February 2017- Spring Like Weather Returns

[jasons2k]

We got a jump start on yard work over the weekend. The azaleas are blooming out. I'm loving this spring weather and so thankful I don't live up north. The timing of the rain will be great for the spring bloom.

[tireman4]

Stay weather aware folks. As Jeff and Steve have alluded to in their forecasts, stay alert. This could be an interesting Tuesday.

[srainhoutx]

Looking ahead to next weekend and beyond, the Madden Julian Oscillation (MJO) is toward a highly amplified Phase 8 and that suggests that an unsettled and potentially stormy pattern will extend into the Medium and Longer Range. A powerful Pacific Jet is headed toward the West Coast and California where additional lower elevation heavy rainfall and higher elevation snow will continue. Next weekend yet another potent 500mb Upper Low will move inland across Southern California and begin heading East across Northern Mexico. The various computer models are indicating the potential of another severe weather episode across Texas and Louisiana late next weekend into early the following week. After tomorrows Heavy Rainfall and Severe threat, we will begin to look closer at what the next Storm System may mean regarding our sensible weather.

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[Katdaddy]

The SPC has just issued an Enhanced Risk across SE TX for tomorrow.

[jasons2k]

Slightly off topic, but when did the SPC add 'enhanced' to the mix? Just my opinion, but "slight, moderate, and high" was just fine how it was. Now, you almost need a calculator just to figure out what category applies to you. I don't think John Q. Public would understand the difference. It's like taking "high, medium and low" and adding-in "medium low"...what's the point?

I digress.

This pattern is more like mid-late March. It seems like spring is a month ahead and fall is a month behind in this new climate regime...

[srainhoutx]

Slightly off topic, but when did the SPC add 'enhanced' to the mix? Just my opinion, but "slight, moderate, and high" was just fine how it was. Now, you almost need a calculator just to figure out what category applies to you. I don't think John Q. Public would understand the difference. It's like taking "high, medium and low" and adding-in "medium low"...what's the point?

I digress.

This pattern is more like mid-late March. It seems like spring is a month ahead and fall is a month behind in this new climate regime...

Enhanced Risk was officially added last year, if I recall correctly. Also the Text is worth repeating here for the Enhanced Risk in the SPC Day 2 Outlook...

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1136 AM CST Mon Feb 13 2017

Valid 141200Z - 151200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
SOUTHEASTERN TX...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN TX
INTO WESTERN LA...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR SOUTHEAST
LA ACROSS COASTAL MS/AL AND THE FL PANHANDLE...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TX
ACROSS THE CNTRL GULF COAST...

...SUMMARY...
Strong to severe thunderstorms are expected to develop from central
into eastern Texas and perhaps western Louisiana throughout the day
on Tuesday, with a few tornadoes and damaging winds expected. A more
conditional threat of isolated severe storms will also exist Tuesday
night into Wednesday morning from the mouth of the Mississippi river
toward the coastal Florida panhandle.

...Synopsis...
A shortwave trough will move eastward across TX and toward the lower
MS valley on Tuesday, losing amplitude overnight and becoming more
zonal. At the surface, low pressure will deepen across east TX ahead
of a cold front, with warm front lifting northward ahead of the low
track. Substantial moisture will be available to support severe
storms as dewpoints rise into the mid to upper 60s beneath cooling
temperatures aloft. Strengthening shear profiles with 60 kt
southwesterly midlevel flow atop a 40-50 kt southerly low level jet
will support the possibility of damaging storms mainly during the
day, including the threat for tornadoes.

...Central and eastern Texas toward the Sabine river...
Substantial low-level moisture is already in place today from the
central TX coast into Deep South Texas, and this air mass will
spread northward on Tuesday ahead of the developing surface low and
cold front. Environmentally, models indicate strong low-level shear
developing with 0-3 km SRH in the 300-400 m2/s2 range, which is very
supportive of supercells given the moist air mass and adequate
instability. Hodographs look most favorable over east central into
southeast Texas between 15Z-21Z, before the low-level jet veers as
the shortwave passes to the north.

As for storm evolution, scattered storms are forecast to be ongoing
along the cold front over central TX at the beginning of the period.
Some of these storms may contain a hail or wind risk, but the threat
should increase further by late morning mainly east of the I-35
corridor. By 15Z-18Z, a marked uptick in storm strength is expected,
with storms both just ahead of and along the cold front. In both
cases, supercells are expected initially, with a threat of
tornadoes. The threat might transition to damaging winds during the
late afternoon and with northward extent, as the cold front and
outflows result in merged storms and instability wanes.

Any discrete supercells will have a threat of tornadoes in this
environment. Mitigating factors to tornado longevity may be some
weakness in wind fields around 700 mb especially in southern areas,
and potential for numerous storm interactions. However, a strong
tornado or two cannot be ruled out.

...Southeast Louisiana, coastal MS and AL and the far western FL
Panhandle...
Flow aloft will become quite strong Tuesday night into Wednesday
morning as the shortwave trough deamplifies. However, gradual height
falls/cooling aloft will persist, and a warm front will be located
from southeast LA eastward along or just off the coast. Lift via
warm advection is likely to result in a few storms over the northern
Gulf, perhaps affecting the coast. Models insist on far southeastern
LA as the main threat area, but a few also show storms as far east
as the western FL panhandle by 12Z Wednesday. Thus, will maintain a
conditional Slight risk, for these areas for tornado/wind potential.

..Jewell.. 02/13/2017

[StormOne]

We got a jump start on yard work over the weekend. The azaleas are blooming out. I'm loving this spring weather and so thankful I don't live up north. The timing of the rain will be great for the spring bloom.

Spring-like up here too. We hit 70 on Friday which is near-record.

[tireman4]

We got a jump start on yard work over the weekend. The azaleas are blooming out. I'm loving this spring weather and so thankful I don't live up north. The timing of the rain will be great for the spring bloom.

Spring-like up here too. We hit 70 on Friday which is near-record.

I am not sure, but I could be wrong ( pro mets can chime in) if Winter is over for the Plains, but who knows..LOL

[srainhoutx]

Monday afternoon briefing from Jeff:

Late morning update from SPC has upgraded nearly all of SE TX into an enhanced risk for damaging winds and tornadoes on Tuesday.

Becoming increasingly concerned with forecast soundings showing very strong low level wind shear values across SE TX on Tuesday and slightly better instability. Short range models suggesting 40-50kt low level jet beneath 60kt mid level jet resulting in 300-400 m^2/s^2 helicity values across SE TX from mid morning to mid afternoon on Tuesday. Looking at a significant increase in storm structure, organization and intensity in the 900am to noon time period on Tuesday with potential for numerous discrete supercells capable of producing tornadoes. Very moist southerly feed off the Gulf will help to promote low cloud bases within the maximum low level shear. Current indications suggest this may be a more significant setup than the usual weak tornadoes we see over this area…and a couple of strong tornadoes (EF2 or greater) appear at least possible.

While meso models maintain a fast moving line of thunderstorms along and ahead of the cold front, they have also indicated the potential for a cluster of potentially high precipitation supercells to develop along/ahead of the cold front possibly leading to a period of cell training. These storms would be capable of producing both tornadoes and excessive short term rainfall rates. Looks like the region along or about 30 miles either side of US 59 is where potential for cell training appears greatest and where quick storm totals of 2-4 inches could occur in a few hours. Main threat continues to be rapid onset street flooding under 1-3 inch per hour rainfall rates.

Will need to pay very close attention to both the severe weather and flash flood threat for Tuesday.

SPC Day 2 (Tuesday) Severe Weather Outlook:

[sau27]

Sounds like tomorrow will be an interesting day. Its not very often that potentially significant tornadoes are the primary severe threat around here.

[StormOne]

I agree with Jeff's earlier statement in that even though CAPE values are unimpressive (<1000 j/Kg if we're going by GFS), shear values are colorful on maps. Decent LI values too. The true severity of the event depends on which model you want to go by, but even with the weak GFS, you guys could still see a couple of tornado warnings and a watch go up tomorrow morning.

We got a jump start on yard work over the weekend. The azaleas are blooming out. I'm loving this spring weather and so thankful I don't live up north. The timing of the rain will be great for the spring bloom.

Spring-like up here too. We hit 70 on Friday which is near-record.

I am not sure, but I could be wrong ( pro mets can chime in) if Winter is over for the Plains, but who knows..LOL

Ha. Winter is never over here until it's over. March has been known to be the snowiest moth of the year nearly as much as January and February, and even moreso than December. Not looking good for Winter at this point, but not ready to start growing crops yet

[DoctorMu]

Enhanced is indeed between slight and moderate





The graphic helps, but the use of enhanced could cause confusion. There is pretty good confidence in the forecast though.

[DoctorMu]

I agree with Jeff's earlier statement in that even though CAPE values are unimpressive (<1000 j/Kg if we're going by GFS), shear values are colorful on maps. Decent LI values too. The true severity of the event depends on which model you want to go by, but even with the weak GFS, you guys could still see a couple of tornado warnings and a watch go up tomorrow morning.

Spring-like up here too. We hit 70 on Friday which is near-record.

I am not sure, but I could be wrong ( pro mets can chime in) if Winter is over for the Plains, but who knows..LOL

Ha. Winter is never over here until it's over. March has been known to be the snowiest moth of the year nearly as much as January and February, and even moreso than December. Not looking good for Winter at this point, but not ready to start growing crops yet

Yep - another freeze is always possible and potential for icy stuff. The trees and grass appear to be getting a head start, but I've seen them get slapped down before.

Lawn & garden in Texas - it's not for the faint of heart.

[DoctorMu]

"Enhanced" shear tomorrow, most of the energy is south. Any Action could be near the coast. Unusual.

[StormOne]

Yep - another freeze is always possible and potential for icy stuff. The trees and grass appear to be getting a head start, but I've seen them get slapped down before.

Lawn & garden in Texas - it's not for the faint of heart.

Still no leaves on the trees here, but wouldn't be surprised to see some here soon. This would be the earliest on record it has happened here in NE I believe.

[jasons2k]

As Harold Taft used to say: "Spring hasn't arrived until the mesquite trees start to bloom"...take it for what it's worth

I'm betting no more freezes this season for IAH/DWH and points south. Doubtful for CXO too, but sometimes the late-season 'marginal' last blasts will dip them to 32 on a calm, clear night. Not looking likely this year, but you never know...

[Andrew]

While higher speed shear will exist further to the southwest, the best low level directional and speed shear exists closer to central Southeast Texas. The GFS and NAM indicate that surface winds could begin to back late in the morning tomorrow and as the shortwave rotates through an impressive low level jet could develop. When it comes to tornado development the lowest 1km are dramatically more important than the upper 2/3. The largest issues will be CAPE and upper level lapse rates. These remain rather marginal but the dynamics of this system may help to overcome that.

[DoctorMu]

As Harold Taft used to say: "Spring hasn't arrived until the mesquite trees start to bloom"...take it for what it's worth

I'm betting no more freezes this season for IAH/DWH and points south. Doubtful for CXO too, but sometimes the late-season 'marginal' last blasts will dip them to 32 on a calm, clear night. Not looking likely this year, but you never know...

We often have a frost all the way through the end of spring break time in College Station. There's usually a brief cold blast around NCAA conference tournament time and the first week of the NCAAT.

Who knows this year...

[Cromagnum]

The model Fox 26 just put up shows a broken line of weak storms rolling through around noon. The south side of Houston barely had anything while forecasts had been pegging that to be the hot spot.

[ticka1]

if it holds together and the cape stays strong - have to wait and see.