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Storm Chase Club. Meeting 3. Topics. UTC/Z/Zulu – What does this mean for me? Watches and Warnings – Basic and Advanced SPC Products Mesoanaylsis , WWA, MD’s, Conv. Outlooks, Update Times. UTC/Z/Zulu. UTC – Universal Time Coordinated Z – Zulu Both are the SAME
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Storm Chase Club Meeting 3
Topics • UTC/Z/Zulu – What does this mean for me? • Watches and Warnings – Basic and Advanced • SPC Products • Mesoanaylsis, WWA, MD’s, Conv. Outlooks, Update Times
UTC/Z/Zulu • UTC – Universal Time Coordinated • Z – Zulu • Both are the SAME • CDT is -5 hours and CST is -6 hours • Important times • 0Z, 12Z, 18Z 21Z During “Storm Chasing Season” • 0Z and 12Z during the Winter
Watches and Warnings • Tornado Watch/Warning • Severe Thunderstorm Watch/Warning • Flash Flood Warning
Tornado Warning • 2 reasons for issuing warning - tornado/funnel cloud spotted - Doppler Radar indicated rotation - Beware of public/law enforcement reports sometimes can be suspect
Tornado Watch/Severe T-storm Watch • 2 Types of Watches • “Normal” – What Hazards are Going to Happen? • “PDS” – Particularly Dangerous Situation • Don’t happen often, and warrant an increase in vigilance around any storms that develop
URGENT - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 678 NWS STORM PREDICTION CENTER NORMAN OK 345 PM CDT SAT AUG 8 2009 • THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF EASTERN MINNESOTA WESTERN WISCONSIN EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 345 PM UNTIL 1000 PM CDT. • SEVERAL TORNADOES SCATTERED DAMAGING WINDS ISOLATED WIND GUSTS TO 70 MPH POSSIBLE SCATTERED LARGE HAIL HAIL TO 3.0 INCHES IN DIAMETER LIKELY • THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES NORTH NORTHWEST OF MANKATO MINNESOTA TO 60 MILES EAST OF EAU CLAIRE WISCONSIN. • FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8). • 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 677....
DISCUSSION...UPPER IMPULSE OVER THE ERN DAKOTAS IS EXPECTED TO AID IN INCREASED STORM DEVELOPMENT ACROSS ERN MN AND WRN WI INTO THE EVENING HOURS. EFFECTIVE SHEAR NEAR 50 KT AND EXTREME INSTABILITY AROUND 5000 J/KG WILL BE FAVORABLE FOR INTENSE SUPERCELLS WITH VERY LARGE HAIL AND WIND DAMAGE. ALTHOUGH THE LOW LEVEL SHEAR IS ONLY AROUND 15 KT...THE PRESENCE OF LOW LEVEL BOUNDARIES AND AMOUNT OF INSTABILITY MAY COMPENSATE FOR THE WEAKER LOW LEVEL SHEAR AND YIELD A COUPLE OF TORNADOES.
Severe Thunderstorm Warning • Identify the Hazards in the Text of the Warning • Is it Wind? Hail? “Doppler Radar has indicated Some Weak Rotation Within This Storm”? • The warnings and all text are important to read in full, they can provide you some information to skip one storm and go for another one
Convective Outlooks • Day 1 • Day 2 • Day 3 • Day 4-8
Day 1 Convective Outlook • 13Z Outlook • 8AM In Summer • Gives a Preliminary outlook, decides wether to be watching for the day or not (usually) • 1630 Z Outlook Most Important • 11:30 In Summer • If You Need To Drive More Than 4 Hours to a potential target you need to leave NOW! This is your point of no return for the day! • 20Z Outlook • 3:30 In Summer • If Chasing Locally ~1/2 Hours MAX You Can Wait Until the 20Z Update for Guidance
Outlooks for August 8th, 2009 • http://www.spc.noaa.gov/products/outlook/archive/2009/day1otlk_20090808_1300.html • http://www.spc.noaa.gov/products/outlook/archive/2009/day1otlk_20090808_1630.html • http://www.spc.noaa.gov/products/outlook/archive/2009/day1otlk_20090808_2000.html
Day 2 Convective Outlook • Good To Watch For Confidence from Day 3 Outlook • Good To Target a General Area From This Outlook • http://www.spc.noaa.gov/products/outlook/archive/2009/day2otlk_20090807_1730.html
Day 3 and Days 4-8 • Generally you will never see higher than a slight risk for day 3..if you see moderate or high risk you should be cancelling plans! • Forecasting on a time budget…Pouring over models is GREAT and the SCC does that regularly, but when you don’t have time to pour over data, a quick glimpse at these can save you a lot of time.
MD’s • Your Best Friend in the World. Learn to Love these! • Basically amounts to a convective outlook update • Tells you what the SPC is thinking in terms of storm development, and currently analyzed boundaries
MESOSCALE DISCUSSION 1831 • NWS STORM PREDICTION CENTER NORMAN OK 0852 PM CDT SAT AUG 08 2009 AREAS AFFECTED... • E-CNTRL MN INTO W-CNTRL WI CONCERNING...TORNADO WATCH 678... VALID 090152Z - 090315Z • THE SEVERE WEATHER THREAT FOR TORNADO WATCH 678 CONTINUES. • TORNADIC SUPERCELL WHICH RECENTLY DEVELOPED OVER THE MINNEAPOLIS METRO AREA WILL LIKELY CONTINUE TO POSE A TORNADO THREAT WHILE PROGRESSING NEWD TOWARD THE ST. CROIX RIVER. A TORNADIC SUPERCELL HAS RAPIDLY DEVELOPED NEAR SYNOPTIC SURFACE LOW INVOF MSP. WHILE CURRENT MSP VWP INDICATES ONLY MODEST LOW-LEVEL SHEAR...EARLIER ELEVATED TSTMS HAVE RE-ESTABLISHED EFFECTIVE WARM FRONT FARTHER TO THE S...GENERALLY FROM THE N SIDE OF MSP EWD TO NEAR OR JUST N OF EAU. SUPERCELL WILL LIKELY CONTINUE ENEWD ALONG THIS BOUNDARY...INGESTING A VORTICITY RICH LOCAL ENVIRONMENT. THIS CORRIDOR OF ENHANCED LOW-LEVEL SHEAR COINCIDES WITH A MODERATE TO STRONGLY UNSTABLE AIR MASS /MLCAPE OF 3000-3500 J PER KG/ WHICH SHOULD MAINTAIN CURRENT ACTIVITY WITH A CONTINUED THREAT OF TORNADOES IN ADDITION TO LARGE HAIL AND LOCALLY DAMAGING WIND GUSTS.
MESOSCALE DISCUSSION 1833 • NWS STORM PREDICTION CENTER NORMAN OK 1106 PM CDT SAT AUG 08 2009 AREAS AFFECTED...PARTS OF NRN/CNTRL WI CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE • VALID 090406Z - 090530Z • THE THREAT FOR ISOLATED SEVERE STORMS CAPABLE OF MAINLY DAMAGING WINDS AND HAIL IS EXPECTED TO CONTINUE OVERNIGHT. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW. COMPLEX SUPERCELL STRUCTURE CONTINUES EWD THROUGH ST. CROIX COUNTY WI AS OF 0355Z WITH ADDITIONAL STORMS FORMING DOWNSTREAM OVER CNTRL WI. THE FORMER REMAINS COINCIDENT WITH EWD-MOVING SURFACE LOW WHILE THE LATTER APPEARS TO BE ASSOCIATED WITH STRENGTHENING LOW-LEVEL WAA REGIME FOCUSED NEAR AND N OF WARM FRONT EXTENDING FROM N OF EAU TO N OF OSH. AIR MASS ALONG AND S OF WARM FRONT REMAINS WARM AND MOIST WITH AROUND 30 KT OF 0-1 KM SHEAR PER CURRENT LACROSSE WI VWP. THE GREATEST TORNADO THREAT WILL EXIST WITH SUPERCELL COMPLEX AS IT INTERACTS WITH WARM FRONT. THIS THREAT SHOULD TEND TO DECREASE WITH TIME AS BOUNDARY LAYER CONTINUES TO COOL/STABILIZE. OTHERWISE...THE COMBINATION OF A MODERATELY UNSTABLE AIR MASS AND 40-50 KT OF DEEP-LAYER SHEAR WILL CONTINUE TO SUPPORT ORGANIZED STORM STRUCTURES CAPABLE OF HAIL AND DAMAGING WINDS. ..MEAD.. 08/09/2009
Mesoanlysis • Is also your friend BUT you have to use it wisely! • Can show you CAPE, Composite Parameters, SFC observations, etc
What else can I use? • RUC – Rapid Update Cycle • Weather.cod.edu • RUC tends to break the CAP too early, so use convective precip forecast instead of CIN strength on the RUC model (Next Meeting)
http://www.spc.noaa.gov • Help forecast from days out to hours out on severe weather days • Get to know the SPC website! It can help considerably when deciding where to forecast your storm target.