Thursday, April 1, 2010

No Fooling: Early April Temperature Record Predicted, Without Extremes

Date Forecast Actual
Low High Low High
1 75 46 74
2 51 79 53 77
3 51 83 49 73
4 53 78 54 77
5 50 78 55 83
6 47 78 62 90
7 48 75 63
Avg: 63.7 66.1
Image (click to enlarge): April 1-7 average, record, and 2010 observed temperatures vs. record warmest and coldest years; CapitalClimate chart from National Weather Service data, background © Kevin Ambrose

April 7, AM Update: This morning's low of 63° is just 1° below both the average high for the date and the record warmest low temperature. A high today of 89° or higher will be enough to push the average for the first week of April 4° above the previous highest in at least the last 80 years.

April 6, Midnight Update: With the midnight temperature of 76° higher than last night's reading at the same time by 9°, the record high minimum of 64° for April 7 in 1942 appears to be in a world of hurt.

April 6, Evening Update: Today's high was 90°.
Dulles set a new record at 93°, beating the 86° in 2005.
Baltimore/BWI tied the record of 90°.

This is also the earliest date ever to reach 90° at Dulles, breaking the old record of April 16, 2002 by 10 days. It ties the all-time record high for April at Dulles on April 17, 2002.

April 6, 5 PM Update: The temperature is 90° as of 5 pm, just 2° short of the record. This pushes the average to at least 66.1°.

April 6, 2 PM Update: As of 2 pm, National Airport is reporting a high so far of 88°, which is inconsistent with the temperature on the hour of only 83°. Even assuming 83° for the high, the month-to-date average is now 2° above the previous record.

April 6, AM Update: This morning's low of 62° is only 1° below the long-term average high for April 6 and 15° above the original forecast from last Thursday.

April 5, Evening Update: The high was 83°, pushing the first-week average temperature over half a degree above the record. Record highs:
Washington Dulles 86° (83°, 1985)
Baltimore BWI 84° (83°, 1942/1928)
Salisbury MD 82° (80°, 1985)
Blacksburg VA 82° (77°, 1999)
Danville VA 89° (88°, 1999)
Bluefield WV 81° (80°, 1988)
Beckley WV 78° (77°, 2005)
Georgetown DE 83° (79°, 1956)
Martinsburg WV (82°), Richmond VA (89°), Norfolk VA (88°), Raleigh NC (88°), New Bern NC (87°), Binghamton NY (75°) tied their records.

April 5, 4 PM Update: At 3 pm, Dulles broke its daily record for April 5 with a temperature of 84°; the old record was 83° in 1985. At 4 pm, it's up 2 more degrees to 86°. Baltimore (BWI) has at least tied its 1942 record of 83°.

April 5, PM Update: A wind shift to a more westerly direction (SSW) has popped the 2 pm temperature to 80°. The month-to-date average is now ahead of the 1981 record for the first week of April, with 80s likely again tomorrow and Wednesday.

April 5, AM Update: This morning's low was 55°. A high today of 78° or higher will push the month-to-date average above the 1981 record.

April 4, PM Update: Low 54°, high 77°, April average to date 62.9° (up 0.9°).

April 3, PM Update: Low 49°, high 73°, April average to date 62.0°.

April 2, PM Update: Today's high: 77°, average to date: 62.5°.

April 2, AM Update: This morning's low: 53°.

PM Update: Today's high was 74°, giving an average so far of 60°. Tomorrow's forecast is updated to 80°. Elsewhere in the area, Dulles was 79° and BWI was 73°.

Original post:
Following a cooler than average winter, March temperatures rebounded sharply in the Washington, DC area, finishing the month 4.7° above average. The first 7 days of April promise to be even balmier, with a potentially record-setting first week of the month. (Tip of the wind vane to Chuck Bell of WRC, Channel 4.)

After a morning low of 46° this morning, temperatures at mid day have now risen into the mid 60s toward a forecast high of around 75°. Temperatures are expected to warm further to the upper 70s and low 80s into the weekend.

As a transition month, April has seen its share of extremes in the Mid Atlantic, so what's the big deal? Sure, the average high for April 1 is only 61°, rising to 64° by the 7th, but the record high for today is 88°, set in 1978, and the record for tomorrow is 89°. The lowest record high in the first week of the month is 85° in 1956, and it was as high as 94° on the 7th in 1929.

What's significant here is the persistence of the unusual warmth. Since records began at the current location of National Airport in 1930, there have been only 3 times that the first week of April averaged warmer than 60°. The warmest was 63.5° in 1981. That month as a whole averaged 62.1°, the warmest April in Washington weather records dating back to 1870. Based on the current National Weather Service forecast, the average for April 1-7 this year would exceed 1981 at 63.7°.

How cold can it get in the first week of April? It was almost 20° colder in 1965, when April 1-7 overall averaged 43.9°. High temperatures were above 55° only once, reaching 66° on the 5th, and lows reached freezing or below 4 times.

Stay tuned as we track this potentially record-breaking week.

No comments:

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.