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Commissioning Week Weather Outlook (17 MAY 2017)

  POSTED ON: Wednesday, May 17, 2017 9:29 AM by Meteorologist A.R. Davies

Executive Summary (Updated on 19 May at 0845 EDT):

  • Saturday: Scattered morning showers/drizzle will give way to mostly cloudy skies and noticeably cooler conditions. A slight chance of light rain showers/sprinkles overnight (10% chance). East wind 8-13 mph.  High: 66-70 oF.
  • Sunday: Mostly cloudy with rain showers developing overnight (50% chance). Southeast wind 8-13 mph.  High: 68-72 oF.
  • Monday: Mostly cloudy with showers/storms likely (70% chance). Southwest wind 10-15 mph. High: 74-78 oF.
  • Tuesday: Partly sunny and pleasant. Variable wind around 5 mph.  High: 74-78 oF.
  • Wednesday: Mostly cloudy with showers and thunderstorms likely (60% chance). Southeast wind 8-13 mph. High: 70-74 oF.
  • Thursday: Mostly cloudy with showers and thunderstorms possible (50% chance). Low forecast confidence.  West wind 8-13 mph. High: 68-72 oF.
  • Friday: Mostly cloudy in the morning with a chance for rain showers (25% chance). Low forecast confidence in the morning. Breezy with a mix of sun and clouds in the afternoon. Northwest wind 10-15 mph. High: 68-72 oF.

Forecast Discussion:

A cold front will pass the region on Friday evening with showers and thunderstorms.  The front will likely stall to our south on Saturday, before pushing back to our north on Sunday/Monday as a warm front.  At this time, it remains unclear exactly where the front will stall. Both the GFS (American; shown below) and ECMWF (European) models are suggesting that the front (and associated rain) will stall well south of the region on Saturday afternoon. However, the models have a tendency to perform poorly in these scenarios, and therefore rainfall cannot be all together ruled out at this time (although unlikely). Either way, high pressure will develop along the U.S. Northeast coast on Saturday, resulting in easterly flow, below normal temperatures, and partly cloudy skies. The GFS (American) model below shows the general atmospheric set-up Saturday afternoon/evening with the stalled front to our south and high pressure building to our northeast. Check the five day forecasts (issued daily on weekdays through Graduation) for updates over the coming days.

May 20 Forecast

An active weather pattern will continue into Commissioning Week.  Temperatures will rebound on Sunday and Monday ahead an approaching cold front. The front will likely pass the region on Monday afternoon/evening with showers and thunderstorms, as shown below by the GFS (American) model.  While all operational models agree on a cold front passing Monday, they have been inconsistent with the timing (varying between 1400 and 2000 EDT). Therefore the details will need to be hammered out over the coming days, along with any potential impacts to Yard activities in the afternoon/evening (e.g.  Herndon Climb, 3rd and 4th Batt Supe’s Reception, etc.).

May 22 GFS Forecast

A potent weather system will likely impact the region during the second half of next week (Wednesday-Friday morning time frame). At this time, there is little consensus on the details (timing, rainfall amounts, duration), however the overall pattern supports unsettled weather. Models show the system arriving anytime between midday on Wednesday and Thursday evening, with widely varying impacts. The latest GFS (American) model shown below projects a complex weather system crossing the area on Thursday with periods of steady rain/storms. It is important to note that this is just one in a suite of models, and while it provides some insights into the storm, the details (timing, intensity, etc.) should not be perceived as a fully developed forecast.

May 24 GFS Forecast

However, many of the models are now suggesting that the system could be out of the Annapolis area late Thursday/Friday morning. The figure below shows the percent chance of > 0.25 inches of rainfall on Friday (0200 EDT through 0200 EDT Saturday) from the latest ECMEF (European) Ensemble Model.  The European Ensemble Model indicates that the steadiest rain could be out of the area, with a relatively low chance of >0.25 inches of rainfall during the day on Friday (10-20%).  Fingers crossed that this trend continues; Graduation is still nine days away so a lot can still change, particularly with the active weather pattern next week. Check back for details.  Five day forecast will be issued on weekdays through Graduation, and detailed Graduation/Commissioning Week forecasts will be issued on 22 and 24 May, with an addition forecast on 25 May if needed.  All forecast can be accessed online at www.usna.edu/weather.

May 25 ECMEF Forecast

ISSUED: 17 May 2017 at 0945
FORECASTER: Meteorologist A.R. Davies
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Disclaimer: This is not an official U.S. Navy weather forecast and should not be confused with the official Navy weather forecast provided by the Fleet Weather Center in Norfolk, VA.  Furthermore, the official U.S. Government forecast for the greater Annapolis area is issued by the National Weather Service Baltimore/Washington Forecast Office in Sterling, VA. Click here for full disclaimer.

Category: General Interest

Contact:

Alexander R. Davies
Meteorologist & Oceanographer
Oceanography Department, USNA
  adavies@usna.edu
  410-293-6565