Chase 2010 - Day 25 Discussion

[Paul Sherman]

1st proper Chase Day for Tour 3 and we will be heading towards the Southern Risk in the TX/OK Panhandles where we have a 5% Risk for Tornadoes along the Dryline!

...CNTRL THROUGH SRN HIGH PLAINS...

RICHER MOISTURE RESIDING OVER TX WILL ADVECT NWWD INTO THE SRN AND

CNTRL HIGH PLAINS AS SLY LOW-LEVEL JET STRENGTHENS IN RESPONSE TO

DEVELOPING LEE CYCLONE. SURFACE DEWPOINTS IN THE 50S F WILL ADVECT

AS FAR NORTH AS WRN NEB AND SERN WY...WITH 60S F FARTHER SOUTH INTO

THE SRN HIGH PLAINS BENEATH STEEP MID-LEVEL LAPSE RATES RESULTING IN

AN AXIS OF 1500-2000 J/KG MLCAPE. THE ATMOSPHERE WILL REMAIN CAPPED

TO SURFACE BASED STORMS UNTIL LATE AFTERNOON WHEN INITIATION WILL

BECOME MORE PROBABLE. STORMS MAY DEVELOP OVER THE HIGHER TERRAIN OF

CO AND WY AND INTENSIFY AS THEY INTERCEPT THE MOIST AXIS. OTHER MORE

ISOLATED ACTIVITY MAY DEVELOP FARTHER SWD ALONG THE DRYLINE. UPPER

FLOW IS FORECAST TO BECOME INCREASINGLY DIFFLUENT OVER THE CNTRL

HIGH PLAINS WHERE STORMS WILL LIKELY BE MORE NUMEROUS. STRONG DEEP

LAYER SHEAR OF 45+ KT WILL SUPPORT SUPERCELLS WITH LARGE HAIL

LIKELY. HODOGRAPH SIZE WILL INCREASE SUBSTANTIALLY DURING THE EARLY

EVENING AS THE LOW-LEVEL JET STRENGTHENS RESULTING IN A WINDOW FOR

ISOLATED TORNADOES. ANY STORMS THAT DEVELOP OVER THE CNTRL HIGH

PLAINS SHOULD CONTINUE EWD...POSSIBLY EVOLVING INTO AN MCS OVERNIGHT

SUPPORTED BY ISENTROPIC LIFT AND THETA-E ADVECTION ALONG THE STRONG

LOW LEVEL JET.

Tomorrow also looks good with now most of Kansas in reach for us!

Paul S & Team

[MAF]

Thanks for the new page Paul. lets hope the tour 3 has a good day

SPC is quite active with a slight risk of severe storms

SPC AC 210100

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0800 PM CDT THU MAY 20 2010

VALID 210100Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN TX INTO SRN PARTS OF

THE GULF COASTAL STATES...

full report here >>> http://www.spc.noaa.gov/products/outlook/day1otlk_0100.html

[Nick F]

My target for today is Pampa in the NE Texas Panhandle.

Look at the 15z RUC suggests best SR helicity values in this area by 00z (18z CDT):

Also cap breaking by 18z CDT to allow con. precip along dryline, though obviously their charts can't accurately pinpoint where in the Panhandle:

Should hopefully be a classic panhandle chase with maybe a tornado to bag before dark.

SPC update takes the SLIGHT risk all the way down to Big Bend area of SW Texas now. Only yesterday was the risk confined to NE CO / SE WY / SW NE:

http://www.spc.noaa.gov/products/outlook/day1otlk.html

[NL]

NWS/SPC 1630z update

SPC AC 211625

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1125 AM CDT FRI MAY 21 2010

VALID 211630Z - 221200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER

PARTS OF THE CNTRL AND SRN HIGH PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE OH VALLEY SWD

INTO THE GULF COAST STATES...

...SYNOPSIS...

LARGE-SCALE PATTERN WILL AMPLIFY THROUGH THE PERIOD AS STRONG ERN

PACIFIC JET STREAK DIGS SEWD ALONG THE WEST COAST...EFFECTIVELY

SUPPORTING THE INTENSIFICATION OF A BROAD TROUGH OVER THE WRN

STATES. WITHIN THIS BROADER-SCALE PATTERN...A SHORT WAVE TROUGH NOW

OVER CNTRL ORE/NRN CA WILL TRANSLATE NEWD INTO THE NRN HIGH PLAINS

LATER TONIGHT. ELSEWHERE...A NEGATIVELY-TILTED MIDLEVEL TROUGH WILL

CONTINUE TO LIFT NEWD THROUGH THE OH VALLEY AND GREAT LAKES

REGION...WHILE AN ASSOCIATED VORTICITY MAXIMUM PROGRESSES FROM THE

SRN APPALACHIANS INTO THE PIEDMONT AND COASTAL PLAINS.

...HIGH PLAINS...

MORNING SURFACE ANALYSIS SHOWS A BAROCLINIC ZONE EXTENDING FROM

CNTRL ND SWWD THROUGH SWRN SD...SRN WY TO CNTRL UT. THIS FRONT IS

EXPECTED TO MOVE LITTLE THROUGH THE DAY WHILE A LEE TROUGH

STRENGTHENS SWD ALONG THE CO FRONT RANGE TO ALONG THE TX/NM BORDER.

INTENSIFYING SLY LOW-LEVEL FLOW E OF THIS LEE TROUGH WILL SERVE TO

ENHANCE THE NWD FLUX OF AN INCREASINGLY MOIST BOUNDARY LAYER WITH

DEW POINTS RISING THROUGH THE 50S OVER THE CNTRL HIGH PLAINS...TO

60S FARTHER S. AT THE SAME TIME...STRENGTHENING SWLY MIDLEVEL FLOW

REGIME ACROSS THE ROCKIES WILL RESULT IN THE EWD PROGRESSION OF AN

EML ACROSS THE MOISTURE AXIS WITH MLCAPE INCREASING TO 1000-1500

J/KG AS FAR N AS THE PALMER DIVIDE AND CHEYENNE RIDGE...TO 1500-2000

J/KG OVER THE OK/TX PNHDLS AND W TX.

12Z MODEL GUIDANCE SUGGESTS THAT THE MOST SIGNIFICANT HEIGHT

FALLS/DYNAMIC FORCING FOR ASCENT WILL REMAIN TO THE W OF THE

DEVELOPING INSTABILITY AXIS THROUGH THE DIURNAL HEATING CYCLE.

HOWEVER...THESE DATA DO SUGGEST THAT AFTERNOON/EVENING TSTM

DEVELOPMENT WILL BE MOST LIKELY NEAR THE ABOVE-MENTIONED STATIONARY

FRONT AND NRN EXTENSION OF LEE TROUGH OVER WY/NERN CO/NEB PNHDL.

HERE...THE COMBINATION OF 45-55 KT OF DEEP-LAYER SHEAR AND A

STRENGTHENING LOW-LEVEL WIND FIELD WILL RESULT IN A KINEMATIC

ENVIRONMENT QUITE SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE HAIL AND

A FEW TORNADOES.

FARTHER S ALONG THE LEE TROUGH/DRY LINE...CONVECTIVE INITIATION

BECOMES MUCH MORE UNCERTAIN DUE TO THE ABSENCE OF ANY APPRECIABLE

LARGE-SCALE FORCING MECHANISMS. GIVEN THE DEGREE OF INSTABILITY AND

MODERATELY STRONG LOW/DEEP-LAYER SHEAR...A CONDITIONAL THREAT FOR

SUPERCELLS CAPABLE OF LARGE HAIL AND PERHAPS A COUPLE OF TORNADOES

WILL EXIST SHOULD ISOLATED STORMS DEVELOP AND BECOME SUSTAINED LATER

TODAY.

[Nick F]

The stretch of the I-40 heading out west of Oklahoma City where the team are currently cruising along - I remember is terribly bumpy with big ruts and uneveness all over the carriageway, same as the N-S I-35 up through OK. Can see the cam bouncing up and down. Go over the border into Kansas or Texas and the road surfaces are much smoother and better maintained! Obviously more money to spare.

[paul - stormchase]

You're not wrong nick, the road is a shocker - not good when you've just filled your face with doughnuts!!

[paul - stormchase]

On the move again shortly, couple of hours from our initial target of dumas. Live stream is back on..

http://www.netweather.tv/index.cgi?action=chaselive;sess=

[Tom Lynch]

Hi all

Strange watching it from the UK having only returned yesterday. I could not figure out why not chasing at 4am this morning and realised I was home in bed, ah shucks.

Didnt see a briefing, so where are you heading.

Tom

[Tom Lynch]

On the move again shortly, couple of hours from our initial target of dumas. Live stream is back on..

http://www.netweather.tv/index.cgi?action=chaselive;sess=

Oh ok the answer to my question was on its way whilst I was busy. Dumas but not via the regional hospital.

Tom

[Nick F]

Heads up for the team - MD issued for TX and OK Panhandles. Bit of uncertainty on initiation though:

MESOSCALE DISCUSSION 0651

NWS STORM PREDICTION CENTER NORMAN OK

0325 PM CDT FRI MAY 21 2010

AREAS AFFECTED...TX/OK PANHANDLES AND SWRN KS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 212025Z - 212130Z

ISOLATED STORMS MAY DEVELOP ALONG THE DRYLINE IN THE TX/OK

PANHANDLES LATE THIS AFTERNOON/EARLY THIS EVENING. SHOULD STORMS

DEVELOP...SUPERCELLS WILL BE LIKELY...WITH A PRIMARY THREAT OF LARGE

HAIL AND ISOLATED TORNADOES. AREA IS BEING MONITORED FOR A POSSIBLE

WW.

20Z VISIBLE IMAGERY SHOWS CU FIELD SLOWLY BEGINNING TO INCREASE OVER

THE TX PANHANDLE. AMPLE SURFACE HEATING CONTINUES TO GRADUALLY ERODE

CONVECTIVE INHIBITION OVER THE AREA...WHILE DESTABILIZATION OCCURS.

WV IMAGERY IS SUGGESTIVE OF HEIGHT RISES...WHICH THIS IN COMBINATION

WITH CONVECTIVE INHIBITION MAY SUPPRESS DEVELOPMENT FOR SOME TIME.

HOWEVER...DARKENING ON WV IMAGERY MAY INDICATE A WEAK UPPER WAVE

THAT MAY SUPPORT ISOLATED DEVELOPMENT ALONG THE DRYLINE WHERE

SURFACE CONVERGENCE IS GREATEST. SEVERAL HI RES MODELS SEEM TO

SUPPORT THIS SOLUTION...WITH ISOLATED DEVELOPMENT OVER THE TX/OK

PANHANDLES GRADUALLY MOVING ENEWD. A LEE SURFACE TROUGH CONTINUES TO

DEEPEN...WITH WIDESPREAD SURFACE PRESSURE FALLS NEAR 1 MB/HR NOTED.

AS THIS CONTINUES TO DEVELOP...LOW LEVEL SLY/SELY WINDS WILL

INCREASE...RESULTING IN FAVORABLE LOW LEVEL CURVATURE FOR ROTATING

STORMS. LATER THIS AFTERNOON...FORECAST SOUNDINGS SUGGEST LOWERING

LCL HEIGHTS IN THE ERN TX/OK PANHANDLE...AND AN ISOLATED TORNADO

CANNOT BE RULED OUT /ESPECIALLY AS LOW LEVEL WINDS BEGIN TO

INCREASE/. STEEP MID LEVEL LAPSE RATES AND EFFECTIVE SHEAR NEAR 45

TO 50 KTS WILL BE CONDUCIVE TO LARGE HAIL FORMATION. ALTHOUGH IT IS

UNCERTAIN WHETHER STORMS WILL INITIATE...SHOULD IT APPEAR LIKELY...A

WW WILL NEED TO BE ISSUED.

..HURLBUT.. 05/21/2010

[paul - stormchase]

I hope you all appreciated the dancing to bohemian rhapsody on the stream

[iangec]

Flash - good choice as you drive towards the big clouds!

[Tom Lynch]

Stick in there team , nice cell.

Tom

[Tom Lynch]

Paul

if you are on the cell west of Childress it seems to be a right mover and may not just slide passed.

Tom

ok yes you are on that cell , it is moving right,

Tom

ok Paul it looks like you are off to Childress, Say hello to the manager of the Days Inn.

Tom