Tropical Storm Olga Discussion Number 2
NWS National Hurricane Center Miami FL AL172019
400 PM CDT Fri Oct 25 2019
Although Tropical Depression Seventeen began looking less and less
like a tropical cyclone in satellite imagery, scatterometer data
and reports from an Air Force Reserve Hurricane Hunter aircraft
indicate that so far the tropical cyclone remains just ahead of the
approaching cold front, with the aircraft showing the front located
about 25 n mi from the center in the southwestern quadrant. In
addition, the aircraft and scatterometer data indicate that the
cyclone's winds have increased to 35 kt in the northeastern
quadrant. Based on this, the depression is upgraded to Tropical
Storm Olga. It should be noted that a large area of 35-45 kt winds
is occurring west of the cold front over the western Gulf of Mexico,
although these winds are more due to the cold air surging across the
Gulf than to the cyclone's circulation.
Olga has begun its expected acceleration toward the north-northeast
with the initial motion now 030/16. A deep-layer baroclinic trough
over the southern Plains states should steer the cyclone generally
north-northeastward with an additional increase in forward speed
during the next couple of days. The center is expected to cross the
northern Gulf coast tonight or Saturday morning and eventually reach
the eastern Great Lakes by late Sunday. The new forecast track is
nudged a little to the east of the previous one based on the initial
position and motion through 36 h and an eastward shift in the
guidance at 48 h.
All indications are that Olga will complete extratropical transition
during the next few hours as it merges with the cold front. The
intensity forecast shows slight strengthening during the first
12 h based on the premise that the winds west of the cold front
remain strong as they wrap into the circulation of Olga. The
post-tropical low should weaken after landfall, and it is expected
to dissipate just after the 48-h point.
Key messages:
1. Since Olga is expected to merge with a cold front and become
post-tropical by tonight, hazards related to wind, rainfall and
coastal flooding will be covered by products issued by local
National Weather Service forecast offices, available at weather.gov
Post-Tropical Cyclone Olga Discussion Number 3
NWS National Hurricane Center Miami FL AL172019
1000 PM CDT Fri Oct 25 2019
Earlier this evening, the last 2 passes through Olga made by an Air
Force Reserve Hurricane Hunter aircraft showed that the cyclone
becoming embedded within a cold front. Strong northwesterly flow was
observed within 10 n mi northwest of Olga's center and a sharp
temperature and dew point gradient was measured across the cyclone.
It does not appear that Olga has separated from the front in any
significant way since the plane left. In fact, recent surface
observations suggest that either the front passes through the center
of the cyclone or its circulation has become poorly defined. Based
on all these data, Olga is now classified as post-tropical and this
is the last NHC advisory.
...
組圖打開中，請稍候......