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Tropical Storm Pilar Discussion Number   6
NWS National Hurricane Center Miami FL       EP192023
1000 PM CDT Sun Oct 29 2023
 
A small but concentrated convective burst has been persisting near
the estimated center of the tropical cyclone tonight. After the
prior advisory, we received a fortuitous GPM microwave pass valid
at 2252 UTC that suggested the low-level circulation may have
tightened up some but was located just south of the deepest
convection. Subjective Dvorak intensity estimates were up to T2.5/35
kt form TAFB and T2.0/30 kt from SAB. The objective estimates from
ADT, SATCON, and D-PRINT/MINT are all between 34-36 kt, and thus the
latest advisory is set at 35 kt this advisory, upgrading TD19-E to
Tropical Storm Pilar.
 
A more pronounced east-northeastward motion appears to be starting, 
estimated at 060/4 kt. A continued motion to the east-northwest is 
anticipated over the next 24-48 hours as Pilar's primary steering 
influences are an equatorial ridge south of the storm providing 
deep-layer westerlies in addition to a mid- to upper-level cutoff 
low over the northwestern Caribbean that is interrupting the more 
typical ridging that would be present to the north over Mexico. The 
guidance is in general agreement on this scenario, but how far east 
the tropical storm gets in the next 48 h remains uncertain, with the 
latest HWRF and HAFS-B runs far enough east to affect the Gulf of 
Fonseca with tropical storm conditions. For this reason, the 
tropical storm watch has been extended eastward to portions of the 
Pacific coast of Honduras and Nicaragua this advisory. On Tuesday, 
Pilar is expected to stall and move very slowly as low to mid-level 
ridging attempts to build back in to the north of the tropical 
cyclone and a strong cold front induces a significant gap wind flow 
event in the Gulf of Tehuantepec. By the middle of this week, the 
enhanced low-level flow associated with the ridge and gap winds are 
forecast to push Pilar away from Central America to the 
west-southwest as a weakening tropical storm. As discussed 
previously, the confidence of when or how sharp this turn away from 
Central America will be is low given the inconsistent model guidance 
over the past day. The NHC track this cycle is just a bit closer to 
the coast and a touch east of the prior track, but is roughly in 
between the TVCE and HCCA consensus aids. 

A small core may be starting to take shape given the earlier 
microwave imagery, and the persistent area of convection that Pilar 
has been maintaining over the last 3-6 hours near the estimated 
center. Most of the guidance maintains this small core structure 
with intensification while the storm remains embedded in moderate 
(15-20 kt) easterly vertical wind shear but is over warm 28-29 C 
sea-surface temperatures in a moist mid-level air environment. The 
latest NHC intensity forecast still takes Pilar to near hurricane 
intensity in 36 h, on the higher end of the intensity guidance but 
not far off the hurricane-regional guidance solutions. Afterwards, 
it seems likely a combination of the dry mid-latitude gap-wind flow 
in addition to possible cool upwelling of the shallow warm waters 
due to slow motion near the coast of Central America could begin a 
weakening trend. If the latest HWRF and HAFS-B runs end up being 
correct, land interaction could also result in weakening. The 
intensity forecast beyond 48 h is a little lower than the prior 
advisory, as it is looking more likely that a combination of 
moderate shear and additional dry stable air could prevent the storm 
from re-intensifying even after it begins to move back over warmer 
ocean waters away from its own cold wake.
 
 
Key Messages:
 
1. Heavy rains from the tropical depression will produce flash and
urban flooding, along with mudslides in areas of higher terrain
along the Pacific coast of Central America, including El Salvador,
through Wednesday.
 
2. Tropical storm conditions are possible by early Tuesday into 
Wednesday along portions of the Pacific coast of El Salvador, 
Honduras, and Nicaragua where a Tropical Storm Watch is now in 
effect. Interests elsewhere along the Pacific coast of Guatemala, 
and Nicaragua should monitor the progress of this system as 
additional watches or warnings could be needed tomorrow.
 
3. Swells generated by the depression will begin to affect portions
of the Pacific coast of Central America, including El Salvador,
beginning on Monday.  These swells are likely to cause
life-threatening surf and rip current conditions.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0300Z 11.0N  92.0W   35 KT  40 MPH
 12H  30/1200Z 11.2N  91.3W   45 KT  50 MPH
 24H  31/0000Z 11.6N  90.2W   55 KT  65 MPH
 36H  31/1200Z 12.0N  89.4W   60 KT  70 MPH
 48H  01/0000Z 12.3N  88.9W   55 KT  65 MPH
 60H  01/1200Z 12.0N  88.9W   45 KT  50 MPH
 72H  02/0000Z 11.2N  89.7W   35 KT  40 MPH
 96H  03/0000Z  9.9N  93.0W   35 KT  40 MPH
120H  04/0000Z  9.0N  97.5W   35 KT  40 MPH
 
$$
Forecaster Papin
 
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