Outlook: 2012 May 15

The eastern mid-level trough and near surface cold front moved extremely slowly overnight allowing the east coast another day of good surface-based instability.  Morning soundings in DC, Wallops Island and Blacksburg show near saturation over at least 300 mb above the surface and little cap. Surface moisture values are in excess of 12 g/kg. However lapse rates are relatively poor and deep layer shear is only 25 kts.  The result is expected to be areas of scattered to numerous small multicells forming relatively early in the day off of high terrain to the west and subtle axis of enhanced moisture extending just east of DC.  Steeper lapse rates and similar saturation along coastal North Carolina have allowed the morning sea breeze to more quickly initiate vigorous convection.  Any of these areas will be susceptible to moist downbursts and marginally severe hail.

Further west, a northern stream midlevel short-wave trough is dropping into the western Great Lakes.  A trailing cold front is expected to initiate convection from southeastern MN eastward to central MI.  Here, moisture is sparse with surface values only around 8 g/kg.  But we expect this limited moisture will be able to sustain convection owing to very steep lapse rates in the lowest 400 mb of the atmosphere.  Shear is also expected to remain weak (<30 kts/6km) and thus small multicells are expected.  Due to the limited moisture, we don’t expect any upscale growth here.

The plan is to work the DC LMA area and the Roanoke CWA for the early convection and then shift our focus to WI and MI for the later afternoon.

Jim LaDue, EWP2012 Week#2 Weekly Coordinator

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Daily Summary – 2012 May 14

We started today in Wilmington, NC and San Antonio, TX.  However the CI products were having issues with dense high clouds in NC and we subsequently shifted focus to Melbourne, FL to track convection approaching Orlando.  As we shifted, two supercells formed near Myrtle Beach, SC.  We were initially frustrated but a new tornado warning was issued west of Palm Beach, and the far southern county of Melbourne’s CWA.  Unfortunately the storm evolved into a nonsevere state before we shifted localizations there.  Meanwhile strong supercells developed west of Del Rio and tracked southeast on the Mexican side of the border.  As the thunderstorms grew upscale in Mexico  a spectacular haboob evolved that caused the UAH CI product to track a few cold pixels.  Some were cumulus above the haboob while one of the tracks may have been triggered by the dust as it swept over a mountain range or by a cumulus cloud.  Elsewhere, storms north of San Antonio were too weak to issue warnings.

Thus with the lack of warnings, the teams concentrated on inspecting the products and writing blog entries.

Jim LaDue, EWP2012 Week#2 Weekly Coordinator

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EWP STATUS FOR 15 MAY 2012: 12-8pm SHIFT

EWP STATUS FOR 15 MAY 2012:  12-8pm SHIFT

Based on the available 15 UTC SREF guidance, two areas will be in play for a 12 – 8 pm CDT shift.

The first is along a northern stream wave cold front in WI to MI where instability may result in thunderstorms.  Thunderstorms are likely to develop between 2 and 4 pm CDT.

The second area will be along the slow moving eastern trough where a continued feed of deep moisture intersects a front from VA north to NY.  Both areas appear to be conducive to generate diurnal convection.  In fact the eastern play may develop convection relatively early in the day given the lack of CAP and near saturation in the lowest few hundred mb.  Shear may be strong enough for more supercells or organized bows. Expect convection to develop at 12 pm CDT or perhaps even earlier.

Jim LaDue, EWP2012 Week#2 Weekly Coordinator

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2012 May 14 2020z update

Team 1:  Brian and Todd will be shifting to Melbourne FL due to more convection than earlier expected headed into the CWA from the west.  While the severe weather prospects remain low, the storms are headed into the LMA.

Team 2:  Stephen and Julie will stay in San Antonio to monitor CI.

Jim LaDue, EWP2012 Week#2 Weekly Coordinator

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Outlook: 2012 May 14

For the week of 14-18 May, our distinguished NWS guests will be Brian Carcione (WFO Huntsville, AL), Todd Dankers (WFO Boulder/Denver, CO), Stephen Kearney (CWSU Memphis, TN), and Julia Ruthford (WFO Charleston, WV).  Other visiting participants this week will include Dave Carlsen (Environment Canada), Bob Aune (UW-CIMSS), Jordan Gerth (UW-CIMSS), Lori Schultz (UAH), and Chad Gravelle (GOES-R NWSTC liaison).

The pattern at upper-levels features a large ridge in the western US and a weak but large trough in the eastern third of the CONUS.  Two areas of potential severe convection exists in the CONUS, along the Rio Grande valley in TX and the southeast Atlantic coastal states.

SPC day 1 categorical outlook

The southwest TX threat area comes in response to one weak short-wave trough embedded in northwesterly flow east of the ridge settling southeastward from NM yesterday.  This trough is phasing with a low-level front along the Rio Grande river from south of Marfa to near Del Rio and eastward.  However the moisture has been scoured a bit from an overnight MCS that passed southeast from Del Rio.  We expect diurnal heating and moisture return from the east to destabilize the atmosphere and allow new diurnal convection to form from the Big Bend region, east.  There are factors limiting potential severity of convection including uncertain amounts of destabilization and weak low-level shear.  Nevertheless, supercells  producing large hail and some damaging winds are possible in this threat area.

The second area in the southeastern Atlantic coastal states is already active with convection.  A QLCS is progressing across the central Carolinas while more isolated convective forms are developing all the way down into FL.  The deep layer shear is a modest 25-30 kts/6km in the Carolinas, and weaker further to the south.  The QLCS should continue moving eastward with a small threat of damaging winds while isolated downbursts and marginally severe hail is possible down into FL.

A forecast team is already monitoring Wilmington, NC’s area (Brian Carcioni and Todd Dankers) and the second team is monitoring San Antonio’s area (Stephen Kearney and Julia Ruthford).

Jim LaDue, EWP2012 Week#2 Weekly Coordinator

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Week 3 Summary: 11 – 15 May 2009

LMA:

Kevin – Identify trends and signatures and their meaning could be useful.  Identify what’s useful in developing a storm in initiation.

Chris – Liked the trends in Google Earth.

Steve – VLMA Still needs correlation between its display and other signatures and severe weather events.  Don’t know the benefit of satellite-based sensor in areas of  regular LMA sensor.

Kristen – LMAs are line of sight so they’d need to be smartly located in topography.

John- Would anticipate what it’s coverage would be in poor radar coverage areas and also for coastal areas for advance warning of LTG for mariners and beach-goers.  Concurs more research needed.

What want to see?   Trending, manual area defining intervention to define trending (e.g., distance speed tool or a box),

CASA:

John – anticipates usefulness of 3dvar and multi radars but also big education challenge.  Would like to see vertical cross-section.  Would prefer a 2 min update if they could get some vertical structure.

Steve – Would like cross-section from multi-radar including CASA.  Wed night was a significant stepping stone was like Red Rock was in 1991.  Would like to time-match 88D, CASA, PAR in one 4-panel.

Kevin – CASA saw the circulations 3-5 min ahead of 88D in Gracemont.  Kevin walked into the WFO concerned they were seeing it.  But they had the TOR drafted.  WFO forecasters also walked into the HWT to view the CASA data.

Concerning RFD winds in Anadarko, CASA really showed the winds.  The 3dVAR picked up on the winds as well.  KTLX showed no RFD winds.

Chris – Concurs with the benefits of rapid update.  Drawback is the attenuation.

CASA wishlist:  Can a manual scanning override be accomplished?  This is a workload strategy that could be accomplished by having someone managing scanning while the other interprets storm structure.  The software would need to be made simple.

Would an attenuation product be useful?  Unknown at this time.

PAR:

Kevin:  Liked the mid- upper-level resolution.  Midlevel mesos tightened up more quickly in PAR than 88D.  Did not see any adverse effects of adaptive scanning.  Perhaps would like to see a more frequent full volume scan in explosive initiation environments.  Edge of sector had a bit more velocity problems.

Chris:  Lot of more features visible on PAR.

Steve:  Data quality was better this year’s experiment.

John:  Anticipates much better detection of descending cores in low-shear event.  Worth having superres even with more time.

What tradeoff are the forecasters willing to consider  if one is required to see clear boundaries around the storm?  They are willing to consider a tradeoff depending on how important it is to see the boundaries.

Kevin:  Is CASA network refractivity conceivable?  Feb 10 case refractivity could’ve explained why the following supercells weren’t tornadic.  Could it compensate for sacrificing scanning frequency for sensitivity.

Chris:  Wondered about the impact 2.1 deg beamwidth on edges of sectors?  There was some impact but would be limited in the future with hardware upgrade.

Adam wondered about most what was the most useful scanning stategies.  Not much difference…all were good. 15 elevations was sufficient.

Kevin:  Changing the PRF could be made easier to do but liked the immediate feedback in the PAR.

Multi-radar:

Steve:  What would be the best?  Get it into AWIPS in general

Kevin:  Not a pleasant thought thinking about not using the products.  MESH, 30 and 50dBZ hgt > 0C and -20C,  Reflectivity at 0, -20 C.  Kevin doesn’t look at rotation tracks as much as others in the office.  Though they use it for post-mortem.

The MESH, rotation tracks were used to track motion.  Kevin noticed how big the polygons  are compared to actual tracks.

Chris:  MESH and reports seem to coincide. Rotation tracks showed the strongest tracks were colocated with tornadoes.

John:  MESH and rotation tracks were useful to call in and verify reports.

Merging LMA with multi-radar data?

General comments:

Steve liked the jobsheets for WDSSII.  Should be done on day 1.

Need better AWIPS localization to bring up map products on 4-panels without procedures.

Intro seminars – Good, no death by powerpoint by death.

AWIPS introduction was an added bonus.

Give a chance for forecasters to customize. They could bring their own procedures.  Could use the ‘alter functions’ to change model type or radar ID.

International visitors could benefit from an hour or two of software spinup.

Get SVS capability.

Additional “lost” notes found in an archived draft never published until now:

LMA considerations:  Don’t know what VLMA intensity to consider in warning issuance.  Screen real estate issues.  Would like the source points.  Swears that supercell ID can be done with VLMA and 0.5 deg radar data.  From an Canadian pt of view, if a radar goes out there’s no extra data.  VLMA very useful to see LTG frequency going up just before meso increased north Norman.  MESH would increase after the LTG would peak.  VLMA would indicate splits about to occur.  Might give more confidence about which updraft might be more dominant.  Reflectivity may be more quick to develop but there are lot teaser cores whereas VLMA gives larger view.  One minute update in VLMA really helpful to get the warning out more quickly.

PAR considerations:  So much to see and tremendous detail.  They spent the whole night looking at base data.  Can animate cross section to see the cores going up and then making the plunge.  Were able to change the PRF and see changes almost instantly. Scanning strategies were pumping data so fast that they were not finished with looking at upper tilts by the time new low tilts came in.  Super res in high tilts revealed stuff not seen before.

CASA:  3dvar was very useful showing a meso in all physical dimensions.  Could see the meso forming on the forward flank of the storm.  WFO came in to see the CASA display of the mesocyclone wrap up.  Could see vortex holes and multiple velocity couplets.  Adaptive scanning was easy.  Looked at individual CASA radars but composite CASA was used most often.  3dVAR does have a 10min latency so it was used as confirming evidence.   Long range concern about how many people are needed to monitor a CWA full of CASA radars.  How to display multiple base velocity fields?  3dvar is one way, shear and divergence products are another.  Composite vs. single radar in CASA.  Single radar showed much more pronounced hook but then there’s attenuation issues that composite helps overcome.

No EMs called last night concerning CASA.

Need procedures.  Or better, need to load specific maps even without procedures. Everything was geared to issuing warning earlier.

Jim LaDue (EWP Weekly Coordinator, 11-15 May 2009)

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Live Blog – 13 May 2009 (all live entries concatenated)

Southeastward moving cold front and extreme CAPE with marginal supercell deep layer shear will allow for central OK EWP activities to commence.

Convective initiated near 2230 z near Fairview to Deer Creek.  V2 crew is near Fairview.

We’ve got three projects to run:  LMA and PAR to begin then as convection approaches the CASA network, we’ll go to PAR and CASA.

2315z:  PAR showing very fine TBSS near Okeene, mainly elevated core.  MESH is 1.25″

2330z:  Big core dump observed to fall in cross-section from PAR near eastern Major County.

2341z:  LMA showing big ramp-up in LTG on segment in northern Blaine county.

2349z: Strong LL rotation on Kay county border.

2350z:  video of big funnel embedded in meso in Kay county storm.  Likely tornado.  PAR shows evolution nicely.

2351z:  Fay, THomas storm showed sizeable increase in LTG in LMA.

0001z:  Garfield county storm looks imminent tornadic on PAR and KVNX.

0009z:  PAR sector moved to southwest end of storms.

0017z:  Billings circulation increasing.  Pam suggests going to supercell VCP on PAR.  Anchor storm near Thomas is getting circulation.  V2 is on it but a bit too far northeast.

0021z:  Billings circulations, 2 of them, tighter one southwest of Billings.  LMA catching recycling over Billings.

0023z:  PAR team will now issue TORs, LMA team will issue SVRs.

0026z:  DOWs just saw shear get down to the ground on anchor storm west of Geary.

0031z:  Circulation driven by strong RFD near Billings with circulation visible in lowering.   Watonga storm (Geary storm) filled in with precip and new storms forming on its southwest side.

0046z:  Moving PAR sector 10 deg to the south to catch anchor storm crossing I-40 west of Hinton.  In NOble county LMA VLMA increased before MESH increased.  Increased confidence in severe warning.

0055z:  Possible LTG hole in VLMA in Blaine county storm.  It’s colocated with meso and BWER.

0105z:  VLMA is highest of the day for Canadian county with evidence of a lightning hole near the elevated meso.

0112z:  PAR noted rear inflow notch onset 0110z.  POssible new product idea for LMA:  LMA level -20C product to match radar layer reflectivity at -20, -10, 0 C.

0157z:  Look for storm top divergence on the PAR.  It was up to 240kts over the last 20 min from KTLX over Guthrie.

0201z:  Mode of southwestern storm is changing, beginning to bow more to the southeast with new cells growing to the east.

0213z:  CASA fully engaged in southwestern storm complex.  They’re seeing circulations not seen before on 88D.

0220z:  CASA showing circulation via velocity and rotating rain bands going around the notch near Gracemont.

0223z:  CASA showing reflectivity hole near circulation in Gracemont.

0232z:  CASA showing multi-vortices just south of Gracemont both in reflectivity holes and velocity centers.  PAR showing northern storm backbuilding south on I-35 into Edmund.  Transient TVSs observed.  They’re lasting around 10 min and we’re getting 8 or so volume scans to sample them.

0249z:  CASA showing weakening circulatoin.  BTW, 3DVAR showed circulation at least 1km wide south of Gracemont.  New intense push of outflow north of KGYR may result in new LLmeso.  Meanwhile northern storm is backbuilding over the city.

0253z:  VLMA showing a burst over OKC in last 5 min.

0256z:  OUN chat sais circulation SE of Anadarko but PAR showing strengthening.  CASA Chickasha radar showing precip wrapping around center.

0309z:  TOR warning for us.  Hook echo on PAR near OKC airport with convergence along the RFD but no vortex yet.

0409z:  TOR warned storm for Cleveland county showed small circulations forming on leading RFD edge from Stanley Draper to the north arm of Lake T-bird.  Now the storm is dying as new convection forms under the anvil of the western activity and to our south.

Jim LaDue (EWP Weekly Coordinator, 11 – 15 May 2009)

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Live Blog – 12 May 2009 (6:28 pm)

23:00 UTC briefing:

A shortwave trough has come out of southern NM and began to initiate convection as it became juxtaposed over the low-level dryline west of Lubbock, TX.  Initial high-based convection has generated a small but forward propagating cold pool northwest of Lubbock while an enhanced HCR has initiated more discrete, outflow starved and high-based convection from Floydada to south of Silverton.  See image below.

Note that the field here has not only numerous spotters with live video feeds but the VORTEX2 project has targeted this area.

Forecasters will be using multi-sensor products including Z, Z>-20C level, gridded hail, Azimuthal shear, and more.

Forecasters are:

Chris Wielke, EC Edmonton,
Steve Hodanish, NWS PUB
John Billet, NWS AKQ
Kevin Brown, NWS OUN

2330z:  Steve and Kevin will localize to AMA, John and Chris will take LBB’s CWA.

2350z:  John and Chris are seeing MEHS values to 1.2″ for the storm near Turkey.  It’s within the county where the backed winds and near 70 F dewpoints begin.  But the storm is in a small multicell cluster with potential for outflow dominance.  Storm shows only 3kft of 50dBZ above -20C.   Meanwhile Kevin and Steve are limited by the RPS list of only lowest 2 tilts.

0002z:  Both teams drafting respective SVR warnings.  One for the forward propagating storm in Armstrong county based on report as they’ve had issues with products.  MEHS was <1″ but there was an inch hail report.  They’re looking at MEHS and height of 50dBZ > -20 level.  The other one for the multicell event in Hall county.  They based their warnings on the MEHS, all-tilts and height of 50dBZ>-20 C level.

0010z:  Steve and Kevin issued a new warning for Donley and Collingsworth. MEHS and MEHS track for motion.

0011z:  John and Chris issued a new warning for northern Hall and far NE Briscoe counties.  New cell to the northwest based on the core peaking in the MEHS algorithm.

0024z:  John and Chris are looking at a new left mover approaching the southern LBB CWA from MAF.  No warning yet.

0029z:  Both teams drafting warnings for the line bridging both CWAs from Donley to Hall counties.

0039z:  Severe warning issued for Collingsworth county issued by Steve and Kevin for 70mph and tennisballs.  MEHS and 50dBZ height above -20C.

0042z:  Chris and John issuing SVR for Stonewall and SW Kent counties for that left mover coming out of MAFs.  MARC signature aloft, MEHS, and weak rotation.

0045z:  Chris and John impressed by the 50dBZ height 4kft > -20C.

0051z:  Steve says the Donley county storm is going downhill based on looking at FSI X-sections.

0100z:  Chris and John just issued a warning for Motley county minutes before a report came in.

0110z:  Storm acquiring supercell characteristics in northern Cottle county. GRLEVELx MEHS shows 3.2″ while gridded MEHS shows 1.88″.

0017z:  Chris and John issued a SVR

end of period discussion:

What to think of new products?  Took some time to get used to products in order to start warnings.  What value to use in shear?  Nobody knows.  Useful for pulse storms? Yes, it’s nice to isolate the bigger storms when there are many.  What’s popped up at 50dBZ above -20C level?

Nobody looked at biased MEHS.

Technology-wise, it would be nice to have two screens.  Could have NSE data on one screen.  Also add the WDSS signature into the templates.

Jim LaDue (EWP Weekly Coordinator, 11 – 15 May 2009)

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Outlook – 11 May 2009

For week 3, the participants are Steve Hodanish NWS PUB, Chris Wielke EC Edmonton, Kevin Brown NWS OUN, and John Billet NWS AKQ.

This is orientaton day.  The IOP begins at 5:30 pm Four projects are on tap for week 3 of the 2009 EWP.

Stabilized air over OK in the wake of last night’s MCS precludes the possibility of convection over TX .  Overnight, lee troughing in the high plains will help lift the front in central TX northward toward the Red River Valley.  An intensifying LLJ interacting with the front could create another MCS over OK after the planned IOP closes.  No IOP is likely for CASA, PAR or the OK LMA region.

Of the HSV and IAD LMA regions, only the IAD region has the potential for convection.  A weak midtropospheric shortwave trough is expected to cross the IAD region accompanied by weak instability and marginally strong enough convection to product lightning.  However the possibility for severe weather events is too low to consider an LMA IOP there.  The following graphics show the SPC general thunder risk (left, top) and the day 1 outlook (right, bottom).

The four EWP participants will go through a CASA and a PAR case.

Jim LaDue (EWP Weekly Coordinator, 11 – 15 May 2009)

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