Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Mon Dec 17, 2007 9:57 pm
STORM2K
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Overnight Wednesday/Thursday Morning SE Texas Severe?
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Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Mon Dec 17, 2007 10:00 pm
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Mon Dec 17, 2007 11:33 pm
almost day old SWODY3 snippet
...ARKLATEX REGION TO UPPER TX/LA COAST...
SVR TSTMS MAY DEVELOP MAINLY DURING LATTER HALF OF PERIOD
ALONG/AHEAD OF COLD FRONT/DRYLINE...POTENTIAL BEING VERY CONDITIONAL
ON CHARACTER OF RETURN FLOW. BROAD SFC ANTICYCLONE NOW CENTERED
OVER W GULF COAST REGION IS FCST TO SHIFT NEWD OFF CAROLINA COAST
WITH STRONG RIDGING STILL TRAILING SWWD AS FAR BACK AS MS/AL BY
ABOUT 19/06Z. ASSOCIATED TRAJECTORIES INDICATE MOST FAVORABLE AIR
MASS MODIFICATION WILL REMAIN OVER GULF THROUGH PERIOD.
HOWEVER...INCOMPLETELY MODIFIED AIR MASS WITH MIX OF MARINE AND
CONTINENTAL TRAJECTORIES MAY RESULT IN LOW 60S DEW POINTS INLAND
ACROSS MUCH OF E TX...LA AND PERHAPS SWRN MS BY 20/12Z. ACCORDINGLY
MODIFIED NAM/NAM-KF FCST SOUNDINGS INDICATE EFFECTIVE PARCELS MAY
BECOME SFC BASED UNDER MOST AGGRESSIVE RETURN FLOW
SCENARIOS...AMIDST STRENGTHENING LOW-LEVEL AND DEEP-LAYER SHEAR.
THEREFORE...MRGL SVR PROBABILITIES ARE INTRODUCED ATTM...WITH MORE
SPECIFIC SPATIAL REFINEMENTS AND PERHAPS UPGRADE POSSIBLE IN
SUBSEQUENT OUTLOOKS.
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Tue Dec 18, 2007 12:04 am
0Z GFS has over 1000 Joules/Kg CAPE Thursday morning.
Looks like low level winds may be a shade on the light side for tornadoes, but 1.5" PW in December, I'm sure the cloud bases would be low.
The NIU skew-T forecast looks like storms may be slightly elevated per GFS
Went with BPT sounding for WRF, as it looks like storms already in HOU by that model. Not an absolute knock out, but a 2.3 EHI ain't shabby
Edit to change 'a' to 'an' before 'absolute'
Looks like low level winds may be a shade on the light side for tornadoes, but 1.5" PW in December, I'm sure the cloud bases would be low.
The NIU skew-T forecast looks like storms may be slightly elevated per GFS
Went with BPT sounding for WRF, as it looks like storms already in HOU by that model. Not an absolute knock out, but a 2.3 EHI ain't shabby
Edit to change 'a' to 'an' before 'absolute'
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Tue Dec 18, 2007 1:51 am
SPC AC 180548
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1148 PM CST MON DEC 17 2007
VALID 191200Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SE TX AND SRN LA...
...SYNOPSIS...
PROGRESSIVE PATTERN FCST TO CONTINUE OVER CONUS THROUGH THE PERIOD.
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OFFSHORE
NRN CA NEAR 135W -- IS FCST TO MOVE ESEWD AND AMPLIFY SLIGHTLY
THROUGH MIDDLE OF DAY-2 PERIOD. TROUGH IS EXPECTED TO MOVE FROM SRN
GREAT BASIN AND LOWER CO RIVER VALLEY AROUND 19/12Z TO NEAR ARKLATEX
REGION 24 HOURS LATER.
MEANWHILE...SFC LEE TROUGHING SHOULD DEEPEN WITH CYCLONE FORMING
INVOF CO/OK BORDER BY 19/18Z. THIS LOW IS EXPECTED TO MOVE
ESEWD...GENERALLY ALONG RED RIVER AND ALONG DEVELOPING WARM FRONT
TOWARD PRX AREA BY END OF PERIOD. WEAK FRONTAL ZONE...ALSO ACTING
AS DRYLINE AND WLY WIND SHIFT BOUNDARY...IS EXPECTED TO DEVELOP AND
MOVE ESEWD ACROSS TX...EXTENDING FROM LOW ROUGHLY SWD ACROSS
MID/UPPER TX COAST BY 20/12Z.
...E TX TO LOWER MS VALLEY AND CENTRAL GULF COAST...
SCATTERED TSTMS IN BANDS OR CLUSTERS MAY DEVELOP LATE IN PERIOD --
PRIMARILY AFTER 20/03Z. MUCH OF THIS ACTIVITY -- PARTICULARLY WITH
MORE NWD/INLAND EXTENT -- WILL BE ELEVATED...WITH POTENTIAL FOR
ISOLATED HAIL. FAVORABLE BUOYANCY FOR THIS CONVECTION SHOULD RESULT
FROM STEEPENING OF LOW-MIDDLE LEVEL LAPSE RATES ASSOCIATED WITH
LARGE SCALE ASCENT/COOLING ALOFT...JUXTAPOSED WITH INCREASING
MOISTURE ABOVE BOUNDARY LAYER AND INVOF 35-45 KT LLJ. STRENGTHENING
KINEMATIC FIELDS ALOFT WILL INCREASE DEEP-LAYER SHEAR TO SUPPORT
SOME STORM ORGANIZATION.
POTENTIAL FOR SFC-BASED SVR TSTMS -- INCLUDING SUPERCELLS AND SMALL
BOWS -- SHOULD INCREASE WITH TIME OVERNIGHT...AND WITH SWD EXTENT
FROM WARM FRONT TOWARD GULF COAST. VERTICAL SHEAR SHOULD STRENGTHEN
WITH TIME IN WARM SECTOR...WRN BOUND OF SVR THREAT BEING COLD
FRONT/DRYLINE.
MOST CRITICAL ELEMENT FOR THIS FORECAST APPEARS TO BE QUALITY OF
MOISTURE RETURN FROM GULF...AND HOW FAR INLAND SUFFICIENT BOUNDARY
LAYER THETAE MAY PENETRATE TO SUPPORT NEARLY SFC-BASED EFFECTIVE
LIFTED PARCELS. 00Z OPERATIONAL WRF INITIALIZED SFC DEW POINTS
AROUND BUOY 42002 ROUGHLY 5 DEG F TOO HIGH...AND ABOUT 3 DEG TOO
HIGH NEAR BRO. THIS MODEL...AS WITH ITS PREDECESSOR ETA...HAS SHOWN
TENDENCY TO OVER-MOISTEN LEADING/NRN PORTION OF RETURN FLOW AIR MASS
IN COOL SEASON WITH IMPROVING MOISTURE FCSTG FARTHER S INTO RETURN
FLOW AIR MASS...AND SO FAR THIS TREND APPEARS TO BE CONTINUING.
THEREFORE CONFIDENCE IS LOWER IN CONVECTION ROOTED AT SFC CLOSE TO
WARM FRONT...AND GREATER ALONG AND NEAR COAST. GIVEN OPEN GULF DEW
POINTS APCHG EQUILIBRIUM AND MOST PROBABLE TRAJECTORIES FROM
NWRN/W-CENTRAL GULF...SFC DEW POINTS LOWER 60S SHOULD PENETRATE
INLAND WITH MID 60S POSSIBLE ALONG IMMEDIATE COASTAL AREAS.
ACCORDINGLY MODIFIED NAM-KF SOUNDINGS YIELD 500-1000 J/KG MLCAPE BY
20/12Z ALONG COAST...WEAKENING NWD ACROSS LA/MS.
..EDWARDS.. 12/18/2007
Link
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Tue Dec 18, 2007 1:39 pm
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CST TUE DEC 18 2007
VALID 191200Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF ERN TX INTO THE
LOWER MS VALLEY...
...SYNOPSIS...
SYNOPTIC PATTERN WILL REMAIN PROGRESSIVE THIS PERIOD. UPPER TROUGH
NOW APPROACHING WRN U.S. COAST WILL ADVANCE INTO THE CNTRL AND SRN
PLAINS WEDNESDAY NIGHT ACCOMPANIED BY A PACIFIC FRONT. THE FRONT
SHOULD EXTEND FROM A WEAK LEE LOW OVER OK SSWWD INTO SWRN TX BY THE
END OF THIS PERIOD. WARM FRONT WILL LIKELY DEVELOP INLAND AND EXTEND
SEWD FROM THE LOW THROUGH THE LOWER MS VALLEY WEDNESDAY NIGHT.
...ERN TX THROUGH LOWER MS VALLEY REGION...
SERN U.S. SURFACE HIGH WILL SHIFT EAST THROUGH WEDNESDAY...AND THIS
SHOULD EXPEDITE BOUNDARY LAYER RECOVERY OVER THE WRN GULF. LOW LEVEL
WINDS HAVE ALREADY SHIFTED TO SLY OFF THE TX COAST WITH LOW 60S
DEWPOINTS OBSERVED OVER DEEP SOUTH TX AND OFFSHORE. LOW LEVEL FLOW
WILL TEMPORARILY VEER TO WSWLY TUESDAY EVENING AS A LOW AMPLITUDE
UPPER TROUGH MOVES THROUGH THE PLAINS AND MS VALLEY. HOWEVER...THE
SLY LOW LEVEL JET WILL REDEVELOP OVER ERN TX WEDNESDAY EVENING IN
ADVANCE OF APPROACHING SHORTWAVE TROUGH. THIS WILL CONTRIBUTE TO
NEWD ADVECTION OF PARTIALLY MODIFIED GULF AIR. LOWER TO MID 60S
DEWPOINTS WILL LIKELY ADVECT INTO ERN TX AND THE LOWER MS VALLEY AS
THE WARM FRONT DEVELOPS INLAND. UPPER 60S DEWPOINTS WILL BE POSSIBLE
IN VICINITY OF THE TX AND LA COASTS. WSWLY FLOW DOWNSTREAM FROM
UPPER TROUGH WILL ADVECT STEEPER MID LEVEL LAPSE RATES OVER MOIST
AXIS...CONTRIBUTING TO DESTABILIZATION. MUCAPE FROM 500 TO 1000 J/KG
WILL BE POSSIBLE OVERNIGHT. INCREASING DEEP LAYER ASCENT AHEAD OF
UPPER TROUGH AND ALONG LOW LEVEL JET AXIS WILL RESULT IN DEVELOPMENT
OF THUNDERSTORMS WEDNESDAY NIGHT. MOST OF THE STORMS INLAND WILL
LIKELY BE ELEVATED ABOVE A SHALLOW SURFACE INVERSION WITH A THREAT
FOR MAINLY LARGE HAIL. HOWEVER...DEPENDING ON THE DEGREE OF MOISTURE
RETURN...SOME STORMS DEVELOPING NEAR THE COAST COULD BECOME SURFACE
BASED. EFFECTIVE SHEAR OF 40+ KT WILL BE SUPPORTIVE OF ORGANIZED
STORM STRUCTURES INCLUDING SUPERCELLS.
..DIAL.. 12/18/2007
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0800Z
CURRENT UTC TIME: 1835Z (12:35PM),
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Tue Dec 18, 2007 6:43 pm
Relevant snip from HGX AFD
HWO from NWS LCH
THE MAIN WEATHER QUESTION OF THE DAY IS WHETHER WE WILL GET SEVERE
OUT OF EARLY THURSDAY`S VERY PROGRESSIVE UPPER TROF/DRY LINE
PASSAGE. SPC HAS OUR EASTERN 2/3 RDS IN A SLIGHT RISK. AS OF THIS
AFTERNOON...CONFIDENCE IS HIGHEST WITH ISOLATED STRONG
CELLS...PREDOMINATELY ELEVATED CONVECTION...WHICH MAY PRODUCE A VERY
SMALL RISK FOR SEVERE WEATHER. TOO MANY QUESTION MARKS ABOUT
WHETHER NORTHEASTERN DECENT MID-LEVEL LAPSE RATES WILL DESCEND TO
SURFACE WITH THIS FAST MOVING BOUNDARY. MODELS STILL HAVE A WEDGE OF
1.5-1.6" AIR IN THE WARM SECTOR DURING THE 20/03-09Z TIME FRAME.
OVER THE NE ZONES...SEVERE INDICES ARE STILL UP... -5 TO -6 L.I.S.
SURFACE BASED CAPE IS QUESTIONABLE AOA 1KFT J/KG...BUT IF BOUNDARY
DOES SLOW...WE MAY HAVE SOME OF THE ELEVATED INSTABILITY DOWN TO
SURFACE. THE PROGRESSION OF THE LINE IS CRUCIAL...IT LINE SLOWS AS
IT NEARS OUR NORTHERN ZONES AROUND 20/06Z...THEN IT IS ANOTHER BALL
GAME. THE NORTHERN SEVERE THREAT WILL MOST LIKELY BE HAIL WITH THE
REINFORCING MID-LEVEL DRY AIR ENTRAINMENT AND LOWER WET BULB ZERO
HEIGHTS...POSSIBLE WEAK TORNADOES WITH A FAVORABLE HODOGRAPH. A HIGH
CHANCE OF MOST OF THE NORTH-EAST CWA TO EXPERIENCE MODERATE TO
STRONG CONVECTION OVER A VERY SHORT THURSDAY 6Z~12Z PERIOD.
HWO from NWS LCH
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE NORTHWEST
GULF OF MEXICO...CENTRAL LOUISIANA...SOUTH CENTRAL LOUISIANA...
SOUTHWEST LOUISIANA...WEST CENTRAL LOUISIANA AND SOUTHEAST TEXAS.
.DAY ONE...THIS AFTERNOON AND TONIGHT
PATCHY DENSE FOG IS POSSIBLE ACROSS SOUTHEAST TEXAS AND SOUTHWEST
LOUISIANA DURING THE OVERNIGHT HOURS.
.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY
AN APPROACHING COLD FRONT WILL SET-OFF NUMEROUS SHOWERS AND
THUNDERSTORMS OVERNIGHT WEDNESDAY INTO THURSDAY MORNING. DAMAGING
WINDS AND LOCALLY HEAVY RAINFALL ARE POSSIBLE...AS THESE
THUNDERSTORMS ORGANIZE INTO LINES.
ANOTHER EVEN STRONGER COLD FRONT WILL MOVE THROUGH THE AREA ON
SATURDAY. EARLY SIGNS SHOW THAT THIS MORE POTENT FRONT MAY ALSO
PRODUCE SOME SEVERE WEATHER AS IT MAKES ITS WAY ACROSS THE REGION.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED OVERNIGHT WEDNESDAY INTO THURSDAY.
$$
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Tue Dec 18, 2007 9:44 pm
WRF still looks onboard for at least isolated severe in Southeast and East Texas
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 8:59 am
HOU, LCH, SHV all in 5% tornado risk on SWODY1
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0702 AM CST WED DEC 19 2007
VALID 191300Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS E TX INTO LA...
...NW GULF COAST THIS EVENING INTO TONIGHT...
A MID LEVEL SHORTWAVE TROUGH OVER THE LOWER CO VALLEY THIS MORNING
WILL PROGRESS EWD TO THE SRN PLAINS TONIGHT. IN ADVANCE OF THIS MID
LEVEL WAVE...SURFACE CYCLOGENESIS WILL OCCUR TODAY OVER THE SRN HIGH
PLAINS...AND THE LOW IS EXPECTED TO DEVELOP ESEWD OVER THE RED RIVER
VALLEY TONIGHT. WITHIN THE WARM SECTOR OF THE DEVELOPING
CYCLONE...BOUNDARY LAYER DEWPOINTS GENERALLY IN THE LOW-MID 60S WILL
SPREAD INLAND FROM THE WRN GULF TO E TX/LA LATER THIS AFTERNOON INTO
TONIGHT. MEANWHILE...MID LEVEL LAPSE NEAR 7 C/KM WILL OVERSPREAD
THE MOIST SECTOR FROM THE W...RESULTING IN THE DEVELOPMENT OF MUCAPE
FROM 1000-1500 J/KG ACROSS E TX THIS EVENING INTO EARLY TONIGHT.
THE PRIMARY THUNDERSTORM DEVELOPMENT IS NOT ANTICIPATED UNTIL EARLY
TONIGHT IN CONJUNCTION WITH THE APPROACH OF THE MID LEVEL WAVE AND
AN INCREASINGLY MOIST WAA REGIME...NEAR AND S OF THE ARKLATEX.
FORECAST SOUNDINGS FROM THIS REGION REVEAL SUBSTANTIAL LOW-LEVEL
SHEAR BY TONIGHT /EFFECTIVE SRH 0F 200-300 M2/S2/...ALONG WITH
INSTABILITY BASED AT OR VERY NEAR THE SURFACE. THE NET RESULT
SHOULD BE SEVERAL CLUSTERS OF STRONG/SEVERE STORMS...WITH THE
POSSIBILITY OF SUPERCELLS AND/OR SHORT BOWING SEGMENTS. THE INITIAL
SEVERE STORM THREAT SHOULD BE LARGE HAIL BEGINNING THIS EVENING
ACROSS E TX...WITH A GRADUALLY EVOLVING AND EWD EXPANDING THREAT FOR
DAMAGING WINDS AND A COUPLE OF TORNADOES OVERNIGHT.
..THOMPSON.. 12/19/2007
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 2:31 pm
12Z WRF still ha snear 1000 J/Kg CAPE and almost 50 knots deep layer shear
6 am CST WRF forecast skew-T
6 am CST WRF forecast skew-T
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 3:22 pm
Special Weather Statement
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
640 AM CST WED DEC 19 2007
LAZ027>033-041>045-051>055-TXZ180>182-201-215-216-192200-
VERNON-RAPIDES-AVOYELLES-BEAUREGARD-ALLEN-EVANGELINE-ST. LANDRY-
CALCASIEU-JEFFERSON DAVIS-ACADIA-LAFAYETTE-UPPER ST. MARTIN-
CAMERON-VERMILION-IBERIA-ST. MARY-LOWER ST. MARTIN-TYLER-JASPER-
NEWTON-HARDIN-JEFFERSON-ORANGE-
INCLUDING THE CITIES OF...LEESVILLE...ALEXANDRIA...MARKSVILLE...
DERIDDER...OAKDALE...VILLE PLATTE...OPELOUSAS...LAKE CHARLES...
JENNINGS...CROWLEY...LAFAYETTE...ST. MARTINVILLE...CAMERON...
ABBEVILLE...NEW IBERIA...MORGAN CITY...WOODVILLE...JASPER...
NEWTON...LUMBERTON...BEAUMONT/PORT ARTHUR...ORANGE
640 AM CST WED DEC 19 2007
...SEVERE THUNDERSTORMS POSSIBLE OVERNIGHT WEDNESDAY INTO THURSDAY...
A SURFACE LOW PRESSURE SYSTEM WILL FORM OVER THE FRONT RANGE OF
THE NEW MEXICO ROCKIES ON WEDNESDAY...THEN MOVE EAST SOUTHEAST
ACROSS OKLAHOMA WEDNESDAY NIGHT...AND INTO ARKANSAS ON THURSDAY.
A SURFACE FRONT WILL TRAIL SOUTH-SOUTHWEST FROM THIS EVOLVING CYCLONE
ACROSS TEXAS...AND WILL FOLLOW THIS CYCLONE IN TOW.
FAVORABLE MOISTURE...LIFT...INSTABILITY...AND WIND SHEAR OVER THE
PRE-FRONTAL WARM SECTOR...WILL CREATE AN ENVIRONMENT FAVORABLE
FOR SHOWERS AND THUNDERSTORMS...SOME OF WHICH COULD BECOME SEVERE.
LARGE HAIL...DAMAGING WINDS...AND TORNADOES WILL BE POSSIBLE WITH
ANY THUNDERSTORMS THAT DO BECOME SEVERE...WITH VERY HEAVY RAINFALL
ALSO POSSIBLE DUE TO THE HIGH MOISTURE CONTENT OF THE ATMOSPHERE.
LISTEN TO NOAA WEATHER RADIO OR YOUR LOCAL MEDIA FOR THE LATER
UPDATES ON THIS SITUATION.
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 5:21 pm
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
353 PM CST WED DEC 19 2007
LAZ027>033-041>045-051>055-TXZ180>182-201-215-216-200900-
VERNON-RAPIDES-AVOYELLES-BEAUREGARD-ALLEN-EVANGELINE-ST. LANDRY-
CALCASIEU-JEFFERSON DAVIS-ACADIA-LAFAYETTE-UPPER ST. MARTIN-
CAMERON-VERMILION-IBERIA-ST. MARY-LOWER ST. MARTIN-TYLER-JASPER-
NEWTON-HARDIN-JEFFERSON-ORANGE-
INCLUDING THE CITIES OF...LEESVILLE...ALEXANDRIA...MARKSVILLE...
DERIDDER...OAKDALE...VILLE PLATTE...OPELOUSAS...LAKE CHARLES...
JENNINGS...CROWLEY...LAFAYETTE...ST. MARTINVILLE...CAMERON...
ABBEVILLE...NEW IBERIA...MORGAN CITY...WOODVILLE...JASPER...
NEWTON...LUMBERTON...BEAUMONT/PORT ARTHUR...ORANGE
353 PM CST WED DEC 19 2007
...SEVERE THUNDERSTORMS POSSIBLE AFTER MIDNIGHT TONIGHT THROUGH THURSDAY...
DAMAGING WINDS AND LARGE HAIL WILL THREATEN SOUTHEAST TEXAS STARTING
TONIGHT...MAINLY AFTER MIDNIGHT. AS THIS STORM COMPLEX MOVES
EAST...THE THREAT FOR SEVERE WEATHER WILL SPREAD ACROSS WESTERN
LOUISIANA BEFORE DAYBREAK ON THURSDAY. SOME OF THESE STORMS WILL
HAVE THE POTENTIAL TO DEVELOP TORNADOES. BY MID-MORNING
THURSDAY...THE SEVERE WEATHER THREAT WILL EXTEND TO SOUTH CENTRAL
LOUISIANA.
THE SEVERE WEATHER THREAT WILL END BEFORE THURSDAY EVENING.
BECAUSE THESE STORMS WILL BEGIN LATE AT NIGHT...BE SURE TO HAVE A WAY
TO RECEIVE SEVERE WEATHER WARNINGS WHILE YOU ARE ASLEEP. NOAA
WEATHER RADIOS SHOULD BE SET TO THE ALERT MODE BEFORE YOU GO TO
BED TONIGHT.
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 7:09 pm
It's going to be an interesting night for sure. I expect the storms to be here after midnight, most likely from 2:00 to 6:00 AM.
Re: Overnight Wednesday/Thursday Morning SE Texas Severe?
Posted: Wed Dec 19, 2007 10:06 pm
Based on the WRF- Navasota is my early morning severe weather pick city (complete amateur status- see your doctor for more information)
Posted: Wed Dec 19, 2007 10:08 pm
What is Helicity?
Re:
Posted: Wed Dec 19, 2007 10:20 pm
fact789 wrote:What is Helicity?
Storm Relative Helicity (SReH)
The SReH calculated by SCAN is an integrated total value for the atmospheric layer from the surface to 3 km AGL. Proportional to both streamwise vorticity and storm-relative winds , SReH over the depth, h, of the storm inflow is defined as:
where vector V is the environmental wind vector, C is the storm's translation velocity, k x dV/dz is the horizontal vorticity, and vector k is the unit vector in the vertical. In SCAN, h is taken as 3 km as in most studies. The V(z) wind profile is obtained from the LAPS model data. Unlike most other studies, which use an averaged storm motion for SReH calculation, SCAN uses radar detected storm cell motion (direction and speed obtained from Composite Reflectivity radar product) for each individual storm cell as the vector C in the formula to calculate SReH.
Link
I suspect a pro met can explain that better. Energy-Helicity Index combines CAPE and helicity in a unit less number that gives an approximate idea of the probability of tornadic storms.
EHI
Posted: Wed Dec 19, 2007 10:25 pm
In english? lol
Re:
Posted: Wed Dec 19, 2007 10:31 pm
fact789 wrote:In english? lol
I believe helicity is a measure of how much twisting is occuring in the lowest km or three kilometers of the atmosphere, but you'll need a pro-met probably to give a technically correct and understandable answer.
Re: Re:
Posted: Wed Dec 19, 2007 10:32 pm
Ed Mahmoud wrote:fact789 wrote:In english? lol
I believe helicity is a measure of how much twisting is occuring in the lowest km or three kilometers of the atmosphere, but you'll need a pro-met probably to give a technically correct and understandable answer.
isnt that voticity?
Re: Re:
Posted: Wed Dec 19, 2007 10:41 pm
fact789 wrote:Ed Mahmoud wrote:fact789 wrote:In english? lol
I believe helicity is a measure of how much twisting is occuring in the lowest km or three kilometers of the atmosphere, but you'll need a pro-met probably to give a technically correct and understandable answer.
isnt that voticity?
I have a BS in petroleum engineering. Ask me questions about the diffusivity equation applied to a multi-phase fluid moving in a heteregeneous formation (well, maybe if you asked a decade ago before I forgot) and I might answer you. D'Arcy's Law, Archie's Law, writing programs to model fluid flow in a waterflood.
But the met questions, you need someone with the specialized training.
Oh,
¡First Storms of Tonight/Tomorrow's Severe Outbreak now forming in SE Texas!