12:00 PM | **Tropical Storm Philippe to energize incoming “pattern-changing” upper-level trough…Pacific Ocean tropical storm may cross Mexico and spawn Gulf of Mexico system**
Paul Dorian
Deep upper-level trough will be positioned over the NE US/southeastern Canada by Sunday morning and it’ll bring about a significant temperature pattern change to the eastern US. This upper-level trough will be “energized” by the absorption of Tropical Storm Philippe later this weekend. 00Z GFS map courtesy NOAA, tropicaltidbits.com
Overview
Tropical systems in both the Atlantic and Pacific Oceans may impact the weather across the US in coming days in somewhat unusual manners. Tropical Storm Philippe has been meandering over the southwestern Atlantic Ocean recently and it will soon accelerate to the north and impact Maine/Nova Scotia with rain and wind later this weekend. After that, the remnants of TS Philippe will get “absorbed” into an incoming upper-level trough over the southeastern part of Canada. This influx of tropical moisture into the upper-level trough will act to energize the system and it will become a big contributor to a temperature pattern change in the eastern states with much cooler weather from this weekend and well into next week. Meanwhile, the eastern Pacific Ocean is now featuring multiple tropical systems and one of these is likely hit the west coast of Mexico by the middle of next week. After that, this tropical system that originated in the Pacific Ocean is likely to cross over Mexico and help to spawn tropical activity over the Gulf of Mexico which potentially can result in rain across the southeastern states.
Tropical Storm Philippe will push northward this weekend and likely reach Maine/Nova Scotia by early Sunday. At this point, the remnants of TS Philippe may take a turn to the west, get absorbed into and upper-level trough, and act to invigorate this pattern-changing system. Maps courtesy ECMWF, tropicaltidbits.com (24-hour loop of 06Z Euro surface forecast maps from Saturday night to Sunday night)
Details
Big-time changes are on the way for the eastern states as a much cooler air mass is headed this way from central Canada. The upper-level trough associated with this incoming chilly air mass will drop southeastward across the Great Lakes from tomorrow into Saturday and then it reaches the northeastern states on Sunday. Meantime, Tropical Storm Philippe will accelerate northward over the western Atlantic during the next couple of days and it likely reaches Maine/Nova Scotia by early Sunday. It is at this point that the “post-tropical” Philippe will turn to the west and get “absorbed” into the incoming “pattern-changing” upper-level trough system. Surface low pressure over southeastern Canada will intensify rapidly on Sunday and its pressure gradient field will tighten across the Northeast US and Mid-Atlantic region resulting in stiff northwest winds. Once this upper-level trough becomes established over southeastern Canada, it will tend to hang around for awhile assuring cooler-than-normal weather will remain through much of next week in the eastern US.
A tropical storm along the west coast of Mexico by mid-week will cross the country and help to spawn tropical activity over the Gulf of Mexico. Ultimately, this potential tropical system over the Gulf of Mexico may produce rainfall in the southeastern states and perhaps even up along the east coast. Maps courtesy NOAA, tropicaltidbits.com (loop of surface 00z GFS forecast maps from Tuesday night (October 10th) to Saturday morning (October 14th))
Meanwhile, a highly active eastern Pacific Ocean will likely result in a tropical storm system near the west coast of Mexico by the middle of next week. This system may then cross over Mexico and it could help to spawn the formation of a tropical storm over the Gulf of Mexico at the end of next week. If this scenario indeed takes place, the end result could be lots of tropical moisture feeding into the southeastern states in about ten days or so and ultimately, some of this moisture could ride up along the eastern seaboard.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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