Grading NHC's Tropical Weather Outlook
The National Hurricane Center's Tropical Weather Outlook (TWO) is a text-only product that rates the potential of disturbed areas of weather to turn into tropical depressions or tropical storms. The outlooks are issued four times daily, at 5am, 11am, 5pm, and 11pm EDT. I've found them to be an excellent guide to what to watch out for. But how accurate are these outlooks? To find out, Jamie Rhome and Dan Brown, who are two of the hurricane specialists that write the Tropical Weather Outlook, verified the accuracy of all the outlooks issued in 2005 and 2006. They used a three-tiered classification of threat based on the following language appearing in the TWO:
High: "A tropical depression could form tonight or the next day."
Medium: "Some slow development is possible."
Low: "Tropical storm formation is not expected."
These forecasts were then graded by looking at the "best track" database of Atlantic hurricanes and seeing if a tropical depression formed within 48 hours of each TWO issued. The results, shown below, reveal that for the Atlantic in the years 2005 and 2006:
-When the TWO said, "A tropical depression could form tonight of the next day," a depression formed within 48 hours 53% of the time.
-When the TWO said, "Some slow development is possible," a tropical depression formed within 48 hours about 20% of the time.
-When the TWO said, "Tropical storm formation is not expected," a tropical depression formed within 48 hours only 3% of the time.
Figure 1. Verification of the Atlantic and Eastern Pacific Tropical Weather Outlooks issued in 2005 and 2006. Image credit: Jamie Rhome and Dan Brown, National Hurricane Center.
Jeff Masters
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 — Blog Index
Posted By: Vanagew at 10:59 PM GMT on June 06, 2007.
The shear is predicted to be highly favourable for development in 48 hours time.
So how come this says no develop ment is likely on 48 hrs? http://www.wunderground.com/tropical/ABNT20.RAW.html Just asking cuz now i'm confused.
Because nothing is going to develop.
After the 48hr period of no development the situation changes is what he is implying.
Posted By: Vanagew at 10:59 PM GMT on June 06, 2007.
The shear is predicted to be highly favourable for development in 48 hours time.
So how come this says no develop ment is likely on 48 hrs? http://www.wunderground.com/tropical/ABNT20.RAW.html Just asking cuz now i'm confused.
Because there are no storms over the concerned regions. Just because shear is low doesn't mean that a disturbance will form.
Here is the visible loop for GOM http://www.ssd.noaa.gov/goes/east/gmex/loop-vis.html
Windshear values presently are running anywere from 40-60kts across the gulf.Adrian
It looks like Gonu didn't make landfall at hurricane strength after all...
Migrant? Doesn't sound like it to me, Groundman! Hey, it's the "Hospitality State" -- we hope you've felt welcome. We certainly appreciate all that came from near and far to help in the recovery efforts!!! Appreciate it, BIG TIME!
Of course, the real MS qualifications are: eating turnip greens, cornbread and sweet tea....lol, you many indeed qualify! Thanks much for your help, too!
Thanks, we have made many friends and many memories here. Like I said most people are VERY appreciative.
Curteous is the name of the game down here, I've seen men walk 20 ft to open a door for me and carry a 5 lb package out of the store!! The 5 lb. package is rather embarassing. LOL
And people down here will let someone out in traffic and I try to repay the favor when driving.
Don't know about the turnip greens, I'm more a grits person. LOL
SCATTERED
MODERATE CONVECTION IS ALONG THE COAST OF THE YUCATAN PENINSULA
FROM 21N-22N BETWEEN 86W-88W. ELSEWHERE...SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS OVER W CUBA...THE SE GULF...AND
FLORIDA FROM 22N-29N BETWEEN 80W-85W.
I'm not concerned about the SE Gulf... I'm concerned about that thunderstorm area southeast of New Orleans. If it persists into tommorow, then what?
Conditions at 42003 as of
(2:49 pm CDT)
1949 GMT on 06/06/2007:
Wind Direction (WDIR): SSE ( 150 deg true )
Wind Speed (WSPD): 19.4 kts
Wind Gust (GST): 21.4 kts
Wave Height (WVHT): 4.9 ft
Dominant Wave Period (DPD): 6 sec
Average Period (APD): 4.4 sec
Mean Wave Direction (MWD): SSE ( 150 deg true )
Atmospheric Pressure (PRES): 29.94 in
Pressure Tendency (PTDY): -0.02 in ( Falling )
Air Temperature (ATMP): 78.6 °F
Water Temperature (WTMP): 82.0 °F
Dew Point (DEWP): 74.7 °F
Heat Index (HEAT): 81.9 °F
Conditions at 42040 as of
(6:50 pm CDT)
2350 GMT on 06/06/2007:
Wind Direction (WDIR): SSE ( 160 deg true )
Wind Speed (WSPD): 13.6 kts
Wind Gust (GST): 17.5 kts
Wave Height (WVHT): 2.6 ft
Dominant Wave Period (DPD): 5 sec
Average Period (APD): 3.8 sec
Mean Wave Direction (MWD): SSE ( 150 deg true )
Atmospheric Pressure (PRES): 29.88 in
Pressure Tendency (PTDY): -0.04 in ( Falling )
Air Temperature (ATMP): 79.9 °F
Water Temperature (WTMP): 81.3 °F
Dew Point (DEWP): 71.6 °F
Heat Index (HEAT): 83.5 °F
http://www.ndbc.noaa.gov/maps/Florida.shtml
Viewing: 201 - 251
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 — Blog Index