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srainhoutx wrote:

The overnight guidance has come into somewhat better agreement suggesting a strong upper low/trough will develop across the Four Corners Region and eject NE into the Central Plains beginning on Monday. The fly in the ointment continues to be a secondary vort max along the southern end of a positive tilted trough and capping issues with SW winds aloft while strong southerly surface winds increase off the Gulf. The models continue to suggest that a dry line will develop across W Texas late Monday into Tuesday. On Tuesday, a Pacific cold front will race SE across the Southern Plains and meet that dry line generating strong to severe storms from San Antonio/Austin on NE into the Dallas area and on NE. The most likely scenario will be that a squall line will develop and march E into SE/E Texas during the early morning hours of Wednesday, but the timing may be a bit slower if the secondary energy holds back a bit as the European models suggests. The best chance of heavy rainfall appears to be across Louisiana and Arkansas and possibly portions of E and NE Texas where capping issues will not be a problem. The main threat at this time appears to be large hail with damaging winds, but an isolated tornado or two are not out of the question. Being 2-3 days out, we will continue to monitor for any changes.

Dear Srainhoutx:

Am I imagining things or does this look like the same wx regimen that pelted galveston with giant hailstones, left 17,000 Centerpoint customers in the dark, and gave us a spectacular lightning show on Tuesday of this past week? If so, should residents say---"Oh, no! Here we go again!"?

^^

This is a bit different setup than what we experienced last week, Paul. The main energy and better dynamics are much further N and capping appears to be a big limiting factor for our Region. The better chance of strong to severe storms look to be around NE Texas and Arkansas. There is a chance that some stronger storms with hail and damaging winds may develop along a strong cold front late Tuesday in Central Texas and for SE Texas during the mid day time frame on Wednesday as a squall line moves through. Areas N of I-10 appear to be in a slightly more favorable location to see larger hail and possibly an isolated tornado or two where the cap may erode and allow stronger storms to form. We still have a day or two to watch how things evolve, but it doesn't appear we are likely to see a repeat of last Tuesday night around these parts at this time. We will see.

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT MON APR 08 2013

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE MIDWEST TO
THE WRN GULF COAST STATES...

...SYNOPSIS...
AN AMPLIFIED UPPER-LEVEL TROUGH WILL CONTINUE TO GRADUALLY PROGRESS
EWD FROM THE ROCKIES ACROSS THE GREAT PLAINS THROUGH EARLY THU. A
DOWNSTREAM MID-LEVEL RIDGE WILL PERSIST FROM THE SOUTHEAST TO THE
GREAT LAKES. AT THE SURFACE...A CYCLONE SHOULD SLOWLY MOVE EWD IN
PARTS OF THE MIDWEST WITH AN ATTENDANT COLD FRONT FROM THE LOWER MO
VALLEY TO THE SRN PLAINS PROGRESSING AT LEAST ACROSS THE MID/LOWER
MS VALLEY BY 12Z/THU. A QUASI-STATIONARY FRONT SHOULD BE DRAPED E OF
THE MIDWEST CYCLONE TO THE NRN APPALACHIANS.

...MIDWEST TO THE WRN GULF COAST STATES...
A BROAD SWATH OF ORGANIZED SEVERE POTENTIAL IS EXPECTED DURING THE
PERIOD WITH ALL SEVERE HAZARDS PROBABLE.

MODEL PREDICTABILITY LESSENS SUBSTANTIALLY FROM D2 WITH THE
EVOLUTION OF KEY SYNOPTIC FEATURES...RENDERING LOW CONFIDENCE IN
BOTH THE AMPLITUDE OF THE SEVERE THREAT AND IN IDENTIFYING ANY
CORRIDOR OF COVERAGE AOA 45 PERCENT. MODELS DIFFER WITH THE EJECTION
OF A SRN HIGH PLAINS SHORTWAVE IMPULSE...WITH THE MORE CONSISTENT
ECMWF/CMC SUGGESTING A SLOWER AND MORE N/NELY TRACK TOWARDS THE
MID-MO VALLEY. THIS YIELDS A SLOWER EWD PROGRESSION OF THE SURFACE
COLD FRONT AND LOW/MID-LEVEL S/SWLYS NOT AS INTENSE OVER THE WARM
SECTOR COMPARED TO THE GFS/NAM.

REGARDLESS OF THE MODEL DISCREPANCIES...SCATTERED TO WIDESPREAD
CONVECTION IS EXPECTED ALONG THE FRONTAL ZONES. SURFACE DEW POINTS
WILL CONTINUE TO INCREASE WITHIN THE WARM SECTOR...LIKELY THROUGH
THE 60S FROM PARTS OF THE MIDWEST TO THE GULF COAST. WITH A REMNANT
EML PLUME OVER MOST OF THE ERN CONUS CONTRIBUTING TO STEEP MID-LEVEL
LAPSE RATES...STRENGTHENING LOW/DEEP-LAYER SHEAR SHOULD PROVE
FAVORABLE FOR SCATTERED DAMAGING WINDS...A FEW TORNADOES...AND
ISOLATED LARGE HAIL. AS FLOW BECOMES INCREASINGLY PARALLEL TO THE
COLD FRONT...AN EXTENSIVE QLCS MAY ULTIMATELY FORM PRIOR TO THE
FRONT REACHING THE MS VALLEY.

..GRAMS.. 04/08/2013

Morning e-mail from Jeff:

Windy, warm, and humid for the next 36-48 hours as the next storm system approaches the state.

Lower pressures over the central plains will result in gusty southerly winds today and Tuesday and severe weather across the plains mainly north of TX. This is a result of pieces of energy ejecting out of the mean upper level trough over the western US. SE TX will lie too far south and removed from the main thrust of the dynamics aloft to generate any significant deep convection. A few showers may try and develop under the increasing capping inversion, but suspect these will be isolated.

Large scale western US upper trough will begin its eastward movement by mid-week while a downstream blizzard develops over the central plains forcing a cold front into TX late Tuesday. This front will reach the region early Wednesday and cross off the coast by late in the afternoon. Still looks like the main dynamics are aimed north of SE TX and capping concerns look likely especially south of I-10. However latest guidance has been trending slightly wetter with the front and suspect a line of showers and thunderstorms will develop just NW of SE TX early Wednesday morning and cross the area during the day. Any severe weather threat appears to be located north of I-10 where the capping stands the best chance of being broken. SPC does bring the slight risk outline into a good portion of our northern counties, but this may be somewhat overdone given the time of day and potential warm mid-levels.

Cold front moves off the coast late Wednesday but main upper trough is slower and lags behind the front resulting in the potential for some elevated showers and thunderstorms Wednesday night into Thursday morning in the cold air. Shorter range models are just now starting to run to this time period and are giving some support to the ECMWF over the drier GFS.

Dry and cold again Thursday and Friday with well below normal temperatures for April. Lows fall back into the low to mid 40’s by Friday morning with highs on Thursday only in the mid to upper 60’s. Warming trend starts late Friday as winds swing back around to the ESE.

Morning e-mail from Jeff:

Humid and breezy morning in progress will become and warm and windy afternoon as the next storm system approaches the state from the west.

An upper level trough over the western US is creeping into the plains with surface low pressure deepening over KS with blizzard conditions developing NE from CO into the central and northern plains. A secondary surface low pressure will be developing over NE NM and the TX panhandle today and will help be response for an outbreak of severe weather over N TX into OK this afternoon and evening. Surface cold front will dive southward into TX late today and into SE TX on Wednesday. Defined and established warm sector will remain capped off by warm air in the mid levels for today and into early Wednesday. While some models are attempting to erode the capping, I think they may be overdoing the cooling in the mid levels. Even so, strong frontal push could be enough to overcome the warm layer and force surface parcels through the cap. Shear and instability will be favorable for strong to severe storms should the cap break. Think the best chances for active weather will be north of I-10 where the capping is weakest and jet stream dynamics strongest and this is where SPC has outlined a slight risk of severe weather on Wednesday. South of I-10, capping may hold back storms to just a thin line of showers as suggested by the TX TECH model. Will review the severe threat again early Wednesday, but at this time it looks like most of the action will be north and east of our region.

A secondary short wave rounding the base of the mean upper trough will move across the area Wednesday night. May see some additional development of showers and thunderstorms in the post frontal cold air mass late Wednesday night into Thursday morning.

With decent moisture profiles in place widespread rains of .5 to 1 inch will be possible with isolated totals up to 2 inches especially north of I-10 and east of I-45. Lower rainfall amounts will be found around the Matagorda Bay area southward.

Another cold air mass will drop into the region behind the Wednesday cold front with lows falling back into the 40’s on Thursday and Friday mornings. Highs on Thursday may not reach 70 depending on when clouds clear. Slow warming trend starts Friday on into the weekend.

SPC Day 2 Severe Weather Outlook (Wednesday):

Ok why is no one on here??

wxman666 wrote:Ok why is no one on here??

Hurricane season hasn't started yet, and it's still cool enough to go outside.

Morning e-mail from Jeff:

Impressive late season cold front marching through TX this morning.

Current temperature at Waco is 45 while Austin is 74. Strong cold front is moving SE at 15-20mph and will be entering our northern counties by mid-morning. Temperatures will rapidly fall from the mid to upper 70’s into the upper 40’s and low 50’s with the frontal passage. This system is very dynamic and cold and this is resulting in rare April winter precipitation across portions of W and NC TX this morning with thunderstorms ongoing in the cold/near freezing air mass. Currently Abilene is 33 with a thunderstorm. This is a result of the warm moist Gulf air being pushed up and over the surface cold dome which is very cold for April. Thus far on the warm side of the front, capping has held strong and there appears to be few signs of it starting to weaken yet. Combined effect of strong surface lift with the sharp front, approaching cooler air in the mid-levels with the upper trough, and broad spreading apart of upper level winds (divergence aloft) all should help to weaken the capping today. However, with that said, still think it will be hard to get strong to severe storms south of I-10 where the cap is strongest with an isolated severe storm north of I-10 possible. Short term forecast models are not overly impressive with thunderstorms today as the main dynamics do not match up with the frontal timing….the front is running ahead of the main thrust of lift due to the slow movement of the upper trough and the fast movement of the dense cold air. Think most of the area will see a line of showers and maybe a thunderstorm move from NW to SE across the region from late morning through late afternoon.

Based on upstream trends, think the better chances for showers and thunderstorms may actually come this evening and overnight in the cold air behind the front as the upper trough axis moves across the area lifting the warm Gulf air mass over the surface cold dome. This is supported by the 4km WRF and seems reasonable.

Skies should clear on Thursday as the trough moves east of the area, but it will be cool to cold by April standards with highs in the low to mid 60’s. Could see some locations east of I-45 stay in the 50’s if cloud cover hangs around most of the day. Coldest morning will be Friday with lows in the lower 40’s under clear skies and calm winds.

Weekend forecast looks to be mainly dry and mild as SE winds begin to return moisture to the area. There is some interest in a strong short wave for Sunday, but meager moisture return should negate rainfall…but this feature will be something to keep an eye on over the next few days.

Ed Mahmoud wrote:Someone at NWS HGX has obviously confused "pessimistic" with "optimistic".

Yeah, they also don't know the difference between 'do' and 'due' or 'quiet" and 'quite' either. Anyway....

Someone was asking why nobody was posting yesterday....basically there wasn't anything new to add. This is one of those wait-and-see events that comes down to the cap busting - not much change from day to day and you just have too see how everything lines-up the day of.

I'm betting the cap breaks, at least for Ed, Steve and I up on the north side.

The front is nearing Palestine....


http://www.wunderground.com/cgi-bin/fin ... -95.366997

Could someone explain to me what the CAPE is? In layman terms what is Ed's post saying? We are one of the lucky ones to be under this cap and receiving no rain (Jackson County). Is it looking like we are going to be cursed with this cap like 2011?

Get ready, Southeast Texans ... this front means business. It has dropped temperatures here in Austin roughly 30 degrees in just a matter of a few hours!

NWS Houston/Galveston suggesting a stout capping inversion for College Station requiring 90 degrees to break that cap. That looks very unlikely with all the cloud cover and the fact the cold front is racing SE into the Brenham area at this time. The area that Ed mentions out W near San Antonio is the secondary vort max along the trough axis that the models were sniffing out several days ago. The temperature drops are going to come as a big shock for those that have not been following the weather as of late. Those colder temps will likely be the bigger headline than any rainfall we may get from this very strong late season Canadian front.

Wow I didn't expect the front to race so fast - I don't see the cap breaking in time so I'll take my crow. Still hoping for some post-frontal fun....we shall see....

Ed Mahmoud wrote: Judging from radar, SRain is only minutes away from reporting the wind shift...

Front just passed Hockley in NW Harris County. The frontal boundary extends from S of Madisonville to just W of Brookshire at this time.

So, Srain, you are thinking...one hour to IAH.....or less?

tireman4 wrote:So, Srain, you are thinking...one hour to IAH.....or less?

The frontal boundary has slowed just a bit. That said it is just about to pass Cypress at this time. An hour or two for IAH seems reasonable. Also the temps in Waller have fallen from the upper 70's to the low 50's with gusty NW winds...

The front just passed my back yard in NW Harris County. Temp fell from 81F to 63F with the frontal passage.

yes, quite the refreshing wake-up !

Front just came through the 1960/Jones area.

Rain, wind, and a big drop in temps.

The front just passed the office here at 45 & Woodlands Parkway (btw - I don't work downtown any more...5 minutes from home).

I had run an errand and was in the parking garage just before it passed -- it was all warm & muggy, and I noted the wind shift just slammed into the trees as I stepped into the elevator. When I got out, it was already much cooler than when I had just stepped into the elevator moments earlier. Crazy.