662  
WTPZ45 KNHC 272035  
TCDEP5  
 
TROPICAL STORM SELMA DISCUSSION NUMBER 3  
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202017  
400 PM CDT FRI OCT 27 2017  
 
THE CENTER OF SELMA BECAME EXPOSED SHORTLY AFTER THE ISSUANCE OF THE  
PREVIOUS ADVISORY, HOWEVER, DEEP CONVECTION HAS REDEVELOPED NEAR AND  
JUST SOUTH OF THE CENTER THIS AFTERNOON. THE SYSTEM IS FEELING THE  
AFFECTS OF MODERATE NORTHEASTERLY SHEAR AND DOES NOT APPEAR TO HAVE  
STRENGTHENED. SUBJECTIVE DVORAK T-NUMBERS FROM BOTH TAFB AND SAB  
ARE 2.0 (30 KT), HOWEVER, THE INITIAL INTENSITY IS MAINTAINED AT  
35 KT IN AGREEMENT WITH THE OVERNIGHT ASCAT DATA. UNFORTUNATELY,  
THE ASCAT SATELLITES DID NOT PASS OVER THE TROPICAL CYCLONE TODAY.  
 
SATELLITE AND MICROWAVE FIXES SHOW THAT SELMA HAS TURNED MORE  
POLEWARD AND IS NOW MOVING NORTH-NORTHWESTWARD OR 345/6 KT. A  
LARGE MID-LATITUDE TROUGH IS FORECAST TO MOVE OVER THE GULF OF  
MEXICO TONIGHT AND SATURDAY WHICH SHOULD CAUSE SELMA TO TURN  
NORTHWARD LATER TODAY OR TONIGHT. THE 12Z TRACK GUIDANCE HAS COME  
INTO BETTER AGREEMENT AND BRINGS SELMA ONSHORE IN EL SALVADOR  
OR EASTERN GUATEMALA ON SATURDAY, AND LITTLE CHANGE WAS MADE TO THE  
PREVIOUS NHC FORECAST TRACK.  
 
MODERATE TO STRONG NORTHEASTERLY SHEAR IS EXPECTED TO REMAIN OVER  
THE TROPICAL CYCLONE DURING THE NEXT 24 HOURS, AND LITTLE OVERALL  
CHANGE IN STRENGTH IS EXPECTED BEFORE LANDFALL. SELMA SHOULD  
RAPIDLY WEAKEN AND DISSIPATE OVER THE MOUNTAINS OF CENTRAL AMERICA  
SATURDAY NIGHT OR SUNDAY.  
 
IT SHOULD BE NOTED THAT THE PRIMARY THREAT ASSOCIATED WITH SELMA  
IS HEAVY RAINFALL, WITH TOTALS POSSIBLY AS HIGH AS 10 INCHES  
OVER PORTIONS OF EL SALVADOR AND GUATEMALA. THIS RAINFALL COULD  
CAUSE LIFE-THREATENING FLASH FLOODS AND MUDSLIDES.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT 27/2100Z 11.7N 89.4W 35 KT 40 MPH  
12H 28/0600Z 12.5N 89.7W 35 KT 40 MPH  
24H 28/1800Z 13.6N 89.8W 35 KT 40 MPH...INLAND  
36H 29/0600Z 14.8N 89.5W 25 KT 30 MPH...POST-TROP/REMNT LOW  
48H 29/1800Z...DISSIPATED  
 

 
FORECASTER BROWN  
 
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