It’s looking pretty good tonight.

Well not too bad looking for today.

Looks okay for tonight.

Dammit. Looks like I will have to write another discussion in light of the recent east trend.

I will probably wait for 12z EURO.

First official track. I think they will shift east.

Shifts east and forecasts a hurricane.

Today is now the first official day of fall in the north.

Went through the whole summer without bringing out the air conditioner, all because temperatures stayed below 32C/90F.

Currently it's raining and 14C/57F.

It's an overcast 91° day here in Penn's Woods. My air conditioner is on the fritz, and I am miserable. First day of Fall my ass.

It's cloudy but it's still hot and humid af.

Terrain of Puerto Rico might have disrupted the core of Tropical Storm Karen during the day as the system approached land and a surface center shifted to northeast farther away from central convection. Nevertheless, recon data still supported maximum wind of 40 knots when the system was over Vieques.

Although the current structure of TS Karen is still not very well orgaized, since that time, there has been some pressure fall and corresponding wind shift associated with a secondary weak center to the west of the original center, directly underneath heavy convection and a mid-level vortex (captured by radar images attached below). The current wind shear is not too strong to inhibit further organization and the secondary center could become the dominant one, while the original center weakens and dissipates.

NHC is clueless as to why TS Karen fails to sustain convection this morning.

The biggest hint is the fact that mid level center is not aligned with the low level center and this has negative consequences despite the otherwise favorable environment.

Mid level vortex protects a cyclone from ingesting dry mid-level air. If the vortex is displaced well away from LLC, the system is more susceptible to dry entrainment. Another consequence is that the displaced mid-level vortex could induce subsidence over the LLC. This can be seen from HWRF analysis below. The sounding is an average of approx 1 deg grid around the analysed LLC.

I will post detailed updates on TS Karen a couple of days later, if its fate becomes clearer. Right now, nothing big to worry about.

Tropical disturbance 90L that emerged as a vigorous tropical wave off West Africa has developed rapidly into Major Hurricane Lorenzo, making it one of the strongest systems to have traveled across the far Eastern Atlantic.

Part of the reason of its strengthening is of course a warmer than average SST, leading to above-average Maximum Potential Intensity of 135 knots (about 10 knots above climatological average), but that alone would not be sufficient, especially as the maximum intensity of the system is very close to that value (125 knots per NHC).

Other factors that came into play included a favorable MJO, leading to increased upper level outflow and a higher than normal precipitable water (around 1-2 SD above mean, according to the GFS), with the latter probably being the most crucial one. A glimpse at the GFS output showed another wave ahead helped mix out the drier air.

Its future track depends on the interaction with the upper trough that is forecast to stretch across the Northern North Atlantic, with a deeper trough base favoring earlier extra-tropical transition and a more northerly path, most likely passing west of Ireland. Recent guidance has trended toward a weaker trough, a consequence of a more zonal westerly upper level flow. The JMA is the southern outlier, showing landfall near Portugal, as a post-tropical cyclone.

It is anticipated that the environmental conditions over the far northeastern Atlantic will not sustain a tropical cyclone. The most intuitive result is a rapid transition to an extra-tropical cyclone and continues to head N to NE, before the center of former Lorenzo has a chance to make landfall. This is the most likely consequence, assuming stronger trough interaction as advertised by earlier models.

Even assuming a much weaker interaction, Lorenzo is still expected to lose tropical characteristics, since it will likely be embedded underneath 60+kts of westerly flow aloft and encounter unsupportive SST.

Regardless of the evolution, large swells and strong winds should occur over widespread coastal areas.

JMA model run initialized at 27/12z. Currently the southernmost outlier. The 28/12z run has trended toward a more amplified pattern.

The 28/12z run from ICON, on the other hand, shows a much more pronounced trough/ridge pattern and tracks the remnants of Lorenzo almost due north toward Iceland at later times. It is currently the northernmost outlier.

Current thinking is it may make direct hit at England as a strong post-tropical cyclone.

I don't normally write discussions on post-tropical/extratropical systems, even those that affect land. But further trends will be watched and if it is anticipated that the cyclone could take a more tropical characteristics and impact land, this might warrant an update on the Hurricane/Typhoon thread.

Here is the NHC track. As I see, they are basically following multimodal consensus.

I think they are too far north with the long range track.

https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2019/how-will-storm-lorenzo-affect-the-uk

Lorenzo becomes the first (winter) storm of the 2019/20 season.

The system has weakened considerably, but could still produce gale force winds to coastal Ireland and the extreme west part of England.

Fairly typical system for this time of the year.

UKMET thermal structure analysis at 03/00z, showing the system has completely lost its upper warm core (and thus, no tropical characteristics)

ASCAT at 02/21z indicates a few 50-knot winds a couple of hundred miles southwest of the center. Based on this, the intensity at 00z is assessed at 50 knots. Its center should be over Ireland by 04/06z and the circulation will dissipate over England by 05/00z.

Considerable cloudiness with occasional rain showers. High 77F. Winds S at 10 to 20 mph. Chance of rain 60%.

Sweater weather.

It's slightly cloudy...

Cold and dark.

Burnaby, BC Weather: Clear Sky -3.09 °C/26.44 °F/270.06 K, Wind:7.56km/h NE(20°), Humidity:68%

it cold

i had a Vision that vancouver will finally get its massive earthquake after i leave thats comforting

Not too shabby for Houston standards if I do say so myself

It sounds like rain.

0.9C today at Tai Mo Shan (3,000 feet above sea level)

Historcial moment. Arctic Oscillation index is a measure of how strong the polar vortex is. The AO reached a record peak value of 6.34 standard deviations, and reflected the strength of the vortex. It contributed to widespread winter warmth across the North Hemisphere.

Here is a graph showing the variation of anomalously high/low heights with time. Vertical axis is the pressure-height (altitude). The downward propagation of stratospheric signal is apparent.

And here is a ECMWF analysis chart from Freie Universität Berlin, on the first of February. At this time, the stratospheric polar vortex is relatively strong, with some warming on the Russian side of the Arctic observed. That warming appeared to have originated from a strong MJO activity and eventually caused minor cold intrusions into parts East Asia and Western US, a few days later. However, the magnitude of the event was insufficient to trigger any other significant impacts.

There wasn't a lot of wave activity directed toward the north pole throughout the 2019/20 winter. The bottom-most chart is the time-series of EP flux. Arrows pointing to the left means equator-directed flux, which resulted in less disruptions to stratospheric polar vortex. One reason for this is a lack of El-Nino/La Nina event and a westerly Quasi-Biennial Oscillation. The forecast low activity toward mid-February may be a result of a lack of atmospheric blocking.

It's just humid.

Wind and rain, there's a storm.

At day 4 models are hinting at another round of severe weather outbreak in the Southeast.

Bad weather is associated with a developing surface cyclone as the troughs in the north and south branch become in phase. The southerly winds will push surface dew points to near 70F. In addition, the GFS suggests enough low level helicity for development of tornadoes (0-1km SRH >200), arising from weak low level frontogensis. Regardless of the exact evolution, some threats of hail and winds are likely.

In the day 7 range, ECMWF develops a strong lee-cyclone from a cut off low embedded in westerly flow aloft and tracks it toward the central Gulf coast, but I will not be surprised if ECMWF weakens this feature in subsequent runs.

Cloudy with a chance of meatballs

25 degrees dis afternoon.

wrong thread

It is raining men.

DoctorDerp