2000AEST Super Typhoon Mangkhut remains Category 5 as it approaches the Philippines. Mangkhut appears to have peaked around 0700AEST this morning 13th with sustained winds (one-minute average) estimated at 290km/h and gusts to 350km/h. It was over open water at that time, and is expected to reduce intensity to Category 4 when it hits the northern end of Luzon, Philippines, during Saturday morning AEST. Sustained wind shortly before landfall is forecast to be 250km/h with gusts to 300km/h. Interaction with Luzon will reduce wind speeds to 205 with gusts to 250 by late morning as the typhoon is passing over the island, dropping it to Category 3.
The UK Met Office posted this animation of Mangkhut, known in the Philippines as Ompong, about 3 hours ago and this image showing where it is headed just now. Again, the size of the typhoon will cause widespread harm as it is 700 to 900km across. The Red Cross (IFRC) posted this Information Bulletin on the situation and the preparations it is making yesterday. There are good summaries of the situation on ABC News and in The Guardian.
1900AEST Dramatic imagery from NOAA of Florence. NOAA's latest Loop of The Day features this dramatic animation of Hurricane Florence's advance on the US east coast yesterday morning 12th local time. The scale of the hurricane compared to the Carolinas it is approaching is awe-inspiring in this imagery from the USA's GOES-16 satellite.
1505AEST Hurricane Florence update. The latest NHC Forecast Discussion issued 1300 Australian EST indicates storm surge and flood rainfall forecasts remain the same, but significant changes in the structure and environment of Florence have weakened it to a borderline Category 2/3 system. The good news is that landfall is likely to be delayed until late Friday morning and winds will be relatively lighter at that time (sustained speeds of 150km/h, or strong Category 1), though cover a larger area. The changed track of the Hurricane makes landfall more likely in southern North Carolina.
Edited details are:
...the convection on the southern side of the storm has been disrupted, and reports from an Air Force Reserve Hurricane Hunter aircraft indicate the eyewall now wraps less than 50 percent of the way around the center...The convection seems to have been affected by 20-25 kt of southerly vertical wind shear, most of which appears to be due to strong winds between 200-250 mb...The central pressure has risen to 957 mb, and the maximum 700-mb flight-level winds reported so far are 103 kt. Based on the latter data, the initial intensity reduced to a probably generous 95 kt [which is on the boundary between Category 2 and Category 3 (Major)].
...During the next 12-36 hours, the hurricane is expected to turn toward the west-northwest and west with a decrease in forward speed as it moves into an area of weakening steering currents near and over the southeastern United States. The new forecast track now brings the center onshore in southern North Carolina near the 36 h point [0100 Saturday AEST, 1100 Friday US EDT]. After landfall, the cyclone should move slowly [W to WSW for 1½ days then turn NW to N] through the Appalachian Mountains...
...sea surface temperatures near 29C [and a return to reduced upper wind shear] would allow a last chance for strengthening before landfall, but because of the storm structure and its size, it] would likely be slow to respond to the more favorable environment. The pre-landfall part of the intensity forecast thus calls for little change in strength, but given the uncertainties the confidence in this is low. After landfall, Florence should gradually weaken during the 36-48 h period while the center is near the coast, then weaken more quickly when the center moves farther inland.
While Florence has weakened below major hurricane intensity, the wind field of the hurricane continues to grow in size. This evolution will produce storm surges similar to that of a more intense, but smaller, hurricane, and thus the storm surge values seen in the previous advisory are still valid. The threat of rainfall has also not diminished, and these impacts will cover a large area regardless of exactly where the center of Florence moves.
1230AEST Seasonal Outlook Update out. The BoM's mid-month update and video for the Seasonal Outlook is now available, and unfortunately promises more of the same:
- Below-average rainfall likely for large parts of the country
- Day and night-time temperatures likely to be warmer than average
- While the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are currently neutral, observations and model outlooks indicate El Niño and a positive IOD could develop in spring
If you're reading this after September,
the archive summary version is here. The BoM's Climate Outlooks are now produced using the much higher-definition ACCESS-S model, developed by the Bureau in collaboration with the UK Met Office. Here's an interesting blog on the improvements you'll see.
1100AEST Hurricane Florence. The good news in the NHC Forecast Discussion issued 0700 Australian EST is that Florence has somewhat weakened rather than strengthened, but the bad news is that at the same time it has become larger. Here's the main part of their notes. The latest Forecast Discussion for Florence is here. EDT in the USA is 14 hours behind Australian EST.
If you're not up to speed on developments, see the analysis I posted yesterday.
Data from an Air Force Reserve hurricane hunter aircraft along with satellite imagery and various intensity estimates indicate that Florence has weakened instead of strengthening. However, while the hurricane hasn't strengthened in terms of peak winds, the inner-core and outer wind fields have continued to expand, resulting in an increase the cyclone's total energy, which will create a significant storm surge event. The upper-level outflow remains impressive and is still expanding except toward the south.
Florence is moving toward the northwest or 315/14 kt. The new 12Z global and regional model runs have come into much better agreement on Florence moving steadily northwestward around a strong ridge located between Bermuda and the U.S. mid-Atlantic region for the next 48 hours or so. By late on day 2, Florence is forecast to approach the southern portion of the North Carolina coast, then slow down considerably and turn westward within collapsing steering flow, with a very slow westward motion near the coasts of North and South Carolina continuing into Friday and Saturday. Corrected-consensus models HCCA and FSSE remain very close to each other and are quite similar to the simple consensus model TVCA. Therefore, only a slight eastward shift was needed to the previous forecast track through 36 hours or so, mainly due to the more eastward initial position based on the reconnaissance fixes. At 48 hours and beyond, no significant changes were required to the previous advisory track, which still shows Florence moving slowly westward across South Carolina and western North Carolina on day 4, followed by a slow northward motion up the Appalachian mountain chain on day 5.
A narrow window of opportunity remains during the next 24 hours or so for Florence to strengthen a little when the hurricane passes over the warmer SSTs and deeper warm water/higher upper-ocean heat content associated with the Gulf Stream, and low vertical shear conditions of 5-10 kt will aid in any strengthening process. However, significant strengthening is not anticipated due to Florence's large and expanding inner-core wind field. By 36 h and beyond, decreasing ocean heat content along with the slowing forward speed of Florence will likely produce cold upwelling beneath the hurricane, inducing a gradual weakening trend. When Florence moves over the shallow coastal shelf waters in 48-72 h, land interaction and more significant upwelling are anticipated, which should further enhance the weakening process. The NHC intensity forecast remains near the higher statistical guidance through 48 hours, then follows the trend of the decay SHIPS model after that time.
Although the maximum winds are expected to weaken a little more, Florence is still expected to remain a dangerous major hurricane as it approaches the coast. The threat to life from storm surge and rainfall will not diminish, and these impacts will cover a large area regardless of exactly where the center of Florence moves.