Jump to content
  • Member Statistics

    17,607
    Total Members
    7,904
    Most Online
    NH8550
    Newest Member
    NH8550
    Joined

June 28-July 1 Severe Threat


Thundersnow12

Recommended Posts

  • Replies 1.1k
  • Created
  • Last Reply
MESOSCALE DISCUSSION 1215

NWS STORM PREDICTION CENTER NORMAN OK

0127 PM CDT MON JUN 30 2014

AREAS AFFECTED...PORTIONS OF WRN...CENTRAL AND ERN IA/NWRN AND NRN

IL/SRN WI

CONCERNING...TORNADO WATCH 373...

VALID 301827Z - 302000Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 373 CONTINUES.

SUMMARY...SEVERE WEATHER THREAT...INCLUDING A FEW TORNADOES...VERY

LARGE HAIL AND DAMAGING SWATHS OF STRONG WINDS...SOME SIGNIFICANT

GUSTS POSSIBLE...PERSISTS ACROSS THE ERN HALF OF WW 373 /IN IOWA/.

THESE SVR THREATS ARE EXPECTED TO PROGRESS EWD THIS AFTERNOON WITH A

NEW WATCH LIKELY NEEDED EAST OF WW 373 BY 19Z.

STORM DEVELOPMENT IN THE WRN PART OF WW 373 SHOULD CONTINUE TO

DIMINISH WITH THE PASSAGE OF A WIND SHIFT /SURFACE WINDS BECOMING

NLY/.

DISCUSSION...COMPLEX STORM ORGANIZATION IS UNDERWAY ACROSS CENTRAL

IOWA EARLY THIS AFTERNOON WITH A LINE OF STORMS EXTENDING FROM

WEBSTER/BOONE COUNTIES TO ADAIR COUNTY MOVING ESEWD AT 40-45

KT...WITH AT LEAST ONE SUPERCELL EMBEDDED WITHIN THIS LINE NEAR DSM.

ADDITIONAL STORM MERGERS HAVE OCCURRED IN HAMILTON/HARDIN AND STORY

COUNTIES. THE ENVIRONMENT NEAR AND EAST OF THIS ACTIVITY IS VERY

STRONGLY UNSTABLE /MLCAPE 2500-4000 J PER KG/ WITH EFFECTIVE BULK

SHEAR OF 50-70 KT MAINTAINING STORM ORGANIZATION. SELY SURFACE

WINDS IN ADVANCE OF THESE STORMS IS RESULTING IN ENHANCED LOW-LEVEL

SHEAR FOR A TORNADO THREAT.

CURRENT EWD TO ESEWD MOVEMENT OF THE CENTRAL IA STRONG-SEVERE STORMS

SUGGESTS ACTIVITY WILL EXIT WW 373 BY 19Z. AIR MASS RECOVERY

PERSISTS DOWNSTREAM ACROSS ERN IA INTO NRN IL AND SRN WI GIVEN

LIMITED CLOUD COVER ALLOWING FOR STRONG SURFACE HEATING.

INSTABILITY GRADIENT EXTENDS ESEWD FROM THE ONGOING CENTRAL IA

STORMS SUGGESTING A GENERAL ESEWD MOVEMENT MAY PERSIST.

..PETERS/CORFIDI.. 06/30/2014

Link to comment
Share on other sites

Anyone catch the LOT briefing and if so, summary please?

Pretty general info, as should be expected...

 

Heating and high dp's will lead to an unstable environment. Organizing complex of storms in C. IA is expected to race eastward and into the CWA this evening. All modes of severe wx possible, but he hit the sig wind threat hard. Threat along/west of McHenry-Pontiac from 3-6PM, then after 6PM to the east.

Link to comment
Share on other sites

Pretty general info, as should be expected...

Heating and high dp's will lead to an unstable environment. Organizing complex of storms in C. IA is expected to race eastward and into the CWA this evening. All modes of severe wx possible, but he hit the sig wind threat hard. Threat along/west of McHenry-Pontiac from 3-6PM, then after 6PM to the east.

Also, though not as exciting, they spent some time on the heavy rain threat. 3"/hr isolated rates I heard.
Link to comment
Share on other sites

izzi update, quality as usual

 

SEVERE THUNDERSTORMS ARE LIKELY LATE THIS AFTERNOON INTO EARLY THIS
EVENING ACROSS THE ENTIRE CWA. PRIMARY HAZARD APPEARS TO BE DAMAGING
WINDS...INCLUDING A THREAT FOR WIDESPREAD AND LOCALLY HIGH END
DAMAGING WINDS...AND A THREAT OF LARGE HAIL AND EVEN TORNADOES AS
WELL.

OVERNIGHT CONVECTION HAS DISSIPATED AND MOVED WELL OUT OF THE AREA
WITH RAPIDLY ERODING DEBRIS CIRRUS CANOPY OVER THE EASTERN PORTIONS
OF THE OUTLOOK AREA. REMNANT OUTFLOW BOUNDARY FROM THIS CONVECTION
HAS SURGED WELL SOUTH INTO SOUTHERN ILLINOIS EXTENDING NORTHWEST
INTO SOUTHEAST IOWA. AIR MASS BEHIND THIS OUTFLOW OVER OUR AREA IS
IN THE PROCESS OF QUICKLY RECOVERING. SEVERAL HOURS OF AT LEAST
PARTIAL SUNSHINE APPEAR LIKELY WHICH SHOULD ALLOW FOR
DESTABILIZATION OF THE BOUNDARY LAYER. IN ADDITION...LOW/MID LEVEL
WARM AIR ADVECTION IS TAKING PLACE WITH APPROXIMATELY 4C OF WARMING
HAVING TAKEN PLACE ON AT DVN IN THE PAST 6 HOURS BETWEEN THE 12Z AND
18Z SOUNDINGS. THIS WARMING IN THE LOW LEVELS IS RESULTING IN A
CONSIDERABLE STEEPENING OF THE LOW AND MID LEVEL LAPSE RATES.

THE STRONG WARMING BETWEEN 900-700MB HAS RESULTED IN A LOW LEVEL
INVERSION BASED NEAR 900MB WHICH IS CURRENTLY PROVIDING FOR A
MODERATELY STRONG CAP OVER THE CWA. ANTICIPATE THIS CAP TO WEAKEN
WITH CONTINUED HEATING/SUNSHINE...THOUGH THE ABSENCE OF STRONG
FOCUSED LOW LEVEL CONVERGENCE OUT AHEAD OF THE DEVELOPING MCS WOULD
SEEM TO SUGGEST A LOWER LIKELIHOOD OF DISCRETE CONVECTION DEVELOPING
AHEAD OF THE ORGANIZING MCS OVER CENTRAL IOWA. GIVEN SIGNS OF
CONVECTION ALREADY BEGINNING TO ORGANIZE OVER CENTRAL IOWA AND
LIKELIHOOD OF COLD POOL DEVELOPING/EXPANDING IT SEEMS VERY PLAUSIBLE
THAT STORMS OVER IOWA NOW COULD MORPH INTO A FORWARD PROPAGATING
MCS/POSSIBLE DERECHO THIS AFTERNOON INTO THIS EVENING. FORWARD
PROPAGATING CORFIDI VECTORS IN EXCESS OF 50KT SUGGEST A VERY RAPID
STORM MOTION IS POSSIBLE WHICH WOULD ENHANCE THE DAMAGING WIND
THREAT.

MODEL PROGGED WIND FIELDS ARE LIKELY BEING SKEWED BY POTENTIALLY
ERRONEOUS MASS FIELDS DUE TO CONVECTIVE FEEDBACK/MODELS ATTEMPTING
TO RESOLVE CONVECTION. EVEN SO...SYNOPTIC SCALE WIND FIELDS ARE MORE
THAN SUFFICIENT TO SUPPORT BOW ECHO/SUPERCELL STORMS. SHOULD
DISCRETE STORMS FORM AHEAD OF THE BOW...SIGNIFICANT TORNADO THREAT
MAY BE LIMITED BY A WEAKNESS IN THE FLOW AROUND 700MB...HOWEVER
VERY PLAUSIBLE THAT MESO VORTICIES FORMING WITHIN THE BOW ECHO COULD
RESULT IN BRIEF QLCS TORNADO TYPE THREAT.

IZZI
 

Link to comment
Share on other sites

Tornadoes

Probability of 2 or more tornadoes 

Mod (50%)

Probability of 1 or more strong (F2-F5) tornadoes

Low (20%)

Wind

Probability of 10 or more severe wind events

High (>95%)

Probability of 1 or more wind events > 65 knots

Mod (60%)

Hail

Probability of 10 or more severe hail events

High (90%)

Probability of 1 or more hailstones > 2 inches

Mod (30%)

Combined Severe Hail/Wind

Probability of 6 or more combined severe hail/wind events

High (>95%)

 

post-3774-0-53410100-1404155337_thumb.gi

Link to comment
Share on other sites

 

 

DISCUSSION...ORGANIZING CONVECTIVE SYSTEM WITH EMBEDDED SUPERCELLS
IN CNTRL IA EXPECTED TO CONTINUE GENERALLY E INTO IL THROUGH LATE

AFTN. ADDITIONAL DEVELOPMENT MAY OCCUR BOTH ON THE NRN AND SRN

FLANKS OF THE SQLN...WITH SOME POTENTIAL FOR REAR-INFLOW JET

DEVELOPMENT AND ASSOCIATED EVOLUTION INTO A DERECHO-PRODUCING MCS.

QUALITY OF MOISTURE INFLOW...STRENGTH OF WSWLY DEEP SHEAR...AND

PRESENCE OF EXISTING EMBEDDED CIRCULATIONS SUGGEST POTENTIAL FOR

OCCASIONAL TORNADOES...IN ADDITION TO INCREASINGLY BROAD SWATHS OF

DMGG WIND/HAIL.

Link to comment
Share on other sites

URGENT - IMMEDIATE BROADCAST REQUESTED  TORNADO WATCH NUMBER 374  NWS STORM PREDICTION CENTER NORMAN OK  205 PM CDT MON JUN 30 2014    THE NWS STORM PREDICTION CENTER HAS ISSUED A    * TORNADO WATCH FOR PORTIONS OF     EASTERN IOWA    WESTERN AND NORTHERN ILLINOIS    NORTHEAST MISSOURI    SOUTHERN WISCONSIN    * EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 205 PM UNTIL    700 PM CDT.    * PRIMARY THREATS INCLUDE...    A FEW TORNADOES POSSIBLE    WIDESPREAD DAMAGING WINDS EXPECTED WITH ISOLATED SIGNIFICANT      GUSTS TO 85 MPH LIKELY    WIDESPREAD LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL      EVENTS TO 2.5 INCHES IN DIAMETER POSSIBLE    THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 90 STATUTE  MILES NORTH AND SOUTH OF A LINE FROM 35 MILES WEST SOUTHWEST OF  CEDAR RAPIDS IOWA TO 40 MILES SOUTH SOUTHEAST OF ROCKFORD  ILLINOIS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE  ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).  

 

DISCUSSION...ORGANIZING CONVECTIVE SYSTEM WITH EMBEDDED SUPERCELLS  

IN CNTRL IA EXPECTED TO CONTINUE GENERALLY E INTO IL THROUGH LATE  

AFTN. ADDITIONAL DEVELOPMENT MAY OCCUR BOTH ON THE NRN AND SRN  

FLANKS OF THE SQLN...WITH SOME POTENTIAL FOR REAR-INFLOW JET  

DEVELOPMENT AND ASSOCIATED EVOLUTION INTO A DERECHO-PRODUCING MCS.  

QUALITY OF MOISTURE INFLOW...STRENGTH OF WSWLY DEEP SHEAR...AND  

PRESENCE OF EXISTING EMBEDDED CIRCULATIONS SUGGEST POTENTIAL FOR  

OCCASIONAL TORNADOES...IN ADDITION TO INCREASINGLY BROAD SWATHS OF  

DMGG WIND/HAIL. 

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...