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TS Olga - 40 mph/NNE 18 mph/998 MB


yoda
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BULLETIN
Tropical Depression Seventeen Advisory Number   1
NWS National Hurricane Center Miami FL       AL172019
1000 AM CDT Fri Oct 25 2019

...TROPICAL DEPRESSION FORMS IN THE WESTERN GULF OF MEXICO...
...EXPECTED TO BECOME A GALE-FORCE POST-TROPICAL LOW TONIGHT...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.6N 94.4W
ABOUT 320 MI...515 KM SSW OF LAKE CHARLES LOUISIANA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal tropical cyclone watches or warnings in
effect.

Please see High Seas Forecasts issued by the National Weather
Service and products from local National Weather Service forecast
offices for information on the non-tropical watches and warnings
associated with this system.


DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Depression
Seventeen was located near latitude 25.6 North, longitude 94.4 West.
The depression is moving toward the north near 16 mph (26 km/h).  A
motion toward the north-northeast at a faster forward speed is
expected this afternoon through Sunday.  On the forecast track, the
center of the cyclone should move across the northwestern Gulf of
Mexico this afternoon and then move over the northern Gulf coast
tonight or Saturday morning.

Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some strengthening is expected today, and the depression could
become a tropical storm this afternoon.  The cyclone is then
expected to merge with a cold front and become a post-tropical low
with gale-force winds tonight before the center reaches the Gulf
coast.  An Air Force Reserve Hurricane Hunter aircraft is scheduled
to investigate the depression this afternoon.

The estimated minimum central pressure is 1006 mb (29.71 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Gale-force winds associated with this system should spread
over portions of the northern Gulf coast tonight and Saturday
morning.

RAINFALL: The depression and rainfall ahead of the system along and
north of the frontal boundary across the Central Gulf coast is
expected to produce total rainfall accumulations of 2 to 4 inches
with maximum totals of 8 inches across the Central Gulf coast into
the Lower Mississippi Valley through Saturday morning.  These rains
may produce flash flooding across the Central Gulf coast into the
Lower Mississippi Valley.

COASTAL FLOODING: Above-normal tides and associated coastal
flooding are possible across portions of the northern Gulf coast.
Please see products from local National Weather Service forecast
offices for additional information.

TORNADOES:  A couple tornadoes are possible through tonight across
southeast portions of Louisiana and Mississippi into southwest
Alabama.


NEXT ADVISORY
-------------
Next complete advisory at 400 PM CDT.

$$
Forecaster Beven
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Tropical Depression Seventeen Discussion Number   1
NWS National Hurricane Center Miami FL       AL172019
1000 AM CDT Fri Oct 25 2019

Satellite imagery indicates that the low pressure system in the
western Gulf of Mexico has developed a well-defined circulation.
In addition, a cluster of strong convection is located near and to
the northeast of the low-level center.  Thus, advisories are being
initiated on Tropical Depression Seventeen.  The initial intensity
is set at 30 kt, and it is possible based on last night's
scatterometer data that this is conservative.

A deep-layer baroclinic trough over the southern Plains states
should steer the cyclone north-northeastward with an increase in
forward speed during the next couple of days, with the center
crossing the northern Gulf coast tonight or Saturday morning.  The
track guidance is in good agreement, and the forecast track lies
close to the various consensus models.

A surface cold front associated with the baroclinic trough is
quickly approaching the center of the depression, and the tropical
cyclone is expected to merge with the front during the next 12 h.
Based on this, the cyclone is expected to become a gale-force
post-tropical low before it reaches the northern Gulf coast.  The
low should weaken after landfall, with dissipation expected just
after 48 h.  There is a chance that the system could briefly become
a tropical storm this afternoon before it merges with the cold
front.  However, even if this occurs it will make little difference
to the impacts on the northern Gulf coast.

Key messages:

1. Since depression 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


FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 25.6N  94.4W   30 KT  35 MPH
 12H  26/0000Z 28.2N  93.1W   35 KT  40 MPH...POST-TROP/EXTRATROP
 24H  26/1200Z 32.6N  91.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  27/0000Z 38.1N  89.1W   25 KT  30 MPH...POST-TROP/EXTRATROP
 48H  27/1200Z 43.2N  85.4W   20 KT  25 MPH...POST-TROP/EXTRATROP
 72H  28/1200Z...DISSIPATED

$$
Forecaster Beven
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Nice write up by MOB on the tornado threat.

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1111 AM CDT Fri Oct 25 2019

.DISCUSSION...See updated information for land and marine areas below.

&&

.UPDATE...A complicated synoptic pattern exists over the local
area. First off, a warm front was draped from off the Louisiana
coast up across the MS Sound, east northeast to the I-10 corridor
over the northwest FL Panhandle. Tornado watch is in effect thru 4
pm this afternoon over the western half of the local area. A brief
discussion on notable late AM mesoscale analysis data shows bulk
shear magnitudes 35 to 50 kts from the MS sound northward over the
watch area. Co-located with this area, 0-1km storm relative
helicity values range from 200-300 m2/s2 mostly north of the warm
front, while the highest instability resides south of the warm
front where a strong gradient of mixed layer capes of 1000-2000
J/KG is positioned from the coast, southward out over the marine
area. Along the warm front and the strongly backed low level flow,
there is an increased potential for any updrafts lifting up off
the Gulf and across the coast to stretch and tighten as cells
approach and move across the boundary where the low level
helicity begins to increase. Tornadoes can spin up quickly in this
environment.

Tropical depression 17 has formed over the southwest Gulf and the
expectation is that as this feature gains latitude, it will merge
with a cold front approaching slowly from the west and transition
into a post-tropical cyclone. No coastal tropical hazards at this
time due to the expected transition, but may result in the
necessity of the issuance of a gale warning over portions of the
marine area and perhaps a high surf warning. That decision will be
made this afternoon.

Heavy rain threat continues. No changes made to flash flood
watches. High risk of dangerous to potentially deadly rip
currents continues. /10



.

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Olga has been born -

Quote

000
WTNT32 KNHC 252034
TCPAT2

BULLETIN
Tropical Storm Olga Advisory Number   2
NWS National Hurricane Center Miami FL       AL172019
400 PM CDT Fri Oct 25 2019

...DEPRESSION BECOMES TROPICAL STORM OLGA...
...EXPECTED TO MERGE WITH A COLD FRONT AND BECOME A POST-TROPICAL
LOW WITH GALE FORCE WINDS DURING THE NEXT FEW HOURS...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...26.3N 93.2W
ABOUT 260 MI...420 KM S OF LAKE CHARLES LOUISIANA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNE OR 30 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal tropical cyclone watches or warnings in
effect.

Please see High Seas Forecasts issued by the National Weather
Service and products from local National Weather Service forecast
offices for information on the non-tropical watches and warnings
associated with this system.


DISCUSSION AND OUTLOOK
----------------------
At 400 PM CDT (2100 UTC), the center of Tropical Storm Olga was
located near latitude 26.3 North, longitude 93.2 West. Olga is
moving toward the north-northeast near 18 mph (30 km/h) and this
motion is expected to continue with an increase in forward speed
during the next couple of days.  On the forecast track, the center
of Olga should move over the northern Gulf coast late tonight or
early Saturday and then move through the Mississippi and Ohio River
Valleys later Saturday through Sunday.

Reports from an Air Force Reserve Hurricane Hunter aircraft indicate
that maximum sustained winds are now near 40 mph (65 km/h) with
higher gusts.  Olga is expected to merge with a cold front and
become a post-tropical low with gale-force winds during the next few
hours before the center reaches the Gulf coast.

Tropical-storm-force winds extend outward up to 90 miles (150 km)
mainly to the northeast of the center.  Satellite wind data and
surface observations indicate that a large area of gale-force winds
is occurring to the west of the cold front that is currently just
west of Olga.

The minimum central pressure just reported by the Hurricane Hunter
is 998 mb (29.47 inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Gale-force winds associated with Olga and its remnants should
spread over portions of the northern Gulf coast tonight and Saturday
morning.

RAINFALL: Olga, its remnants, and rainfall ahead of the system along
and north of the frontal boundary across the Central Gulf coast is
expected to produce total rainfall accumulations of 2 to 4 inches
with maximum totals of 8 inches across the Central Gulf coast into
the Lower Mississippi Valley through Saturday morning.  These rains
may produce flash flooding across the Central Gulf coast into the
Lower Mississippi Valley.

COASTAL FLOODING: Above-normal tides and associated coastal
flooding are possible across portions of the northern Gulf coast.
Please see products from local National Weather Service forecast
offices for additional information.

TORNADOES: A couple tornadoes are possible through tonight across
southeast portions of Louisiana and Mississippi into southwest
Alabama.


NEXT ADVISORY
-------------
Next complete advisory at 1000 PM CDT.

$$
Forecaster Beven

 

Quote

000
WTNT42 KNHC 252035
TCDAT2

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

FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 26.3N  93.2W   35 KT  40 MPH
 12H  26/0600Z 29.8N  91.7W   40 KT  45 MPH...POST-TROP/EXTRATROP
 24H  26/1800Z 35.2N  89.8W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  27/0600Z 40.1N  86.4W   25 KT  30 MPH...POST-TROP/EXTRATROP
 48H  27/1800Z 44.5N  81.5W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  28/1800Z...DISSIPATED

$$
Forecaster Beven

 

143243_5day_cone_no_line_and_wind.png

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As of 10 pm CDT last night, Olga went post-tropical -

Quote

ZCZC MIATCPAT2 ALL
TTAA00 KNHC DDHHMM

BULLETIN
Post-Tropical Cyclone Olga Advisory Number   3
NWS National Hurricane Center Miami FL       AL172019
1000 PM CDT Fri Oct 25 2019

...OLGA BECOMES POST-TROPICAL...
...EXPECTED TO BRING HEAVY RAIN AND SEVERE WEATHER TO THE CENTRAL
GULF COAST AND LOWER MISSISSIPPI VALLEY ON SATURDAY...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.8N 92.2W
ABOUT 170 MI...275 KM SSE OF LAKE CHARLES LOUISIANA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NE OR 40 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal tropical cyclone watches or warnings in
effect.

Please see High Seas Forecasts issued by the National Weather
Service and products from local National Weather Service forecast
offices for information on the non-tropical watches and warnings
associated with this system.


DISCUSSION AND OUTLOOK
----------------------
At 1000 PM CDT (0300 UTC), the center of Post-Tropical Cyclone Olga
was located near latitude 27.8 North, longitude 92.2 West. The
post-tropical cyclone is moving toward the northeast near 17 mph (28
km/h). Olga is forecast to move quickly northward to
north-northeastward on Saturday and then turn northeastward late
Saturday or Sunday. On the forecast track, the center of the
post-tropical cyclone will move up the Mississippi Valley tomorrow
and toward the Great Lakes later this weekend.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Weakening is expected after the cyclone moves over land Saturday
morning.

Tropical-storm-force winds extend outward up to 140 miles (220 km)
from the center.

The estimated minimum central pressure based on earlier data from
an Air Force Reserve hurricane hunter aircraft and surface
observations over the northern Gulf of Mexico is 999 mb (29.50
inches).


HAZARDS AFFECTING LAND
----------------------
WIND: Gale-force winds associated with Olga and its remnants should
spread over portions of the northern Gulf coast tonight and Saturday
morning.

RAINFALL: The post-tropical cyclone, along with rainfall ahead of
the system along and north of the frontal boundary across the
Central Gulf coast, is expected to produce total rainfall
accumulations of 3 to 6 inches with maximum totals of 8 inches
across the Central Gulf coast into portions of the Lower Mississippi
Valley and western Tennessee Valley through Saturday morning. These
rains may produce flash flooding across the Central Gulf coast into
the Lower Mississippi Valley and western Tennessee Valley.

COASTAL FLOODING: Above-normal tides and associated coastal
flooding are possible across portions of the northern Gulf coast.
Please see products from local National Weather Service forecast
offices for additional information.

TORNADOES: Isolated tornadoes are possible tonight into Saturday
morning across parts of southeast Louisiana, southern Mississippi,
and western Alabama.


NEXT ADVISORY
-------------
This is the last public advisory issued by the National Hurricane
Center on this system. Additional information on this system can be
found in High Seas Forecasts issued by the National Weather Service,
under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at
ocean.weather.gov/shtml/NFDHSFAT1.php

Additional information about heavy rainfall and wind gusts can be
found in storm summary products issued by the Weather Prediction
Center at www.wpc.ncep.noaa.gov/discussions/nfdscc3.html

$$
Forecaster Zelinsky

NNNN
Quote

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM

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.

Since Olga is entangled with the front, the winds and seas
associated the front are now considered to be representative of the
overall system. The intensity of the post-tropical cyclone is set at
45 kt based on SFMR winds of 48 kt and flight-level winds of 54 kt
found by the plane behind the front. No substantial change in Olga's
strength is anticipated before it reaches the coast Saturday
morning, and the winds should decrease quickly thereafter. The
post-tropical cyclone is forecast to move quickly up the Mississippi
Valley on Saturday, before turning northeastward toward the Great
Lakes late Saturday or early Sunday. Dissipation is anticipated
before the end of the weekend.

Severe weather, including heavy rain, gusty winds, and isolated
tornadoes will be the primary hazard associated with post-tropical
Olga as it races northward. Coastal flooding is also possible
tonight along portions of the Louisiana coast. For more information
specific to your area, please see products from your local weather
service office at weather.gov.

Key messages:

1. Olga is now a post-tropical cyclone. Detailed information about
hazards related to wind, rainfall, coastal flooding, and tornadoes
can be found in products issued by local National Weather Service
forecast offices, available at weather.gov


FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 27.8N  92.2W   45 KT  50 MPH...POST-TROPICAL
 12H  26/1200Z 31.8N  90.4W   35 KT  40 MPH...POST-TROP/EXTRATROP
 24H  27/0000Z 38.0N  88.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  27/1200Z 43.5N  83.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  28/0000Z...DISSIPATED

$$
Forecaster Zelinsky

NNNN

 

post-tropical-olga-5day-cone-10252019.png

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