April - Ends on Mild Note

[srainhoutx]

Morning e-mail from Jeff:

Strong cold front will bring near record cold temperatures by the end of the week.

In a pattern that continues to repeat, another strong upper level storm system will cross the state on Thursday ushering in a strong cold front. Ahead of this feature a warm and muggy air mass is noted across much of eastern TX with dewpoints well into the 60’s and at some sites the lower 70’s. Warm layer of air aloft is keeping a cap on any convective chances with some slight potential especially on Wednesday of a showers or two moving inland off the western Gulf in the offshore flow. Onshore flow is also bringing in a large amount of haze/smoke from agriculture fires in Mexico. There will be little change to the pattern until Thursday when a strong cold front sweeps across the area.

Models have shown a general slowdown in the frontal timing with the boundary entering our W counties in the mid to late morning and moving off the coast toward the early evening. This paces the boundary across the region during maximum heating and during the greatest amounts of instability. As with the past front past week, the capping inversion held strong along the boundary allowing no development until the lift from the upper trough arrived during the overnight hours. Capping looks to be a problem with the upcoming front also, especially across areas south of I-10. Areas north of I-10 stand at least a decent shot of the cap being broken, and with good instability and strong shear, any storms that develop in this region will likely become severe. Hard to pin down the severe threat still over 48 hours out and will take a closer look tomorrow.

Post front air mass will be cold from mid April with lows both Friday and Saturday mornings falling into the upper 30’s and lower 40’s which is near record temperatures. Highs on Friday will only reach the mid to upper 60’s and only 70 on Saturday or roughly 10 degrees below daytime highs. The dry and cold air mass will feel much different than the current air mass in place.

[Ptarmigan]

Another cold front? Is it common to see this kind of cold weather this far into spring? When do we on average see the last of cold fronts?

I think strong Canadian cold fronts stop coming by April as we have more Pacific fronts that are less cooler and more drier. I have seen cold fronts come into May, June, and even July. The last happened in July 1994. As for August, there was a cold front in 2004, which allowed Hurricane Charley to make landfall further south in Florida.

http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_may
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_jun
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_jul
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_aug
http://docs.lib.noaa.gov/rescue/dwm/dat ... _maps.html

[C2G]

A strong cold front with near record lows by the end of the week.
YUCK.
I HATE this time of year, stay warm already. Just when I start to get acclimated to this nice warmth.

[jasons2k]

All - I'm just curious - has this issue of the "mexican smoke" always been around? The reason why I ask is because I lived in Texas for many many years before I ever once heard anything about it.

Then, in 1998 I believe, it was the spring of smoke. Smoke and haze was everywhere, and it was covered extensively in the news as they were asking people in Houston and South Texas to stay indoors. In short, it was horrible. But I don't remember ever hearing anything about the agricultural fires until then. For me and everyone I knew (some lifelong Texans) that event in 1998 was the first time we had ever heard of "Mexican wildfire smoke".

Now, it seems like since 1998, it is an annual occurence. Even today it was mentioned by the NWS HGX in the discussion that it is common this time of year.

So, what changed? Is this a new thing, or is it just increased awareness & media attention?? I wish it would go away.

[Paul Robison]

Morning e-mail from Jeff:

Strong cold front will bring near record cold temperatures by the end of the week.

In a pattern that continues to repeat, another strong upper level storm system will cross the state on Thursday ushering in a strong cold front. Ahead of this feature a warm and muggy air mass is noted across much of eastern TX with dewpoints well into the 60’s and at some sites the lower 70’s. Warm layer of air aloft is keeping a cap on any convective chances with some slight potential especially on Wednesday of a showers or two moving inland off the western Gulf in the offshore flow. Onshore flow is also bringing in a large amount of haze/smoke from agriculture fires in Mexico. There will be little change to the pattern until Thursday when a strong cold front sweeps across the area.

Models have shown a general slowdown in the frontal timing with the boundary entering our W counties in the mid to late morning and moving off the coast toward the early evening. This paces the boundary across the region during maximum heating and during the greatest amounts of instability. As with the past front past week, the capping inversion held strong along the boundary allowing no development until the lift from the upper trough arrived during the overnight hours. Capping looks to be a problem with the upcoming front also, especially across areas south of I-10. Areas north of I-10 stand at least a decent shot of the cap being broken, and with good instability and strong shear, any storms that develop in this region will likely become severe. Hard to pin down the severe threat still over 48 hours out and will take a closer look tomorrow.

Post front air mass will be cold from mid April with lows both Friday and Saturday mornings falling into the upper 30’s and lower 40’s which is near record temperatures. Highs on Friday will only reach the mid to upper 60’s and only 70 on Saturday or roughly 10 degrees below daytime highs. The dry and cold air mass will feel much different than the current air mass in place.

Well HGX does seem to agree with you, Jeff. Read this:


CONTINUED WARM, BREEZY & MUGGY CONDITIONS WILL PERSIST INTO
THURSDAY MORNING. EXPECT STRATUS TO FILL BACK IN EARLY THIS
EVENING (WHERE IT HASN`T ALREADY). STILL CAN`T RULE OUT AN
ISOLATED SHRA UNDER THE CAP BUT ODDS ARE AGAINST IT. WILL ALSO BE
INTERESTING TO WATCH PROGRESS OF HAZE/SMOKE OVER THE WESTERN GULF
THAT`S ASSOCIATED WITH FARMERS BURNING THEIR FIELDS IN MEXICO &
CNTL AMERICA (FAIRLY COMMON AT THIS TIME OF YEAR). INCREASING
SOUTH WINDS ARE EXPECTED WHICH SHOULD STEER IT FURTHER NORTH...

GENERAL MODEL AGREEMENT WITH THE NEXT FRONT MOVING INTO NRN PARTS
OF SE TX ~2PM THURS...HWY 59 CORRIDOR FOR THE EVENING RUSH HOUR...AND
OFF THE GLS COAST ~7 PM. ANTICIPATE A BAND OF SHRA & TSRA TO
DEVELOP ALONG THE BOUNDARY AS IT MOVES INTO THE REGION. OVERALL
COVERAGE WILL PROBABLY BE HIGHEST N OF I-10 BUT WOULD NOT BE SURPRISED
IF IT EVOLVED INTO JUST A BROKEN THIN BAND OF PRECIP FURTHER SW
TOWARD MATAGORDA BAY WHERE CAPPING LOOKS TO BE A HINDRANCE.
SEVERE WX THREAT LOOKS MARGINAL WITH THE EXCEPTION OF MAYBE OUR NE
COUNTIES AROUND LAKE LIVINGSTON. LESS IMPRESSED WITH OVERALL FCST
DYNAMICS (JET POSITION/ INSTABILITY/ETC) THAN IN PREVIOUS DAYS.
NOT THAT IT CAN`T CHANGE BETWEEN NOW AND THEN - SO WILL CONTINUE
TO EVALUATE. BREEZY & MUCH COOLER CONDITIONS IN THE WAKE OF THE
FRONT THURS NIGHT AND FRI.

RECORD LOWS SAT MORNING COULD BE IN JEOPARDY ACROSS MOST OF SE
TX. APRIL 20TH MIN TEMP RECORDS:
CLL 40/1953 (FCST 40)
IAH 44/1901 (FCST 42)
GLS 52/1884 (FCST 53)

ONSHORE FLOW QUICKLY RESUMES AND INCREASES LATE SAT & SUN AS HIGH
PRES MOVES EAST AND PRESSURES FALL ACROSS W TX. WARMING TREND
WILL ENSUE INTO EARLY NEXT WEEK AHEAD OF THE NEXT FRONT AND SCT
SHRA PENCILED IN FOR TUE AFTN. 47



But then, SPC says:

...THERE IS A SLGT RISK OF SVR TSTMS FROM LOWER MI TO THE UPPER TX
COAST...

...LOWER MI TO UPPER TX COAST...

STRONG MID LEVEL SPEED MAX...100KT+...IS EXPECTED TO ROTATE THROUGH
THE BASE OF THE TROUGH OVER WEST TX THEN EJECT INTO THE MID MS
VALLEY REGION LATE IN THE PERIOD. THIS PROGRESSIVE FEATURE WILL
ENSURE CONVECTIVELY-ACTIVE COLD FRONT WILL BE MAINTAINED AS IT
SURGES TO A POSITION FROM NRN LOWER MI...SWWD ACROSS NRN IL/CNTRL
MO...SWWD TOWARD THE UPPER TX COAST BY 18Z. AN ELONGATED SEVERE
SQUALL LINE IS EXPECTED TO BE ONGOING AT THE BEGINNING OF THE PERIOD
AND ANY DIABATIC HEATING AHEAD OF THIS LINE SHOULD SERVE TO AID
BUOYANCY FOR STRONGLY SHEARED SQUALL LINE. LATEST MODEL GUIDANCE IS
NOT PARTICULARLY AGGRESSIVE REGARDING INSTABILITY...ESPECIALLY THE
GFS...BUT THE NAM DOES FORECAST 1000-1500 J/KG ACROSS THE WARM
SECTOR IMMEDIATELY AHEAD OF THE COLD FRONT. ALTHOUGH THE LIKELY
STORM MODE WILL BE LINEAR...DAMAGING WINDS AND PERHAPS SOME HAIL MAY
ACCOMPANY FRONTAL CONVECTION. IF BUOYANCY IS GREATER THAN FORECAST
THEN SEVERE PROBS WILL NEED TO BE ADJUSTED HIGHER AS LARGE SCALE
FORCING/SHEAR WOULD CERTAINLY SUPPORT AN ENHANCED SEVERE THREAT.

And then, there's THIS little tidbit from ACCUWEATHER.COM, which does not even depict the Houston area as being at risk for anything:




So, is a devastating severe storm plague more likely CITYWIDE than just North of I-10. Would feel better if someone explained.

[Kludge]

All - I'm just curious - has this issue of the "mexican smoke" always been around? The reason why I ask is because I lived in Texas for many many years before I ever once heard anything about it.

Then, in 1998 I believe, it was the spring of smoke. Smoke and haze was everywhere, and it was covered extensively in the news as they were asking people in Houston and South Texas to stay indoors. In short, it was horrible. But I don't remember ever hearing anything about the agricultural fires until then. For me and everyone I knew (some lifelong Texans) that event in 1998 was the first time we had ever heard of "Mexican wildfire smoke".

Now, it seems like since 1998, it is an annual occurence. Even today it was mentioned by the NWS HGX in the discussion that it is common this time of year.

So, what changed? Is this a new thing, or is it just increased awareness & media attention?? I wish it would go away.

----------------
I was thinking the same thing today. The "southwest flow" used to mean the "pineapple express" of pacific ocean moisture across the state. We spent days under streaming storms, and flooding was frequent.

Now, the "southwest flow" means capping, arid air, and smoke from intentionally set fires in Mexico.

I realize everything is cyclic, and that we're in a period of cool SSTs in many pacific regions. Blah blah blah.

The pattern change can't come soon enough....

[Paul Robison]

I live in the Ashford Forest suburb in SW Houston, which is way south of I-10. So, based on AFD discussion and email from Jeff, does that make my risk of getting a severe thunderstorm LESS than if I live in, say, The Woodlands, which is North of I-10?

[srainhoutx]

Folks near Wichita Falls on NE across Oklahoma need to keep an eye to the sky tomorrow. The current Moderate Risk outlined by the Storm Prediction Center along with the latest 00Z guidance suggest there is a strong potential for severe storms and an increased threat of tornadic super cells later tomorrow. Concern is increasing that a rather significant severe weather episode may well develop for that Region.

[Texas Pirate]

To answer the SMOKE QUESTION

FROM HOUSTON NWS DISCO 4/16

WILL ALSO BE
INTERESTING TO WATCH PROGRESS OF HAZE/SMOKE OVER THE WESTERN GULF
THAT`S ASSOCIATED WITH FARMERS BURNING THEIR FIELDS IN MEXICO &
CNTL AMERICA (FAIRLY COMMON AT THIS TIME OF YEAR). INCREASING
SOUTH WINDS ARE EXPECTED WHICH SHOULD STEER IT FURTHER NORTH...

[Ptarmigan]

All - I'm just curious - has this issue of the "mexican smoke" always been around? The reason why I ask is because I lived in Texas for many many years before I ever once heard anything about it.

Then, in 1998 I believe, it was the spring of smoke. Smoke and haze was everywhere, and it was covered extensively in the news as they were asking people in Houston and South Texas to stay indoors. In short, it was horrible. But I don't remember ever hearing anything about the agricultural fires until then. For me and everyone I knew (some lifelong Texans) that event in 1998 was the first time we had ever heard of "Mexican wildfire smoke".

Now, it seems like since 1998, it is an annual occurence. Even today it was mentioned by the NWS HGX in the discussion that it is common this time of year.

So, what changed? Is this a new thing, or is it just increased awareness & media attention?? I wish it would go away.

I am sure it is always happened, but was not really noticed until 1998.

[Paul Robison]

A reasonable assessment of our predicament:





Still looks to me like Lufkin and points north of Houston have the best shot at severe wx. Anyone disagree?

[srainhoutx]

Streamer showers beneath a stout capping inversion will be the theme for the next 24 hours. Further to our W across W Texas, a dry line is established and that will be the focal point for any stronger storms that do develop later this afternoon. A strong Canadian front will race SE tomorrow pushing the dry line into the Hill Country where it appears a squall line will develop and push SE. The best chance of severe storms still look likely along the I-35 Corridor and N of I-10 where the cap may erode enough to allow storms to develop. It appears the greatest threat for strong to severe storms will be NE of Houston near Lake Livingston to Texarkana into Little Rock.

For today, severe storms with a tornado thread is possible from Wichita Falls on NE to near the Joplin, MO area. Much colder temps are still in the cards for early Friday into early Saturday with near record lows in the upper 30's to the N and low to mid 40's elsewhere. Hopefully this will be the last of these late season cold snaps as a we transition to a bit of a progressive pattern with milder Pacific fronts ~vs~ Canadian type air masses as the pattern becomes more zonal in nature.

[jasons2k]

To answer the SMOKE QUESTION

FROM HOUSTON NWS DISCO 4/16

WILL ALSO BE
INTERESTING TO WATCH PROGRESS OF HAZE/SMOKE OVER THE WESTERN GULF
THAT`S ASSOCIATED WITH FARMERS BURNING THEIR FIELDS IN MEXICO &
CNTL AMERICA (FAIRLY COMMON AT THIS TIME OF YEAR). INCREASING
SOUTH WINDS ARE EXPECTED WHICH SHOULD STEER IT FURTHER NORTH...

Yeah, saw that. When I read that, that's what prompted me to make my post. We hear about this every year now...before 1998, never heard of 'mexican smoke' in the any weather context

--------

As far as tomorrow goes, nobody has a clue yet if the cap will break. It won't be clear until we notice something on satellite/radar tomorrow. Wait n' see with this one...

[jasons2k]

To answer the SMOKE QUESTION

FROM HOUSTON NWS DISCO 4/16

WILL ALSO BE
INTERESTING TO WATCH PROGRESS OF HAZE/SMOKE OVER THE WESTERN GULF
THAT`S ASSOCIATED WITH FARMERS BURNING THEIR FIELDS IN MEXICO &
CNTL AMERICA (FAIRLY COMMON AT THIS TIME OF YEAR). INCREASING
SOUTH WINDS ARE EXPECTED WHICH SHOULD STEER IT FURTHER NORTH...

Yeah, saw that. When I read that, that's what prompted me to make my post. We hear about this every year now...before 1998, never heard of 'mexican smoke' in any weather context

--------

As far as tomorrow goes, nobody has a clue yet if the cap will break. It won't be clear until we notice something on satellite/radar tomorrow. Wait n' see with this one...

[Texas Pirate]

Jason - maybe they're bored

[jasons2k]

Bummer:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1105 AM CDT WED APR 17 2013

.UPDATE...
MORNING FORECAST UPDATE.

&&

.DISCUSSION...
DEEP MOISTURE CONTINUES TO INCREASE OVER THE AREA WITH SFC
DEWPOINTS IN THE LOW 70S. THINK LOW STRATOCU WILL BE BKN/OVC FOR
MOST OF THE DAY. NOT SEEING MUCH INDICATION OF SHOWERS DEVELOPING
ALTHOUGH GIVEN THE LOW LEVEL MOISTURE...EXPECT SOME DRIZZLE/MIST
THROUGHOUT THE DAY. POPS WERE DROPPED AS NOT SURE THERE WILL BE
ENOUGH HEATING TO GET SHOWER ACTIVITY UNDER STRONG CAP DUE TO
ELEVATED MIXED LAYER. THE 12Z DRT/CRP/LCH SOUNDINGS SHOW CAPPING
AND SW FLOW ALOFT SO ONLY EXPECT CAP TO INCREASE. BASED ON THE CAP
AND MODELS HOLDING ONTO THE CAP TOMORROW...THINK SEVERE THREAT
WILL BE SMALL AND MAINLY NE OF THE AREA. MESOSCALE MODELS ALL
BRING A THIN LINE OF STORMS THROUGH THE AREA TOMORROW WITH
STRATIFORM RAIN REGION BEHIND IT. MAY GET A FEW STRONG STORMS WITH
WIND GUSTS BUT NOT THINKING OVERALL THREAT WILL BE THAT HIGH.
UPDATED FORECAST PRODUCTS HAVE BEEN ISSUED.

[Texas Pirate]

From HOUSTON NWS DISCO

Another cold front next week:

GFS/ECMWF ON THE SAME PAGE WITH NEXT WEEKS FRONT. LOOKS LIKE LATE
TUE INTO TUE NIGHT THERE IS ANOTHER SOLID COLD FRONT. WILL STICK
WITH 30 POPS FOR NOW AS GFS IS MUCH MORE ROBUST WITH RAIN CHANCES
THAN ECMWF SO THINK THERE IS STILL REASONABLE UNCERTAINY. STILL
THIS LOOKS LIKE THE NEXT BEST CHANCE OF RAIN AFTER TOMORROWS
FRONT. SHOULD HAVE TEMPS IN THE 50S FOR LOWS BEHIND THE FRONT AND
HIGH TEMPS IN THE 70S. NICE TO HAVE BELOW NORMAL TEMPS FOR THE END
OF APRIL.


Who's says?
I'm over this cold weather.

[TexasBreeze]

There is an amazing temp difference across the stalled front across Lubbock's area...

http://www.srh.weather.gov/lub/

Scroll down to where it says ”Latest Reports from Area Weather Stations” to see the difference! 45+ degree difference.

[Paul Robison]

NWS hasn't changed its thinking since this morning:

ISSUED 338 PM CDT WED APR 17 2013/

DISCUSSION...
MID APRIL SURGE OF DEEP MOISTURE ONLY A SIGN OF WHAT IS TO COME
IN MAY/JUNE/JULY/AUGUST/SEPTEMBER. DEWPOINT TEMPS IN THE 70S WITH
SE WINDS AND LOW TEMPS IN THE LOW/MID 70S. THERE MAY BE A FEW
DROPS OF MIST/DRIZZLE TONIGHT BUT NOT SEEING GOOD MUCH IN THE WAY
OF SHOWERS THROUGH THE OVERNIGHT. POSSIBLE TO HAVE MORE VERTICAL
CLOUD DEVELOPMENT TOMORROW MORNING AS THE FRONT APPROACHES THE
AREA SO WILL KEEP SOME MENTION OF SHOWERS AFTER MIDNIGHT BUT THINK
MAJORITY OF ACTIVITY WILL BE RUSH HOUR THROUGH THE MORNING.

THINK MESOSCALE WRF/NAM MODELS ARE ON THE RIGHT TRACK WITH
FRONTAL PASSAGE AND A LINE OF SHOWERS/STORMS. WRF MODELS ALL GO
WITH A THIN LINE OF STORMS WITH NO REAL INDICATION OF A BOWING
SEGMENT WITH IN THAT. LOW LEVEL AND DEEP LAYER SHEAR WOULD
CERTAINLY SUPPORT DAMAGING WIND THREAT HENCE SPC SLIGHT RISK
OUTLOOK FOR THE AREA BUT MODEL SOUNDINGS ALL SHOW LIMITED
INSTABILITY OF 500-1000 J/KG. SREF ENSEMBLE MEMBERS ALSO SUPPORT
THIS IDEA SO THINK AT THIS POINT STORMS WILL BE APPROACHING SEVERE
LEVELS BUT LIKELY HAVE HIGHER THREAT TOWARDS LUFKIN/SHREVEPORT AS
UPPER DYNAMICS AND JET STREAK ROUND THE BASE OF DEEP TROUGH
PULLING ACROSS THE PLAINS TOMORROW MORNING. THE CAP WILL ALSO BE A
BIG PROBLEM FOR CONVECTIVE INITIATION AND LIMIT STORM DEVELOPMENT
IF ANYTHING DOES FORM DUE TO THE WARM/DRY AIR ENTRAINMENT.
AS ALWAYS WITH A STRONG COLD FRONT TEMP FORECAST WILL BE TRICKY
TOMORROW. WILL SEE TEMPS START IN THE 70S FROM COLLEGE STATION TO
CROCKETT AND THEN DROP INTO THE 50S BEHIND THE FRONT REACHING THIS
AREA BETWEEN 14-17Z OR 9AM TO NOON. FRONT EXPECTED TO REACH THE
HOUSTON AREA FROM 18Z TO 21Z OR 1-4PM. EXPECT TEMPS TO REACH
AROUND 80 AHEAD OF THE FRONT AND THEN DROP INTO THE 60S/UPPER 50S.
MODELS DO SHOW STRATIFORM RAIN BEHIND THE FRONT SO THIS WILL HELP
HOLD TEMPS DOWN BEHIND THE FRONT AS WELL. COLD FRONT REACHES THE
COAST SHORTLY BEFORE 00Z FRI AND THROUGH THE OFFSHORE WATERS BY
03Z FRI. EXPECT VERY STRONG POST FRONTAL WINDS WITH GUSTS TO GALE
FORCE.

BTW: Why is SE houston being mentioned for thunderstorms by KHOU when the main threat is in shreveport/lufkin?

[txflagwaver]

Has the front gone through Waco yet?