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summer blizzard

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  1. Have just checked SHIPS, 33% chance that Dorian will be a 100KT cane when it reaches the islands on Tuesday (115mph - cat 3).
  2. Dorian now forecast to be at or near hurricane strength when it reaches the Lesser Antilles. NHC now also note the potential for rapid intensification. Does anybody have the SHIPS probabilities?
  3. Invest 99L has become Tropical Depression 5, forecast to become a Hurricane within 96 hours. Track right now takes it through the Lesser Antilles before a likely recurve towards Haiti. DISCUSSION AND OUTLOOK ---------------------- At 1100 AM AST (1500 UTC), the center of newly formed Tropical Depression Five was located near latitude 10.4 North, longitude 47.9 West. The depression is moving toward the west near 12 mph (19 km/h) and this general motion is expected to continue today. A turn toward the west-northwest is forecast on Sunday, and that motion is expected to continue through Tuesday. On the forecast track, the tropical cyclone is expected to be near the central Lesser Antilles on Tuesday. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Gradual strengthening is forecast during the next few days, and the depression is forecast to become a tropical storm later tonight or on Sunday. The estimated minimum central pressure is 1010 mb (29.83 inches).
  4. For another winter where we may have been very unlucky consider 1991/1992 (not a bad winter, CET was near average until Feb). ENSO/QBO/PDO state all very similar (close to solar maximum though and had a failed SSW in Jan) to 2009/2010. https://acd-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra2/wind/u60n_10_1991_merra2.pdf While 2010 parked the ridge over Greenland, in 1992 the ridge is instead over Canada and thus while the US sees a decent winter the UK sits under a ridge (i imagine cool and frosty). If we be a little optimistic and only look at ENSO (neutral likely) and QBO (likely neutral westerly or neutral easterly) then we are looking at 1981, 1991, 2007 (1981 also had a +PDO) being the closest matches since 1979.
  5. Last winter had a lot of mixed signs to be fair, people just got overexcited because of late winter 2018. Though we were unlucky with the SSW and how January worked out. Sadly this year is no different with mixed signals although a little clearer with only the +PDO really against us. The winter where we really lost out in my opinion was 14/15 which in my opinion was killed by the record +PDO.
  6. I spoke too soon, both GFS models and GEM develop 99L and a recent Ascat pass shows a weak but almost closed circulation. This could become a Tropical Depression fairly quickly.
  7. Not noticed any model development of the wave in the MDR but conditions are generally good.
  8. Would imagine that the models wont be that wrong at their range with background signals. It will be interesting to see how long the signals lags for. The sub-surface is weakening whats left of the Nino fast.
  9. Suprised rainfall has been so low round here. We have had some very heavy showers and last Friday was very wet.
  10. I have been thinking about our Autumn prospects and right now I think we might see quite an average to cool Sep-Oct but probably a milder and wetter Nov-Jan (leaning to a cold Feb-March). With regards to Sep-Oct there seems to be minimal activity in the Tropics to generate MJO interference or a sustained jump in GLAAM so I suspect that we are looking at relatively unsettled weather akin to August and June. October could be quite wet since some US research asserts that +values in Nino region 4 correlate with October -AO so that may push the Jet Stream South. For Nov-Jan although we have solar minimum and a neutral or easterly QBO, a neutral ENSO pattern and +PDO is a relatively unfavourable Pacific pattern so even if we keep a weak stratospheric vortex i suspect we might alternate between zonality and mid-latitude blocking rather than anything which would deliver more than transient spells.
  11. Sub-surface is now down to -4 in the East Pacific and positive anomalies are now almost all west of the dateline. While I was leaning towards neutral, we could see a quicker flip if these reach the surface.
  12. Met Office did a video about it not long ago and they put it down to a decadal cycle of the NAO (similar in the 60’s apparently). Also worth saying that 09, 10, 13, 14, 16, 17, 18 all had two reasonable months so the sentiment is being overdone.
  13. 18z is a very funny run, it puts a high to the east and west of us and then shapes the lows in such a way as to do everything possible to keep pressure over the UK low(ish). Even when it builds pressure it parks a tiny little upper weakness over the south east. Not a chance of occurring but very funny.
  14. Despite being an unremarkable month current model runs might actually produce the warmest August since 2004.
  15. The rate of the last 6 weeks would actually see us beat 2008 to 4th. More likely we’ll drop off though and finish below 260.
  16. Interesting 0z runs this morning. The Euro this morning builds the high to the north and east over the UK while keeping relatively cool uppers. The GFS builds an Azores ridge to our south east (final heatwave of the summer) but actually has the Atlantic back by the 27th.
  17. It looks like the two issues so far have been forcing persisting over the East Pacific (limits us to the eastern Atlantic) and surprisingly the -AO which seems to have led to an abnormally strong mid-latitude jet stream and suppression over the Tropics. The good news however is that firstly ENSO is trending negative so the deeper we go into the season, the better things may be. Also that the AMO is now highly positive. Finally that the Saharan Air Layer is the weakest since 2002. In terms of timing we have a CCKW passing the Atlantic around the 20th which should leave more favourable and moist conditions in its wake however my own thinking is to remember that peak season extends right to late October and so to take the storm total to halfway and expect to beat that in the second half.
  18. Both GFS and Euro this morning now in agreement that ridging will take over from day 9 (should be a good Surinam range at least initially). Some suggestions bourne out by the GFS that the center of the high May stay west allowing low pressure to the east though the Euro looks more sustainable.
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