Wettest April since 1983 in D.C., with mixed temperatures across region

April 2014 was a very variable month over the Mid-Atlantic region.  We had periods of protracted dryness and wetness along with very cool weather including a trace of snow, while also reaching up into the middle 80s.  For National Airport, it was the first warmer-than-normal month of the new calendar year, but BWI and Dulles both continued their 2014 streak of below normal temperatures.   We were about to have a drier-than-normal month too until the precipitation blowout of the last few days!

Here are the National Airport rankings for April.  It was easily the wettest April of the 2000s, and the wettest since 1983.

apriltempprecip

April temperatures (Reagan National Airpoprt)

The  estimated average temperature of 57.3F was +0.5F warmer than normal, but the sixth coolest April of the 2000s.  The variable weather of the month sent temperatures in all sorts of directions with the biggest extremes in the middle third of the month when we hit the middle 80s and the low 30s in just a matter of days.  Here are the ups and downs of the month which include an equal number of above and below normal temperature days.  How’s that for variety!?

dcadailytemps

 

Precipitation

April’s 6.47″ (more than twice of the normal 3.06″) was impressive at National, but it was an inch short of Dulles’ total and more than 2″ below BWI’s big 8.6″ final tally (just 0.1″ away from its wettest April on record, in 1889).  National Airport had three days this month with over 1″ of rain, with two of them being the final two days of the month as shown in the chart below:

dcadailyprecip

Records

There were a few interesting new records were set at all three local airports….

Washington National

April 14, 2014:   Record warm minimum temperature of 65F beating 1896′s 63F

April 30, 2014:  Record daily rainfall of 2.7″ besting 2005′s 1.16″ total

Washington Dulles

April 14, 2014:   Record warm minimum temperature of 63F beating 1972′s 58F

April 15, 2014:  Trace of snow breaks record for date

April 18, 2014:  Record low of 30F beating 1996′s 31F

April 30, 2014:  Record daily rainfall of 3.99″ besting 2005′s 0.72″ total (also most rain in single day in any month between November and May)

Wettest April on record: 7.41″ beats 1973′s 7.35″

Baltimore

April 14, 2014:   Record warm minimum temperature of 62F matching the same value in 1896

April 30, 2014:  Record daily rainfall of 3.06″ matching 1947

The weather pattern

The upper level jet stream pattern for April was quite variable, so the monthly snapshot shown below is probably not as representative of the whole month as periods featuring more stable weather patterns.  The continued upper level low pressure area over the Hudson Bay helped to funnel stronger cool pushes into the Midwest, East, and South at times this past month.  The warm ridging pattern on the West Coast (bringing some stronger heat to California at times) also helped to ripple some cooling into the East.  However, we also had periods of warm ridging on the East Coast, especially in the first two-thirds of the month.  The mean anomaly (or difference from average) map below shows a complicated picture – this is not atypical for the middle of meteorological spring when chaos levels tend to be higher as the seasons transition from winter to summer.

aprilupper

2014-to-Date

Now that we are four months into 2014, I wanted to see how we are tracking relative to other years in the 2000s.  We are now officially the wettest and also the second coolest (after 2003).  The wettest part concerns me a bit because of the developing El Niño pattern in the Pacific.  Usually, that means we see a wetter-than-normal pattern especially by the autumn and next winter (no guarantees on summer).  If that holds up, we could make a run at one of the wettest years on record given the very strong start.  Also, with the Niño developing, we could see a cooler summer, which could keep 2014 tracking as a relatively cooler year compared to especially more recent years (like the 2010-2012 warm period).  You can see the rankings here:

jantoapriltemp jantoaprilprecip

May 2014 outlook: More variability

Like April, the final month of meteorological spring looks to offer up all sorts of weather with likely dry and wet periods along with intermittent warmer and cooler periods.  We could still see cool periods with lows in the 40s (early next week) and other times where highs break into the 80s again (late next week).  My thinking right now is that May should work out to be fairly close to normal temperatures like April did, but precipitation should be near to above normal owing to the active, variable pattern.

The National Weather Service (NWS) final May outlook offers no guidance for our area with EC forecast for both precipitation and temperature.  EC means Equal Chances of above, below, and normal temperatures.  They are forecasting a cool Midwest and warm South with both types of patterns probably affecting us at various times.  You can see the NWS final May forecast here.

For further information

The National Weather Service publishes nice monthly assessments about five days into the start of the next month:

You can click on your closest airport location here:

Reagan National (DCA)

Dulles Airport (IAD)

Baltimore-Washington (BWI)

Also on Capital Weather Gang

American model crushed European model in forecast for record-setting rain in D.C.