April 2011- Dry, dry... and no immediate relief in sight

April 4, 2011

Obviously April continued the recent trend of warmer and much drier than normal. April precipitation is almost not worth mentioning because there was so little of it. None of the west side gauges recorded measurable precipitation while the maximum on the east was a mere 0.9 mm at Five Points. The refuge wide average of 0.2 mm still only makes this the 3rd driest April in our 22 year history as both 1991 and 1996 had completely dry Aprils. There have been 3 other Aprils with less than 1.0 mm.

Temperature-wise, April started out extremely warm with a near-miss of 90 degrees F on the 2nd. Temperatures then took a few big dips with passage of dry cold fronts that brought little but wind. After the middle of the month there was another period of well above normal temperatures followed by a cooling at the end of the month.

April Record Temperatures - High 34.0 (93.2 F), Low -10.2 (13.6 F)
April '11 Record Temperatures - High 31.9 (89.4 F), Low -7.9 (17.8 F)

Another meteorological factor that elicited much comment during April was the wind. Strong winds are not unusual in April but they were indeed stronger than average this year. The long-term average maximum daily wind speed in April is 27 mph. This year the average was 30 mph. This is the 2nd windiest April in Sev's LTER record - 1999 was the windiest with an average maximum wind speed of 32 mph. The highest recorded wind speed on the refuge was 58 mph. Albuquerque had wind gusts of 40 mph or greater on 12 days during the month. A warning: Mays are often as windy or windier than April. The long-term average is only 0.2 mph less than April.

While the wind was almost the highest ever the amount of moisture in the atmosphere near the ground was almost the lowest. In fact the relative humidity, that normally averages 29%, averaged 16.7% this April which is the lowest in LTER history. However the average absolute humidity of 2.84 mb is only 2nd to the 2.31 mb of 2008 but well below the normal 4.04 mb.

April Meteorological Summary

                         April       April '11         April '11
Variable             Long-term* Mean    Mean           Mean Range
-------------------------------------------------------------------
Mean Max Temp (C)         22.23         23.9          21.0 - 25.0
Mean Min Temp (C)          4.74          6.1           4.2 - 7.5
Mean Average Temp (C)     13.48         15.0          13.5 - 16.2 
Mean R.H.  (%)            29.0          16.7          15.6 - 18.6
Mean Vap Press. (mb)       4.04          2.84         2.77 - 2.92
Mean Max Wind (m/sec)     12.2          13.3          12.1 - 14.6
Mean Solar Rad. (kWh/m2)  7.14          7.85          7.54 - 8.73
Precip.(mm)               12.5           0.2           0.0 - 0.9
---------------------------------------------------------------------
*Long-term refers to all of the Sevilleta met stations for 1989-2010

Albuquerque - Sevilleta Comparison

Both Albuquerque and the Sev got their only measurable precipitation on the 6th. This is the driest start to any calendar year in history for both sites

                Loc     Precip          Normal       % of Normal
=====================================================================
April           ABQ       0.8 mm        13.2 mm            6 %
                SEV       0.2 mm        12.5 mm            2 %

Year to Date    ABQ       3.6 mm        51.5 mm            7 %
                SEV       1.7 mm        45.6 mm            4 %
====================================================================
Remember to check National Weather Service Monthly highlights at:

http://www.srh.noaa.gov/abq/climate/Monthlyreports/April/2011/index.php

Water-year Precipitation

The water year precipitation is still only the 3rd driest start to a Sev water-year with 2005-06 being the second driest with 29.2 mm and 1995-96 being the driest with 25.7 mm. Excluding last October's precipitation this would be the driest 6 month period with only 7.1 mm of precipitation. 2005-06 had 7.8 mm and 1995-96 had 24.8 mm during the same period.

                1989-2010
Month           Mean            2009-2011    
===========================================
Oct 10          22.7              23.2       
Nov 10          13.3               0.4  
Dec 10          13.4               5.0
Jan 11           8.4               0.1
Feb 11           9.0               0.8
Mar 11          15.7               0.6
Apr 11          12.5               0.2
==========================================
Total           95.2              30.3

Drought

The Palmer Drought Index shows all of NM except the NW quadrant in moderate to extreme drought. The "U.S. Drought Monitor" puts 75% of the state in severe to extreme. It is also projecting the drought to last through July.

The Rio Grande is currently only running at about 1200 cfs at Otowi Bridge whereas the average for May is just about 4000 cfs. Elephant Butte continues to drain. It is now at 30% of average which is only 70% of what it was last year at this time.

La Nina

La Nina continues to hang on with only a slow movement toward a neutral status during April. In fact, although the Southern Oscillation Index (SOI) dropped from +2.5 to +1.9, the 5-month running mean rose to +2.46 which is the highest that it has been in almost 100 years.

Notables from on and off the Sev

Things are really crispy out on the refuge. Very few forbs have managed to bloom but they are hard to locate amid the grays and browns of dry grasses

The creosote bush is finally starting to show the effects of the winter freeze. Their green color has changed to brown and leaves have started to shed although a considerable portion remain. Smaller bushes and those along the road seem to have fared the best while the largest and tallest look the worst. Creosote at the field station definitely look better than those out at 5-points.

In addition to the creosote taking a hit, it appears that the mesquite have fared just as badly or worse. Little of it seems to be leafing out even though it should be well on its way to full foliage by now.

Some new experiments are being started on the refuge this spring. Here is Mike Friggens trying to make it rain from below. I will also post pictures of the jackhammer soil corer ride if someone would like to share theirs.

We should not complain about straight winds - spinning ones can be much worse. There were several outbreaks of tornadoes from the Great Plains to the east coast. The worst was the night of the 27th where a record number of tornadoes hit the Mississippi, Alabama area. It was the deadliest tornado event in past 50 years and 3rd most deadly in recorded history; the death toll approaching 350 people. Two EF-4 and two-EF-5 (the strongest)  tornadoes occurred during this single outbreak. One of the EF-4's traversed the entire are from Tuscaloosa to Birmingham, Alabama.

We could certainly use some of the water from back east. Record flood levels where observed at the confluence of the Ohio and Mississippi River at Cairo Illinois. The Ohio exceeded the previous record flood stage of 59.5' (1937) on May 1st and was expected to peak at 61.5' on May 4. Army Corp of Engineers breached levees above Cairo to alleviate some of the pressure on those in Cairo.

Hurricanes

Sea surface temperatures in the Gulf of Mexico are well above normal for this time of year.  With La Nina or medial conditions expected in the near term there is concern about a very active year. At least there is no gushing wellhead out there... at the moment.

May Forecast

No surprises. NOAA says continued increased chances for both a warmer and drier than normal May.

D.M.