
The greatest risk for severe thunderstorms, capable of producing
damaging winds, hail, and a few tornadoes, exists from southeast
Texas to the lower Mississippi Valley today through tonight.
...Synopsis...
In mid/upper levels, a series of shortwave perturbations now located
from northwestern BC to the Four Corners states will shape the
eastward shift of synoptic troughing across the central CONUS today
and tomorrow. A strong, basal shortwave trough -- now evident in
moisture-channel imagery from southwestern CO across eastern AZ --
is forecast to move east-southeastward by 00Z to southeastern CO,
south-central NM and northern Chihuahua. By 12Z, this trough should
pivot eastward and become less positively tilted, reaching
west-central KS, northwest TX and northern Coahuila. An initially
separate, weaker, southern-stream perturbation -- currently crossing
central Baja and adjoining Gulf of California -- will eject
east-northeastward across northern MX today, its northeastern
fringes reaching south-central TX this evening, before further
deformation and weakening of its vorticity field occurs.
Surface analysis showed a cold front from eastern MO across western
AR and north-central TX, becoming a wavy/quasistationary boundary
over parts of the northern Hill Country and Edwards Plateau regions
to the lower Pecos Valley. As heights fall aloft with the approach
of the strong southwestern CONUS trough, a weak frontal-wave low
should develop over east-central TX mid-late this afternoon, with
cold front southwestward across south-central TX into northern
Coahuila. The low should move northeastward over the Arklatex
region this evening, across AR into the MO Bootheel/extreme western
KY region by the end of the period. By that time, the front should
reach southeastern AR, south-central/southwestern LA and the shelf
waters off the mid/upper TX coast.
...TX to lower Mississippi Valley...
Near the leading edge of the large-scale ascent plume preceding the
mid/upper trough, a plume of convection is gradually strengthening
over west-central TX between ABI-MAF. This activity may offer
severe hail over the next few hours, and the potential for damaging
wind will increase with proximity of its southern portions to the
front and adjoining warm sector. See SPC mesoscale discussion 1599
for more details.
With persistence and eastward shift of the associated
mid/upper-level vertical-motion plume, and as the surface frontal
zone impinges on a diurnally destabilizing warm sector, the morning
convection should persist eastward, expand, and intensify through
the day. With flow aloft largely parallel to the frontal zone,
expect evolution into a broken to solid, quasi-linear configuration
with embedded bow, LEWP and supercell features. Additional
thunderstorms are forecast to develop and grow with time from midday
through afternoon over the weakly capped warm sector in east and
southeast TX, along low-level convergence/confluence axes. Both
processes will occur amidst strengthening mid/upper winds and
continued boundary-layer warming and moisture transport.
Accordingly, a gradual ramp-up in severe potential is expected,
amidst buoyancy/shear parameter spaces favoring the entire spectrum
of severe hazards. Where low- and middle-level lapse rates will be
greatest, overlapping with the western rim of richest low-level
moisture, a narrow plume of 2000-3000 J/kg prefrontal MLCAPE should
develop this afternoon over central/south-central TX, decreasing
gradually eastward and sharply along and behind the front. MLCAPE
500-1000 J/kg should prevail tonight over the LA/MS portion of the
outlook area, weaker but still with sufficiently unstable
surface-based parcels to support the outlined severe threat.
Though winds aloft won't be quite as strong across southeast TX and
LA this afternoon/evening as farther north/west, more-backed surface
winds should help to enlarge both hodographs and the storm-relative
surface vector. Effective SRH in the 150-300 J/kg range should
become common, increasing this evening into overnight over LA and
central/western MS near a 50-60-kt low-level jet. This will boost
the tornado risk for any relatively sustained/discrete supercells,
and even for line-embedded storms. Such an environment supports the
somewhat conditional potential for strong tornadoes, with storm mode
being a major influence on their number and longevity.
A separate round of thunderstorms may develop late this afternoon
and this evening over parts of southwest TX near the Rio Grande and
lower Pecos River regions, and over the Serranias del Burro range of
Coahuila. Severe hail/gusts will be possible from this activity as
it tracks eastward across parts of southeast and south-central TX,
with wind more probable along and south of the front in
more-unstable boundary-layer air.
..Edwards/Peters.. 10/31/2018
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
CURRENT UTC TIME: 1340Z (8:40AM), RELOAD THIS PAGE TO UPDATE THE TIME
Really bad timing on Halloween night because a lot of people will be out and about. Let's be weather aware today and tonight!tireman4 wrote:HGX Forecast Halloween
Code: Select all
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1018 AM CDT Wed Oct 31 2018
.UPDATE...
Radar imagery shows showers and thunderstorms mostly west of I-45
this morning, with the best convection currently located over
Matagorda moving into Brazoria and Fort Bend counties. Winds
associated with these storms have been hovering around 30-35 mph,
with the storm motion to the northeast near 25 mph. IR imagery
shows cloud tops continuing to cool to near -67 dec C, as the
storms tap into some mid to upper level instability.
The 12Z upper level sounding out of College Station shows a
small, breakable cap at 950 mb. With daytime heating, this cap
should erode by the early afternoon hours. Most of the short term
guidance continues to develop showers and thunderstorm this
afternoon out ahead of the cold front. These storms could become
severe with strong winds, hail and an isolated tornado possible.
Have gone ahead and raised PoPs to account for current radar
imagery and trends in the short term guidance. Considering this
morning's model guidance, the timing of the cold front at this
time appears to be about the same. Expecting storms to reach our
northern tier of counties from Caldwell to Crockett late this
afternoon into early this evening, moving into the Houston metro
and along I-10 during the evening hours, and reaching the coast
around midnight. Much of SE TX remains in an enhanced risk for
severe storms today and through the evening hours, issued by SPC.
Additionally, localized heavy rainfall will be possible with this
precipitation. The HRRR appeared bullish with precip totals in
the first few runs this morning, but has backed off with its
extremes. At this time widespread amounts of 1-2 inches will be
possible with isolated higher totals of 4-6 inches. Also worth
mentioning, trends in the recent runs of both the HRRR and RAP13
have also focused these higher amounts over the coastal counties
such as Brazoria and Galveston. Though the severe threat remains
the primary risk this afternoon and into the evening, we will also
need to monitor the potential for localized heavy rainfall especially
over our already fairly saturated soils.
Hathaway
&&
.PREV DISCUSSION... /ISSUED 525 AM CDT Wed Oct 31 2018/
DISCUSSION...
Bands of light rain developing over the coastal waters are moving
up into southern portions of the CWA this morning. To the west...
a skinny line of showers are developing along the prefrontal trof
(and likely aided by a shortwave aloft). The activity moving from
the Gulf appears to associated with a stray upper low tracking up
the coast from BRO. All of this looks to be setting the stage for
a rather active day/evening...and probably to much dismay for all
the ghouls getting ready to haunt the streets tonight.
Short-range models are indicating the development of scattered TS
this afternoon for SE TX...out ahead of the main front. Depending
on how much heating we get, there may be enough instability/shear
to support strong to marginally severe storms later this morning/
early afternoon (with the aforementioned upper low). However, the
main threat of severe weather will be late this afternoon (start-
ing up north) through the evening hours (further to the south) as
the cold front moves into the region. Very favorable jet dynamics
aloft along with the progged deep-layer shear/lift from the front
itself should be supportive for severe weather for much of SE TX.
Primary threats will be damaging winds, hail and possible tornado
development. See SPC Day 1 Outlook for more details.
Also of note for the event will be the possibility of brief/local-
ly heavy rainfall with the line of storms. While they will be mov-
ing at a decent rate (and not training), rainfall totals could av-
erage from 1 to 2 inches with isolated amounts from 4 to 6 inches.
This should be enough to produce some urban/small stream flooding.
All of this activity will be moving E/SE out of the area into the
coastal waters by early Thur morning (09-12Z). A cooler/drier air
mass should settle across the CWFA for Thur/Fri as the upper trof
axis shifts east. However, the ensuing NW upper flow is then exp-
ected to push a strong upper low/shortwave down into the state by
Sun. Elevated POPs to return for Sun/Mon. 41
MARINE...
South winds 10-20 knots bays and 15 to 25 knots over the Gulf waters
with building seas. S/W moving up from the southwest will likely
bring scattered showers and even a few thunderstorms this morning.
Waterspout threat this morning with the stronger storms. Have issued
an SCA for late afternoon over the 20-60nm waters then expanding
into the nearshore waters this evening. Strong to severe
thunderstorms with primary threat of severe from winds in excess of
40 knots tonight. A cold front pushes off the coast overnight into
early Thursday morning. Winds become northwest in the wake of the
frontal boundary and steep waves/chaotic seas should form and could
see some isolated 9-10 foot seas. SCA will need extending. The
offshore flow persists well into Friday morning. Weak high pressure
slides out into the Gulf early Saturday morning varying winds back
to the southwest. Light to moderate south winds Saturday afternoon
through Sunday evening. Another cold front slides through Monday
morning.
45
AVIATION...
Patchy MVFR ceilings this morning beneath the expanding cirrus
shield. S/W producing a few showers beneath the cap around 800mb.
Cap should strengthen somewhat this morning with steepening lapse
rates above. May need to add VCSH this morning in upcoming package.
Cold front through FTW and nearing SJT and will continue to push
southward today and should reach the CLL area around 21z with a few
hours of showers and thunderstorms...gusty winds likely with these
storms. Band of storms coalescing as it comes with more linear wind
profile over IAH/HOU area 00-04z. If storms get more organized late
this morning or more likely this afternoon ahead of the frontal
boundary could see impacts at IAH/HOU hubs...latest HRRR has been
pinging moreso on this likelihood. Northwest gusty winds in the wake
of the frontal storms tonight.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 80 53 66 46 71 / 90 80 20 0 0
Houston (IAH) 82 59 67 50 71 / 80 100 30 0 0
Galveston (GLS) 80 64 69 57 69 / 70 100 60 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 PM CDT this evening
for the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM...Galveston Bay...
Matagorda Bay.
Small Craft Advisory from 7 PM this evening to 7 AM CDT Thursday
for the following zones: Coastal waters from Freeport to
Matagorda Ship Channel TX out 20 NM...Coastal waters from
High Island to Freeport TX out 20 NM.
Small Craft Advisory from 4 PM this afternoon to 7 AM CDT
Thursday for the following zones: Waters from Freeport to
Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION until 4 PM CDT this
afternoon for the following zones: Waters from Freeport to
Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.
&&
$$
Update...08