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Posted at 5:00 AM ET, 09/23/2010

Forecast: Hot and humid for two more days

By David Streit

Noticeably cooler Sunday but with clouds

* Global warming or what? | When weather was a secret | NatCast *
* Outside now? Radar, lightning, temps & more: Weather Wall *
* Number of 90+ days: 64 (Record: 67, 1980) *

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Ugh. Four points for no rain, no hail, no snow and, as far as I know, no pestilence!
 
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EXPRESS FORECAST

Today: Mostly sunny and humid. 89-93. | Tonight: Fair and warm. 65-71. | Tomorrow: Sunny and hot. 91-97. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

By David Streit, CWG Meteorologist

Even the sun angle now says it is fall, yet summer remains steadfast with two more 90+ days likely to go in the books. A cool front gently pushes through the area on Saturday and saves us from tying the record for most 90+ days for the year, we hope. An isolated thundershower is possible. Finally by Sunday, seasonable weather arrives but likely under cloak of clouds due to a strong onshore flow. An upper level low brings the prospect of much needed rain to the area on Monday.

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Today (Thursday): There may still be some scattered clouds lingering in the morning but the sun wins this contest and burns them off quickly. Calm winds only accentuate the unkindly heat that is in full force. Highs in the upper 80s to lower 90s are about 15 degrees above the norm for the date. A few pop up clouds and even an isolated shower could fire up late, but rain chances are less than 20%.Confidence: High

Tonight: The saving grace this time of year is that the sun disappears much earlier (around 7 pm). Nevertheless, readings in the 80s make for a warm and fairly humid evening. The breeze is but a whisper from the south. Skies are mostly clear but overnight lows only fall to the mid-60s burbs to lower 70s downtown. Confidence: High

Keep reading for the forecast through Monday....

Tomorrow (Friday): The relentless sun and warm start to the day allow temperatures to take a run at the record books (94 F at Washington National). In general, highs range from the upper 80s to mid-90s. At least the breeze picks up by afternoon from the south at 10 to 15 mph. Confidence: Medium-High

Tomorrow Night: A breeze helps to make the 80s more bearable this evening. Clear skies allow a nice view of Jupiter with the Harvest moon in close pursuit across the eastern sky. Overnight lows remain at least 10 degrees above normal in the upper 60s to lower 70s. Confidence: High

A LOOK AHEAD

Saturday dawns promising another warm one but a cool front does pass through mid-morning. Winds shift to come out of the north but this is going to be one slow transition. i would not be surprised in the least to see highs still reach the mid-to-upper 80s. An isolated thundershower is possible in the afternoon but is more likely to be well south of the city in the early evening. A noticeably milder and drier feel with upper 70s to lower 80s greets the dusk. Clouds increase overnight as winds turn to come from the northeast and lows bottom out in the upper 50s to lower 60s. Confidence: Medium

Sunday temperatures are much more pleasant but the price is a mostly cloudy day. Highs only in the lower-to-mid 70s should be worth the lack of sun. There is an outside chance of a spot of drizzle late in the day due to the moist ocean inflow but nothing measurable. The evening has a bit of a damp feel but readings in the upper 60s to lower 70s are comfortable. Confidence: Medium

Monday continues mostly cloudy with morning lows in the upper 50s to lower 60s. An upper level low over the Mississippi valley approaches and may set off a few sprinkles mid-day and scattered showers by evening (30% chance). On the other hand, high pressure may suppress it south keeping us dry. Any rainfall totals are likely to be quite light but could be just a small preview of things to come. Highs top out in the low to mid 70s. Confidence: Low-Medium

By David Streit  | September 23, 2010; 5:00 AM ET
Categories:  Forecasts  
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Next: Comparing, defining D.C.'s record summer heat

Comments

Ian, regarding cooling day data online, which you asked about last evening, I saw it somewhere this summer (not at the link below), but don't remember where. My source is The Weather Alamanc, Tenth Edition, p. 407, and similar data is online at http://www.weatherexplained.com/Vol-2/2001-Washington-D-C-Ronald-Reagan-National-Airport-DCA.html

The big difference is the print edition starts at 1970 and the online data starts in 1972. However, the 1970-71 numbers are nowhere near 1980's 2,006 CDDs, which we will almost surely surpass today, given this a.m.'s above average low temps (it has yet to drop below 70 degrees on my indoor/outdoor where I live, in Glover Park).

Posted by: JerryFloyd1 | September 23, 2010 5:40 AM | Report abuse

any chance of saturday's high reaching 90? maybe that cool front arrives late or something?

Posted by: walter-in-fallschurch | September 23, 2010 7:51 AM | Report abuse

Yesterday was the 27th day of 95+, how does this fit in history (last year we had 4)

Also just for fun I looked up our last 90+ day in 2009-- Aug 27

Posted by: minerdude | September 23, 2010 8:05 AM | Report abuse

@walter-in-fallschurch

Yes indeed, Saturday could reach 90F but probably not because of a late frontal arrival but because of it! We often see a warm up behind a frontal passage at National. As winds come out of the west, the cooling influence of the Potomac river is diminished, there is some downsloping from the Appalachians (sinking air heats up) and the real cool air from the front is slowed getting over the Appalachians. Probably more than you bargained for, but a true quirk of this area!

Posted by: davidstreit1 | September 23, 2010 8:17 AM | Report abuse

@minerdude I don't have the 95+ statistic on hand but will try to dig it up for you unless someone out there alread has the answer.

Posted by: davidstreit1 | September 23, 2010 8:20 AM | Report abuse

thanks david. i take it you guys will be able to evaluate that possibility saturday morning? i'm as ready as anyone for temperate temps, but we're sooo gosh darn close to that 90 degree record that i'd like to see us get it.

then i'd like to see record snows for this winter... guess i'm an extremist...

Posted by: walter-in-fallschurch | September 23, 2010 8:29 AM | Report abuse

The National Book Festival is Saturday on the Mall.

I remember some cool and or rainy ones so we'll take the short-sleeve weather.


Posted by: jaybird926 | September 23, 2010 8:47 AM | Report abuse

Brief non-weather related question (but related to website): Is anyone else having RSS feed problems with CWG site? I haven't had a reload since Tuesday afternoon.

Posted by: see1 | September 23, 2010 9:12 AM | Report abuse

@Walter, record snowfalls, yes. Record heat, miserable. Take a look at this link http://forums.accuweather.com/index.php?showtopic=8952 and check out the snow totals from 1890-95. About 160" of snow in five winters. Was that sweet, or what?

Posted by: JerryFloyd1 | September 23, 2010 9:31 AM | Report abuse

jerry, you say,
"....160" of snow in five winters. Was that sweet, or what?"

well, i'm not old enough to remember that... :-) ...so i can only imagine....and then i see you got 54" in the 1898/99 winter followed by 35" the next year...

but seriously, that chart shows an average of 15.4", but i see very few years with only a few close to 15.4. and, the "big years" seem to come in clumps(like snowflakes...) it's feast or famine on two levels. it would be interesting to see that table in graphic form. anyway, hopefully all this means lots of snow this winter... (of course w/no structural damage or leaks in peoples' houses....)

Posted by: walter-in-fallschurch | September 23, 2010 10:19 AM | Report abuse

Why are we following the number of 90+ degree days at DCA? I thought we determined last winter that readings taken at DCA are inaccurate and don't reflect Washington DC weather. Or are the readings just wrong for snow totals?

Posted by: jlexi72 | September 23, 2010 10:22 AM | Report abuse

@jlexi72, as one of the folks that hollered about DCA snow totals, some of what was said was snarky jesting. I don't think anyone is really questioning the accuracy of DCA measurements; it's the location that's the issue, since DCA in the region's heat island. (Interesting, though, that Camden reported a high of 93 yesterday in downtown DC, compared to DCA's 95.)

@Walter, I too hope that those late 1890s snow figures are repeated in the next few winters, but with La Nina it doesn't look encouraging. Had you been around in the late 1900s, you might have been snow sculpting blue whales?

Posted by: JerryFloyd1 | September 23, 2010 10:45 AM | Report abuse

i suppose the river actually has a moderating effect: cools in summer, warms in winter (unless it freezes over). so, it's not just unrepresentative in the winter...

Posted by: walter-in-fallschurch | September 23, 2010 10:46 AM | Report abuse

Can anyone advise me? I am taking my first vacation in 3 years next week...to Assateague. It looks like rain the entire week!! Yet just 1 day ago the forecast showed mostly sunny days. I have to let the hotel know by 4 pm TOMORROW, Friday, if I want to cancel. I love a rainy day at the beach, but not the entire week. Please advise. I greatly appreciate it! What are the chances that forecast can switch back to at least a few sunny days btwn Mon-Thur?

Posted by: Boellhoff | September 23, 2010 11:10 AM | Report abuse

Thanks Jerry.

minerdude, re: 95+ days, I have the numbers at home and can post them later today either here or in the summer stats post.

Posted by: Ian-CapitalWeatherGang | September 23, 2010 11:54 AM | Report abuse

while we're on statistics, the weather section of the Post this morning said that the nation's highest temperature yesterday wasn't too far afield from DC (99 in Culpeper, Va) Could that be possible? (and is there a site somewhere that backs this up?) Normally you expect someplace in Arizona or Death Valley to top that. On the other hand, I believe the heat we're experiencing now originated in the Southwest, so I guess it made it's way up here to create some more mid-Atlantic misery.

Posted by: meteorolinguist | September 23, 2010 12:34 PM | Report abuse

Will we get a reasonably good rain by the middle of next week??? Model analyses seem to be pushing back our shower chances to next Wednesday or so. [It was this weekend in earlier forecasts, but now they're favoring a "dry" cold frontal passage over the weekend.]

Another heat factoid...it may be possible to hit records in the nineties AFTER Oct. 11. Back in 1974 Bruce F. Watson authored a weather almanac for WCCO radio/TV in Minneapolis/St. Paul, and on page 32 included a table of how hot or cold it could POSSIBLY get in the Twin Cities [well to our north] on any day of the calendar year. According to Watson's table, ninety degrees is possible as early as March 31 or as late as October 24 in the Twin Cities! The actual latest date as of that year that it hit 90 was Oct. 8, [1928] not too far from our latest ninety on Oct. 11 [in 1954]. Since I've never seen a table similar to Watson's for this area, I'm not too sure how these possible extreme temperatures translate to DCA, but there may have been one or two nineties here prior to March 31. It's in the area of COLD extreme temperatures where our location should differ markedly from the Twin Cities, where it might drop to 47 below zero in late January to early February. I do know that Danbury, WI has had an official low of minus 54 and Rice Lake, WI had an unofficial minus 62 or minus 63 in recent memory.

Posted by: Bombo47jea | September 23, 2010 1:32 PM | Report abuse

seems to be developing agreement among the models of at least a moderate rainfall Monday/Tuesday.

Posted by: foul_throw | September 23, 2010 3:04 PM | Report abuse

Regarding 95+ days and how it matches up... I see 26 this yr including yesterday rather than 27, though maybe I'll double check. 1980 had 28, 1991 had 27, 1930 had 26. So we're up there...

Posted by: Ian-CapitalWeatherGang | September 23, 2010 6:55 PM | Report abuse

The comments to this entry are closed.

 
 
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