The North Atlantic Tropics Looking to become Active Again This Weekend or Next Week

It’s August and with that it’s time for the North Atlantic to show its tropical cyclone “muscle”. Tropical waves become more numerous as mesoscale convective systems form over the tropics of West Africa and race off into the open Atlantic; their mid-level “vorticity” or spin the seed for possible further development. The National Hurricane Center in Miami has pegged one Thursday with an 80% chance of development between now and Tuesday (40% chance between now and Saturday).

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Shortwave infrared image (sometimes known as “nighttime visible”) taken at 8 pm EDT Thursday. This shows a cloud mass moving off West Africa associated with a new tropical wave south of the Cape Verde Islands. (NOAA)

Mid-range models suggest the system will develop possibly into a depression or tropical storm, moving generally westward toward the Lesser Antilles heading toward Tuesday. Much more on what will happen will depend on the system’s development. Mid-level dry air brought in from the Sahara Desert will be an issue for this system as it approaches the Lesser Antilles if it moves north of 15N. As far as upper-level winds, forecast shows a modestly favorable environment for development, but details will wait until down the road. Water temperatures in this part of the Atlantic – known as the Main Development Region (MDR) – are running up to 1.5 C (~3 F) above average with abundant warm sea surface temperatures above 26 C (79 F) west of 35 W.

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Current Sea Surface Temperatures over the tropical Atlantic Ocean. The orange-red and red shades indicate temps at and above 26 degrees C. (Wunderground.com)

Because of the strong semi-permanent “Bermuda High” expected to dominate the Central and Western Atlantic next week, this system will need to be watched by interests in the Western Atlantic Basin for potential impacts in case it does not curve northeastward out to sea because of the subtropical high pressure system to its north (assuming it develops).

Also of interest is a system in the Eastern Caribbean Sea. It is in a more hostile environment (shear and dry air main problems) and only has a 40% chance of development over the next 5 days.

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Shortwave IR image at 8:45 pm EDT showing generally disorganized thunderstorm activity associated with a tropical wave in the Eastern Caribbean. (NOAA)

The Atlantic has been running about a month ahead of schedule on named storms, but has been dead quiet on hurricanes. The 1966-2009 average for the first hurricane in the basin is coming up (August 10th), but given recent years of activity, the Accumulated Cyclone Energy (ACE) thru Aug. 2nd is running at its lowest level in the basin since 2009. But still 90% of the ACE on average occurs from here on out, so much can still happen, especially given the lack of one otherwise major hindering presence in El-Nino.

I’ll keep track of these disturbances in the coming days and have more for you if they develop into organized systems. Stay tuned!

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Is it a Heat Wave or a BBQ Pit? Fires Add Smoke to the Misery

It was VERY smoky in the Northwest Wednesday unfortunately because of major fires in the Interior US and Canada.

Satellite image of Washington State showing abundant smoke over much of Puget Sound and the Strait of Juan de Fuca Wednesday.
Photo from Seattle’s Lake Washington of the sunset view Wednesday evening through the thick smoke haze produced from Canadian fires. (Photo by NWS Seattle on Twitter)

BELOW were the highs Wednesday for select cities. Southwest WA and Western OR are being particularly hit hard by this heat wave. Interior Western WA and Puget Sound were actually sparred some of the worst of the heat today by the smoke; it was thick enough to act as a cloud to dampen the radiation and limit warming in places such as Seattle. It remains to be seen if that will be the case Thursday. If not, the hottest day if the heat may very well be Thursday for Western WA (and about the same for Western OR). This, along with an Air Quality Alert in effect for much of Western WA/OR means those in the area will need to not only be careful with strenuous activity to avoid heat-related illnesses, but also avoid breathing problems, if sensitive to such smoke particulates.

(record highs in red)

WASHINGTON

Seattle (National Weather Service Office): 88

Seattle (International Airport): 91 – Old Record 89 (2009). Special Note: Seattle also shattered its daily record for warmest minimum temperature with a morning low of 69 (old record was 61 set back in 2015) and it ranks as the 2nd warmest daily minimum temperature on record.

Olympia: 91

Hoquiam: 89 – Old Record 81 (1993)

Vancouver: 102

Quillayute (North WA Coast): 98 – Old Record 89 (1993). Special Note: This was likely caused by easterly downslope winds; easterly surface winds flowing along the higher hilly terrain descends down the slopes resulting in “adiabatic heating” (compression heating from increasing pressure on the air molecules as the flow drops in elevation). This hot air blows into town and shoots the temperature up fast. This process occurs throughout the region and is the reason why it is typically a “dry heat” in Western WA/OR during heat waves. The heated air becomes dry, with little moisture added to it.

OREGON

Astoria: 93 – Old Record 88 (1939)

Portland (International Airport): 103 – Old Record 96 (1986)

Troutdale (East Portland Metro): 105 – Old Record 99 (1995)

Hillsboro: 105 – Old Record 99 (1939)

Salem: 107 – Old Record 102 (1939)

Eugene: 102 – Old Record 99 (1939)

Medford: 112 – Old Record 105 (1993)

Klamath Falls: 99 – Old Record 94 (1977)

As you see, for Oregon, there was a major theme in the records for Wednesday’s climate stations. It was the hottest day many of these locations had seen on this date since 1939.

Please be safe if you live in this region the next couple of days. Drink PLENTY of water, take breaks from the heat as necessary, use fans if you don’t have air conditioning (common problem in this region, I lived there without air conditioning and the summers statistically are generally getting warmer because of anthropogenic climate change…), and again, like me, I have asthma; if you don’t need to do anything strenuous outside DON’T! Just drive instead of walk or just stay inside, cool and relax. The slightly cooler weather (still above normal, however) starts Friday.

Tropical Storm Emily impacting much of Florida Monday

Tropical Storm Emily formed last night over the eastern Gulf of Mexico.  An area of low pressure developed thunderstorm activity which managed to consolidate and organize as it approached the central gulf coast of Florida overnight. Meteorologists began to notice the increasing organization of the system on local radar and at 6 am EDT this morning, the National Hurricane Center in Miami declared the system “Emily”.

Regional radar showing huge rain extent associated with Emily near and south of the center.
Enhanced infrared image showing cloud temperatures of Emily. Coldest temps (reds) near center along central gulf coast.
 

As an upper atmospheric trough of low pressure digs southeastward from the upper-Midwest over the next 2-3 days, this is expected to steer Emily northeastward. It will move out of Florida by overnight tonight/early Tue and head off into the open waters of the Atlantic well-offshore the East Coast. Land interaction today will weaken it but it may regain some strength over the waters of the Gulf Stream mid-week.

Atlantic tropical cyclone statistics thus far this season: 5 named storms, 0 hurricanes, 0 major hurricanes. On July 31st, on average the Atlantic is expected (based on 1966-2009 data) to have observed only 1 named storm, 0 hurricanes, 0 major hurricanes (on Aug 1st, the average named storms increases to 2). As we go deeper into the month of August expect the hurricane numbers to go up thanks to favorable below average wind shear and above normal oceanic heat content currently in existence in the Main Development Region (MDR) of the Tropical Atlantic. 


This area is largely turned off in earlier months but ramps ups later in the season as tropical waves develop from the tropics of West Africa and moves south and west of the Cape Verde Islands. So the Atlantic still has a lot left in the tank as far as heat energy to release.

Hilary and Irwin making plans for a Fujiwhara waltz over the open ocean

Let’s learn something cool about the tropics!

The past couple of weeks, the Eastern Pacific Basin has been quite active with multiple active tropical cyclones churning, dying and new ones forming. All while the North Atlantic Basin has been largely silent. We’ll get into the pattern set up for tropical activity between the two basins in the coming few weeks in a moment. But first, let’s discuss two interest systems in process in the EPac – Hilary and Irwin.

(Intensities are as of 4 pm CDT Thurs)

Hurricane Hilary is currently a Category 1 with max winds of 75 mph moving to the west-northwest. Meanwhile, ~480 nautical miles southwest of Hilary is Tropical Storm Irwin. It has max winds of 60 mph and drifting westward. Neither system is a threat to populated land masses and both are quickly heading for cooler waters north of the subtropical Pacific, where much drier air also exists in the mid-levels of the atmosphere. Both will lead to rapid deterioration of the cyclones this weekend.

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Visible satellite image showing Tropical Storm Irwin and Hurricane Hilary in close proximity at 4 pm CDT July 27, 2017. Cooler waters are noted to the north producing stable air mass near the sea surface, including deep marine stratus clouds and “closed cell” cumulus cloud deck. Stable air mass is non-conducive for thunderstorms hurricanes need to sustain themselves.
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Same image at same time as above in the “water vapor” infrared channel, where mid-level water vapor is detected. The circled area is a fairly dry area where air is experiencing sinking motions, coinciding with the cooler surface waters and the lack of thunderstorm activity for deep atmospheric moisture. Deep dry air can disrupt thunderstorm activity in tropical cyclones and weaken them.

Later Sunday and into Monday, an amazing phenomenon is expected to occur. Because of the very close proximity of Hilary and Irwin – only several hundred miles apart – the two cyclones are expected to undergo a Fujiwhara Interaction. This describes when two vortices in close proximity begin to rotate around a common center or one around another if one is more dominant. It is named after the Japanese meteorologist Sakuhei Fujiwhara who first described the interaction scientifically in a 1921 paper.

It does not happen very often, but it is typically more common in the Western Pacific basin where a very large surface area of favorable tropical development and maintenance exists and many cyclones can develop simultaneously and sometimes in close proximity.

Numerical models have shown the possible interaction for days.

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The slideshow above displays the Hurricane Weather Research & Forecasting Model forecast initialized at 11 pm PDT Wednesday with the forecast valid 5 pm PDT Sunday – 11 am PDT Monday. This model is “nested” on Hilary to show its evolution (the colors are surface temperatures in degrees C and wind barbs are in knots). However, you can see Irwin orbiting around it on its south and east sides Sunday evening – Monday morning. Irwin will likely weaken and die (along with Hilary, not long after), or will become absorbed by Hilary.

Nature never ceases to amazes in what it can do with the laws of physics!

 

Northern Plains becoming hard hit by severe to extreme drought

The Northern US Great Plains into the southern Canadian Prairies are suffering from a growing drought problem. The National Drought Mitigation Center at the University of Nebraska-Lincoln released their weekly drought monitor which updates on the drought situation for the entire country (every Thursday based on Tuesday data). Drought overall across the United States has begun to grow in coverage and intensity. This can happen just from the local abnormalities in a summer season. However, a persistent pattern of dryness has developed over the Northern Plains beginning in May where significantly below normal rainfall has caused soils and hydrologic sources to begin to dry out.

I took a look at some meteorological stations for their recent climate records. Rapid City, SD (currently in the moderate drought zone) is running 3.37 inches below normal in rainfall for the May 1st-July 21st period. In Bismarck, ND (in severe drought) is even worse at 4.01 inches below normal for the same period. May dryness hit the region hard with a major monthly deficit then it simply continued into the summer. At least moderate drought covers ~28% of the above region (ND, SD, NE, KS, WY, CO). Moderate conditions can result in some damage to crops and reduction in stream/river flows and lowering of lake levels. Extreme – which now exists in spots of southwest ND – can mean widespread and devastating agricultural losses and severe reductions in hydrologic sources.

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Above average temperatures likely over the Great Plains (and rest of the country) over the next 3 months. (Climate Prediction Center)
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Meanwhile, there are equal chances (~33% each) for above, near, or below normal precipitation during the same 3 month period. (Climate Prediction Center).

Obviously, “equal chances”- which is based on the expected evolution of various climate patterns – means that there could very well be above average rainfall, which the region really needs at this point to get out of the growing deficit. However, if it ends up being near-normal, they may continue to simply lag behind with similarly bad impacts. Below normal means a worsening and spreading of drought conditions and further difficulty removing the existing drought (anyone remember the difficulty California had in getting out of drought?). Folks in these areas should be prepared for any further water restrictions and do what they can now to conserve in case the dryness lasts longer than expected.

Elsewhere, dryness and moderate drought has begun to spread into parts of the Intermountain West and Four Corners.


Quick update from the Eastern Pacific tropics…new tropical depression! Tropical Depression Ten-E is rolling around between Tropical Storm Greg and TD Nine-E. It’s expected to become a tropical storm in the coming days as it generally moves westward over the open ocean. So there are now 4 existing cyclones in the tropical North Pacific east of 180 longitude. Although Fernanda is dying quickly over cooler waters and dry mid-level air and will likely dissipate by tomorrow.

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Good weekend to you all!

Intense heat dominating Central US; Active Eastern Pacific Hurricane Season continues

Welcome to the inaugural post of Weather and Climate News! There’s much going on this week, but the most significant has been the intense heat over the center of the country as very strong high pressure system has entrenched itself over the region. This, in combination with dew points of 70-80 degrees, was allowed for heat indices of 105-115 degrees F to steam much of Plains, Midwest and Deep South. This, while periodic areas of thunderstorms, some severe, form around the periphery of the clockwise high pressure system. Heat advisories and excessive heat warnings are in effect today as a result of the potential health hazards of the heat.  Be safe and drink lots of water! Particularly in areas with heat or heat indices in the triple digits when you may be outdoors for long periods.

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Analysis of features over the United States (July 21, 2017).
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National Weather Service Forecast map for 7 pm CDT Saturday evening. The cold front will depress the intense heat and humidity over the Central Plains, restricting it to the Southern Plains and Midwest.

The intense heat will relax a bit over the Central Plains this weekend as a result of a “cold” (more like cool?) front with temperatures closer to seasonal norms.


The Central and Eastern Pacific is quite active with the tropical cyclone activity! Eastern Pacific activity can of course impact Mexico, but (more typically later in the season) enhance the Southeast US monsoon with either additional atmospheric moisture for afternoon thunderstorms or (rarely) move ashore Mexico or into the United States as an organized tropical depression or weak tropical storm. Today, however, neither country has any issues from any of these systems today. Three to be exact, with a four likely imminent. All of these cyclones…Tropical Storm Fernanda (born in the East, but now in the Central Pacific west of 140W longitude), Tropical Storm Greg, and Tropical Depression Nine-E are all moving away from major land masses and populated areas.

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The Eastern Pacific Basin (defined as 140W east to the continents and north of the equator) is running ahead of schedule in terms named storms to date (7), hurricanes (3) and major hurricanes…defined as Category 3 or higher strength (2). Fernanda was at one point the most intense hurricane of the season in the Eastern Pacific with maximum winds of 145 mph on July 14-15.

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It’s now a shell of its former self and while it’s heading in the general direction of the State of Hawaii, it should continue to weaken dramatically as it encounters drier mid-level air and cooler waters. High surf and hazardous rip currents are the biggest threats to anyone doing recreational activity around the Big Island the next couple of days as the dying system moves to the north.