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Tropical Storm Pilar Discussion Number  11
NWS National Hurricane Center Miami FL       EP192023
400 AM CDT Tue Oct 31 2023

While deep convection has increased with Pilar overnight, the 
center of the storm remains mostly exposed on the southeastern 
side of a burst of deep convection.  It seems like moderate shear 
is preventing the system from strengthening, with basically no
thunderstorm activity southeast of the center.  The initial wind 
speed remains 45 kt based on a blend of the available intensity 
estimates.  
 
Pilar continues to creep east-northeastward, or 075/3 kt, a little 
slower than the previous advisory.  The steering flow is expected to 
collapse later today, with most of the guidance stalling Pilar just 
east of 90W, then accelerating the storm west-southwestward as a 
mid-level ridge builds by Thursday.  Generally, the model guidance 
stays a touch farther offshore than the last cycle, and the official 
forecast follows the trend.  Little change was made at long range, 
with the previous forecast coming in very close to the model 
consensus.  It is possible that later today the Tropical Storm Watch 
could be discontinued for portions of Central America, but there 
remains a significant heavy rain and flash flooding threat.

The storm still has a chance to intensify over the next day or so 
within moderate wind shear conditions but in a moist and unstable 
air mass along with warm ocean waters.  It seems like the chances of 
Pilar becoming a hurricane have decreased, and the peak NHC wind 
speed forecast is dropped 5 kt from the previous one, slightly above 
the model consensus.  It remains to be seen how Pilar maintains 
itself in a challenging environment after 60 hours, with dry air 
intrusions from a gap wind event and easterly wind shear.  The 
intensity forecast is maintained at 45 kt at long range, blending 
reliable guidance showing tropical depression to hurricane strength, 
and the uncertainty is high at long range.
 
Key Messages:
 
1. Heavy rains from Pilar will produce flash and urban flooding,
along with mudslides in areas of higher terrain of the Pacific coast
of Central America from El Salvador southward to Costa Rica through
Wednesday.
 
2. Tropical storm conditions are possible beginning later today
along portions of the Pacific coast of El Salvador, Honduras, and
Nicaragua, where a Tropical Storm Watch remains in effect. 
 
3. Swells generated by Pilar will continue to affect the Pacific
coast of Central America during the next few days.  These swells are
likely to cause life-threatening surf and rip current conditions.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/0900Z 11.4N  90.4W   45 KT  50 MPH
 12H  31/1800Z 11.6N  89.9W   50 KT  60 MPH
 24H  01/0600Z 11.8N  89.9W   55 KT  65 MPH
 36H  01/1800Z 11.7N  90.6W   55 KT  65 MPH
 48H  02/0600Z 11.3N  92.1W   50 KT  60 MPH
 60H  02/1800Z 10.7N  94.3W   45 KT  50 MPH
 72H  03/0600Z 10.1N  97.0W   45 KT  50 MPH
 96H  04/0600Z  9.2N 102.5W   45 KT  50 MPH
120H  05/0600Z  9.5N 108.0W   45 KT  50 MPH
 
$$
Forecaster Blake
 
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