March - Slow Warming Trend With Rain Chance This Weekend?

[srainhoutx]

The overnight guidance continues to flip flop with the handling of the weekend strong cold front and embedded short waves moving inland along the Pacific NW Coast and dropping SE into the Plains. The general trend has been to slow the strong cold front down by about 12-18 hours, but much uncertainty remains in the eventual forecast. A slower progression may lend to slightly better rain chances as the dry line across West Texas moves E slower and longer fetch Gulf moisture return, but capping issues are still a big question mark. Additional Winter Storm RECON has been tasked from Anchorage for the next couple of days fly over the N Pacific/Gulf of Alaska to assist the computer models, so hopefully clarity can be gained be that additional data.


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 AM EDT TUE MAR 19 2013

VALID 12Z FRI MAR 22 2013 - 12Z TUE MAR 26 2013

...OVERVIEW...

THE HIGH LATITUDE BLOCKING IN PLACE THROUGH THE WEEKEND MAY
FINALLY SHOW SIGNS OF BREAKING DOWN BY THE END OF THE MEDIUM RANGE
PERIOD. THE VERY NEGATIVE AO WILL KEEP A WINTER-LIKE PATTERN OVER
THE CENTRAL/EASTERN CONUS WHILE THE SOUTHWEST ENJOYS THE BENEFITS
OF UPPER RIDGING FROM THE NORTHEAST PACIFIC. THE ATMOSPHERE SEEMS
PRIMED FOR ANOTHER ROBUST SYSTEM NEAR THE EAST COAST BY ABOUT
MON/D6... BUT MUCH DISAGREEMENT REMAINS.


...MODEL/ENSEMBLE EVALUATION...

FOR SEVERAL DAYS THE STICKING POINT TO THE FORECAST LIED IN THE
WAY THE MODELS/ENSEMBLES HANDLED WESTERN CONUS ENERGY DROPPING OUT
OF THE THE ROCKIES AND INTO THE SOUTHERN PLAINS FRI-SAT/D3-4 AS IT
TURNS EASTWARD. THE ECMWF/ECENS MEAN HAVE SUGGESTED A SUPPRESSED
POLAR FRONT ALONG THE GULF COAST WITH SFC WAVE DEVELOPMENT NEAR
THE SOUTHEAST/CAROLINA COAST. THE GEFS MEAN HAD BEEN FARTHER NORTH
WITH ITS POSITION SEVERAL DAYS AGO BUT HAS DRIFTED SOUTH IN RECENT
RUNS AND NOW LIES CLOSE TO THE ECMWF ENSEMBLE MEAN. THE
DETERMINISTIC MODELS HAVE BEEN MUCH LESS CONSISTENT... WITH THE
ECMWF BUT ESPECIALLY THE GFS GENERALLY TRENDING TOWARD A DEEPER
AND FARTHER NW SFC LOW IN TANDEM... BUT MILES APART. THE 18Z GFS
AND 12Z UKMET TAKE THE MAIN SFC LOW INTO THE CENTRAL MS VALLEY
BEFORE DEVELOPING ANOTHER COASTAL CYCLONE ALONG THE FRONTAL
BOUNDARY /MILLER TYPE B DEVELOPMENT/. GIVEN ONGOING WPC CONTINUITY
AND THE AGREEMENT BETWEEN THE GEFS AND ECMWF ENSEMBLE MEANS HAVE
OPTED TO STAY NEAR THE ECMWF THINKING IN THE EAST THROUGH ABOUT
SAT/D4 BEFORE TRANSITIONING TO THE ENSEMBLE MEANS. THE NAEFS MEAN
ACTUALLY SHOWED A GOOD COMPROMISE BETWEEN THE GEFS AND ECENS MEANS
WITH ITS DEEPER SFC PRESSURES. THE POTENTIAL IS CERTAINLY THERE
FOR A SIGNIFICANT SYSTEM SOMEWHERE IN/NEAR THE EAST SUN-MON/D5-6
AS SOME ENSEMBLE MEMBERS BOMB THE SYSTEM INTO THE 980S /GEFS/ OR
EVEN THE 960S /ECENS/. COLD TEMPERATURES ARE EXPECTED TO PERSIST
EAST OF THE ROCKIES AND NORTH OF THE POLAR FRONT... SPARING SOUTH
FLORIDA UNTIL NEXT WEEK.

IN THE WEST... ENSEMBLES SHOW POOR AGREEMENT OVER THE NORTHEAST
PACIFIC WITH INCOMING ENERGY OVER THE WEEKEND. DETERMINISTIC
MODELS HAVE NOT BEEN CONSISTENT EITHER OVER THE PAST TWO DAYS SO
HAD TO COMPROMISE BETWEEN THE GEFS/ECENS WHICH WORKED OUT WELL
CONSIDERING A SIMILAR COMPROMISE IN THE EAST.


FRACASSO




DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0355 AM CDT TUE MAR 19 2013

VALID 221200Z - 271200Z

...DISCUSSION...
MEDIUM RANGE MODELS EXHIBIT RUN-TO-RUN INCONSISTENCY --LENDING
APPRECIABLE UNCERTAINTY-- ON THE EVOLUTION OF A DEVELOPING UPPER
TROUGH AND ASSOCIATED DIGGING JET STREAK ACROSS THE ROCKIES DURING
THE FRIDAY-SATURDAY /D4-D5/ PERIOD. OF NOTE...THE ECMWF SHOWS A
FARTHER S SOLUTION IN THE PLACEMENT OF A RESIDUAL FRONTAL ZONE OVER
TX/LA...WHEREAS THE GFS SHOWS THIS BOUNDARY ADVANCING FARTHER N AS A
WARM FRONT. THIS WOULD HAVE A SIZABLE IMPACT REGARDING THE SPATIAL
FOOTPRINT OF A DEVELOPING WARM/MOIST SECTOR. NONETHELESS IT APPEARS
MODELS ARE TRENDING TOWARDS A SEVERAL DAY RETURN FLOW INTO THE NWRN
GULF BASIN...WHICH WOULD SUPPLY A MORE MOISTURE-RICH LOW-LEVEL
AIRMASS INTO PORTIONS OF TX/OK AND LOWER MS VALLEY BY DAY 4 AND DAY
5...RESPECTIVELY. ANY SEVERE POTENTIAL DAY 6 FARTHER E OVER THE
DEEP SOUTH IS INHERENTLY MORE UNCERTAIN GIVEN MODEL TIMING/PLACEMENT
DIFFERENCES. DESPITE MORE FAVORABLE SIGNALS FOR SEVERE IN THE
EXTENDED PERIOD...CONSIDERABLE UNCERTAINTY PRECLUDES POSSIBLE AREAS
FROM BEING HIGHLIGHTED ATTM.

..SMITH.. 03/19/2013

03192013 00Z Euro Ensembles 00zECMWFENS500mbHeightAnomalyNA120.gif

03192013 00Z GEFS 00zgfsensembles500mbHeightAnomalyNA120.gif

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT TUE MAR 19 2013

VALID 191300Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS CENTRAL/S TX...

...SYNOPSIS...
THROUGH REMAINDER PERIOD...BROAD SWATH OF CYCLONIC FLOW WILL
CHARACTERIZE UPPER-AIR PATTERN ACROSS ROUGHLY ERN 2/3 OF CONUS...E
OF PROGRESSIVE SYNOPTIC RIDGE NOW CROSSING PAC COAST. BY
20/12Z...THIS RIDGE SHOULD EXTEND FROM AZ-AB. ANCHORING CYCLONIC
GYRE NOW CENTERED OVER LS AREA SHOULD MEANDER ERRATICALLY NEAR LS
BEFORE EJECTING ON DAY-2. WEAK PERTURBATION IS EVIDENT IN MOISTURE
CHANNEL IMAGERY E OF RIDGE...OVER PORTIONS CENTRAL/SERN NV. THIS
FEATURE IS FCST TO MOVE ESEWD ACROSS SRN ROCKIES TODAY...REACHING
SRN PORTIONS TX PANHANDLE AND ADJOINING SOUTH-PLAINS REGION AROUND
00Z...THEN LA/LOWER DELTA REGION BY END OF PERIOD.

AT SFC...COLD FRONT WAS DRAWN AT 11Z FROM WRN SC SWWD ACROSS CENTRAL
FL PANHANDLE TO N-CENTRAL GULF...BECOMING QUASISTATIONARY OVER NWRN
GULF OFFSHORE TX/LA TO NEAR BRO. FRONT AND RELATED THERMAL/THETAE
GRADIENTS ARE EXPECTED TO BECOME DIFFUSE AND RETREAT NWD SOMEWHAT
TODAY OVER S TX.

...CENTRAL/S TX...
ISOLATED TO WIDELY SCATTERED TSTMS MAY DEVELOP LATE THIS AFTN OVER
PORTIONS EDWARDS PLATEAU REGION AND WRN HILL COUNTRY...INITIALLY
HIGH-BASED WITH POTENTIAL FOR HAIL AND STG TO MRGLLY SVR GUSTS.
CONVECTIVE COVERAGE IS FCST TO INCREASE THROUGH EVENING...POSSIBLY
INCLUDING UPSCALE EXPANSION OF ANY LATE-AFTN ACTIVITY...LEADING TO
INCREASING COVERAGE/DENSITY OF LARGE HAIL THREAT IN PARTICULAR.
MAIN CONTRIBUTING FACTORS FOR RELATED OUTLOOK UPGRADE INCLUDE...
1. APCHG MID-UPPER SHORTWAVE TROUGH AND RELATED SUBTLE LARGE SCALE
ASCENT INCREASE MIDLEVEL INSTABILITY AND REINFORCE ALREADY STEEP
LAPSE RATES ALOFT...
2. LOW-LEVEL MOISTURE CONTINUES TO INCREASE ALONG AND N OF FRONT IN
ZONE OF ISENTROPIC ASCENT...MOISTURE TRANSPORT AND ELEVATED WAA...
3. ISALLOBARIC PROCESSES ON BOTH SIDE OF BOUNDARY LEADING TO
INCREASING CONVERGENCE AND FRONTOGENETIC FORCING...AND
4. VERY CONSISTENT TIMING AND GEN MESOSCALE REGION OF TSTM
DEVELOPMENT AND UPSCALE GROWTH THIS EVENING AMONGST LATEST
OPERATIONAL PROGS...MAJORITY OF SREF MEMBERS...AND
CONVECTION-ALLOWING/HIGH-RES GUIDANCE.

LOW-LEVEL MOIST ADVECTION -- BOTH AT AND ABOVE SFC -- SHOULD BE
SUFFICIENTLY STRONG TO OFFSET AFTERNOON DIABATIC HEATING/MIXING IN
SUPPORT OF CONVECTIVE POTENTIAL. MEANWHILE...VEERING/INCREASING
FLOW WITH HEIGHT THROUGH MOST OF LOWER-MIDDLE TROPOSPHERE SHOULD
LEAD TO 50-60 KT EFFECTIVE SHEAR MAGNITUDES...INDICATING POTENTIAL
FOR SUPERCELLS. ACTIVITY SHOUDL SHIFT EWD TO ESEWD TOWARD MID-UPPER
TX COASTAL PLAIN OVERNIGHT...WITH GEN DECREASE IN ORGANIZED SVR
THREAT INTO SE TX.

..EDWARDS/ROGERS.. 03/19/2013

[srainhoutx]

The 12Z WRF/NMM does suggest storms will develop later this afternoon near the Hill Country and slowly move ESE toward Metro Houston before diminishing. Hail appears to be the main threat from these strong to severe elevated storms.

03192013 12Z WRF NMM f18.gif

03192013 12Z WRF NMM f24.gif

[Andrew]

We are launching around 6pm today. Will try and post the results when we get them.

[Katdaddy]

Maybe, just maybe.........

MESOSCALE DISCUSSION 0287
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CDT TUE MAR 19 2013

AREAS AFFECTED...CNTRL THROUGH SERN TX

CONCERNING...SEVERE THUNDERSTORM WATCH 56...

VALID 200059Z - 200230Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 56
CONTINUES.

SUMMARY...TENDENCY SHOULD BE FOR STORMS TO DEVELOP SEWD THROUGH
CNTRL AND SCNTRL TX THROUGH THE EVENING. SOME OF THE STORMS WILL
EVOLVE INTO SUPERCELLS WITH A THREAT FOR ISOLATED LARGE HAIL AND
DAMAGING WIND. SOME POTENTIAL ALSO EXISTS FOR ACTIVITY TO
CONSOLIDATE INTO A SMALL MCS LATER THIS EVENING.

DISCUSSION...EARLY THIS EVENING A FRONT EXTENDS FROM SWRN LA WWD
THROUGH SCNTRL TX NEAR AUSTIN AND FARTHER WEST TO SOUTH OF SAN
ANGELO AND WINK. THIS BOUNDARY HAS BEGUN TO ACCELERATE SWD AS A COLD
FRONT. THE WARM SECTOR REMAINS MODERATELY UNSTABLE /1000-1500 J/KG
MLCAPE/ WITH MARGINAL INSTABILITY /AOB 1000 J/KG MUCAPE/ JUST TO THE
COOL SIDE. EML HAS ADVECTED THROUGH SCNTRL AND S TX RESULTING IN
STRONG CONVECTIVE INHIBITION. THIS SUGGESTS MOST IF NOT ALL
THUNDERSTORM DEVELOPMENT WILL REMAIN CONFINED TO ZONE OF DEEPER
ASCENT NORTH OF THE FRONT AS IT CONTINUES SWD WITH A NET SEWD STORM
MOTION. THESE STORMS WILL BE ELEVATED...BUT SUFFICIENT EFFECTIVE
SHEAR EXISTS TO SUPPORT SOME SUPERCELL STRUCTURES. OBSERVATIONS AND
POINT FORECAST SOUNDINGS INDICATE 15-20F TEMPERATURE-DEWPOINT
SPREADS IN THE COOLER BOUNDARY LAYER NORTH OF FRONT WHICH MIGHT AID
COLD POOL FORMATION AND EVENTUAL UPSCALE MCS GROWTH IF A SUFFICIENT
NUMBER OF STORMS CAN DEVELOP.

[Andrew]

Pretty decent CAP:

[jasons2k]

I don't think it's going to happen tonight - radar trends not so good for us - I just watered the plants.

[jasons2k]

Ray of hope. Storms seem to be on the increase again just west of Austin (instead of falling apart), and HGX Level II radar shows the front moving back south across Montgomery & Liberty Counties, likely placing at least my area north of the boundary overnight as the disturbance moves across.

[jasons2k]

Yeah, that sounding is not looking good, especially since it's NW of here too.

[txflagwaver]

A little rain would certainly be nice. Misty/foggy here but nothing hitting the ground

[unome]

some ugly hail-producung stuff moving into west Harris Co

http://www.srh.noaa.gov/ridge2/

http://www.srh.noaa.gov/hgx/



SEVERE THUNDERSTORM WARNING
TXC015-157-201-473-200815-
/O.NEW.KHGX.SV.W.0012.130320T0728Z-130320T0815Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
228 AM CDT WED MAR 20 2013

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
EXTREME SOUTHEASTERN AUSTIN COUNTY IN SOUTHEAST TEXAS...
NORTHWESTERN FORT BEND COUNTY IN SOUTHEAST TEXAS...
EXTREME SOUTHWESTERN HARRIS COUNTY IN SOUTHEAST TEXAS...
SOUTHERN WALLER COUNTY IN SOUTHEAST TEXAS...

* UNTIL 315 AM CDT

* AT 227 AM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING LARGE HAIL UP TO PING PONG BALL SIZE AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR
BROOKSHIRE...AND MOVING SOUTHEAST AT 40 MPH.

* LOCATIONS IMPACTED INCLUDE...
MISSION BEND...SUGAR LAND...ROSENBERG...PECAN GROVE...KATY...
RICHMOND...STAFFORD...TOWN WEST...MEADOWS...BROOKSHIRE...PLEAK...
SIMONTON...FULSHEAR...BEASLEY...PATTISON AND ORCHARD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS STORM HAS A HISTORY OF PRODUCING GOLF BALL SIZE HAIL. SEEK
SHELTER NOW INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

&&

LAT...LON 2991 9595 2965 9552 2940 9588 2985 9609
TIME...MOT...LOC 0728Z 311DEG 33KT 2976 9595

$$

39

[Metro4001]

STRONG storm blowing in. I've never seen a streak of purple on the radar, just a spot or two. And this is my first time EVER seeing black on the radar. Actually both excited and nervous.

[Katdaddy]

Lots of golfball size hail and creating damage reported in Brookshire earlier this morning.

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
508 AM CDT WED MAR 20 2013

TXC039-157-321-481-201030-
/O.CON.KHGX.SV.W.0014.000000T0000Z-130320T1030Z/
FORT BEND TX-BRAZORIA TX-MATAGORDA TX-WHARTON TX-
508 AM CDT WED MAR 20 2013

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 AM CDT
FOR FORT BEND...WEST CENTRAL BRAZORIA...EXTREME NORTHEASTERN
MATAGORDA AND NORTHEASTERN WHARTON COUNTIES...

AT 506 AM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM
WAS LOCATED NEAR EAST BERNARD...OR 15 MILES WEST OF ROSENBERG...
MOVING SOUTHEAST AT 45 MPH.

LOCATIONS IMPACTED INCLUDE...
ROSENBERG...RICHMOND...NEEDVILLE...EAST BERNARD...BOLING-IAGO...
PLEAK...BEASLEY...KENDLETON...ORCHARD...AND THOMPSONS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 60 MILES
PER HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY RAIN.
FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF
YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT
DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

[srainhoutx]

The AO reached record territory yesterday near 5 standard deviations below normal for March. A very progressive pattern is ahead with an active flow as a series of upper air disturbance drop SE from the Pacific NW into the Great Basin/Southern Rockies carving out a deep trough for the Central/Eastern US this weekend into next week. The next chance of rain appears to come Friday into Saturday as the strongest of the upper air features drops into New Mexico and translates E. Temps will rebound on Thursday as a return flow off the Gulf becomes established and W to SW winds aloft take hold as pressures fall ahead of this deeper 5H low. Capping looks to be the main inhibitor, but that cap may erode enough to bring showers and storms late Friday into Saturday before a strong Polar front sweeps across our Region and brings much cooler temps for Saturday night into early next week. The fly in the ointment may be a slow meandering upper low off the Baja of NW Mexico that some of the guidance develop. Cool and comfortable daytime temps with chilly nights appear likely as we enter the last week of March.

[Houstonkid]

Picked-up a nice .80" from that storm overnight, Mason/Clay Rd. area.

[jasons2k]

Are we just using this thread now? The "local" thread is dead.

[srainhoutx]

Are we just using this thread now? The "local" thread is dead.

We can use the local thread for Jeff's e-mails and if the KHOU Weather Team has some interesting tidbit to post about the local weather and any that care to inquire or make posts there. The consensus from the poll was to keep one monthly thread for the entire Region, so that is probably why the local thread is dead. I picked up about .20 inches of rain with floating pollen on top in the old rain bucket. The good news is we washed away some of the pollen that has be terrible the past week or so.

[Katdaddy]

Thanks Srain. I was wondering if I should have posted the Severe Thunderstorm Warning on this thread. Its basically a flip of the coin......the post would have been fine on either thread.

I only picked up .10". I guess a little moisture is better than none.

On a side note the Red Cross is having is yearly Prepardness on the Square Thursday in front of the Houston City Hall from 11AM-1PM. David Paul will there meet everyone. I will go by and meet Paul during lunch tomorrow.

[srainhoutx]

Morning e-mail from Jeff:

Fairly active night across the region with numerous reports of hail damage mainly west and northwest of the metro Houston area.

Clusters of severe storms that were prodigious hail producers have weakened and moved offshore this morning as the short wave disturbance aloft moves eastward ending lift. At the surface a weak frontal boundary which helped focus much of the overnight activity has moved into the coastal waters with a cooling and drying of the air mass once again over the region. Should see skies slowly clear out by late morning to early afternoon as subsidence behind the departing disturbance takes over. Dry and cool weather will be in place today and Thursday followed by a rapid return of SE winds and low level moisture/humidity. Overnight lows rise from near 50 on Thursday morning to the low 60’s on Friday morning under increasing low level clouds and warm air advection off the western Gulf.

Rain chance sneak back into the forecast on Saturday as the next cold front and disturbance move across the state. Not liking the model forecast soundings of a developing warm nose in the mid levels…the dreaded cap that has been so ever present early in 2013 and basically shut down rainfall across the region. Models try and erode this capping inversion allowing some convection Saturday afternoon, but I am not ready to buy into that just yet given the track record of rainfall lacking storm systems this year so far. Otherwise the cold front should push off the coast with clearing and cooler conditions by midday Sunday.

Storm Reports:

Lexington, Lee: 2.0 inch hail shattered passenger side car window

3SSE Lexington, Lee: 1.50 inch hail dents cars…reported by CoCoRaHS observer

Burton, Washington: 1.75 inch golf ball size hail in the town of Burton

7WNW Somerville, Burleson: 60mph wind gust via trained spotter

8WNW Somerville, Burleson: Ping Pong ball size hail

Bellville, Austin: Golf ball size hail across town, some damage to roofs and windows

Brookshire, Waller: Penny to Golf ball size hail. Numerous windows knocked out. 50% of town without power. Hail covering the ground to several inches.

Brenham, Washington: marble size hail for 20-30minutes. Hail covered the entire ground, still on the ground 5 hours later.

[wxman57]

This cold weather is getting quite old. It's spring now, bring on some heat! Don't see anything in the latest GFS to indicate any significant warmth here, though.