Jump to content
  • Member Statistics

    17,585
    Total Members
    7,904
    Most Online
    LopezElliana
    Newest Member
    LopezElliana
    Joined

April 26th-30th, 2014 Major Tornado Outbreak


Recommended Posts

  • Replies 2.4k
  • Created
  • Last Reply

MESOSCALE DISCUSSION 0479
NWS STORM PREDICTION CENTER NORMAN OK
0327 PM CDT TUE APR 29 2014

AREAS AFFECTED...NERN MS / NRN AND CNTRL AL / SRN MIDDLE TN /
EXTREME NWRN GA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 292027Z - 292100Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...STORMS ARE FORECAST TO DEVELOP OVER NERN MS AND MOVE
DOWNSTREAM INTO NRN AL LATER THIS AFTERNOON. A GRADUAL INCREASE IN
STORMS POTENTIALLY CAPABLE OF AN ISOLD SEVERE THREAT IS EXPECTED. A
WATCH WILL LIKELY BE NEEDED BY 21Z.

DISCUSSION...RADAR MOSAIC SHOWS STORMS BEGINNING TO DEVELOP OVER
NERN MS SWWD INTO CNTRL MS ALONG A NARROW PLUME OF GREATER
INSTABILITY ALONG A COLD FRONTAL SEGMENT. THE AIRMASS OVER CNTRL
AND NRN AL IS BECOMING MORE BUOYANT BUT SIGNIFICANT CONVECTIVE
OVERTURNING OF THIS AIRMASS FROM THE MORNING MCS OVER THE NERN GULF
HAS TEMPERED THE MAGNITUDE OF DESTABILIZATION. THE 18Z BMX RAOB
EXHIBITED POOR MID-LEVEL LAPSE RATES /BELOW 5 DEG C PER KM/ AND
LOW-LEVEL TRAJECTORIES ARE EMANATING FROM THE AREA IN WAKE OF THE
MCS. THIS CASTS SOME UNCERTAINTY REGARDING THE FORECAST SEVERE
THREAT THIS AFTERNOON AND EVENING.

 

Could the MLCAPE partially overcome the poor mid-level lapse rates in ctrl AL?

Link to comment
Share on other sites

MESOSCALE DISCUSSION 0479

NWS STORM PREDICTION CENTER NORMAN OK

0327 PM CDT TUE APR 29 2014

AREAS AFFECTED...NERN MS / NRN AND CNTRL AL / SRN MIDDLE TN /

EXTREME NWRN GA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 292027Z - 292100Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...STORMS ARE FORECAST TO DEVELOP OVER NERN MS AND MOVE

DOWNSTREAM INTO NRN AL LATER THIS AFTERNOON. A GRADUAL INCREASE IN

STORMS POTENTIALLY CAPABLE OF AN ISOLD SEVERE THREAT IS EXPECTED. A

WATCH WILL LIKELY BE NEEDED BY 21Z.

DISCUSSION...RADAR MOSAIC SHOWS STORMS BEGINNING TO DEVELOP OVER

NERN MS SWWD INTO CNTRL MS ALONG A NARROW PLUME OF GREATER

INSTABILITY ALONG A COLD FRONTAL SEGMENT. THE AIRMASS OVER CNTRL

AND NRN AL IS BECOMING MORE BUOYANT BUT SIGNIFICANT CONVECTIVE

OVERTURNING OF THIS AIRMASS FROM THE MORNING MCS OVER THE NERN GULF

HAS TEMPERED THE MAGNITUDE OF DESTABILIZATION. THE 18Z BMX RAOB

EXHIBITED POOR MID-LEVEL LAPSE RATES /BELOW 5 DEG C PER KM/ AND

LOW-LEVEL TRAJECTORIES ARE EMANATING FROM THE AREA IN WAKE OF THE

MCS. THIS CASTS SOME UNCERTAINTY REGARDING THE FORECAST SEVERE

THREAT THIS AFTERNOON AND EVENING.

 

Could the MLCAPE partially overcome the poor mid-level lapse rates in ctrl AL?

 

You can see this well on the SPC site, that's what some have been saying regarding advecting those steeper rates in. There is no question steep mid level lapse rates allow for explosive development of supercells and allow for violent updrafts to help sustain long track storms. However good CAPE in the 0-3km will allow for low level stretching and tornado development too...but perhaps not as strong or long track as what you would see with more of an EML present. That's kind of the wild card we have now. 

Link to comment
Share on other sites

Significant further development of / potential for strong tornadoes in srn and s-ctrl MS will likely wait for a couple more hours before mid-level lapse rates finally steepen enough to allow for such development. Temperatures are well into the 80s over in LA, SW of the MDT Risk area, which may also help develop a hint of a mesolow along the gradient over near the Red River in LA, thereby bolstering low-level helicities a bit. (Or would the hint of a mesolow not develop? Please feel free to correct me.)

Link to comment
Share on other sites

Significant further development of / potential for strong tornadoes in srn and s-ctrl MS will likely wait for a couple more hours before mid-level lapse rates finally steepen enough to allow for such development. Temperatures are well into the 80s over in LA, SW of the MDT Risk area, which may also help develop a hint of a mesolow along the gradient over near the Red River in LA, thereby bolstering low-level helicities a bit. (Or would the hint of a mesolow not develop? Please feel free to correct me.)

Something is definitely missing so far in Mississippi. Not even a tornado-warned cell yet.

Link to comment
Share on other sites

post-6398-0-01208400-1398805567_thumb.gi

   URGENT - IMMEDIATE BROADCAST REQUESTED   TORNADO WATCH NUMBER 118   NWS STORM PREDICTION CENTER NORMAN OK   355 PM CDT TUE APR 29 2014   THE NWS STORM PREDICTION CENTER HAS ISSUED A   * TORNADO WATCH FOR PORTIONS OF      CENTRAL AND NORTHERN ALABAMA     A SMALL PART OF SOUTHERN MIDDLE TENNESSEE   * EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 355 PM UNTIL     1000 PM CDT.   * PRIMARY THREATS INCLUDE...     A COUPLE TORNADOES POSSIBLE     ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE     ISOLATED LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE   THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE   MILES NORTH AND SOUTH OF A LINE FROM 40 MILES WEST NORTHWEST OF   TUSCALOOSA ALABAMA TO 30 MILES NORTHEAST OF GADSDEN ALABAMA.  FOR   A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH   OUTLINE UPDATE (WOUS64 KWNS WOU8).   PRECAUTIONARY/PREPAREDNESS ACTIONS...   REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR   TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS   AND POSSIBLE WARNINGS.   &&   OTHER WATCH INFORMATION...CONTINUE...WW 116...WW 117...   DISCUSSION...SCATTERED THUNDERSTORMS HAVE DEVELOPED ALONG THE WIND   SHIFT ACROSS CENTRAL/NRN MS...IN CONJUNCTION WITH AN EJECTING   MID-UPPER JET STREAK.  RECOVERY FROM THE MORNING MCS HAS BEEN SLOWED   BY CONTINUED STORM DEVELOPMENT ALONG THE GULF COAST...AND LAPSE   RATES ALOFT REMAIN RELATIVELY POOR PER 18Z BMX AND 20Z UAH   SOUNDINGS.  ADDITIONALLY...THE WIND PROFILES ARE CHARACTERIZED BY   MODEST LOW-LEVEL SHEAR AND VERY STRONG SPEED SHEAR ALOFT...IN THE   ZONE OF POOR LAPSE RATES.  THERE ARE A FEW CONCERNS REGARDING ANY   HIGHER-END SEVERE WEATHER THREAT...BUT STILL SOME POTENTIAL FOR   SUPERCELLS AND/OR EVOLUTION OF STORMS INTO A CLUSTER LATER.  A   COUPLE OF TORNADOES ARE STILL POSSIBLE...ALONG WITH LARGE HAIL AND   DAMAGING WINDS.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...