111 replies to this topic

[Taylor Campbell]

ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 310900
   SPC AC 310900
  
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0400 AM CDT THU MAY 31 2012
  
   VALID 031200Z - 081200Z
  
   ...DISCUSSION...
   00Z ECMWF/GEFS SUGGEST THAT A MODERATELY STRONG/INITIALLY LOW
   AMPLITUDE BELT OF WESTERLIES OVER THE NORTHERN THIRD OF
   THE CONUS WILL YIELD TO AN AMPLIFYING LARGE SCALE PATTERN EARLY NEXT
   WEEK...HIGHLIGHTED BY A WESTERN STATES UPPER TROUGH. A COMBINATION
   OF LIMITED/UNCERTAIN POTENTIAL LEADS TO NO 30 PERCENT SEVERE RISK
   AREAS AT THIS TIME IN SPITE OF DAY-TO-DAY SEVERE TSTM POTENTIAL. BUT
   AS THE UPPER TROUGH SLOWLY SHIFTS EAST-NORTHEASTWARD OVER THE
   WESTERN/NORTH-CENTRAL CONUS...IT DOES SEEM PROBABLE THAT SEVERE TSTM
   POTENTIAL WILL GRADUALLY INCREASE/SPREAD EASTWARD EACH DAY ACROSS
   THE NORTHERN PLAINS/UPPER MIDWEST THROUGH DAYS 5-7 MONDAY/WEDNESDAY.
   OTHER SEVERE TSTMS MAY OCCUR ACROSS THE SOUTHEAST STATES EARLY NEXT
   WEEK IN ASSOCIATION WITH A SOUTHWARD SAGGING FRONT.
  
   ..GUYER.. 05/31/2012

[Kim0129]

WTHeck!  Mother Nature, is this your idea of a joke?

[Taylor Campbell]

An organized severe thunderstorm event looks to unfold Monday afternoon and evening. This type of environment is well known to produce significant wind damage.

Edited by Taylor Campbell, 31 May 2012 - 07:57 PM.

[metallicwx366]

Taylor Campbell, on 31 May 2012 - 07:54 PM, said:

An organized severe thunderstorm event looks to unfold Monday afternoon and evening. Past systems of such fashion are well known to produce significant wind damage.

What areas does this event look to cover?

[Kim0129]

I was poking fun at Mother Nature not you Taylor

[Taylor Campbell]

metallicwx366, on 31 May 2012 - 07:57 PM, said:

What areas does this event look to cover?

A good portion of Southeast; this will become clearer in a few more days.

[Taylor Campbell]

Kim0129, on 31 May 2012 - 08:06 PM, said:

I was poking fun at Mother Nature not you Taylor

well maybe you should specify better next time!  

LOL

[Kim0129]

Umm...I did....LOL!  But it's cool.    I like reading your posts, and would appreciate your thoughts on this time frame as we get closer to it. I'm still trying to figure out these models.

[Taylor Campbell]

Kim0129, on 31 May 2012 - 08:44 PM, said:

Umm...I did....LOL!  But it's cool.    I like reading your posts, and would appreciate your thoughts on this time frame as we get closer to it. I'm still trying to figure out these models.

Ha, I know Kim. Thank you for reading and enjoying my post. I'm just as glad to read yours.

I  look forward to posting more.

Edited by Taylor Campbell, 31 May 2012 - 09:18 PM.

[storm5]

Taylor does a great job

[Taylor Campbell]

storm5, on 31 May 2012 - 10:42 PM, said:

Taylor does a great job

Thank you.

The GFS/NAM appear to have the best handle and agreement on this impluse. An active afternoon and evening still looks likely on Monday. A line from northwest to southeast along the rim of an H5 high will be the focus point for development.

[storm5]

Taylor Campbell, on 01 June 2012 - 12:08 PM, said:

Thank you.

The GFS/NAM appear to have the best handle and agreement on this impluse. An active afternoon and evening still looks likely on Monday. A line from northwest to southeast along the rim of an H5 high will be the focus point for development.

Are you thinking this will be localized or widespread

[apocalyptic_pleasures]

Looks like NWS Tallahassee agrees with the potential but thinks it will wait till later in the week.

Quote

.LONG TERM (Monday through next Friday)...Although there don`t
appear to be any major systems that will affect the area next
week, the pattern may still get fairly active towards the middle
and end of the week if a cold front moves down from the north and
stalls over the area per the 01/00z GFS. The 00z GFS moves this
cold front south into the area late Tuesday into Wednesday with
west to northwest flow aloft and steep mid-level lapse rates
around 7C/km. There would probably be a risk of a few strong to
severe storms around mid-week if the GFS verified with continued
wet conditions through the end of the week.

[Taylor Campbell]

There is still good indications that a MCS type of event will unfold on Monday. Tonight's GFS/NAM really increase the H5 and H85 winds associated with this disturbance.

[Taylor Campbell]

storm5, on 01 June 2012 - 01:37 PM, said:

Are you thinking this will be localized or widespread

I think this will cover a large area, but several will be spared too. We will know more over the next few days.

[Taylor Campbell]

[AlabamaStormTracker]

Those values are likely overdone, Taylor.  Earl needs to fix the indices on the pages because the calculations have been off and blow the parameters off the scale quite a bit.  I know this because there has been comparison done on other sites as well as with AWIPS.  However, some of the wind fields are good enough to support long track MCS potential.  Just unsure of how severe they will be at this point.  Coming into the NAM range now and it seems the higher CAPE could be offset from the MCS track slightly.  Still time to iron those things out.

[Taylor Campbell]

AlabamaStormTracker, on 02 June 2012 - 01:21 PM, said:

Those values are likely overdone, Taylor.  Earl needs to fix the indices on the pages because the calculations have been off and blow the parameters off the scale quite a bit.  I know this because there has been comparison done on other sites as well as with AWIPS.  However, some of the wind fields are good enough to support long track MCS potential.  Just unsure of how severe they will be at this point.  Coming into the NAM range now and it seems the higher CAPE could be offset from the MCS track slightly.  Still time to iron those things out.

I think your right. The SB CAPE below is always off the charts and likely the problem. The graphics correlate well with the calculation of

EHI = (CAPE * SRH)/ 160,000.

CAPE = 4,000
SRH = 240

(4000 * 240)/ 160,000 = 6

However, we are more likely looking at CAPE in the 1,500-2,500 range.

CAPE = 1,500/2,500
SRH = 240

(1500 * 240)/ 160,000 = 2.25
(2500 * 240)/ 160,000 = 3.75

We also need to keep in mind that this is really only one of a few runs that had SRH values this high. The NAM is less impressive; still this is primarily a damaging wind type of event.

Edited by Taylor Campbell, 02 June 2012 - 02:39 PM.

[brax]

North GA in another hole... again... Blah.

[Tyler Penland]

brax, on 02 June 2012 - 05:43 PM, said:

North GA in another hole... again... Blah.

Eh, I'm pretty optimistic we get something out of this pattern. It appears there may be more than one MCS and historically (the past few years) we usually take advantage of one of them. Well, I do anyways.

[Taylor Campbell]

brax, on 02 June 2012 - 05:43 PM, said:

North GA in another hole... again... Blah.

The models have been hammering nails in North Georgia, and there hasn't been a sore thumb. We aren't in a hole with this one.

Edited by Taylor Campbell, 03 June 2012 - 11:02 AM.

[Mike Puckett]

This seems like a pretty rare area for this

Monday

NRN ID/WRN AND CENTRAL MT AND VICINITY...
   SUBSTANTIAL SEVERE WEATHER THREAT APPEARS TO BE EVOLVING FOR DAY
   2...AS A VERY STRONG TROUGH/LOWER OVER DIGGING SEWD OUT OF THE GULF
   OF AK BEGINS TO ASSUME A NEGATIVE TILT AS IT MOVES ONSHORE ACROSS
   THE PAC NW.  AHEAD OF THIS TROUGH...FAST/DIFFLUENT SSWLY MID-LEVEL
   FLOW FIELD WILL OVERSPREAD ID/MT THROUGH THE DAY.
  
   AS A COLD FRONT SHIFTS INLAND AND A DEEPENING SURFACE LOW SHIFTS
   TOWARD WRN WY...A DESTABILIZING WARM SECTOR WILL SUPPORT WIDESPREAD
   STORM DEVELOPMENT -- BOTH ACROSS THE HIGHER TERRAIN AS WELL AS INVOF
   THE LOW/TRAILING COLD FRONT...AND THE WARM FRONT ACROSS MT.  WITH
   LOW-LEVEL SELY FLOW ACROSS MT/NRN ID N AND NE OF THE SURFACE LOW
   BENEATH THE FAST/DIFFLUENT FLOW ALOFT...SHEAR WILL FAVOR
   INTENSIFICATION/ROTATION OF THE DEVELOPING STORMS -- WITH SEVERAL
   SEVERE/SUPERCELL STORMS LIKELY BY EARLY EVENING.  ALONG WITH THREAT
   FOR DAMAGING WINDS...LARGE HAIL IS EXPECTED...AND AN ISOLATED
   TORNADO OR TWO WILL ALSO BE POSSIBLE -- ESPECIALLY ACROSS NRN AND
   WRN MT WHERE THE SURFACE WARM FRONT IS EXPECTED TO RESIDE.  SEVERE
   POTENTIAL MAY CONTINUE INTO THE OVERNIGHT HOURS...AS STORMS SPREAD
   EWD INTO CENTRAL MT.

[brax]

Day 2 graphics from SPC.

Edited by brax, 03 June 2012 - 02:31 AM.

[EMSFD6101]

brax, on 03 June 2012 - 02:31 AM, said:

Day 2 graphics from SPC.

...MID MS VALLEY REGION ESEWD ACROSS THE SOUTHEAST...
   A WEAK/DIFFUSE FRONT IS FORECAST TO STRENGTHEN AND SHIFT SWD/SSWWD
   WITH TIME ACROSS THE SOUTHEAST/MID-SOUTH REGION TODAY...IMPINGING ON
   A MOIST/DESTABILIZING LOW-LEVEL AIRMASS.  
  
   STORMS MAY BE ONGOING AT THE START OF THE PERIOD -- PARTICULARLY
   ACROSS NWRN PORTIONS OF THE RISK AREA.  WHILE THIS COULD HINDER
   DESTABILIZATION POTENTIAL...THE ADVANCING FRONT -- AND BROAD ASCENT
   PROVIDED BY THE ASSOCIATED UPPER TROUGH -- SUGGESTS THAT STORMS WILL
   CONTINUE/REDEVELOP THROUGH THE DAY...SPREADING SEWD ALONG THE
   FRONTAL ZONE DRIVEN BY WNWLY STEERING FLOW ALOFT.  
  
   GIVEN THIS FAST FLOW FIELD ALOFT...POTENTIAL FOR ORGANIZED/SEVERE
   STORMS IS EVIDENT...WITH SOME LIKELIHOOD THAT ONE OR MORE
   SEWD-MOVING MCS/S MAY EVOLVE THROUGH THE AFTERNOON.  ALONG WITH HAIL
   POTENTIAL...THREAT FOR DAMAGING WINDS APPEARS SUFFICIENT TO WARRANT
   SLIGHT RISK UPGRADE.  STORMS SHOULD CONTINUE INTO THE EVENING...WITH
   SOME CONVECTION LIKELY TO REACH/MOVE OFF THE SERN U.S. COAST LATER
   IN THE PERIOD.
  
   ..GOSS.. 06/03/2012

Edited by EMSFD6101, 03 June 2012 - 08:11 AM.

[metallicwx366]

In a slight risk area for 2 days.  

[Taylor Campbell]

Time won't be long before things get real real stormy!

Storm Prediction Center has also issued a slight risk to account for today's into tonight's MCS.

Edited by Taylor Campbell, 03 June 2012 - 11:53 AM.

[Taylor Campbell]

...MO/AR TO MS/AL...
   OVERALL FORECAST UNCERTAINTY REMAINS RATHER HIGH OVER THE ENTIRE
   COUNTRY THIS PERIOD AS SHOWN IN THE WIDE RANGE OF CHANGES TO THE
   OUTLOOK OVER THE PAST 72 HOURS. THIS IS DUE IN PART TO STORM SCALE
   AND MESOSCALE INFLUENCES ON BOTH THE BOUNDARY LAYER AND UPPER LEVELS
   THAT ARE NOT ALWAYS WELL DEPICTED OR HANDLED BY TRADITIONAL
   NUMERICAL MODELS.

   LATEST UA AND SURFACE ANALYSIS REVEAL A SHORT WAVE TROUGH/MCV
   DRIVING A SMALL CLUSTER OF CONVECTION ACROSS NERN AR. AIRMASS
   UPSTREAM FROM THESE WEAK TSTMS WILL CONTINUE TO DESTABILIZE BENEATH
   CAPPING INVERSION THAT WEAKENS WITH EWD EXTENT. VERY WARM BOUNDARY
   LAYER AND WEAK BUT PERSISTENT ISENTROPIC ASCENT FROM THE MS RIVER
   EAST ACROSS MS AND AL MAY CONTRIBUTE TO AN INCREASING CHANCE FOR
   SURFACE-BASED TSTM DEVELOPMENT LATER THIS AFTERNOON. THESE AREAS
   RESIDE ON THE SWRN FLANK OF STRONGER WNWLY FLOW ALOFT AND BENEATH
   THE RIGHT ENTRANCE REGION OF MID LEVEL JET SITUATED ACROSS THE CNTRL
   APPALACHIANS AND EAST COAST. ANY DEEP CONVECTION DEVELOPING IN THIS
   REGIME WILL EXIST AMIDST SUFFICIENT SHEAR AND FLOW TO SUPPORT AN
   INCREASING CHANCE FOR MULTICELLS AND PERHAPS EVEN SUPERCELLS WITH
   ATTENDANT THREATS OF HAIL/WIND INTO THE EVENING.
  
   IN ADDITION TO THE POSSIBILITY OF THE ABOVE SCENARIO...LATEST NAM
   SUGGESTS ANOTHER UPSTREAM MCS DEVELOPING FROM THE MO BOOTHEEL ACROSS
   THE MS RIVER LATE TONIGHT. THIS COMPLEX IS FORECAST TO SPREAD SEWD
   ACROSS PARTS OF THE TN VALLEY THROUGH EARLY MONDAY AND COULD ALSO
   BRING WITH IT ANOTHER ROUND OF STRONG WINDS AND PERHAPS SOME HAIL
   EVENTS.
  
   GIVEN THESE PROSPECTS FOR STRONG TO SEVERE STORMS THROUGHOUT THE
   REST OF THIS FORECAST PERIOD...THE SLGT RISK AREA HAS BEEN EXPANDED
   EAST ACROSS THE MS RIVER AND INTO THE TN VALLEY.

Edited by Taylor Campbell, 03 June 2012 - 11:56 AM.

[Cyclogent]

brax, on 03 June 2012 - 02:31 AM, said:

Day 2 graphics from SPC.

Something tells me the day 2 area is too far north/east.  Right now the SPC axis of severe weather runs from Paducah to Savannah, but I tend to think when this is updated it'll be a tad farther south/west with an axis running from Jonesboro to Jacksonville.

[EMSFD6101]

Looks like development in Northeastern Mississippi will continue into Alabama.

MESOSCALE DISCUSSION 1028
   NWS STORM PREDICTION CENTER NORMAN OK
   0111 PM CDT SUN JUN 03 2012
  
   AREAS AFFECTED...MS...AL
  
   CONCERNING...SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY
  
   VALID 031811Z - 031915Z
  
   PROBABILITY OF WATCH ISSUANCE...80 PERCENT
  
   SUMMARY...CHANCES ARE INCREASING THAT SEVERE STORMS WITH HAIL AND
   HIGH WINDS WILL SPREAD EAST FROM NRN MS INTO PARTS OF NRN/CNTRL AL
   THROUGH THE AFTERNOON. A SEVERE THUNDERSTORM WATCH WILL LIKELY BE
   NEEDED AHEAD OF THIS DEVELOPMENT.
  
   DISCUSSION...SCATTERED STRONG TO SEVERE STORMS ARE EXPECTED TO
   INCREASE IN BOTH COVERAGE AND INTENSITY ALONG A WEAK WARM FRONTAL
   ZONE DRAPED OVER NRN MS/AL. LIFT ALONG/ACROSS THIS BOUNDARY IS AIDED
   BY A 20-30KT WLY LOW LEVEL JET AND MODEST 30KT NWLY FLOW AT MID
   LEVELS WILL CONTRIBUTE TO SUFFICIENT SHEAR TO MAINTAIN UPDRAFT
   ORGANIZATION AND PERSISTENCE. AIRMASS ALONG AND SOUTH OF THE
   BOUNDARY IS VERY UNSTABLE ACROSS MS BUT LESS SO TO THE NORTH OF THE
   BOUNDARY...OVER NRN AL. HOWEVER...LATEST SATL IMAGERY INDICATES THAT
   STRONG HEATING SHOULD CONTINUE ACROSS NRN AL IN ADVANCE OF THE
   ONGOING CONVECTION AND ADDITIONAL CELLS MAY DEVELOP ALONG THE FRONT
   AND MOVE INTO AL THROUGH THE AFTERNOON. SOMEWHAT DRIER BOUNDARY
   LAYER IN THIS REGION MAY SUPPORT DOWNBURST WIND POTENTIAL. IN
   ADDITION TO LOCALLY STRONG DOWNBURST WINDS...LARGE HAIL IS POSSIBLE
   WITH ANY OF THE PERSISTENT ROTATING STORMS GIVEN MAGNITUDE OF
   AVAILABLE INSTABILITY TO THIS DEVELOPING CONVECTION.
  
   ..CARBIN.. 06/03/2012

Edited by EMSFD6101, 03 June 2012 - 01:19 PM.

[Argus]

Whats the timing on this MCS for northeast Georgia?