March Weather Disccusion: Severe Storms Possible Tues/Wed

[wxman57]

wxman, you are just dieing to jump into some spandex aren't you?

Are we actually going to go through ANOTHER Spring season without some good storms? Man, I don't even remember the last time we had a good stormy Spring. Yack!

Well, wxman57 did say that we would be paying for all of the hard freezes that south east received during the last month and a half because of how much the icy dry north winds and cold days and nights this past winter easily and nicely chilled most of the Gulf of Mexico. Is that correct, wxman57?

That's correct. It's hard to get deep Gulf moisture with the chilled surface waters. The cool water really knocked out the severe weather season last year.

[srainhoutx]

Sort of an interesting pattern setting up for next week that may bring a bit of a pattern change to the CONUS and our area. We have been in a somewhat dry and boring, but beautiful weather pattern and that may well change just a bit. A zonal flow looks to be replaced by a deepening trough in the Eastern US and a touch of ridging to our West. The storm track looks to shift to a somewhat early February-ish flow pattern where we saw a NW flow and storms riding S/SE from the Pacific NW and riding along the base of the trough. While it appears the trough axis will be far enough to our E to keep the coolest air away from us, the pattern does suggest several Upper Air disturbances tracking across TX/OK and possibly increasing our rain/storm chances next week. The pattern also looks somewhat progressive and may last through the first week of April. Something to watch as we end the month of March and transition into April.

[jasons2k]

wxman, you are just dieing to jump into some spandex aren't you?

Are we actually going to go through ANOTHER Spring season without some good storms? Man, I don't even remember the last time we had a good stormy Spring. Yack!

Well, wxman57 did say that we would be paying for all of the hard freezes that south east received during the last month and a half because of how much the icy dry north winds and cold days and nights this past winter easily and nicely chilled most of the Gulf of Mexico. Is that correct, wxman57?

That's correct. It's hard to get deep Gulf moisture with the chilled surface waters. The cool water really knocked out the severe weather season last year.

How is it that points further north always end-up with deep gulf moisture and we don't? After all, the source is the same body of water and to get up there, is has to go right over us, right? I just never quite understood how oftentimes we are so dry right on the coast, but up in Oklahoma and Kansas they have plenty of rich, deep Gulf moisture. Please explain as this is one item that after all these years of weather watching, I just don't get. I know we are often capped and that squelches our rain chances, but the 'lack of moisture' is something I struggle with, especially when we have dewpoints in the mid-60's. Heck, out in Lubbock, a dewpoint of 55+ and you're talking HP supercells. Why not here?

[jasons2k]

Hey Ed - thanks for your thoughtful reply. Yes, I do understand the factors of closer to the dryline, better proximity to jet dynamics, etc. That makes the cap much easier to break. Yes, often the upper-level energy is better in places further north, especially after about March or so. What I'm struggling with, specifically, is the available moisture. Maybe the answer is a simple as "when we're capped, all the moisture is trapped at the boundry layer". Fine, but what does that have to do with the shelf waters being cool? Either the moisture is being sucked-off the Gulf or not. It's not like the boundry layer over Houston has it's source from *only* the colder shelf waters and the boundry layer in Oklahoma City has it's source region from warmer waters 200nm south of Galveston. That same air still has to come right through us to get there. Am I making any sense or am I just rambling? I'm trying to explain my question as best as I can. How can Houston be too "dry" for storms due to "cool shelf waters" yet OKC can be plenty moist and their southerly winds "fueling the storms" come from.......Houston?

[wxman57]

The deep Gulf moisture doesn't miss us and develop over Oklahoma. It will always be more moist here along the coast than up in Oklahoma. But, as Ed mentioned, the instability may be greater up north, allowing for more rain. Cooler water near the coast keeps our afternoon highs down. That's not so farther north.

[jasons2k]

But we're having highs 10 degrees above normal for early-mid March with dewpoints in the mid 60's. How are the cool shelf waters squelching our rain chances? That argument just doesn't resonate with me. I guess the point I'm making is that I don't see that as much of a factor at all. It's really more about the jet dynamics and persistent cap that are preventing us from having our usual spring storms, not the Gulf's water temps. Am I wrong about this?

[wxman57]

But we're having highs 10 degrees above normal for early-mid March with dewpoints in the mid 60's. How are the cool shelf waters squelching our rain chances? That argument just doesn't resonate with me. I guess the point I'm making is that I don't see that as much of a factor at all. It's really more about the jet dynamics and persistent cap that are preventing us from having our usual spring storms, not the Gulf's water temps. Am I wrong about this?

The cooler Gulf waters (not just shelf waters) are preventing the inflow of DEEP Gulf moisture across our area. Yes, we have some very shallow low-level moisture, taking our dew points into the 60s and surface temps above normal. But above the shallow surface layer there is NOTHING! No moisture. Can't squeeze rain out of such a dry atmosphere aloft.

A warmer Gulf would allow for a deeper moisture layer, increasing our chances for rain considerably. Up north, the situation is a bit different. Even with the limited moisture, the dynamics across OK/KS allow for much greater lifting potential. The atmosphere is just so much more unstable to our north that they can get rain even with the limited moisture inflow off the Gulf.

[srainhoutx]

If only the GFS could be correct regarding next week. My yard would be happy and all the pollen would be washed away.

[srainhoutx]

If only the GFS could be correct regarding next week. My yard would be happy and all the pollen would be washed away.

The 12Z GFS continues the trend of increased rain/storm chances for next Wednesday through April 1st (Friday). In fact, if that model is correct, this will be the best chance we've seen of some widespread rains in a very long time. March may go out like a Lion?

[ticka1]

If only the GFS could be correct regarding next week. My yard would be happy and all the pollen would be washed away.

The 12Z GFS continues the trend of increased rain/storm chances for next Wednesday through April 1st (Friday). In fact, if that model is correct, this will be the best chance we've seen of some widespread rains in a very long time. March may go out like a Lion?

Larry Cosgrove posted that there will be a pattern change and we could possibly see rain here in SE Texas. At least its being talked about...rain that is..my garden needs it - I got plants coming up already after planting the seeds on Saturday.

[jasons2k]

The cooler Gulf waters (not just shelf waters) are preventing the inflow of DEEP Gulf moisture across our area. Yes, we have some very shallow low-level moisture, taking our dew points into the 60s and surface temps above normal. But above the shallow surface layer there is NOTHING! No moisture. Can't squeeze rain out of such a dry atmosphere aloft.

A warmer Gulf would allow for a deeper moisture layer, increasing our chances for rain considerably. Up north, the situation is a bit different. Even with the limited moisture, the dynamics across OK/KS allow for much greater lifting potential. The atmosphere is just so much more unstable to our north that they can get rain even with the limited moisture inflow off the Gulf.

Look at the profile below. Where the red and green lines are close together indicates moisture. Only a very shallow layer of moisture (clouds) over Houston yesterday afternoon.

Thank you!! That explanation does help clarify the "deep moisture" question for me. I can't see the image though.

[wxman57]

Thank you!! That explanation does help clarify the "deep moisture" question for me. I can't see the image though.

That site doesn't allow direct linking to images and I was too lazy to save it and upload it to my web server. It just showed a very shallow moisture layer near the surface here yesterday afternoon and bone dry air aloft.

[Ptarmigan]

Worst Texas Drought in 44 Years Damaging Wheat Crop, Reducing Cattle Herds
http://www.bloomberg.com/news/2011-03-2 ... llies.html

[sleetstorm]

Were those two arctic surges that we received during January and February worth it? I understand that they ushered in much icier temperatures and icy north winds which caused the weather down here to feel more like winter. Yet, at what cost, cooling the surface of the water of the Gulf of Mexico and drying out the air above it to desert moisture level for such a long span of time that it might not be until the middle or late part of spring when this part of Texas does at last get its first severe thunderstorms of the season?

Wxman57, are we nearly done with paying for all of the freezes for the winter 2010-2011?

[wxman57]

Were those two arctic surges that we received during January and February worth it? I understand that they ushered in much icier temperatures and icy north winds which caused the weather down here to feel more like winter. Yet, at what cost, cooling the surface of the water of the Gulf of Mexico and drying out the air above it to desert moisture level for such a long span of time that it might not be until the middle or late part of spring when this part of Texas does at last get its first severe thunderstorms of the season?

Wxman57, are we nearly done with paying for all of the freezes for the winter 2010-2011?

See? I told you that cold is bad! There are some indications that we might see some rain in a few weeks. But you can just feel that cool air coming off the Gulf when we get a SE-S wind now.

It appears my Bluebonnet Metric Century bike ride on Sunday will be dry, though not as warm as I'd like. Guess I can't complain TOO much about a low in the mid 60s and a high near 80, though. Last March we were still hitting the mid 40s late in the month.

[srainhoutx]

Good News! Models are converging on a solution that looks to offer some drought relief for our area. Rain/storm chance look to increasing beginning next Tuesday and continue through Thursday of next week as a potent Southerly tracking Upper Air disturbance moves slowly across TX. We should see a weak cool front Sunday/Monday that quickly retreats N as a warm front bringing a southerly flow off the Gulf with some much deeper moisture than we've seen of late. Rain/thunderstorm chances look fairly widespread on Wednesday continuing into Thursday. Some strong storms are not out of the question and will need to be monitored for a possibility of even some severe storm chances. The pattern change continues to look likely.

[srainhoutx]

Impressive storm, if it verifies...chilly too...

[srainhoutx]

Latest SPC RUC based analysis, the cap is almost gone along what appears to be a diffuse dry line South of DFW.

MESOSCALE DISCUSSION 0271
NWS STORM PREDICTION CENTER NORMAN OK
0343 PM CDT FRI MAR 25 2011

AREAS AFFECTED...NCNTRL/NERN TX...SCNTRL/SERN OK...SWRN AR AND
EXTREME NRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 252043Z - 252315Z

LATEST VISIBLE SATELLITE IMAGERY DEPICTS A DEEPENING CUMULUS FIELD
ACROSS THE WARM SECTOR OVER SCNTRL/SERN OK AND NCNTRL TX.
HOWEVER...RIDGE/ANTICYCLONIC CHARACTER TO HIGH-LEVEL CLOUDS MOVING
OVER THE REGION AND LACK OF SUBSTANTIAL LOW-LEVEL CONVERGENCE WILL
PROBABLY BE DETRIMENTAL TO SURFACE-BASED CONVECTIVE INITIATION UNTIL
AFTER 23Z OR SO. THEREAFTER...WEAK HEIGHT FALLS ASSOCIATED WITH AN
UPSTREAM TROUGH AND THE PRE-EXISTING WARM BOUNDARY LAYER MAY BECOME
SLIGHTLY MORE FAVORABLE FOR INITIATION. THERE APPEARS TO BE ENOUGH
EVIDENCE TO SUPPORT LATEST RUC/GFS/NAM SOLUTIONS FOR AT LEAST
ISOLATED THUNDERSTORMS NEAR THE TRIPLE POINT AND SWD ALONG THE
DRYLINE FROM SCNTRL OK INTO NCNTRL TX NEAR SUNSET WHERE NRN-EXTENT
OF 1000-1500 J/KG MLCAPES WILL EXIST.

SHOULD A STORM FORM...ROUGHLY 45-50 KTS OF LARGELY UNIDIRECTIONAL
DEEP-LAYER SHEAR AND MID-LEVEL LAPSE RATES IN EXCESS OF 7 DEG C PER
KM WILL BE FAVORABLE FOR SPLITTING SUPERCELLS CAPABLE OF LARGE HAIL.
A SUSTAINED SURFACE-BASED STORM EVOLVING ALONG/N OF THE RED RIVER
NEAR A WARM FRONT COULD PRODUCE A TORNADO OR TWO...BUT THE HAIL RISK
WILL DOMINATE.

OTHERWISE...ADDITIONAL ACTIVITY IS EXPECTED TO EVOLVE AND/OR DEVELOP
ALONG/N OF THE WARM FRONT AS ELEVATED ENTITIES OVER ERN OK AND CNTRL
AR LATER THIS EVENING WITH POSSIBLE LARGE HAIL.

..RACY.. 03/25/2011


ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

[Ptarmigan]

See? I told you that cold is bad! There are some indications that we might see some rain in a few weeks. But you can just feel that cool air coming off the Gulf when we get a SE-S wind now.

It appears my Bluebonnet Metric Century bike ride on Sunday will be dry, though not as warm as I'd like. Guess I can't complain TOO much about a low in the mid 60s and a high near 80, though. Last March we were still hitting the mid 40s late in the month.

Cold is not all bad. I like cold. Hot weather means more mosquitoes and less starwatching for me.

[srainhoutx]

The GFS and Canadian continue to advertise a decent chance of rain/storms beginning Tuesday afternoon/evening and continuing into Thursday. The ECMWF suggests a drier pattern, but all the guidance is hinting at a strong cold front mid next week. SPC is hinting a Slight Risk for severe storms as well for our general area in the medium range as well...

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0344 AM CDT SAT MAR 26 2011

VALID 291200Z - 031200Z

...DISCUSSION...

THE LARGE SCALE PATTERN WILL REMAIN CHARACTERIZED BY PROGRESSIVE
QUASI-ZONAL FLOW ACROSS THE SRN TWO THIRDS OF THE COUNTRY THROUGH AT
LEAST DAY 5. HOWEVER...SIGNIFICANT MODEL DIFFERENCES AND RUN TO RUN
DISCREPANCIES EXIST REGARDING AMPLITUDE AND TIMING OF WAVES WHICH
LOWERS OVERALL PREDICTABILITY IN THE EXTENDED RANGE.

DAY 4...MODEL CONSENSUS IS THAT A SHORTWAVE TROUGH WILL MOVE FROM
THE CNTRL PLAINS INTO THE OH VALLEY. WEAK CYCLOGENESIS IS FORECAST
BY ECMWF WITH THE SURFACE LOW MOVING FROM THE SRN PLAINS INTO THE TN
VALLEY BY THE END OF THE PERIOD...WHILE COLD FRONT SWEEPS SEWD
THROUGH TX AND THE LOWER MS VALLEY. THE GFS IS MUCH STRONGER WITH
ITS SURFACE LOW DEVELOPMENT...BUT GIVEN LIKELIHOOD THAT STRONGER
FORCING ASSOCIATED WITH THE PROGRESSIVE WAVE WILL REMAIN IN COOL
SECTOR...LOW LEVEL RESPONSE WILL PROBABLY BE WEAKER SUPPORTING THE
ECMWF SOLUTION. IN EITHER CASE...SOME THREAT FOR SEVERE WEATHER WILL
EXIST IN WARM SECTOR FROM ERN TX INTO THE LOWER MS VALLEY WHERE A
MODERATELY UNSTABLE WARM SECTOR WILL RESIDE AND SHEAR WILL BE
SUPPORTIVE OF ORGANIZED STORMS ALONG AND AHEAD OF SEWD MOVING COLD
FRONT. PORTIONS OF ERN TX INTO THE LOWER MS VALLEY MAY NEED TO BE
INCLUDED IN A RISK AREA IN LATER OUTLOOKS.

DAY 6-7...ENSEMBLE SPREADS AND MODEL DIFFERENCES BECOME LARGE WITH
REGARD TO UPPER TROUGH FORECAST TO AMPLIFY OVER THE SERN STATES. GFS
IS SLOWER AND MORE AMPLIFIED...DEVELOPING A DEEPER SURFACE LOW OVER
THE NERN GULF COASTAL REGION...WHILE THE ECMWF HAS TRENDED TO A LESS
AMPLIFIED...WEAKER SOLUTION. SOME THREAT FOR SEVERE WEATHER COULD
EVOLVE ACROSS FL DAY 6...BUT PREDICTABILITY IS TOO LOW AT THIS TIME
GIVEN THE DISPERSIVE MODEL SOLUTIONS.

..DIAL.. 03/26/2011