March: Comfortable Weekend Weather & Warming Trend

[wxman57]

I've measured a bit over 2.8" of rain so far in February. Not bad for a drought. Could see a line of showers/storms across Houston Sunday evening ahead of the front.

[Paul Robison]

[quote="srainhoutx"]A potent storm system currently offshore of California will advance inland on Saturday as it treks E on Sunday ahead of a deepening Central/Eastern US trough setting the stage for a potential severe weather episode on Sunday basically from Austin on E across SE and E Texas mainly N of I-10 where there are growing indications the capping inversion will erode. A very strong RRQ 110kt jet could allow for strong to severe storms to develop and quickly shift E into Louisiana Sunday afternoon/evening as a strong Polar front drops S. The Storm Prediction Center has placed a Day 3 Slight Risk for Severe Storms across potions of the Eastern half of Texas extending E into Louisiana to around Baton Rogue. The primary threat appears to be damaging straight line winds with some hail and a possible quick spin up of a tornado or two with the veering winds aloft.

The main concern is the strong cap and if it can erode and how quickly the Polar front arrives as suggested by the short term meso models. The severe threat looks a bit less S of I-10 this morning, but will need to be monitored as the storm system moves onshore tomorrow. The primary concern appears to be a squall line or linear storms -vs- rotating super cells, but if the cap does erode quicker across E Texas and Western Louisiana then some discrete rotating super cells may be possible Sunday afternoon.

Much colder air will arrive Sunday night with a possible freeze across our Northern zones early Monday. A very active pattern continues into mid next week as a Coastal Low develops Tuesday into Wednesday offering additional rain chances before we settle down and begin a slow warming trend by the end of next week.


Dear Srainhoutex:

In other words (?) we will begin the day capped but I expect the inversion to break beginning late morning across the Northwestern counties. Cape values: 1000-1200 J/KG and strong low level shear.

Here are some of my worries that I would like to hear your thoughts on:

How far south do YOU think the cap will erode? Will areas generally south of I-10 likely STAY capped?

The NAM believes ALL of SE TX will be uncapped with a massive squall line blasting through H-town. Would the NAM's solution be the more likely one, or could it be going just a tad too fast with this front?

Hope to hear from you soon!

[cristina6871]

what might be the timeline for these possible severe possible storms? Plan to ride it out at the parents' house.

[Paul Robison]

what might be the timeline for these possible severe possible storms? Plan to ride it out at the parents' house.

Where are you located? ATTM areas northeast of Houston stand the best chance of seeing severe storms.

[cristina6871]

what might be the timeline for these possible severe possible storms? Plan to ride it out at the parents' house.

Where are you located? ATTM areas northeast of Houston stand the best chance of seeing severe storms.

I am in The Woodlands area - so are the parents. About 10-15 miles south of Conroe and Hwy 105 area.

[srainhoutx]

As is very typical with Pacific storms systems the overnight guidance continues to struggle with the severe dynamics and the 00Z suite of both meso (short range) and global operational computer models have shifted the severe threat further NE across basically the Lake Livingston area toward Lufkin and on NE toward Shreveport. Capping issues appear to erode Sunday afternoon, but the more favorable dynamics have shifted further NE. The SPC has expanded the Slight Risk area a bit further W and also N and extended the Eastern flank slightly. My hunch with the powerful storm system just now reaching the Central California Pacific Coast is that we may see a strong line of storms as the front sweeps across our Region and that could lead to some isolated straight line wind issues. We will see what the day brings, but I did notice some wild weather videos from California last evening as waves of heavy rains and flash flooding were creating problems as far S as the Los Angeles Metro area as the storm system was still well offshore and sending waves of storms and heavy rainfall inland. The storm complex doesn't appear as tightly wrapped up this morning as it did yesterday, but is send abundant Pacific moisture across the Desert SW and on E towards the Central and Southern Rockies. A large chunk of real estate in the cold sector is going to see on heck of an ice storm extending E into the Mid Mississippi and Ohio Valley Region and even further E along the Atlantic Coast I-95 Corridor on Monday. I wouldn't be surprised to see significant air travel delays on Monday across a large portion of the Eastern half of the US.

[wxman57]

[quote="cristina6871"]what might be the timeline for these possible severe possible storms? Plan to ride it out at the parents' house. [/quote]

Best chance for storms will be between sunset and midnight tomorrow evening.

[srainhoutx]

The concern is growing for the potential of a rather significant freezing rain/sleet event ~vs~ a severe weather event as the trends this morning via the the shorter term meso guidance. Those shorter term models are suggesting the shallow Arctic air mass arrives quicker and undercuts the warm layer at the surface therefore suggesting a quickly moving line of showers and storms with the potential of a bit of post frontal precip in the form of ice across portions of the Northern Hill Country extending E into the ArkLaTex Region and on E.

[Katdaddy]

Latest from the SPC. 30% hatched area moved S to Houston metro for tomorrow:
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CST SAT MAR 01 2014

VALID 021200Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL TO EAST
TX...LA...SRN AR AND SW MS...

...SRN PLAINS/LOWER MS VALLEY...
AN UPPER-LEVEL TROUGH WILL QUICKLY PROGRESS EWD INTO THE SRN PLAINS
ON SUNDAY. AT THE SFC...A STRONG COLD FRONT WILL ADVANCE SWD ACROSS
THE SRN PLAINS AND ARKLATEX BEING POSITIONED FROM NEAR THE TX HILL
COUNTRY NEWD ACROSS EAST TX TO NEAR THE AR-LA STATE-LINE BY
AFTERNOON. WIDESPREAD ELEVATED CONVECTION SHOULD BE ONGOING NORTH OF
THE BOUNDARY FROM THE RED RIVER VALLEY NEWD INTO THE OZARKS. FURTHER
SOUTH ALONG AND JUST AHEAD OF THE BOUNDARY...THE MODELS DIFFER
CONCERNING THE TIMING OF INITIATION AND CONVECTIVE COVERAGE. THE NAM
AND WRF-NMM4 SOLUTIONS KEEP CONVECTIVE COVERAGE MINIMIZED THROUGH
LATE AFTERNOON WHILE THE GFS AND ECMWF APPEAR TO DEVELOP A LINE OR
CLUSTER OF THUNDERSTORMS ALONG THE FRONT...MOVING THIS CONVECTIVE
SYSTEM SEWD ACROSS THE SLIGHT RISK AREA EARLY SUNDAY EVENING. DUE TO
THE DIFFERENCES IN MODEL SOLUTIONS...THERE APPEARS TO BE UNCERTAINTY
CONCERNING THIS UPCOMING EVENT.

GFS FORECAST SOUNDINGS AT 00Z/MONDAY IN SOUTHEAST TX SHOW SFC
DEWPOINTS IN THE MID TO UPPER 60S F WITH LAPSE RATES FROM 700 TO 500
MB NEAR 7.5 C/KM. THIS SHOULD BE ENOUGH FOR A POCKET OF MODERATE
INSTABILITY LATE SUNDAY AFTERNOON FROM NEAR COLLEGE STATION SWD TO
THE UPPER TX COAST WHERE MUCAPE SHOULD REACH THE 1000 TO 1500 J/KG
RANGE. IN ADDITION...0-6 KM SHEAR WILL INCREASE TO 50 TO 60 KT
ACROSS SE TX AS THE UPPER-LEVEL SYSTEM APPROACHES MAKING CONDITIONS
SUPPORTIVE OF SEVERE STORMS. SUPERCELL DEVELOPMENT WILL BE POSSIBLE
DUE TO THE STRONG DEEP LAYER SHEAR BUT A QUICK TRANSITION TO A
LINEAR CONVECTIVE SYSTEM SEEMS LIKELY ALONG THE FRONT DUE TO STRONG
LOW-LEVEL CONVERGENCE. IF A LINEAR MCS CAN ORGANIZE...THEN A
SUBSTANTIAL WIND DAMAGE THREAT MAY DEVELOP SUNDAY AFTERNOON. THE
POTENTIAL FOR AN ENHANCED WIND DAMAGE THREAT APPEARS MOST LIKELY
FROM AUSTIN EXTENDING EWD INTO WRN LA AND SWD TO THE HOUSTON AREA.
HAIL WILL ALSO BE POSSIBLE WITH THE MORE INTENSE CELLS WITHIN THE
LINE. A TORNADO OR TWO CAN NOT BE RULED OUT IF CELLS CAN REMAIN
DISCRETE FOR A FEW HOURS DURING THE AFTERNOON.

AT THIS POINT...UNCERTAINTY CONCERNING SEVERE THREAT COVERAGE IS
SUBSTANTIAL. IF THE COLD FRONT MOVES SWD INTO THE SRN PLAINS FASTER
THAN FORECAST...THEN THE SEVERE THREAT AREA WOULD BE SMALLER IN
REGIONAL EXTENT. THIS COULD ALSO REDUCE TO AREAL EXTENT OF
DESTABILIZATION IN TURN REDUCING SEVERE THREAT COVERAGE. DUE TO
THESE CONCERNS...HAVE REDUCED THE SIZE OF THE 30 PERCENT SEVERE
THREAT PROBABILITY TO FOCUS ON AREAS A BIT FURTHER SOUTH.

[srainhoutx]

A wonderful 82F in NW Harris County at this hour. What a shock to the old system is ahead with that Arctic boundary lurking across Oklahoma where temps are currently 21F in Boise City and in Dodge City, KS it is 16F. It is also interesting to see the freezing rain probabilities have increased rather dramatically for Monday for portions of SE Texas. We will see.

[srainhoutx]

Afternoon Update from Jeff:

Severe thunderstorms possible Sunday afternoon and evening.

A strong storm system currently moving through the SW US will eject across TX on Sunday. At the surface strong southerly flow is pumping Gulf moisture northward from the Bay of Campeche, while to the north a strong late season arctic high pressure dome is moving southward down the plains. Impressive cold front will slice across the region late Sunday afternoon returning winter to the area for much of next week.

Upper level system currently over the SW US will shear into TX on Sunday with fairly strong dynamics forecasted aloft. Low level jet increases to near 40kts from Matagorda Bay NNE across SE TX by early Sunday afternoon. Increased dewpoints in the mid to upper 60’s and steepening lapse rates support instability values of 1000 to 1500 J/kg of CAPE by mid afternoon. Think mid level warm layer (cap) will hold through at least 1-2pm and then begin to erode from both increasing lift and modest surface heating. GFS and ECMWF develop a line of strong the severe thunderstorms from near Austin ENE toward W LA by mid afternoon as the cap is overcome…however the NAM and some of the other short range guidance holds the cap longer over the region and does not develop as much activity. 0-6km shear values will be on the order 50-60kts across the region and this combined with the expected instability would result in severe thunderstorms.

Forecast models that do develop storms show initial mode east of I-35 as supercells with a large hail threat and then quickly transition toward a line with bowing segments which seems likely given the wind energy aloft. Initial supercells could have a slight tornado risk…but think the main threat will be large hail. Storms will move ESE across at least the northern ½ of the region Sunday evening likely becoming increasingly linear. Linear mode favors strong straight line wind damage along the leading edge of the line and in any bowing segments. If a well defined line develops could see a few corridors of wind damage in the region from east of Austin ESE north of US 290 northward toward Huntsville. Will have to watch for the potential for the arctic front to undercut the leading edge of the line and reduce the severe weather threat Sunday evening.

Timing continues to look from mid afternoon into mid to late evening. SPC slight risk includes about 75% of the area, but think capping to the SW will be too much to overcome and the main severe threat will be NE of a line from Austin to Columbus to Houston to High Island.

Other item is fairly impressive cold air advection with this system and expect cold temperatures Monday-Wednesday. Modified arctic air mass will be fully entrenched by Monday morning with lows in the 30’s across the entire area and possibly upper 20’s northern counties. Will see only modest recovery on Monday as strong north winds continue to transport cold air southward with highs likely in the upper 40’s and low 50’s….a big difference from the highs near 80 on Sunday.

SPC Day 2 (Sunday) Severe Weather Outlook:

03012014 Jeff image001.gif

[Paul Robison]

I like what texas storm chasers said:


What we think will happen is a line of storms will develop from DFW to Waco Sunday morning and that will push east into the afternoon. The cold front will likely undercut the storms, keeping them from getting that strong. If any storms can form ahead if the line, those could produce brief tornadoes. Overall, this is not going to be major event but you should stay alert to changing conditions.

right, srainhoutex?

[skidog40]

the temps up north are really cold, are we sure the forecast is right. Ive looked all year at temps this looks the coldest.

[ronyan]

the temps up north are really cold, are we sure the forecast is right. Ive looked all year at temps this looks the coldest.

The 0z GFS has come in a few degrees colder, now has 34F at IAH tomorrow night. About a 40 degree temperature drop is in store for tomorrow from a high in the 70s.

[ronyan]

Here's a snippet taken from tonight's HGX discussion:

IT`S ALL IN THE TIMING AND...CONSIDERING THE ANTICIPATED SHARP DECLINE
OF LATE DAY INTO EVENING NORTHERN COUNTY LOWER LEVEL TEMPERATURES...THERE
EXISTS A MENTIONABLE CHANCE FOR LIGHT FREEZING RAIN AND/OR DRIZZLE.
IF THIS FRONT IS AS AGGRESSIVE AS FORECAST...THEN MOST OF THE PRECIPITATION
WILL BE EAST OF THOSE COUNTIES WHERE THE MERCURY DIPS BELOW FREEZING.
WITH THAT BEING SAID...ANY LINGERING LIGHT PRECIPITATION WILL BE FALLING
THOUGH A SHALLOW NEAR SURFACE SUB-FREEZING LAYER. WET ELEVATED ROADWAYS/BRIDGES
MAY BECOME SLICK AS A THIN LAYER OF BLACK ICE FORMS UPON THOSE SURFACES.
THE WINDOW FOR THE BEST CHANCE OF FREEZING RAIN/DRIZZLE WILL BE FROM
9 PM THROUGH AROUND MIDNIGHT MONDAY. THE HWOHGX PRODUCT HAS BEEN UPDATED
TO INCLUDE THIS LATE SUNDAY NIGHT (TRAVELING) HAZARD. 31

[jasons2k]

For real? I was anticipating a low of about 35-36 so I cut everything back yesterday. Now the NWS has me at 32 tonight, with wind. Grrrr.

[srainhoutx]

The Arctic front appears to be pushing SE faster than expected and that suggests the severe potential would be a bit less except for areas across Metro Houston on E into Louisiana. The may threat appears to a some gusty winds and perhaps a very brief spin up of a tornado with the greatest threat E of Houston into Lake Charles and on E towards Baton Rogue late tonight.

The next interest is the freezing rain potential. It is not out of the question that a brief window for freezing rain may exist mainly N of I-10 and probably along a Columbus to Hempstead to Lake Livingston line with the faster arriving Arctic front. It is note worthy that additional upper level disturbances are lagging back to our W across Arizona and may offer an additional threat for freezing rain Monday evening/night across the Austin to College Station area. The inhibiting factor for any accumulation is the very warm ground temperatures and the warm weather we have seen that past couple of days. If and it is a big if, we see any problems with ice the time frame to watch would be on Monday and the mainly on elevated surfaces. The big weather story will likely be the big temperature drops in the order of 20 to 30 degrees as the front passes and the very gusty Northerly winds that will remind us that Winter 2013-2014 has one last gasp before we transition into Spring. I personally hope this winter is done. Those 80's yesterday sure felt good...

[srainhoutx]

Morning Update from Jeff:

Powerful arctic cold front will sweep across the region today with a significant drop in temperatures.

Arctic boundary is moving quickly southward this morning with a 30-40 degree temperature drop across the boundary (Austin is 72 while Waco is 35). Boundary will race southward and reach our NW counties before noon and push to near US 59 by 300-400pm and off the coast by early evening. Upstream temperatures at Amarillo are 8 and in the teens across much of OK so this air mass is very cold for early March.

Severe Threat:
Mornings soundings from LCH and CRP showed a fairly impressive capping inversion in place across the region with saturation of the air mass below the cap. With better moisture in place today…it will be hard to mix out the low stratus clouds over the region and suspect there will only be a few breaks in the overcast across the region which will keep instability on the lower side in the 800-1000J/kg instead of closer to 1500J/kg. Forecast models erode the cap this afternoon and allow convection to develop along the leading edge of the frontal lift. Think the arctic boundary will move too fast southward and outrun the developing storms cutting the updrafts off from the surface and making them quickly elevated which lessens the severe threat over the region. Could still see a few severe hail and wind reports especially NE of a line from College Station to Conroe to Liberty where capping will be weakest and storms have the best chance of being rooted near the surface.

Winter Precipitation:
Incoming air mass is very cold and forecast models have been too warm with upstream temperatures which raises the concern this evening that light rain following the frontal passage could change to freezing rain along a north of a HWY 105 line. Warm temperatures since Friday has greatly warmed both ground and roadway surface temperatures and even if temperatures fall into the 30-32 range do not think ice accumulation will be significant. With that said overnight lows will fall into the upper 20’s north of HWY 105 which may result in freezing over residual water on bridges and overpasses after the precipitation ends around midnight. Given very warm roadway surface conditions, think surface temperatures will need to fall into the 27-29 range for ice to form and this will be possible in the region from College Station to Lake Livingston after midnight.

Other aspect will be the potential for a freeze warning for areas N of I-10 tonight. While the area has had several hard freezes this winter the recent warm spells have allowed vegetation to bud and freezing temperatures will damage the new sensitive growth which would fall within the range of a late season freeze warning. Wind chills tonight will run 15-25 degrees across the area.

Early Week:
Cold arctic dome will entrench over the area for much of the week with active flow remaining in place from the WSW. This flow will bring several disturbances across the area and generate periods of rainfall. First disturbance will cross the area late Monday into Tuesday. Surface temperature profiles suggest mainly a rain event, but surface temperatures could be very near freezing Tuesday morning north of HWY 105 for a brief period of freezing rain or sleet. Highs on Monday will only reach the mid 40’s under north winds and cloudy skies (about 35 degrees colder than today). Next system approaches late Tuesday into Wednesday with another chance of rainfall across the area. Temperatures will remain cold for early March for most of the week with lows 30-35 Monday and Tuesday and highs only in the 40’s both Monday and Tuesday. Wednesday will again be cold with clouds and rain with lows in the upper 30’s and highs in the lower 50’s.

Should start to see a warming trend toward the end of the week ahead of yet another weather system next Saturday.

Day 1 Severe Weather Outlook:

[srainhoutx]

The SPC 09Z SREF continues to be very suggestive of a freezing rain/sleet potential across our Region early tomorrow morning and again mainly across Central Texas early Tuesday morning.

Valid 09Z Monday:

Valid 09Z Tuesday:

[Portastorm]

The SREF has shown something similar the last few runs. Yesterday's 15z run showed some light wintry mix for the AUS area late Mon into early Tues.

Cold front came through here about 45 minutes ago. Temperature has dropped from 71 to 53 in 30 minutes.