Tropical Cyclone Discussion
545 WTNT41 KNHC 210240 TCDAT1 Tropical Storm Fay Discussion Number 7 NWS National Hurricane Center Miami FL AL062026 300 AM GMT Mon Sep 21 2026 Fay is beginning to feel the effects of increasing northwesterly shear over its circulation, with satellite images showing its outflow pattern becoming restricted in that quadrant. However, an ASCAT-C pass received after the prior advisory showed a peak wind retrieval of 53 kt, and that the center was a little further south and east of what was previously estimated. Assuming some wind undersampling of this instrument along with a slight increase in the DMINT and DPRINT intensity estimates, the initial intensity is being nudged up to 60 kt for this advisory, making Fay just shy of hurricane intensity. Fay appears to have turned east-southeastward tonight, with an estimated motion of 130/4 kt. Over the next day or so, a building ridge to the northwest should continue to turn Fay southward and then southwestward with gradually increasing forward motion. The NHC track forecast this cycle was shifted a bit southward compared to the previous one, but converges close to the previous forecast track in 60-72 h. This track forecast remains in good agreement with the reliable HFIP Corrected Consensus Approach (HCCA) and Google DeepMind ensemble mean (GDMI) aids. The tropical storm is just about out of time to intensify further, though it remains possible Fay could briefly become a hurricane tonight before the northwesterly vertical wind shear becomes prohibitively strong from an amplifying upper-level ridge to the northwest. This shear will ultimately import very dry mid-level air into Fay's core, causing the cyclone to quickly decouple in the next 24-36 h. The global and hurricane-regional model guidance remains in good agreement on Fay struggling to produce organized convection by 48-60 h, and that continues to be when the NHC forecast indicates the cyclone becoming post-tropical. The NHC intensity forecast is largely an update of the prior one beyond the next 12 h, in good agreement with the intensity aid consensus. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 34.1N 31.9W 60 KT 70 MPH 12H 21/1200Z 33.7N 31.8W 55 KT 65 MPH 24H 22/0000Z 32.7N 32.5W 45 KT 50 MPH 36H 22/1200Z 31.6N 33.9W 40 KT 45 MPH 48H 23/0000Z 30.8N 35.7W 35 KT 40 MPH 60H 23/1200Z 30.1N 37.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 24/0000Z 29.6N 39.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 25/0000Z 29.6N 42.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 26/0000Z...DISSIPATED