#eiwn

Powerful Cyclone Strikes Pacific Islands

The strongest Pacific cyclone of 2015, Pam, struck the small island nation of Vanuatu located in the South Pacific this past week and brought with it extreme conditions as it topped the cyclone scale at a category five storm.

The cyclone developed about 1,000km northwest of Fiji last weekend as an area of thunderstorms organized under ideal conditions – sea surface temperatures were very high in the region, as high as 31°C, and shear was minimal. Pam continued to organize early this week. It struggled as it ingested some dry air into its core while heading towards Vanuatu but by Thursday morning it formed a large eyewall that was fairly symmetric. This meant that it had fought off the dry air and was intensifying rapidly. Peak strength was reached several hours before it reached the Vanuatu Islands, winds were sustained at 270km/h, gusting over 300km/h, and pressure bottomed out at extremely low values estimated by satellites to be around 890mb. Early Friday morning the storm’s eye passed very close to several of Vanuatu’s islands making it a worst case scenario situation. The islands were battered with 250km/h winds, storm surges of 6-8m and extremely heavy rainfall.

Typical buzz-saw appearance of a category five cyclone seen as Pam approached Vanuatu and was near peak strength. (Source: NOAA)

As of Friday evening rescue efforts were still underway while searchers made their way into remote regions that were completely isolated from the storm. Overall the infrastructure on the islands is not the best, with some houses simply made out of mud resulting in more damage than you’d typically see in a developed country. The largest city, Port Vila, was reported to be out of power and running water and had debris scattered across roads making travel difficult. There are unconfirmed reports of numerous deaths associated with this storm, but they have not been confirmed yet.

Damage seen on Friday evening (our time) as Pam was on its way out. (Source: UNICEF Pacific)

#### Winter Storm Races across Southern, Midwest US #### This past week a strong late season winter storm made its way across the southern and east-central parts of the United States bringing with it all kinds of precipitation; rain, snow, ice pellets and freezing rain. An Arctic front pushing south across the region was the culprit for the mixed precipitation types. Warm air was able to ride over the cooler air racing south near the surface which made for a melting layer above ground and able to melt/partly melt the precipitation. Before it reached the ground the precipitation encountered below freezing temperatures once again which resulted in the freezing rain, or ice pellets if the melting layer was not as deep.

Sounding from Little Rock, AR show a melting layer with below-freezing temperatures closer to the surface. Black line is the 0°C isotherm.

Large traffic jams on the freeways due to accidents, school closures and power outages were the result of the storm and 13 deaths across several states were directly related to the storm. Impressive and unusual snow amounts for this time of the year were recorded anywhere from Dallas, Texas to Lexington, Kentucky. Here are a few impressive amounts recorded from the storm, provided by the National Weather Service: - Lexington, KY: two-day total of 43.4*cm* (all-time two day record) - Tupelo, MS: one-day total of 18.5*cm* (second snowiest day on record) - Dallas, TX: storm total of 8.9*cm*

#### Two Cyclones Strike Australia #### This past week Australia got hit with two powerful cyclones, both of which made landfall on Thursday. The first, Cyclone Lam, struck the Northern Australian Territory and the second, Marcia, made landfall in Queensland.

Marcia was the stronger of the two cyclones and intensified rapidly just off the coast. It only took one day for the cyclone to strengthen from category one to a category four. On Friday it increased to a category five cyclone – equivalent to a category four hurricane, bearing sustained winds of 215km/h (gusting to 285km/h) and bottoming out with a central pressure of 929mb. Although Cyclone Marcia was the stronger of the two, Cyclone Lam still packed quite the punch as it reached a category four and brought with it sustained winds of 190km/h.

NASA satellite captured both cyclones on February 19th spinning off Australia`s coast before they made landfall. (Source: NASA)

In the aftermath of these storms making landfall, the damage was significant which is to be expected for the regions closest to where Marcia struck due to its severity. Yeppon, a town on the northeast coast of Queensland, was one of the hardest hit in the region whereby roofs got torn off homes and large trees were knocked down. In addition to that the storm left 30,000 residents in the dark. Some flooding still occurred in both affected regions. Thankfully the majority of residents near the shore took necessary precautions to avoid the worst of the storm surge – with both storms no injuries were reported.

It’s not uncommon to see cyclones hit Australia at this time of year as the cyclone season runs from November to the end of April, but to have two strong cyclones to hit Australia on the same day is uncommon. Since yesterday, both cyclones have significantly weakened as they moved inland and were cut off from their main source of energy – the ocean.

Maritimes Slammed by Another Blizzard

Elsewhere in weather news, the strong east coast storm that was talked about in last week’s EIWN was captured some incredible pictures. Summerside, PEI, was one of the maritime cities that was hit the strongest with winds gusting up to 115km/h. That, combined with around 25cm of snow, made for huge snow drifts. Most highways were impassable for several days after the storm.

#### Mozambique and Malawi See Widespread Flash Flooding #### This past week severe flooding occurring in the southeast African countries of Malawi and Mozambique has been the focus of severe weather news across the planet.

A tropical disturbance that has been spinning off the coast of Africa in the Mozambique Channel for several days this week has been the culprit for producing heavy rains over southeast Africa. Significant amounts of rain fell over a one week period (Jan. 7th to Jan 14th) resulting in widespread flash flooding, especially in regions that already had saturated grounds from previous rainfall in the month. The bulls-eye of the rainfall fell over Mozambique – over 400mm of rainfall fell in one week. In the neighbouring country of Malawi, the eastern half of the country was hardest hit as anywhere between 150 and 300mm fell. Because of the flooding, 110,000 people were displaced from their homes, 176 deaths were reported as a result of the flooding and an estimated 1,200 people are still stranded. Most were stranded as five of Malawi’s main roads are still washed out as of Friday.

Rainfall map of Malawi and neighbouring countries between January 7 to January 14. Intervals are every 75mm - red is >300mm. Note the blue bulls-eye in Mozambique. (Source: UNOSAT)

Last night there was still some convection occurring in the area resulting in occasional downpours which is typical for this time of the season. The main disturbance which caused the persistent heavy rains has moved further west over Madagascar. Malawi sees on average 220mm during the month of January.

Super Typhoon Hagupit Heads towards the Philippines

The Philippines are bracing for a very strong typhoon that is expected to make landfall this weekend. Hagupit, which was formerly known as a super typhoon (with winds exceeding 240km/h) has lowered in intensity but is still considered dangerous. The slight weakening was due to an eye wall replacement that took place. As of Friday afternoon, the typhoon was located in the West Pacific and heading west towards the central islands as well as the main islands where Manila is located.

This region has seen numerous strong typhoons in the last five years including super typhoon Haiyan, which made landfall in the Philippines 13 months ago just south of where Hagupit is expected to make landfall.

Hagupit looking more ragged as it approaches the Philippines after the eye wall replacement, however the bigger eye signifies a larger wind field. (Source: NOAA)

Yesterday, Hagupit had already begun lashing the islands with its outer rain bands. Evacuations were underway this past week where around 500,000 people have already been evacuated from areas most at risk including along small coastal fishing villages and in unsafe structures. The typhoon is expected to make landfall tonight near Sorsogon City, and will likely reach a high end category three or low end category four equivalent storm, bearing sustained winds of around 200km/h. Storm surges are sure to be a problem, especially along the front right quadrant of the typhoon, where surges could exceed 10 feet. Rainfall will also be of concern since Hagupit is fairly slow moving and will be able to drop copious amounts of rain. It is expected that the hardest hit areas, around where Hagupit makes landfall, could see around 500mm of rainfall.

#### Vancouver Sees Significant Rain Event #### The city of Vancouver has seen its fair share of rainfall this past week, causing flooding problems throughout the metro. What was to blame for this event was an *atmospheric river* that came onshore the BC Coast, aided by a large upper level trough off the West Coast on Wednesday. Atmospheric rivers are narrow plumes of significant moisture which originate from the subtropics and flow from the southwest onto the shores of the west coast. On Wednesday morning fairly high PWAT[1] values (>1”), a product of the atmospheric river, nosed into the Vancouver region which set the stage for the heavy rainfall event.

Atmospheric river (high PWAT values) making its way onto Vancouver island. (Source: Twisterdata)

The rainfall started early Wednesday morning for Vancouver, including a thunderstorm that went through the city around 7am dropping heavy rain. With already saturated soil from the rain earlier in the week, flooding problems ensued. Metro Vancouver saw anywhere between 20-35*mm*, and pockets of locally higher amounts Wednesday. This event comes a day after the same system offshore brought very strong winds (gusts >100*km/h*) to Vancouver Island as well as downing power lines and snapping trees in metro Vancouver. It was reported that Tuesday night a total of 80,000 people in southern BC were without power at some time.

Flooding in Port Moody, just east of Vancouver, on Wednesday. (Source: Port Moody Fire Rescue)

As this mid-week system departs, it makes way for the next system upcoming system this weekend. This will be yet another fairly strong system to impact the west coast, bringing with it more heavy rains and strong northwest winds. Unfortunately, unsettled weather is expected to last for the Vancouver region into next week.