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9/30-10/5 Joaquin-Trough Interaction-DISCUSSION/OBS


bluewave

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If it were to make landfall in southern Virginia what effects do you guy's think we would get in terms of rain and wind? Especially considering the wind field is small with this as hurricane winds extend only 35 miles from the center.

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WTNT41 KNHC 302055

TCDAT1

HURRICANE JOAQUIN DISCUSSION NUMBER 12

NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015

500 PM EDT WED SEP 30 2015

There has been little change in the organization of Joaquin during

the past several hours. While the hurricane continues to produce

cloud tops colder than -80C in the eyewall, the eye has not become

better defined since the last advisory. Satellite intensity

estimates are 77 kt from both TAFB and SAB, so the advisory

intensity is now 75 kt.

The initial motion is 225/7. The shortwave ridge causing this

motion is expected to weaken during the next 24-48 hours as a strong

deep-layer trough develops over the southeastern United States.

Thus, a generally southwestward motion is expected for the next 36

hours or so, followed by a turn toward the north as the trough

becomes the dominant steering mechanism. There is an increased

disagreement between the GFS, UKMET, Canadian, and NAVGEM models

versus the ECMWF since the last advisory. The ECMWF has continued

its forecast of showing a northeastward motion after 72 hours,

taking Joaquin just west of Bermuda and out to sea. The other

models have all shifted their forecasts to the left and now

call for landfall in the Carolinas and the mid-Atlantic states,

followed by merger with the baroclinic trough. Given the shift in

the non-ECMWF models, a major westward adjustment has been made to

the forecast track at 96 and 120 hours, bringing the center of

Joaquin near or over portions of the mid-Atlantic states. Due to

the use of the ECMWF in the consensus models, the new track lies

near the various consensus models. However, it lies well to the

east of the GFS and the other similar models. The NOAA G-IV jet is

currently flying a synoptic surveillance mission, which, along with

special rawinsonde launches, hopefully will reduce the spread of the

guidance.

There is little change to the intensity forecast philosophy since

the last advisory. Joaquin is expected to remain in an environment

of moderate northeasterly vertical shear for the next 24-36 hours,

possibly including strong winds seen at 400 mb in recent dropsondes

from the G-IV aircraft. However, since it has been steadily

strengthening in such an environment, there is no obvious reason to

think it will stop doing so. After 36 hours, the hurricane is

likely to move into an area of divergent southerly upper-level winds

associated with the eastern U. S. trough. While there is

uncertainty as to how much shear should occur, it is expected that

additional intensification could occur through at least 48 hours.

Based on this, the intensity forecast calls for Joaquin to peak as a

major hurricane in 48-72 hours, and it is possible it could be

stronger than currently forecast. After 72 hours, increasing shear,

cold air intrusion, and land interaction should cause weakening and

the start of extratropical transition.

KEY MESSAGES:

1. Preparations to protect life and property within the warning

areas in the Bahamas should be rushed to completion.

2. A significant adjustment to the forecast has been made this

afternoon, and this shows an increased threat to the mid-Atlantic

states and the Carolinas. However, confidence in the details of the

forecast after 72 hours remains low, since we have one normally

excellent model that keeps Joaquin far away from the United States

east coast. The range of possible outcomes is still large, and

includes the possibility of a major hurricane landfall in the

Carolinas.

3. Every effort is being made to provide the forecast models with

as much data as possible. The NOAA G-IV jet has begun a series of

missions in the storm environment, and the National Weather Service

is launching extra balloon soundings.

4. Because landfall, if it occurs, is still more than three days

away, it is too early to talk about specific wind, rain, or surge

impacts from Joaquin in the United States. Even if Joaquin stays

well out to sea, strong onshore winds will create minor to moderate

coastal flooding along the coasts of the mid-Atlantic and

northeastern states through the weekend.

5. A hurricane watch for a portion of the U.S. coast could be

required as early as Thursday evening.

6. Many areas of the eastern U.S. are currently experiencing heavy

rains and gusty winds associated with a frontal system. This

inclement weather is expected to continue over the next few days,

which could complicate preparations for Joaquin should it head

toward the coast, and greatly exacerbate the impacts from the

hurricane. Heavy rains are likely to continue over these areas

even if the center of Joaquin stays out to sea.

FORECAST POSITIONS AND MAX WINDS

INIT 30/2100Z 24.3N 73.1W 75 KT 85 MPH

12H 01/0600Z 24.0N 73.8W 85 KT 100 MPH

24H 01/1800Z 23.9N 74.5W 90 KT 105 MPH

36H 02/0600Z 24.5N 75.0W 95 KT 110 MPH

48H 02/1800Z 25.8N 75.0W 100 KT 115 MPH

72H 03/1800Z 30.5N 74.5W 100 KT 115 MPH

96H 04/1800Z 36.0N 75.5W 85 KT 100 MPH

120H 05/1800Z 38.5N 76.5W 55 KT 65 MPH

$$

Forecaster Beven

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If it were to make landfall in southern Virginia what effects do you guy's think we would get in terms of rain and wind? Especially considering the wind field is small with this as hurricane winds extend only 35 miles from the center.

 

As it moves northward, its wind field will expand, similar to Sandy. This is always happens when hurricanes undergo extratropical transitions. A landfall in southern Virginia (or even NC) would still affect the NYC metro and many areas would experience tropical storm force winds and heavy rains. However, the worst would be to our south.

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The landfall position is so reliant on exactky where the capture occurs and how far NE it jogs from the interaction with Ida. We may honestly not know for sure until it happens.

With Sandy I remember watching to see if the eye crossed 70W when it was heading NE, to see if it would make landfall over or east of NYC or southwest. It just about made it to 70W and then hooked sharply NW to hit Atlantic City. So when the time is right, the storm can turn pretty fast. 

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Woah:

 

SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...24.0N 73.0W
ABOUT 95 MI...150 KM E OF SAN SALVADOR BAHAMAS
ABOUT 80 MI...125 KM NE OF SAMANA CAYS BAHAMAS
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...SW OR 225 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES

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