**March 2007 NC Weather Review**

**Overview**

March 2007 was much warmer and drier than average throughout North
Carolina.

March was dominated by two extensive periods of very warm weather. The
periods of warmth overwhelmed the few short stints of chilly weather
during the month, which led to well above normal final monthly average
temperatures. The monthly average temperatures generally ranged between
4 to 7 degrees above the 30 year averages. These readings were warm
enough to make March 2007 the third warmest on record at both
Raleigh-Durham and Greensboro.

The warmest temperatures this month occurred between the periods of
March 10-17 and March 20-31. During these periods the daily temperatures
averaged as much as 25 degrees above normal, as daily highs topped out
well into the 80s. These temperatures were comparable to the average
temperatures for the month of June. Chilly weather was limited to only a
few days during the month, mainly occurring between March 4-9, March
17-19, and on March 29. The monthly low temperatures fell into the 20s
March 18 and 19. The March 2007 average temperatures for selected
stations across the state are depicted in figure 1.

Rain events were few and far between throughout March. The only
significant rain events occurred March 1-2, and March 16-17. Although
there were only two significant rain events this month, the rains came
at very opportune times and were significant enough to keep the concerns
of drought low. Most reporting stations across the western and northern
sections of the state recorded only slightly below normal rainfall
totals. It was much drier in the eastern third of the state, where most
stations finished the month with 2 to 3 inch rainfall deficits. These
totals equated to only 25 to 50 percent of normal. The March 2007
monthly precipitation totals for selected stations across the state are
plotted in figure 2.

![](media/image1.png){width="6.958333333333333in"
height="3.3229166666666665in"}

**Figure 1. Average monthly temperatures during March 2007 across North
Carolina.**

![](media/image2.png){width="6.989583333333333in"
height="3.6666666666666665in"}

**Figure 2. Estimated rainfall for March 2007. Plotted data was recorded
by National Weather Service observation systems or cooperative
observers.**

**Details**

**March 2007 Temperatures**

March is typically a transitional month with regard to temperatures, as
winter turns to spring. There are often wide swings in temperatures,
even on a daily basis. March 2007 was no exception, as temperature
readings at Raleigh, for example, ranged from a low of 25 (March 19) to
a high of 87 (March 27). In addition, there was a high of 81 (March 14)
followed by a high of only 48 degrees 4 days later on the 18th. However,
March 2007 will be most remembered for the extended periods of very warm
and dry weather, which is atypical of late winter or early spring.

These extended periods of well above normal temperatures led to some
daily record highs, and ultimately resulted in the third warmest March
on record at both Greensboro and Raleigh-Durham. Greensboro had an
average monthly temperature of 55.7 degrees, which was a whopping 6.6
degrees above normal. There were daily record highs set on March 23 (81
degrees), March 27 (85 degrees), and March 28 (85 degrees).
Raleigh-Durham averaged 55.9 degrees for the month, which was 5.2
degrees above normal. Daily record highs were set on March 23 (83
degrees), March 24 (86 degrees), March 27 (87 degrees), and March 28 (86
degrees). The final monthly temperatures across the state generally
averaged 4 to 7 degrees above normal except 1 to 3 degrees above normal
along the immediate coast.

The early warmth was enough to allow early budding of important
agricultural crops such as peaches and strawberries, and ornamental
plants such as azaleas and hydrangeas. Since the average date of the
last spring freeze is typically in mid April over central North
Carolina, there were concerns that a pattern change to colder weather
would still bring a hard freeze that could damage these early budding
plants and trees in April.

An early and persistent upper ridge that developed from the Gulf of
Mexico into the south central and southeastern United States was
responsible for the warmth. Figure 3 depicts the average 500 MB height
across North America during the last week of March 2007. Note the large
ridge centered in the Gulf of Mexico. This ridge effectively shut off
any moisture flow into the southeastern states and resulted in the well
above normal temperatures.

![](media/image3.png){width="6.25in" height="5.315972222222222in"}

**Figure 3. 500 MB heights (in meters) over North American during the
record warm pattern over southeastern and south central United States
March 20-31, 2007.**

Figures 4 and 5 depict the daily maximum and minimum temperatures
observed at Raleigh-Durham (RDU) and Greensboro (GSO) during March 2007.
The dashed lines represent the normal maximum temperature (red) and the
normal minimum temperature (blue).

![](media/image4.wmf){width="5.375in" height="3.1979166666666665in"}

**Figure 4. Daily maximum and minimum temperatures observed during March
2007**

**at Raleigh-Durham (RDU).**

![](media/image5.wmf){width="5.333333333333333in"
height="3.1979166666666665in"}

**Figure 5. Daily maximum and minimum temperatures observed during March
2007**

**at Greensboro (GSO).**

**March 2007 Precipitation**

There were extended periods during March in which little or no rain
fell. Significant rain fell across the state on March 1-2 and again on
March 16-17. As it turned out, 95 percent of the monthly rainfall totals
for both Raleigh and Greensboro fell during these two rain events alone.
In between these two rain events, there were 13 consecutive days with no
measurable rainfall between March 3-15, followed by a 10 day dry streak
between March 17 and 27. The rain that fell late in the month to end the
dry streak only amounted to between one tenth and one quarter of an
inch.

Most areas throughout the state generally totaled 75 to 90 percent of
the 30 year normal rainfall, except at coastal sites, which recorded
less than 50 percent of normal. The monthly totals generally ranged
between 3 and 5 inches across the western and central portions of the
state, with lesser amounts between 1 and 3 inches along the coast. The
highest totals occurred in the Mountains, where 5 to 6 inches were
recorded from Pisgah Forest, in Buncombe County, northeast to Boone, in
Watauga County. The minimum rainfall amounts occurred near and along the
coast, where Elizabeth City in Pasquotank County, only received three
quarters of an inch. Figure 6 is a comparison of observed and normal
precipitation for March 2007 at selected locations across North
Carolina.

Severe weather occurrences were below normal during March. There was a
severe weather event that affected the northern portions of North
Carolina on March 28, 2007. A case event summary for this March 28, 2007
event can be found at:

<http://www4.ncsu.edu/~nwsfo/storage/cases/20070328/>

![](media/image6.wmf){width="5.583333333333333in"
height="3.8020833333333335in"}

**Figure 6. Comparison of observed precipitation and normal
precipitation for March 2007 at selected locations across North
Carolina.**

**Current, Semi-Annual and Annual Temperature Trends**

The warmer than normal March broke the one month trend of below average
temperatures for the month of February. It also marked the fourth time
in five months with above normal temperatures at both Raleigh and
Greensboro. Four of the past six months have been warmer than normal at
Raleigh and Greensboro. The past two winter seasons, consisting of the
months of December, January, and February, have averaged well above
normal. The warmth peaked each winter season in January, when the
monthly average temperatures averaged 6 to 8 degrees above normal.

Figure 7 illustrates the monthly temperature departures from normal at
Raleigh-Durham and Greensboro. Note that 4 of the past 5 months have
been significantly above normal. Also of note is that eight of the past
twelve months have been warmer than normal at Raleigh-Durham. Nine of
the past twelve months have been warmer than normal at Greensboro.

![](media/image7.wmf){width="5.59375in" height="3.59375in"}

**Figure 7. Monthly temperature departures from normal at Raleigh-Durham
and Greensboro from March 2006 through March 2007.**

**Current, Semi-Annual, and Annual Precipitation Trends**

The sub par rainfall recorded during March marked the fourth consecutive
month of below normal rainfall at Raleigh-Durham. The rainfall deficit
during the four months totaled only 3.14 inches. This marked the fifth
time in the past eight months in which rainfall averaged below normal at
Raleigh. RDU finished 2006 with a 12 month surplus of 10.64 inches.
Figure 8 depicts the precipitation trends at RDU during the past year.
The dry pattern during the first half of 2006 was replaced by wet
conditions in June, which lasted through November 2006. It has been dry
every month thus far in 2007.

Greensboro's string of consecutive months of sub par rainfall also
reached four. It also marked the fifth month in the past eight with sub
par rainfall. Greensboro completed a dramatic turn from a 7.50 inch
rainfall deficit for 2006 at the start of June, to an 8.55 inch 2006
rainfall surplus by November 30. Greensboro ended 2006 with a final
surplus of 7.22 inches. It has since been dry every month to begin 2007.
Figure 9 depicts the monthly precipitation totals and the departure from
normal during the past year at Greensboro.

![](media/image8.wmf){width="5.416666666666667in" height="3.3125in"}

**Figure 8. Semi-annual and annual precipitation trends at
Raleigh-Durham (RDU).**

![](media/image9.wmf){width="5.447916666666667in"
height="3.3645833333333335in"}

**Figure 9. Semi-annual and annual precipitation trends at Greensboro
(GSO).**

**North Carolina Water Resources Information and Outlook**

The drier than normal conditions that have been observed during the
first three months of 2007 have resulted in a return to discussions of
potential drought. However, the wet weather experienced during the
latter half of 2006 continued to offset the short term dryness. The more
rapid demise than expected of the El Nino conditions in the equatorial
Pacific during the mid to late winter season, seemed at least partly
responsible for the recent dry weather. The precipitation was generally
less than forecast during the first half of the winter season from the
Gulf Coast states northeastward across North Carolina. This was
especially true for areas along and west of the eastern continental
divide, mainly along and west of Asheville and Boone.

The latest Drought Monitor indicated that abnormally dry conditions had
crept throughout the North Carolina Mountains. Stage one drought
conditions were being observed in the southwestern Mountains of North
Carolina. These drought conditions become severe to extreme across the
Tennessee Valley region. East of the eastern continental divide, the two
significant rainfall events during March kept abnormally dry conditions
at bay. These rains also kept the levels of streams, rivers, lakes, and
reservoirs at near normal. Most reservoirs that supply water to the
major cities in the center of the state were near normal on April 1,
2007. The latest Drought Monitor can be viewed in Figure 10. For the
latest information concerning the drought, visit
<http://www.ncwater.org/drought/>

![](media/image10.png){width="7.03125in" height="5.239583333333333in"}

**Figure 10. U.S. Drought Monitor as observed on April 17, 2007.**

**Climate Outlook for the spring and summer 2007**

The Climate Prediction Center recently released the spring and summer
outlooks. Details concerning this forecast can be found at the web
address below:

<http://www.cpc.ncep.noaa.gov/products/predictions/multi_season/13_seasonal_outlooks/color/page2.gif>

The headline for the spring season has been centered on the rapid demise
of El Nino conditions in the equatorial Pacific and a return to near
neutral ENSO conditions. The rapid demise of the El Nino during the late
winter was thought to be at least partly responsible for the very dry
weather currently observed across the Gulf Coast states, the Tennessee
Valley, and the southeastern United States. However, forcing from the
Tropical Pacific does not typically have a great impact on the climate
across the United States during April (greatest impact occurs during the
winter season). Therefore, the near neutral ENSO, or possibly a
potential development of weak La Nina conditions in the coming months,
is expected to have little effect on the climate outlook for North
Carolina during the upcoming warm season.

The very dry weather observed over southwestern North Carolina, and
especially to our south and west this spring, is expected to slowly
improve. This improvement is depicted in the latest U.S. Seasonal
Drought Outlook released on April 19, 2007, shown in figure 11. This
outlook is valid through July 2007.

![](media/image11.png){width="5.625in" height="4.34375in"}

**Figure 11. U.S. Seasonal Drought Outlook issued on April 19, 2007.
This product is valid through July 2007.**

North Carolina may once again be on the northern periphery of the driest
conditions, but there were no clear signals concerning the precipitation
forecast for the upcoming spring season. Therefore, equal chances of
above normal, near normal, or below normal precipitation are forecast.

The temperature forecast for the spring season indicated that there is
an equal chance of above normal, near normal, or below normal
temperatures during the next three months as well. As is typically the
case during the spring season across North Carolina, there will likely
be large variability in temperatures and rainfall from week to week.
Some weeks will likely average above normal, while others will be below
normal. The temperature and precipitation outlooks for the United States
for the spring can be viewed in Figure 12.

You can keep up with latest monthly and seasonal forecasts by visiting
the Climate Prediction Center website at
<http://www.cpc.ncep.noaa.gov/>.

Enhanced local three month temperature outlooks are now available at
<http://www.weather.gov/climate/calendar_outlook.php?wfo=rah>

![](media/image12.png){width="5.625in" height="5.229166666666667in"}

![](media/image13.png){width="5.625in" height="5.229166666666667in"}

**Figure 12. Temperature and Precipitation Outlooks from the Climate
Prediction Center for May through July 2007.**

**NC Weather Review Team**

Phillip Badgett

Michael Strickler