ATL HANNA: Personal Forecasts

[Evil Jeremy]

Since one was not created yet...

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Tropical Storm Hanna
Advisory #1

For the past 12 hours, Tropical Storm Hanna has been enduring heavy upper level shear being produced by an Upper Level Low to the west of Hanna. Over the past few hours however, convection has re-fired over the center recently, although this should only be temporary, and I expect shear to pick back up before sunrise.

Since the center of Hanna, which is very well defined, is back under convection, Hanna should be able to strengthen a little before the shear kicks back in. Already, the 00:00 UTC Best Track indicates that Hanna has strengthened, and winds are now at 45 MPH with a pressure of 1001 MB. Some slight intensification should occur overnight, followed by a steady or weakening trend tomorrow.

Hanna is currently heading WNW at about 285 degrees. The longer that the ULL affects Hanna, the more of a westward component it will have compared to its northward component. Based on this, I expect Hanna to continue on a WNW path through tomorrow, when a NW track should begin to prevail. This is because Hanna is raveling around a ridge positioned in the Atlantic Ocean.

A majority of the global computer models are agreeing on a WNW-NW track through 3 days. However, the steering currents are expected to weaken in the 4-5 day period, and Hannah will drastically slow down, and will move erratically. After 3 days, the computer models start to differ in where Hanna will go. The EURO model has been very constant with showing a hit in SE Florida. It was actually one of the first models to show that path, and since then, the other models have been showing a similar path. Joining the EURO are the GFS, which up to the latest run has been showing a recurve, and the BAM models. The HWRF is the only global model still showing a recurve, and other models like the NOGAPS, GFDL, and UKMET are in the middle, and shove Hanna southwards or SW in 4-5 Days. My cone takes the path of the GFS and EURO models. However, a change will need to be made if other models continue to show a SW path at the end of the run.

Intensity wise, the shear provided by the ULL should keep Hanna as a minimal Tropical Storm through tomorrow, followed by gradual strengthening. Unlike the National Hurricane Center, I think that intensification will be very gradual, and Hanna will not become a hurricane until early next week.

INITIAL 40 KT
12HR 40 KT
24HR 45 KT
36HR 50 KT
48HR 55 KT
72HR 60 KT
96HR 65 KT
120HR 70 KT

Forecaster Silberman

[Tampa Bay Hurricane]

Thanks for opening this thread!

***The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.***

Hanna Forecast 1:

High Ocean Heat Content and a Strong Ridge.
Ridge induces faster forward speed- so the distance traveled
is greater IMO than in NHC guidance.

Number/Color indicates category.

Day 5 and Day 7 points marked with arrows/markers.
Cuba to Carolinas in the cone of uncertainty



Forecaster N. Singh (Tampa Bay Hurricane)

[Evil Jeremy]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

I am to tired to type up a full forecast, which I will write up in the morning, so here are tonight's basics:

Currently 50 MPH winds, but the entire western side of the storm is getting sheared to pieces, so Hanna could weaken overnight.

Majority of models not curving Hanna as much to the south tonight, GFDL is the outlier. My track tonight is a blend of the latest model runs, but leaning on the GFS and EURO.

Heading WNW at 285 degrees at 13 MPH and gaining speed

Should become a Category 1 before weakening due to increasing shear

INITIAL 50 MPH
12HR 55
24HR 60
36HR 65
48HR 75
72HR 75
96HR 75
120HR 65

[PhillyWX]

http://philadelphiaweather.blogspot.com ... -move.html

Some Frequently (and Philly-centric) Asked Questions About Hanna?

(1) Will Hanna be a hurricane in our area?

No

(2) How strong will the winds be?

Depending on how strong Hanna is at landfall. Right now, Hanna is forecast to have about 80 or 85 mph winds according to the National Hurricane Center at landfall. Based on this, winds could gust over 50 mph at the coast, up to 40 mph inland. Nothing nasty, but with heavy rains a few trees could fall.

(3) How much rain for my backyard?

Right now, 2-4" of rain looks likely but this is still three days out so the rainfall totals may be adjusted based on Hanna's track. The closer to the track of Hanna the more rain you will get, especially on the west side of the track.

(4) Flooding possible?

It is possible there is some stream flooding and localized ponding of water in those low lying areas and roadways that typically get it.

(5) Any severe weather?

Tropical systems have a vigorous circulation with them and weak tornadoes are certainly possible, especially to the right (east) of the track of Hanna. This is something that won't be figured out with certainty until we see where Hanna will make landfall.

(6) Where will Hanna make landfall?

It could be near Charleston, SC, although given the angle of the coastline a slight shift left or right will change the landfall location a fair bit. If Hanna landfalls farther upcoast, we could see a bit more wind but as of this point we should not see hurricane force winds here in the region.

(7) When does Hanna move through?

Clouds will be on the increase Friday afternoon, with rain starting from south to north overnight Friday night. The worst of the storm should be Saturday from midday through evening, with rains ending from south to north as Hanna's center of circulation passes by.

(8) How will Sunday be?

It will feature improving conditions with mostly sunny skies.

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[PhillyWX]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Hanna has 65 mph winds as of this afternoon and while intensification to a hurricane is certainly possible, it will not be a major hurricane at landfall nor will it be a hurricane across our latitude. This is a quasi-tropical storm that will bring some beneficial, if not heavy rains, to the region tonight and Saturday.

The HPC forecast suggests the possibility of four or five inches of rain in the region. While in isolated areas that is certainly possible I think since Hanna is a fast moving system the potential of widespread rainfall of that amount is a bit low. Still, however, two to four inches of rain is likely.

Hanna will bring gale-force (it's the same as tropical storm force) winds to areas south and east of 295 in New Jersey and south of 95 in Delaware. Wind gusts to at least 50 mph at the coastline should be expected as well.

As for timing, look for rain to be moving into Delaware and South Jersey by early evening, spreading from south to north overnight. There might be a lull in the rainfall overnight and early on Saturday before the motherload moves through with Hanna.

Some Frequently Asked Questions About Hanna:

(1) Will Hanna be a hurricane in our area?

No. It will either be a tropical storm or declared extropical, i.e. a non tropical low pressure center.

(2) How strong will the winds be?



Winds will gust to and over 50 mph at the coast, to over 40 mph across Southern Delaware and south/east of 295 and the New Jersey Turnpike, and to over 30 mph in Philadelphia. Given the setup with the storm, the strongest winds will be before the center of the low passes, with gradual slackening of wind Saturday night.

(3) How much rain for my backyard?


2-4" of rain looks likely across New Jersey, Southeast PA, Delaware, and the New York City area, with isolated higher amounts of rain across some areas in that corridor. 1-2" of rain will fall farther west along the I-81 corridor. There will probably be a sharp gradient in rainfall totals across Central Pennslyvania.

(4) Flooding possible?

It is possible there is some stream flooding and localized ponding of water in those low lying areas and roadways that typically get it.

(5) Any severe weather?

Unless Hanna takes a track more inland, the severe weather threat in our region should be limited. This looks like a heavy rain event for our region but the possibility exists for some wind damage and a very slight possibility for a tornado exists across Delaware and South Jersey, closer to the track of the low...but this possibility is quite low. Keep in mind that the greatest threat for tornadic activity is in the right-front quadrant of the storm (north of the low and east of the low). Much of the region will be in the left-front quadrant (west of the track of the low).

(6) Where will Hanna make landfall?

It could be near the North Carolina/South Carolina border, although given the angle of the coastline a slight shift left or right will change the landfall location a fair bit.

(7) How will the event break down?

Clouds will be on the increase this afternoon, with rain starting from south to north at night. The worst of the storm should be Saturday from midday through evening, with rains ending from south to north as Hanna's center of circulation passes by. Rain will be occasional in nature, with times where the rain may let up somewhat during the morning hours Saturday. Saturday will be a miserable weather day.


http://philadelphiaweather.blogspot.com ... hanna.html