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
I hope today won't be a bust for me as well, I live in pinnelas county, yesterday the problem was high clouds which kept numerous storms well inland and south.
Where as today appears storms may not be very numerous anywhere, despite lingering high moisture levels with PWATS around 2.00 in and relatively cold air aloft, I see clouds that have no vertical motion at all yet and its already 1:00 PM here.
Its all possible that whats limiting activity is leftover convective debris from late night gulf convection and storms last night along the east coast.
Usually though thats only a temporary limitation and storms just get a really late start, which in this case could be better because it would allow more heating which in the end I believe we would still see a lot of storms today.
However if it turns out that isn't the factor I'm seeing supressing development then its something I'm not sure of and forecasters are blind to which would severely limit convection.
Of course lets just hope its some boundy layer stability from gulf convection and east Floridas massive rains last night, because by later in the day the storms have no problem overcoming it.
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MIAMI FL
139 PM EDT THU JUN 7 2007
THE NATIONAL WEATHER SERVICE IN MIAMI HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
EASTERN BROWARD COUNTY IN SOUTH FLORIDA.
* UNTIL 245 PM EDT
* AT 139 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED 11
MILES NORTHWEST OF CORAL SPRINGS...AND MOVING SOUTHEAST AT 5 TO 10
MPH.
* THE STORM WILL AFFECT...
CORAL SPRINGS
MARGATE
SUNRISE
SAWGRASS MILLS MALL
SEVERE THUNDERSTORMS CAN PRODUCE DAMAGING WINDS IN EXCESS OF 60
MPH...LARGE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAINFALL. STAY
INSIDE AWAY FROM WINDOWS UNTIL THE STORM HAS PASSED.
A TROPICAL WAVE HAS BEEN REPOSITIONED ALONG 47W/48W S OF 11N
ESTIMATED TO BE MOVING W AROUND 15 KT. AS MENTIONED IN THIS
MORNING'S DISCUSSION...SATELLITE HOVMOLLER DIAGRAMS SUGGEST THE
FEATURE IS MUCH FURTHER W THAN PREVIOUS THOUGHT. THESE DIAGRAMS
SHOW GOOD WWD CONTINUITY IN THE CONVECTIVE BURSTS WHICH BEGAN TO
FADE NEAR 35W ON JUNE 4TH. BASED ON EXTRAPOLATION AND A NOTABLE
PERTURBATION IN THE ITCZ SEEN ON VIS PICTURES...THIS PSN APPEARS
REASONABLE. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE AXIS.
The information you posted is on a tropical wave in the central Atlantic.
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1130 AM EDT THU JUN 7 2007
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS.
$$
FORECASTER BROWN
light rain? Umm not to be critical but barry produced a minimum off 3 inches, with some places up to 6.00 inches like largo recorded, as well as my rain guage also recorded 6.00 here in central pinnelas county.
But don't worry, we are transitioning into a much better pattern, lets look at the glass half full, there is absoluelt no fire threat through the entire week and all of south Florida and about 20 to 30% of central Florida has cut the deficit completely for the year.
I wouldn't worry too much, remember, theres hope the convective inhibition today is from convective debris from gulf storms as well as storms leftover from last nightand convection may turn out numerous, it will just take longer.
Really a tough call if storms will be numerous after all or not today.
I do not see this. And also you said around the end of the month, that is a long way off.
Medium Blue area and no convection??????? Hmmm... They need to update this. :O
No convection in southwestern Gulf of Mexico. There is hardly any cloud cover, let alone convective activity.
Current wind shear map.
Infrared Image of African Coast. Continual persistence of Tropical Waves, but none have persisted enough to traverse the Atlantic yet. It's only June....
...HurricaneFcast, they must "smell" something down in the sw GOM...could be the big fellow!!! (lol)
Patrap that isn't the climatological version, that's the Real-Time version. It isn't due to climatology.. Sorry.. They obviously see something I don't, They will probably change it on the next update.
Patrap- This Is the Climatological version.
Viewing: 351 - 401
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