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Spotlight on Ernesto: Drought-Busting Time?

Josh Larson @ 2:30 PM

It looks like our moderate drought may finally come to an end over the next few days as we expect heavy rain from the remnants of now strengthening Tropical Storm Ernesto tonight through mid-day Saturday. The rest of the weekend, however, looks like it might be quite salvageable.


Forecast Confidence: MediumOvercast; showers? Expect overcast skies today as clouds and moisture stream in from the south ahead of the precipitation shield from Ernesto. Occasional showers are possible, especially to the south and during the second half of the day, though many areas may remain dry much of the day. It will be breezy, with ENE winds from 15-20mph at times. High temperatures will top out only in the low to mid 70s. Overnight expect overcast skies with precipitation becoming steadier and more widespread by dawn Friday; lows will be in the mid 60s.

The detailed forecast for tomorrow and the holiday weekend continues after the Ernesto Overview.

Ernesto Overview

There is now relatively good agreement in computer modeling regarding the forecast track that Ernesto will take. After emerging off the eastern coast of Florida last night, it is likely to make a second U.S. landfall somewhere not far from the South/North Carolina border and then continue northward, with the center of the depression passing over, or just west of, the DC area. However, there remains significant model disagreement regarding the timing of Ernesto's rains for our area, as well as the total rainfall we can expect. As such, this is still a relatively low confidence forecast that should come into much clearer focus by later today.

What can the DC metro area expect?
  • Scattered showers turning into heavier rain sometime overnight Thursday into mid-day Friday
  • Periods of moderate to heavy rain Friday afternoon through Saturday morning.
  • The potential for severe thunderstorms, and an isolated tornado, Friday afternoon.
  • Gusty northeasterly winds 10-25mph at times.
  • The likelihood for 1-3" of rain to fall; the potential for 5+ inches to fall in some locations. I believe that the National Weather Service's call for 5-10" is probably overdone.
  • Significantly varying local rainfall totals based on the potential for banding and training of precipitation over some locations; heaviest amounts will probably be over the western suburbs.
Pictured above: Computer model forecasts of Ernesto's track, courtesy Weather Underground.


Forecast Confidence: MediumWASHOUT! Breezy with storms. Friday will be a total washout with thick overcast skies, periods of moderate to heavy rain, especially during the second half of the day, and the potential for scattered thunderstorms, some of which may be severe and/or capable of producing isolated tornadoes. Expect palpable northeasterly winds from 10-20mph and gusty. Isolated flash flooding is possible in heavier bands of rainfall. Expect abnormally cool daytime highs in the upper 60s -- some 15 degrees below normal and more typical of the second week of October. Overnight temperatures will hold steady in the mid to upper 60s.


Forecast Confidence: LowRain to continue? Unfortunately, model guidance is in poor agreement regarding when precipitation may taper off on Saturday. Some models suggest that the bulk of rain will have fallen by mid-morning Saturday; others suggest that rain, possibly still heavy, may continue through much of the day Saturday. So, expect overcast skies with scattered showers and thunderstorms, especially during the first half of the day. We'll likely see warmer highs in the mid to upper 70s. Expect mostly cloudy skies with only isolated showers possible Saturday night, with lows in the mid 60s.

Sunday & Labor Day

Forecast Confidence: MediumSome sunshine and drying? Though there is still some uncertainty regarding how much drying (and how much sunshine) we may see Sunday and Labor Day, the most recent guidance suggests at least partial sunshine with only widely scattered showers or sprinkles. Due mostly to more sunshine, I anticipate that afternoon highs will creep into the lower 80s, with partly cloudy overnight lows in the 60s.


Next week's forecast
Forecast highs/lows: 83/64 (normal = 82/65)
Forecast precip: Near normal

Forecast Confidence: Medium-High It appears that we'll see partly sunny skies on your back-to-work Tuesday, with just the slightest chance of a few scattered showers; highs in the low to mid 80s with overnight lows in the 60s. We're likely to finally see the return of full sunshine on Wednesday, with clearing and seasonable conditions expected to hold through Friday. I envision highs in the low 80s during this time, with overnight low in the low to mid 60s.

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