Earlier this afternoon, before the Hurricane Center issued its 5:00 PM update on Katrina, I sent an instant message to my friend Bob at FSU. I told him I was putting up a dollar that Katrina’s forecast would be shifted left.
It was.
I had the exact same feeling tonight… and NHC moved it again.
Maybe feeling is the wrong word, because this isn’t intuition or guesswork. I could see signs. The storm was refusing to make the predicted right turn. In fact, it was traveling south of west.
To the north there was some sort of convergence. Feeder bands from the hurricane were meeting something moving from the north. Clouds were showing up bright white – a sign they were developing vertically.
Whatever it was to the north, it would impede that right turn forecast at the Hurricane Center.
I’m sure I’ve said this before, but it’s worth repeating. The best hurricane information is often contained in the forecaster’s technical discussion. These really were meant to be ‘internal use only’ documents, but you can’t do that when you work for the government.
In these the lead forecaster discusses what has gone into the latest forecast package. I’m sure it’s very helpful at NHC after the hurricane season is over or whenever post mortems are done.
I’ll attach tonight’s at the end of this message so you can get a feel for yourself. This one was written by Dr. Lixion Avila, one of NHC’s hurricane specialists. Four of the six specialists are Ph D’s. This is specialized work.
Sometimes, I sense, things are thrown in with the understanding that it’s more than meteorologists reading.
LOOP CURRENT OF THE GULF OF MEXICO…WHICH IS LIKE ADDING HIGH
OCTANE FUEL TO THE FIRE
No one trained in weather needed that line. Some surface water in the Northern Gulf of Mexico is 90+. Without a doubt, this is a dangerous storm and getting more dangerous by the minute.
My biggest fear is Katrina will head west of New Orleans and strike the coast there. A Category 4 storm (which is the forecast) in that location would be devastating. For a variety of reasons, New Orleans is incredibly vulnerable and a strike like that would be the worst of all possible scenarios!
Man, I hope he’s right. So far, this storm has been poorly forecast¹. And, recently, each succeeding forecast has moved the path farther left… farther to the west.
Today alone, the center of the forecast path for landfall has moved a few hundred miles.
More on Katrina later. We have a few days with this storm at sea before the real trouble begins.
¹ – By poorly forecast, I don’t mean NHC did a bad job. I mean the ability to forecast this particular storm was beyond the capabilities of science at the moment. Something’s there that no one can get a handle on. That we don’t know exactly why it went wrong is as troubling as it going wrong… maybe more.
000
WTNT42 KNHC 270247
TCDAT2
HURRICANE KATRINA DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT FRI AUG 26 2005
THE SATELLITE PRESENTATION HAS CONTINUED TO IMPROVE AND CONSISTS OF
A PERFECT A COMMA-SHAPED CLOUD PATTERN WHICH BEGINS OVER WESTERN
CUBA AND WRAPS AROUND A LARGE CLUSTER OF VERY DEEP CONVECTION. THIS
BAND IS PROBABLY PRODUCING NEAR TROPICAL STORM FORCE WINDS ALONG
THE NORTH COAST OF WESTERN CUBA. ALTHOUGH THE EYE IS NOT CLEARLY
VISIBLE ON IR IMAGES…RADAR DATA INDICATE THAT THE EYE IS EMBEDDED
WITHIN THIS CIRCULAR AREA OF DEEP CONVECTION. T-NUMBERS FROM SAB
AND TAFB HAVE INCREASED TO 5.0 ON THE DVORAK SCALE. THEREFORE…
THE INITIAL INTENSITY HAS BEEN ADJUSTED TO 90 KNOTS. AN AIR FORCE
RECONNAISSANCE PLANE IS SCHEDULED TO BE IN KATRINA IN THE NEXT FEW
HOURS. THE HURRICANE IS EXPECTED TO BE UNDER A TYPICAL 200 MB
ANTICYLONE…WITH A CYCLONIC CIRCULATION EXTENDING UPWARD TO THAT
LEVEL. THIS IS THE TYPICAL PATTERN OBSERVED IN INTENSE HURRICANES.
IN ADDITION…KATRINA IS FORECAST TO MOVE DIRECTLY OVER THE WARM
LOOP CURRENT OF THE GULF OF MEXICO…WHICH IS LIKE ADDING HIGH
OCTANE FUEL TO THE FIRE. THEREFORE…THE OFFICIAL FORECAST BRINGS
KATRINA TO 115 KNOTS…OR A CATEGORY FOUR ON THE SAFFIR-SIMPSON
HURRICANE SCALE. THE GFDL IS MORE AGGRESSIVE AND CALLS FOR 124
KNOTS AND 922 MB. THE FSU SUPERENSEMBLE IS EVEN MORE AGGRESSIVE
BRINGING KATRINA TO 131 KNOTS.
KATRINA CONTINUES TO MOVE STUBBORNLY TOWARD THE WEST-SOUTHWEST OR
250 DEGREES AT 7 KNOTS ALONG THE EASTERN SIDE OF A VERY STRONG
DEEP-LAYER MEAN HIGH CENTERED OVER TEXAS. IN FACT…DATA FROM THE
NOAA JET JUST RELAYED BY THE METEOROLOGIST ONBOARD INDICATE THAT
THE HIGH CONTINUES TO BE VERY STRONG. HOWEVER…THIS FEATURE IS
EXPECTED TO MOVE WESTWARD AND LEAVE A WEAKNESS OVER THE CENTRAL
GULF OF MEXICO. KATRINA WILL LIKELY TAKE THAT OPPORTUNITY AND
BEGIN TO TURN GRADUALLY TOWARD THE WEST-NORTHWEST AND THEN
NORTHWARD. THE OFFICIAL FORECAST BRINGS THE CORE OF THE INTENSE
HURRICANE OVER THE NORTH CENTRAL GULF OF MEXICO IN 48 HOURS OR SO.
IT IS WORTH NOTING THAT THE GUIDANCE SPREAD HAS DECREASED AND MOST
OF THE RELIABLE NUMERICAL MODEL TRACKS ARE NOW CLUSTERED BETWEEN
THE EASTERN COAST OF LOUISIANA AND THE COAST OF MISSISSIPPI. THIS
CLUSTERING INCREASES THE CONFIDENCE IN THE FORECAST.
FORECASTER AVILA
FORECAST POSITIONS AND MAX WINDS
INITIAL 27/0300Z 24.6N 83.6W 90 KT
12HR VT 27/1200Z 24.6N 84.6W 100 KT
24HR VT 28/0000Z 25.0N 86.0W 115 KT
36HR VT 28/1200Z 26.0N 87.5W 115 KT
48HR VT 29/0000Z 27.0N 89.0W 115 KT
72HR VT 30/0000Z 30.5N 89.5W 115 KT
96HR VT 31/0000Z 35.0N 87.5W 35 KT…INLAND
120HR VT 01/0000Z 40.5N 81.0W 25 KT…BECOMING EXTRATROPICAL
$$