TTCM () > WeatherSunday, September 26, 2021 — W1 W2 W3 W4 W5 68°F
Washington DC Climate ReportDeckSunrise: 7:00; Solar Noon: 12:59; Sunset: 6:59

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Last 72 Hours: ObservationsCurrently: 68°F  — USNO Clear Sky ChartHeavens-Above

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DCwx
...THE WASHINGTON NATIONAL DC CLIMATE SUMMARY FOR SEPTEMBER 25 2021...

WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR
                                                  NORMAL
TEMPERATURE (F)
 TODAY
  MAXIMUM         77   3:43 PM  95    1930  77      0       69
  MINIMUM         57   6:19 AM  39    1963  61     -4       62
  AVERAGE         67                        69     -2       66

PRECIPITATION (IN)
  TODAY            0.00          3.46 1975   0.12  -0.12     0.40
  MONTH TO DATE    4.03                      3.27   0.76     4.88
  SINCE SEP 1      4.03                      3.27   0.76     4.88
  SINCE JAN 1     39.21                     31.18   8.03    40.73

Observations Archive

Today: Sunny, with a high near 74°. Northwest wind 6 to 11 mph, with gusts as high as 18 mph.

Tonight: Clear, with a low around 55°. West wind around 6 mph becoming calm in the evening.

Monday: Sunny, with a high near 81°. Calm wind becoming southwest 5 to 9 mph in the afternoon.

Monday Night: Mostly clear, with a low around 62°. South wind 3 to 7 mph.

Tuesday: A chance of showers and thunderstorms after 3pm. Mostly sunny, with a high near 82°. West wind 3 to 6 mph. Chance of precipitation is 40%.

Tuesday Night: A chance of showers and thunderstorms before midnight, then a slight chance of showers between midnight and 3am. Partly cloudy, with a low around 59°. Chance of precipitation is 40%.

Wednesday: Sunny, with a high near 73°.

Wednesday Night: Mostly clear, with a low around 54°.

Thursday: Sunny, with a high near 72°.

Thursday Night: Mostly clear, with a low around 52°.

Friday: Sunny, with a high near 70°.

Friday Night: Mostly clear, with a low around 52°.

Saturday: Sunny, with a high near 71°.

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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
347 AM EDT Sun Sep 26 2021

.SYNOPSIS...
High pressure returns today in the wake of a weak cold front.
Another cold front will move across the region on Tuesday, with
high pressure returning in its wake once again for the rest of
the week.


.NEAR TERM /THROUGH TONIGHT/...
A weak cold front has pushed through the region, as observed by
the wind shift out of the northwest. Mostly clear skies being
observed for much of the region in its wake. Not much of a
temperature/moisture gradient with this front though, so really
not much change in the sensible weather expected today. Perhaps
we drop a few degrees for highs today, and dew points will also
be a bit lower. Overall, a quiet autumn day is expected with
highs in the 70s as high pressure approaches. Main story of the
day will be some gusty winds behind the front, but only in the
15-20 mph range for most. However, the higher elevations could
see gusts closer to 30 mph, so perhaps a bit more impact there,
but not expecting any headlines from this event. Any gusts peak
during the afternoon before tapering off during the
evening/overnight hours.

Certainly a cooler night expected tonight, with lows into the
low to mid 50s for much of the area. Higher elevations will see
readings into the 40s, while areas along the water will be
closer to 60.


.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Winds turn out of the south as high pressure drifts to our
southeast tonight into Monday. Another quiet day expected with
some gusty southerly winds. This will raise temperatures back
above average, with highs into the upper 70s to low 80s for
most.

By Tuesday, a weak shortwave rotating about a stronger upper
low over Quebec will move across the region. A weak cold front
will accompany this feature, attached to a surface low well to
our northeast over Quebec as well. Ahead of this boundary,
temperatures will warm even a bit more compared to Monday, with
continue moisture advection in southerly flow. This will allow
for some decent instability (around 1000 J/kg or so) during the
afternoon ahead of the front. This, paired with the upper- level
feature moving overhead, should spark off some thunderstorms
Tuesday afternoon. With about 20-30 knots of shear available,
can`t rule out some isolated stronger storms capable of some
gusty winds and/or small hail during this time, particularly
along/east of the I-95 corridor. Think the threat will be
relatively isolated, but will have to monitor as more data is
combed over in the coming days.


.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Omega blocking will develop toward the middle and end of the week as
a closed upper low forms near Maine/Maritime Canada, with a high
amplitude ridge across the central US/Canada. At the surface, the
cold front should be south of the area by Wednesday morning,
allowing high pressure to push south from Canada. Overall, there is
fairly good agreement on the synoptic pattern for Wednesday and
Thursday, with the upper low far enough east not to have an effect
locally. Temperatures will cool back down to near or slightly below
normal values, with dew points/humidity lowering likewise.

Model spread increases Friday and Saturday with at least two
possible scenarios to monitor. The first is that the upper low could
retrograde or pivot more southward, which could open the door to
additional clouds or even a chance of showers. The other is that the
upper low pivots farther away, allowing the upstream ridge to break
down, and a trough potentially bringing showers by some time next
weekend. Of course, the "middle" is possible too, with surface high
pressure remaining in control. Due to the disparate model solutions,
the forecast will remain dry for now. The exact pattern could have
some effect on temperatures, but exceptionally warm or cold weather
appears unlikely.


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