Hurricane Forecasting

Hurricane forecasting is still not an exact science. Mother Nature has a way of throwing you a curve (literally in this case). Hurricane forecasting is heavily reliant on computer models. There are many different hurricane forecasts available, which are built on different mathematical equations.

Hurricanes form in tropics between the latitudes of 10 degrees and 30 degrees north during hurricane season, which lasts from June to October. Hurricanes need warm water at least 80 degrees Fahrenheit (27 degrees Celsius) for their formation and to sustain them. Hurricanes form over the ocean. Hurricanes form in the tropical oceans between the latitudes of about 8 degrees to 15 degrees north and south of the equator, and aren't simply natural disasters. They can cause great devastation to populated areas. They do not form within 5 degrees latitude of the equator because the coriolis effect isn't strong enough to generate the required circular rotation.

Hurricanes form there because the correct ingredients can be found to make the hurricane. One ingredient is that the water in the ocean needs to be at least 27 degrees celsius on the top 61 meters of water. Hurricanes form in tropical waters when evaporating water is sucked up into storms. As the vapor rises, it condenses, releasing energy that fuels the storm. Hurricanes form over water, and the water must be warm. During the hurricane season the water temperature along the east coast is at least eighty degrees Fahrenheit.

Do you think better weather forecasting requires a degree in meteorology? Maybe a degree in statistical analysis would be more helpful. Consider this following new way to forecast the weather with more accuracy and less knowledge.

Friday, February 2, 2007 - Canon City, Colorado. I brought in my Canon City Daily Record from the porch when it arrived, at about 3 in the afternoon. I opened the newspaper to the page with the weather forecast, wondering how cold it would be the following day.

The paper forecast a high temperature was 13 degrees Fahrenheit. I knew this was way too low. Forecasts on television and on the internet said that we would reach 23 or 27 degrees the following day. I knew they were also too low, and I told my wife it would be in the 30s at least. The actual high temperature the next day was 53 degrees Fahrenheit.

No, that's not a typo. The various weather forecasting "experts" were off by as much as 40 degrees - and that was for a simple 24-hour forecast. How could they be so far off? And how could I be better than them at forecasting the weather?

I can't answer the first question. The weather here is more unpredictable than in most places. Also, perhaps the meteorologists follow there computer models too slavishly, even when their experience and intuition tell them to adjust the forecast.

However, I can answer the second question. My guess was closer because the forecasters were so consistent in the way they made their errors. Around this time, I remember counting something like 15 out of 20 days when all the various weather forecasts predicted a high temperature that was 5 degrees or more too low. All I needed to do was take the highest temperature forecast and add five degrees.

A New Weather Forecasting Model

Consistency in their errors was the key to my success. They weren't forecasting too high one day and too low the next. They were wrong in the same ways over and over.

Are the errors as consistent in other parts of the country? That could be determined by looking at the statistics. Check the forecast highs and lows for the last 365 days, and check the actual temperatures for those days. See what the predicted probabilities of rain or snow were, and what actually happened.

Suppose that of the last 24 times a forecaster predicted a 50% chance of rain, it actually rained 18 times. He may have the best data, but he may be too conservative in how he uses it. Suppose this was not a fluke - which can be determined by doing more statistical analysis. You could know nothing about weather forecasting and provide a more accurate forecast simply by saying "A 75% chance of rain tomorrow" every time he said there was a 50% chance, right?

That's the basis for this new forecasting model. First gather the statistical information on the forecasts of several weather forecasting services or meteorologists. Compare this to the actual weather that happened, and look for any consistencies in the inaccuracies. Then you create a computer program. As you enter each of these forecasts into it, they are adjusted for known tendencies. The result is a more accurate forecast.

If Forecaster A has managed over the last year to forecast a high that averages 4 degrees over the actual high, the computer adjusts for that. More sophisticated analysis might show that Forecaster B is consistently predicting a higher probability of rain than there is in the fall, but a lower probability of rain than there actually is in the spring. The computer can take this into account. Finally, it may work best if the adjusted forecasts of three or more sources are then averaged.

There really is no need to know anything at all about weather forecasting. This is based on the idea that even when experts have all the best knowledge and data, they sometimes apply it incorrectly, and do so in consistent ways. Don't be surprised if some television stations get rid of their meteorologists and take advantage of this new weather forecasting idea.

"Now your electronic weather forecast, from our Statistical Analysis Weather Machine."

About the author:

Copyright Steve Gillman

Tropical Storm Kyle NHC 5 AM Discussion

AIR FORCE RECON REPORTS INDICATE LITTLE CHANGE IN THE STRENGTH AND STRUCTURE OF KYLE DURING THE PAST 6 HOURS. THERE WERE TWO REPORTS OF 70 KT AT 850 MB FLIGHT-LEVEL IN THE NORTHEAST QUADRANT...WHICH WOULD TYPICALLY CORRESPOND TO ABOUT 55 KT SURFACE WINDS. SFMR WINDS IN THAT SAME AREA ALSO ONLY SUPPORT ABOUT 55 KT. HOWEVER...THE MAXIMUM FLIGHT-LEVEL WINDS OCCURRED ABOUT 30 NMI NORTHWEST OF THE MOST INTENSE CONVECTION...SO IT IS POSSIBLE THAT STRONGER WINDS MAY HAVE BEEN MISSED ALONG THE NORTHEAST FLIGHT LEG. THE HIGHER LATITUDE AND INCREASING PRESSURE GRADIENT TO THE EAST ALSO SUPPORTS KEEPING THE INTENSITY A LITTLE HIGHER THAN WHAT THE STANDARD PRESSURE-WIND RELATIONSHIP FOR A 996 MB PRESSURE WOULD SUPPORT. KYLE HAS MADE A SHORT TERM JOG TO THE NORTHWEST...OR 330 DEGREES AS A MID- TO UPPER-LEVEL SHORTWAVE TROUGH HAS PASSED TO THE NORTHWEST OF THE CYCLONE. HOWEVER...A 9-HOUR AVERAGE MOTION YIELDS 345/14... AND THAT IS WHAT WAS USED FOR THIS ADVISORY. KYLE REMAINS WEDGED BETWEEN A LARGE DEEP-LAYER RIDGE TO THE EAST AND A DEEP-LAYER BUT WEAKENING LOW TO THE WEST OVER WESTERN NORTH CAROLINA. THE COMBINED SOUTHERLY TO SOUTH-SOUTHEASTERLY FLOW BETWEEN THESE TWO SYSTEMS IS EXPECTED TO GRADUALLY ACCELERATE KYLE NORTHWARD TODAY AND THEN NORTH-NORTHEASTWARD ON SUNDAY. ALTHOUGH THE GLOBAL MODELS REMAIN TIGHTLY CLUSTERED...THE VARIOUS SURFACE TRACKS HAVE SHIFTED SLIGHTLY WESTWARD DUE TO THE RIDGE TO THE EAST BEING STRONGER THAN THE MODELS HAVE BEEN FORECASTING OVER THE PAST 24 HOURS. HOWEVER... SOME UNCERTAINTY STILL REMAINS ON THE EXACT TIME AND LOCATION OF RECURVATURE OF KYLE TO THE NORTHEAST. IF THE EXPECTED TURN TOWARD THE NORTH-NORTHEAST IS DELAYED BY JUST 6 HOURS ...THEN KYLE WOULD PASS CLOSER TO CAPE COD THAN INDICATED BY THE OFFICIAL FORECAST. WATER VAPOR IMAGERY INDICATES THE RIDGE TO THE EAST OF KYLE CONTINUES TO AMPLIFY NORTHWARD OVER THE NORTHEASTERN U.S. AND THE CANADIAN MARITIMES REGION. IF THIS TREND CONTINUES IN CONTRAST TO WHAT THE MODELS ARE FORECASTING...THEN SUBSEQUENT FORECAST TRACKS WILL HAVE TO BE SHIFTED WESTWARD AND CLOSER TO EASTERN NEW ENGLAND. AS A RESULT...WATCHES OR WARNINGS MAY BE REQUIRED FOR PORTIONS OF THE COASTAL NEW ENGLAND AND CANADIAN MARITIMES REGION LATER THIS MORNING. THE OVERALL CONVECTIVE PATTERN HAS IMPROVED...EVEN THOUGH CLOUD TOPS HAVE WARMED. ONE MID- TO UPPER-LEVEL SHORTWAVE THAT PASSED TO THE NORTHWEST OF KYLE LATE YESTERDAY ALLOWED THE CYCLONE TO BRIEFLY INTENSIFY. ANOTHER SHORTWAVE TROUGH LOCATED ALONG 30N LATITUDE IS LIFTING NORTHWARD AS NOTED IN WATER VAPOR IMAGERY. ONCE THIS SYSTEM PASSES TO THE NORTHWEST OF KYLE AND RELIEVES PRESSURE ON THE WEST SIDE OF THE CYCLONE...AN INTENSIFICATION PHASE SHOULD RESUME AND KYLE IS EXPECTED BECOME A CATEGORY 1 HURRICANE LATER TODAY. THE OFFICIAL INTENSITY FORECAST IS ONLY SLIGHTLY HIGHER THAN THE PREVIOUS FORECAST...AND IS A BLEND OF THE ICON...SHIPS...AND THE GFDL MODELS.

FORECAST POSITIONS AND MAX WINDS INITIAL 27/0900Z 30.5N 69.4W 60 KT 12HR VT 27/1800Z 33.0N 69.7W 65 KT 24HR VT 28/0600Z 36.8N 69.4W 70 KT 36HR VT 28/1800Z 41.0N 68.4W 70 KT 48HR VT 29/0600Z 44.9N 66.7W 60 KT...BECOMING EXTRATROPICAL 72HR VT 30/0600Z 50.5N 64.0W 40 KT...EXTRATROPICAL INLAND 96HR VT 01/0600Z...ABSORBED BY FRONTAL SYSTEM

Tropical Storm Kyle NHC Discussion 5 PM

REPORTS FROM AIR FORCE AND NOAA RESERVE HURRICANE HUNTER AIRCRAFTINDICATE THAT KYLE IS SOMEWHAT DISORGANIZED THIS AFTERNOON...WITHTHE FLIGHT-LEVEL CENTERS AT 850 MB AND 700 MB DISPLACED TO THENORTH OR NORTHEAST OF THE SURFACE CENTER BY 15-20 KT OF WESTERLYVERTICAL WIND SHEAR. THE CENTRAL PRESSURE HAS RISEN TO 1003MB...AND THE CONVECTIVE PATTERN HAS BECOME ELONGATED NORTH-NORTHWEST TO SOUTH-SOUTHEAST IN SATELLITE IMAGERY. THE AIR FORCEAIRCRAFT REPORTED 56 KT FLIGHT-LEVEL WINDS AT 850 MB...WITH SFMRWINDS OF 45-48 KT IN THE NORTHEAST QUADRANT. BASED ON THIS...THEINITIAL INTENSITY REMAINS 50 KT.AFTER A NUDGE TO THE LEFT THIS MORNING...KYLE HAS MADE A NUDGE TOTHE RIGHT THIS AFTERNOON. THE 12 HR MOTION AND ADVISORY MOTION IS345/11...BUT THE SHORT-TERM MOTION IS ALMOST DUE NORTH. KYLEREMAINS ON THE SOUTHWEST SIDE OF A BUILDING RIDGE OVER THE CENTRALATLANTIC...AND SOON SHOULD PASS BETWEEN THE RIDGE AND A DEEP-LAYERLOW PRESSURE AREA OVER THE EASTERN UNITED STATES. THIS PATTERNSHOULD STEER KYLE GENERALLY NORTH-NORTHWESTWARD AND NORTHWARD FORTHE NEXT 24-36 HR. AFTER THAT...THE GUIDANCE FORECASTS KYLE TOTURN MORE TOWARD THE NORTH-NORTHEAST AS IT APPROACHES THE MAINBRANCH OF THE WESTERLIES AND THE NORTHERN END OF THE ATLANTICRIDGE. THE MODEL GUIDANCE HAS SHIFTED A LITTLE TO THE RIGHT TOWARDWESTERN NOVA SCOTIA OVER THE PAST 6 HOURS...WITH MOST OF GUIDANCENOW SHOWING A SLIGHTLY SLOWER FORWARD MOTION THAN PREVIOUSLY. BASED ON THE NEW GUIDANCE AND THE INITIAL POSITION/MOTION...THE NEWFORECAST TRACK IS SHIFTED A LITTLE TO THE EAST OF THE PREVIOUSTRACK. HOWEVER...IT LIES ALONG THE WESTERN EDGE OF THE MODELCONSENSUS.IF ANYTHING...THE INTENSITY FORECAST HAS BECOME MORE COMPLEX THAN ITWAS 6 HOURS AGO. THE CURRENT SHEAR MAY DECREASE SOMEWHAT OVER THENEXT 24 HOURS...WHICH WOULD ALLOW KYLE TO GRADUALLY INTENSIFY. AFTER THAT...KYLE IS FORECAST TO ENCOUNTER STRONG...BUTDIVERGENT...UPPER-LEVEL SOUTHWESTERLY FLOW....WITH THE RESULTINGSHEAR TRYING TO WEAKEN THE CYCLONE AND THE DIVERGENCE TRYING TOSTRENGTHEN IT. A NEW COMPLICATION IS A COLD AIR MASS APPROACHINGKYLE FROM THE EAST...WHICH IF IT REACHES THE CYCLONE COULD CAUSEWEAKENING OR A FASTER EXTRATROPICAL TRANSITION. DESPITE THENEGATIVE FACTORS...THE SHIPS...HWRF...AND GFDL MODELS CALL FOR KYLETO BECOME A HURRICANE. THE NEW INTENSITY FORECAST THUS CALLS FORTHE CYCLONE TO REACH A PEAK INTENSITY OF 65 KT IN 36 HR. AFTERTHAT TIME...KYLE WILL MOVE OVER COLD SEA SURFACE TEMPERATURES ANDBEGIN EXTRATROPICAL TRANSITION...AND THIS COMBINATION SHOULD CAUSEWEAKENING. KYLE SHOULD LOSE TROPICAL CHARACTERISTICS AFTERLANDFALL AND EVENTUALLY BE ABSORBED IN A FRONTAL SYSTEM IN AFRONTAL SYSTEM OVER EASTERN CANADA.INTERESTS IN EASTERN NEW ENGLAND AND THE CANADIAN MARITIMES SHOULDCLOSELY MONITOR THE PROGRESS OF KYLE. WATCHES MAY BE REQUIRED FORPORTIONS OF THE NEW ENGLAND COAST ON SATURDAY.

FORECAST POSITIONS AND MAX WINDSINITIAL 26/2100Z 27.6N 68.7W 50 KT 12HR VT 27/0600Z 29.5N 69.3W 55 KT 24HR VT 27/1800Z 32.6N 69.5W 60 KT 36HR VT 28/0600Z 36.5N 69.0W 65 KT 48HR VT 28/1800Z 40.3N 67.8W 65 KT 72HR VT 29/1800Z 47.5N 64.5W 45 KT...EXTRATROPICAL 96HR VT 30/1800Z 52.0N 62.0W 35 KT...INLAND EXTRATROPICAL120HR VT 01/1800Z...ABSORBED BY FRONTAL SYSTEM

Tropical Storm Kyle NHC Discussion 11AM EST

KYLE IS SHOWING A CLASSIC SHEAR PATTERN IN SATELLITE IMAGERY THISMORNING...WITH THE LOW-LEVEL CENTER PARTLY EXPOSED TO THE WEST OFTHE CONVECTION BY 15-20 KT OF WESTERLY VERTICAL WIND SHEAR. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 KT...WHILERECENT QUIKSCAT DATA INDICATES BELIEVABLE WINDS OF 45 KT. BASED ONTHIS AND CONTINUITY FROM THE PREVIOUS ADVISORY...THE INITIALINTENSITY REMAINS 50 KT.THE INITIAL MOTION IS A SOMEWHAT WOBBLY 340/11...SLIGHTLY TO THELEFT OF THE PREVIOUS ADVISORY. OTHER THAN THAT...THERE IS LITTLECHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS ADVISORY. KYLEIS ON THE SOUTHWEST SIDE OF A BUILDING RIDGE OVER THE CENTRALATLANTIC...AND SOON SHOULD PASS BETWEEN THE RIDGE AND A DEEP-LAYERLOW PRESSURE AREA OVER THE EASTERN UNITED STATES. THIS PATTERNSHOULD STEER KYLE GENERALLY NORTHWARD FOR THE NEXT 24-36 HR. AFTERTHAT...KYLE MAY TURN MORE TOWARD THE NORTH-NORTHEAST AS ITAPPROACHES THE MAIN BRANCH OF THE WESTERLIES AND THE NORTHERN ENDOF THE ATLANTIC RIDGE. SOME UNCERTAINTY EXISTS AS TO HOW FAST THENORTHERN END OF THE RIDGE MAY WEAKEN AND HOW SOON KYLE MAY ACQUIREAN EASTWARD COMPONENT OF MOTION...AS SOME OF THE GFS ENSEMBLES SHOWA STRONGER RIDGE AND A MORE NORTHWARD MOTION THAN THE OPERATIONALMODEL. HOWEVER...THE MODEL CONSENSUS HAS CHANGED LITTLE SINCE THEPREVIOUS PACKAGE...WITH THE CENTER OF THE GUIDANCE ENVELOPE OVERNORTHEASTERN NEW ENGLAND AND THE CANADIAN MARITIME PROVINCES. THENEW FORECAST TRACK IS SIMILAR TO...BUT A LITTLE SLOWER THAN THEPREVIOUS FORECAST AND IS NEAR THE CENTER OF THE GUIDANCE ENVELOPE.THE INTENSITY FORECAST IS PROBLEMATIC. THE CURRENT SHEAR MAYDECREASE SOMEWHAT OVER THE NEXT 24 HOURS...WHICH WOULD ALLOW KYLETO GRADUALLY INTENSIFY. AFTER THAT...KYLE IS FORECAST TO ENCOUNTERSTRONG...BUT DIVERGENT...UPPER-LEVEL SOUTHWESTERLY FLOW....WITH THERESULTING SHEAR TRYING TO WEAKEN THE CYCLONE AND THE DIVERGENCETRYING TO STRENGTHEN IT. WHICH OF THESE INFLUENCES WILL BE THESTRONGEST IS UNCLEAR AT THIS TIME. THE INTENSITY FORECAST CALLSFOR KYLE TO SLOWLY INTENSIFY DURING THE FIRST 48 HR IN AGREEMENTWITH MOST GUIDANCE...BECOMING A HURRICANE IN ABOUT 36 HR. AFTER 48HR...KYLE IS EXPECTED TO MOVE NORTH OF THE GULF STREAM INTO VERYCOLD WATER. WHILE THIS AND THE EXPECTED ONSET OF EXTRATROPICALTRANSITION SHOULD CAUSE KYLE TO WEAKEN...IT MAY STILL BE OFHURRICANE STRENGTH WHEN THE CENTER REACHES NEW ENGLAND OR THEMARITIMES. AFTER LANDFALL...KYLE SHOULD WEAKEN AND BECOMEEXTRATROPICAL...EVENTUALLY BEING ABSORBED IN A FRONTAL SYSTEM.INTERESTS IN EASTERN NEW ENGLAND AND THE CANADIAN MARITIMES SHOULDCLOSELY MONITOR THE PROGRESS OF KYLE.

FORECAST POSITIONS AND MAX WINDSINITIAL 26/1500Z 26.4N 68.8W 50 KT 12HR VT 27/0000Z 28.6N 69.4W 55 KT 24HR VT 27/1200Z 31.7N 69.9W 60 KT 36HR VT 28/0000Z 35.5N 69.8W 65 KT 48HR VT 28/1200Z 39.5N 68.7W 70 KT 72HR VT 29/1200Z 46.5N 66.0W 50 KT...INLAND EXTRATROPICAL 96HR VT 30/1200Z 52.0N 62.0W 40 KT...INLAND EXTRATROPICAL120HR VT 01/1200Z...ABSORBED BY FRONTAL SYSTEM$$FORECASTER BEVEN

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