949  
NOUS41 KNHC 131254  
PNSNHC  
 
PUBLIC INFORMATION STATEMENT  
NWS NATIONAL HURRICANE CENTER MIAMI FL  
900 AM EDT THU SEP 13 2018  
 
TO: SUBSCRIBERS:  
-NOAA WEATHER WIRE SERVICE  
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK  
-NOAAPORT  
OTHER NWS PARTNERS AND NWS EMPLOYEES  
 
FROM: ALLISON ALLEN  
CHIEF, MARINE, TROPICAL AND TSUNAMI SERVICES BRANCH  
 
SUBJECT: ALERTING PARTNERS TO THE POTENTIAL FOR NON-SEQUENTIAL  
TROPICAL CYCLONE (TC) STORM NUMBERING IN THE ATLANTIC  
BASIN EFFECTIVE IMMEDIATELY  
 
THIS PUBLIC INFORMATION STATEMENT IS INTENDED TO ALERT USERS OF  
NATIONAL WEATHER SERVICE (NWS) TC PRODUCTS THAT NON-SEQUENTIAL  
NUMBERING OF TCS IN THE ATLANTIC BASIN MAY BE NECESSARY.  
 
NWSI 10-601: "TROPICAL CYCLONE FORECAST CENTER PRODUCTS" DETAILS  
STORM NUMBERING AND NAMING CONVENTIONS IN SECTION 3, WHICH EXPLAINS  
THAT ALL SYSTEMS REQUIRING ADVISORY PACKAGES (I.E., TCS OR POTENTIAL  
TCS, WHETHER TROPICAL OR SUBTROPICAL) WILL BE SEQUENTIALLY NUMBERED  
WITHIN THEIR BASIN OF ORIGIN. NWSI 10-607: "TROPICAL CYCLONE  
ADVISORY PRODUCTS" CAN BE FOUND HERE:  
 
HTTP://WWW.NWS.NOAA.GOV/DIRECTIVES/SYM/PD01006007CURR.PDF  
 
TC ADVISORY PRODUCTS FROM THE NATIONAL HURRICANE CENTER INCLUDE:  
 
PRODUCT AWIPS PIL* WMO HEADER  
--------- --------- ----------  
TC PUBLIC ADVISORY TCPAT/1-5/ WTNT/31-35/ KNHC  
TC WIND SPEED PROBABILITIES PWSAT/1-5/ FONT/11-15/ KNHC  
TC FORECAST / ADVISORY TCMAT/1-5/ WTNT/21-25/ KNHC  
TC DISCUSSION TCDAT/1-5/ WTNT/41-45/ KNHC  
NATIONAL TC VTEC PRODUCT TCVAT/1-5/ WTNT/81-85/ KNHC  
TC UPDATE TCUAT/1-5/ WTNT/61-65/ KNHC  
AVIATION TC ADVISORY MESSAGE TCANT/1-5/ FKNT/21-25/ KNHC  
 
* AWIPS PIL - AWIPS PRODUCT IDENTIFIER LABEL  
 
THESE PRODUCTS USE FIVE DISTINCT "BINS" (I.E., AWIPS PILS AND WMO  
HEADERS THAT VARY ONLY BY THE LAST DIGIT WHICH IS A NUMERICAL VALUE  
1-5). THE BINS ARE USED IN SEQUENTIAL ORDER SUCH THAT THE FIRST  
SYSTEM REQUIRING ADVISORY PACKAGES IN THE ATLANTIC BASIN IS STORM  
NUMBER AL01 AND HAS PRODUCTS WITH AWIPS PILS AND WMO HEADERS ENDING  
IN 1 (I.E., BIN 1), THE SECOND SYSTEM (AL02) HAS PRODUCTS ENDING IN  
2, ETC. THE SIXTH SYSTEM OF THE YEAR (AL06) IN A PARTICULAR BASIN  
WILL HAVE PRODUCTS THAT END IN 1, CYCLING BACK TO THE BEGINNING OF  
THE BIN NUMBERS AS ALL OF THE BIN NUMBERS UP TO THAT POINT (I.E.,  
1-5) HAVE RECENTLY BEEN USED.  
 
HOWEVER, THERE IS A COMPLICATION IN THE 2018 HURRICANE SEASON.  
HURRICANE FLORENCE HAS THE STORM NUMBER AL06 AND IS USING AWIPS PILS  
AND WMO HEADERS ENDING WITH "1". CURRENTLY, ADVISORIES ARE BEING  
WRITTEN FOR SYSTEMS ENDING WITH "3", "4", AND "5", FOR HELENE  
(AL08), ISAAC (AL09), AND JOYCE (AL10), RESPECTIVELY. THE NEXT  
SYSTEM IN THE ATLANTIC WOULD NORMALLY BE AL11, WHICH WOULD USUALLY  
CORRESPOND TO AWIPS PILS AND WMO HEADERS ENDING WITH "1". HOWEVER,  
PRODUCTS FOR HURRICANE FLORENCE ARE ALREADY USING THESE AWIPS PILS  
AND WMO HEADERS.  
 
IF ANOTHER TC, POTENTIAL TC, OR SUBTROPICAL CYCLONE FORMS IN THE  
ATLANTIC BASIN BEFORE ADVISORY PACKAGES ARE DISCONTINUED FOR  
FLORENCE, IT WILL HAVE AWIPS PILS AND WMO HEADERS ENDING WITH "2"  
AND WILL BE NUMBERED AL12.  
 
THE AWIPS TC SOFTWARE USED BY THE NWS WEATHER FORECAST OFFICES  
(WFOS) ASSUMES A STRICT RELATIONSHIP BETWEEN THE STORM ID AND THE  
BIN NUMBER. IF THE STORM NUMBER AL11 WAS USED WHILE ADVISORIES ARE  
STILL BEING WRITTEN ON HURRICANE FLORENCE, ADVISORY PRODUCTS FOR  
AL11 WOULD BE ASSUMED BY THIS SOFTWARE TO USE THE EXACT SAME AWIPS  
PILS AND WMO HEADERS AS FLORENCE. GIVEN THIS ASSUMPTION AND  
POSSIBLE NWS USER SOFTWARE DEPENDENCIES ON THE EXPECTED RELATIONSHIP  
BETWEEN STORM NUMBER AND THE AWIPS PIL/WMO HEADER, STORM NUMBER AL11  
WILL NEED TO BE SKIPPED IN ORDER TO ENSURE NO CONFLICT WITH  
HURRICANE FLORENCE ADVISORY PRODUCTS.  
 
IF THIS OCCURS, NHC WILL PROVIDE AN EXPLANATION OF THE ISSUE IN THE  
TROPICAL CYCLONE DISCUSSION PRODUCT FOR THE NEW STORM.  
 
QUESTIONS SHOULD BE DIRECTED TO:  
 
JESSICA SCHAUER  
NWS TROPICAL SERVICES PROGRAM LEADER  
NWS MARINE, TROPICAL AND TSUNAMI SERVICES BRANCH  
MIAMI, FL 33165  
TELEPHONE: 305-229-4476  
EMAIL: TROPICAL.PROGRAM@NOAA.GOV  
 
OR  
 
DR. MICHAEL BRENNAN  
BRANCH CHIEF, HURRICANE SPECIALIST UNIT  
NATIONAL HURRICANE CENTER  
MIAMI, FL 33165  
TELEPHONE: 305-229-4436  
EMAIL: MICHAEL.J.BRENNAN@NOAA.GOV  
 
NATIONAL PUBLIC INFORMATION STATEMENTS ARE ONLINE AT:  
 
HTTPS://WWW.WEATHER.GOV/NOTIFICATION  
 
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