Jack Wales

000 WTNT34 KNHC 230025 TCPAT4 BULLETIN HURRICANE IRENE SPECIAL ADVISORY NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011 830 PM AST MON AUG 22 2011 ...IRENE INTENSIFIES TO A CATEGORY TWO HURRICANE...FURTHER STRENGTHENING EXPECTED... SUMMARY OF 830 PM AST...0030 UTC...INFORMATION ---------------------------------------------- LOCATION...19.7N 68.7W ABOUT 200 MI...320 KM SE OF GRAND TURK ISLAND ABOUT 130 MI...210 KM E OF PUERTO PLATA DOMINICAN REPUBLIC MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/H PRESENT MOVEMENT...WNW OR 295 DEGREES AT 10 MPH...17 KM/H MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES WATCHES AND WARNINGS -------------------- CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... NONE. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A HURRICANE WARNING IS IN EFFECT FOR... * NORTH COAST OF THE DOMINICAN REPUBLIC FROM THE HAITI BORDER EASTWARD TO CABO ENGANO * TURKS AND CAICOS ISLANDS...SOUTHEASTERN AND CENTRAL BAHAMAS A HURRICANE WATCH IS IN EFFECT FOR... * NORTH COAST OF HAITI FROM LE MOLE ST. NICHOLAS EASTWARD TO THE DOMINICAN REPUBLIC BORDER * NORTHWESTERN BAHAMAS A TROPICAL STORM WARNING IS IN EFFECT FOR... * SOUTH COAST OF THE DOMINICAN REPUBLIC FROM SANTO DOMINGO EASTWARD TO CABO ENGANO * ALL OF HAITI FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 830 PM AST...0030 UTC...THE CENTER OF HURRICANE IRENE WAS LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR LATITUDE 19.7 NORTH...LONGITUDE 68.7 WEST. IRENE IS MOVING TOWARD THE WEST-NORTHWEST NEAR 10 MPH...17 KM/H. A MOTION TOWARD THE WEST-NORTHWEST WITH A SLIGHT INCREASE IN FORWARD SPEED IS EXPECTED TONIGHT AND TUESDAY. ON THE FORECAST TRACK...THE CORE OF IRENE WILL MOVE JUST TO THE NORTH OF THE DOMINICAN REPUBLIC AND HAITI TONIGHT...NEAR OR OVER THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS ON TUESDAY...AND NEAR THE CENTRAL BAHAMAS EARLY WEDNESDAY. DATA FROM THE HURRICANE HUNTER AIRCRAFT INDICATE THAT MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 100 MPH...160 KM/H...WITH HIGHER GUSTS. IRENE IS A CATEGORY TWO HURRICANE ON THE SAFFIR-SIMPSON SCALE. ADDITIONAL STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...AND IRENE COULD BECOME A MAJOR HURRICANE ON TUESDAY. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 45 MILES...75 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM. THE MINIMUM CENTRAL PRESSURE BASED ON DATA FROM THE HURRICANE HUNTER AIRCRAFT IS 981 MB...28.97 INCHES. HAZARDS AFFECTING LAND ---------------------- WIND...TROPICAL STORM CONDITIONS WILL SPREAD OVER THE NORTHERN PORTIONS OF DOMINICAN REPUBLIC TONIGHT AND LOCALIZED HURRICANE CONDITIONS ARE EXPECTED OVER THE NORTHERN PORTIONS OF THE DOMINICAN REPUBLIC BY TONIGHT AND EARLY TUESDAY. THE HIGHEST WINDS ARE LIKELY TO OCCUR OVER AREAS OF ELEVATED TERRAIN. HURRICANE CONDITIONS ARE EXPECTED TO REACH THE SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS ISLANDS TUESDAY...AND THE CENTRAL BAHAMAS BY LATE TUESDAY AND WEDNESDAY. RAINFALL...IRENE IS EXPECTED TO PRODUCE ADDITIONAL RAINFALL ACCUMULATIONS OF 1 TO 2 INCHES ACROSS PUERTO RICO AND THE VIRGIN ISLANDS. RAINFALL AMOUNTS OF 3 TO 6 INCHES ARE EXPECTED OVER NORTHERN HISPANIOLA...WITH ISOLATED AMOUNTS OF UP TO 10 INCHES POSSIBLE OVER HIGHER TERRAIN. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN AREAS OF STEEP TERRAIN. RAINFALL ACCUMULATIONS OF 5 TO 10 INCHES ARE IN THE SOUTHEASTERN BAHAMAS...THE TURKS AND CAICOS ISLANDS AND THE CENTRAL BAHAMAS. STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 9 TO 13 FEET ABOVE NORMAL TIDE LEVELS OVER THE SOUTHEASTERN AND CENTRAL BAHAMAS...AND THE TURKS AND CAICOS ISLANDS. STORM SURGE WILL ALSO RAISE WATER LEVELS BY AS MUCH AS 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS ALONG THE ENTIRE COAST OF THE DOMINICAN REPUBLIC. NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES. NEXT ADVISORY ------------- NEXT COMPLETE ADVISORY...1100 PM AST. $$ FORECASTER BRENNAN Pretty much as expected but pressure remains at 981mb for now.........

I think with those cloud tops and the mass sink scenario referred to by the nhc, the system could now be in the 970's. Don't bet against cat 3 by tomorrow morning. I'll stay up until 1:30 to see the nhc update (if it's there), after that I'm off to bed!

Irene now up to Cat 2, 100mph, 981mb. She appears to be strengthening rapidly now.

Irene seems to have taken a more northwestward motion in the last couple of hours, which is good news for the Dominican north coast. Here is the link to the weather station in Cabarete which should make some interesting readings in the next few hours... http://www.kaoba.com/meteo.html

Weather models are far less accurate at predicting the strength of tropical cyclones than they are with baroclynic systems, simply due to their complexity and internal dynamics. As the NHC forecast is a combination of model input and human analysis, I think they will always tend to be more on the objective side whilst some models (e.g. ships / hwrf) only have to see the hint of a tropical wave before ramping it up to a hurricane forecast! The difficulty the NHC have with Irene is the projected land interaction with mountainous Hispaniola. If the eye passes overland, there is a distinct possibility that the system could decouple which would lead to rapid weakening. Alternatively (and as suggested in the NHC discussion notes) if the eye stays offshore then this could aid rapid intensification. I therefore think they have no option but to forecast a halfway house between the two until the track consensus becomes tighter. I personally feel that she will stay just off shore but as we have just seen from the recon data, the continued interaction with land may inhibit significant intensification until Irene moves away from Hispaniola tomorrow. The 48 hours after this will be crucial as this will be when Irene is sitting in what appears to be an ideal environment of moisture, >30C sst’s and low wind shear.

A long way to go before it hits the USA. Land interaction with Hispinola will play a big part in forecasting the strength of Irene. If the weakness in the ridge to the north proves to be more profound than expected, she could take a path through the bahamas and loop out into the atlantic, thus missing the US mainland altogether. It's also worth noting that the NHC rate the chances of Irene becoming a cat 5 at any stage in the next 5 days at less than 1%.

Yes, radar images show the eye forming about 20-30nm north of Peurto Rico with the north coast of the island being lashed by the southern sector of the developing eyewall. Irene is clearly undergoing rapid intensification, this process itself can cause mesovortices within the eyewall which are probably resonsible for the damage currently being observed. Don't be surprised to see this system upgraded to a Cat 2 + by the end of today. I only hope it does not make a direct hit on Hispinola. Ice, I predict 975mb but as the system is fairly tight, I would expect 90kt flight winds.

Here is the latest unisys sst chart where you can see the La nina building with negative anomolies of 2°C in region 3.4 of already being obseved... And here are the latest forecasts, this one is from the CPC which predicts the ENSO pattern to remain neurtral or weak la nina... And finally here are the CFS ensembles, which given the recent rapid onset of La Nina, may prove to be the most accurate... Strommad is correct in that a weaker La Nina is more favourable for a colder winter but I've been suprised by how rapid the onset of the current enso -'ve conditions have been, hence my predictions.

Very intersting post and articles, particularly with regards to the hourly temperature readings, 30C by 10am! After the last few years, its even more hard to imagine such synoptics, 2006 seems like decades ago!

we are seeing subtle differences from last year coming into autumn. E'ly QBO, La Nina building more intensly and slightly earlier, Atlantic SST profile not as indictive of -NAO. To me the early indications are... September: Zonal, above average precip, average temps October: Zonal to start, cold & dry finish, overall temps just below average. November: Cold with just below average precip, temps well below average. Winter too early to call but I'm going for less blocked synoptics than last year, could be very stormy with jet squeezed between arctic / azores heights. Average temps with a milder trend later on.

I think it will probably end up at around 16 or just above. I've noticed the -15 isotherm making an appearence over greenland on the 850hpa charts too. Although the cold will not effect us, the ever increasing atmospheric thermal gradient should invogorate the jet in the next few weeks and flatten out any ridges over the uk,

Interesting forecast (or should I say hopecast!!) from A Winters Tale. If your prediction is a serious one, would you mind posting what your methodology was for arriving at such a forecast please? Thanks.

Phew, just got back from hols to get my prediction in on time!! I think this month will be average to start then trending cool. My prediction is 15.8°C

As we issue LRF’s here on this site, I think it’s a bit rich if we deride similar attempts from other groups, no matter how unrealistic they seem at the time. As for the PWS forecast, it may prove to be not too far off the mark. As Rodger says the sst profile is intriguing for the coming autumn/winter (although this is liable to change). Plus with an easterly QBO, neutral ENSO and a seemingly embedded long-term pattern of northern blocking, I don’t see mild as an option for late autumn / winter, more a question of how cold.

NHC have Beatriz up to 65mph, just short of hurricane status. The system now appears to be more vertically aligned so there is potential for rapid intensification given the 29C sst's and low shear environment. Here is the live loop which shows the dense CDO and possibly the beginning of an eye feature starting to form.

I agree, the outlandish forecasts seem to get away scott free yet GP's summer forecast has come in for a lot of criticism despite the fact it was created using a great deal of research and technical knowledge. If only certain people were as quick to congratulate him when he is correct. Lol! Yes pretty much, can't see much change for the rest of summer either although there is a stronger signal for the mid atlantic ridge to activate again for July / August which may dry things up a bit in the west. I think 'Cool' is probably going to be the best descriptor of this summer.

I disagree. I don't think they are having a dig at NW as they didn't mention us by name and there were a plethora of other LRF's forecasting a hot and dry summer. As for their longer term forecast, I don't necessarily think it's doom and gloom but actually a fairly realistic projection of what we can expect over the next month, which just happens to be cool and changeable.

Looks like my 15C is dead in the water!! Judging by the models I'd say that it will probably end up somewhere between 13.5C and 14.2C

Thermostat is permanently on 16C and yes, as soon as we entered June the temp drops low enough for the CH to kick in!

We need to see the line moving upwards into high AAM values, thus indicating a more 'El nino' type atmospheric base state if we are to see a pattern change. That chart doesn't look to be setting any trends as yet unfortunately.

Absolute shocker here today, if we've had less than an inch and a half of rain I'd be surprised. I can't recall a day during the whole of winter as wet and miserable as it's been today.

I'm no expert on the MJO but from my understanding phases 1,6,7,8 are symptomatic of 'El Nino' type conditions with phases 2,3,4,5 more typical of a 'La Nina' pattern. As for that chart, it looks very neutral as it indicates little or no MJO activity at all. Therefore, as I see it, the implications are that the current atmospheric pattern for the northern hemisphere will remain fairly unchanged over the next two to three weeks.

Not too bad for a first attempt W12. Even though it is fairly simplistic to interpret the main models, I would be intrigued to know your thoughts behind your forecast and indeed those for the next few months. I eagerly anticipate your contributions to the tech' thread.............

The best place would probably be the 'In depth techical model discussion' thread. This is where most of the forecasters show their predictions plus it will allow you to demonstrate your depth of knowledge and provide the thought provoking technical analysis which I'm sure will be forthcoming.... Here is the link... Technical thread

John, Don't take it to heart mate, he's obviously a wind up merchant or a Bill Farkin type character (remember him from the beeb forum!!) who just craves the attention he is now getting. I suspect his forecasting credentials are probably non existent, hence his reluctance or incapability to enter into reasoned discussion.