**February 2007 NC Weather Review**

**Overview**

February 2007 was decidedly colder than previous months and drier than
normal.

The colder than normal pattern that began in the middle of January,
persisted through the first 3 weeks of February. The temperatures during
this period averaged much below normal throughout the state, which was a
result of several shots of very cold air delivered into the central and
eastern United States from central Canada. The coldest air masses
affected North Carolina between February 4-6, February 8-11, and
February 14-19. The temperatures during these cold outbreaks averaged 10
to 15 degrees below normal. Morning lows frequently fell into the single
digits and teens over the western sections of the state, with 20s
observed all the way to the Outer Banks and immediate beach locations.
It turned warmer during the last week of February, highlighted by daily
highs in the 70s on February 21 and 22. The February average
temperatures for selected stations across the state are depicted in
figure 1.

The persistent northwest flow pattern that brought the cold temperatures
also led to dry weather. Most reporting stations across the state
recorded much drier conditions than the 30 year average. Total
precipitation amounts generally averaged between 1 and 3 inches below
normal, which equates to only 25 to 50 percent of normal. Monthly
snowfall was also well below normal. There was only one system that
brought light accumulations to the state, which occurred on February 1.
There were additional upslope snow events along the northwest facing
slopes of the North Carolina Mountains. However, even with these events,
the snowfall across the Mountains still averaged below normal due to the
lack of winter storms this month. The February monthly precipitation
totals for selected stations across the state are plotted in figure 2.

![](media/image1.png){width="7.114583333333333in"
height="3.2604166666666665in"}

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

![](media/image2.png){width="6.989583333333333in"
height="3.2291666666666665in"}

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

**Details**

**February 2007 Temperatures**

February is typically one of the coldest months of the year throughout
North Carolina, second only to January. However, February 2007 turned
out to be colder than January 2007, due to the persistent upper level
trough that kept reloading over the eastern part of the United States.
Figure 3 depicts the 500 MB Height Anomalies from the Pacific Ocean
across North America during the first 3 weeks of February. Note the
large negative anomalies (120 to 150 meters) centered along the east
coast of the U.S., which resulted in the well below normal temperatures
with frequent cold outbreaks during this period. Figure 4 depicts a
pattern change to near normal 500 MB anomalies over the region during
the last week of the month, which resulted in a return to warmer
weather.

![](media/image3.png){width="5.626388888888889in"
height="4.351388888888889in"}

**Figure 3. 500 MB Height Anomalies (in meters) over North American
during the cold pattern over eastern North America February 1-16,
2007.**

![](media/image4.png){width="5.626388888888889in"
height="4.351388888888889in"}

**Figure 4. 500 MB Height Anomalies (in meters) over North America
during the pattern change to warmer temperatures over eastern North
America February 20-28, 2007.**

The average February monthly temperatures generally ranged between 35
and 40 degrees, except 40 to 45 across the southeastern half of the
state. The temperatures over the Mountains averaged in the 20s to lower
30s across the north, into the mid 30s over the southwestern Mountains.
Mount Mitchell had the coldest monthly average temperature at 22.1
degrees, followed closely by Grandfather Mountain at 22.4 degrees. Other
reporting stations included Asheville (36.3 degrees), Mount Airy (33.9
degrees), Greensboro (38.7 degrees), Elizabeth City (38.8 degrees),
Raleigh (40.8 degrees), Charlotte (41.0 degrees), Fayetteville (43.3
degrees), and Wilmington (45.0 degrees). These monthly temperatures
ranged between 2 and 6 degrees below normal. Elizabeth City was most
below the 30-year average at 5.9 degrees below normal, followed by
Charlotte and Mount Airy at 4.0 degrees below normal. Raleigh-Durham and
Asheville averaged 2.2 degrees below normal.

The northern Mountains took the brunt of the cold during the most severe
cold spells. The daily highs remained in the teens and 20s, with lows in
the single digits. The minimum temperatures dipped into the teens over
the Piedmont and portions of the Sandhills. Raleigh-Durham recorded
daily lows of 15 degrees on the 6^th^, 19 on the 17^th^, and 19 again on
the 19^th^. Greensboro fell to 14 degrees on the 6^th^, 19 on the
15^th^, 19 on the 17^th^, and 17 degrees on the 19^th^.

**\
**Figures 5 and 6 depict the daily maximum and minimum temperatures
observed at Raleigh-Durham (RDU) and Greensboro (GSO) during February
2007. The dashed lines represent the normal maximum temperature (red)
and the normal minimum temperature (blue).

![](media/image5.wmf){width="5.375in" height="3.1979166666666665in"}

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

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

![](media/image6.wmf){width="5.333333333333333in"
height="3.1979166666666665in"}

**Figure 6. Daily maximum and minimum temperatures observed during
February 2007**

**at Greensboro (GSO).**

**February 2007 Precipitation**

Along with the persistent cold and dry northwest flow during much of
February came well below normal precipitation totals across the state.
Most areas generally totaled only 25 to 50 percent of the 30 year
normal. The monthly totals generally ranged between 2 and 3 inches
across the state, with lesser amounts recorded over the Mountains and
along portions of the Coastal Area. The highest totals occurred in a
small area of the southern Piedmont, where 3 to 4 inches were recorded.
Rockingham, in Richmond County, tallied 4.01 inches. This was the
highest amount of rain recorded in the state this month. The minimum
rainfall amounts occurred over the central and northern Mountains, where
Hot Springs in Madison County, only received 0.99 of an inch. West
Jefferson and Boone tallied 1.12 inches and 1.29 inches, respectively.
Figure 7 is a comparison of observed precipitation and normal
precipitation for February 2007 at selected locations across North
Carolina.

There were only two significant precipitation events that affected the
state the entire month. The only widespread heavy rainfall event
occurred on February 13-14. The storm total rainfall for this event
generally ranged between 1.0 and 1.5 inches, except only 0.5 to 1.0 inch
over the eastern sections of the state. The only other significant event
brought generally only 0.25 to 0.50 inch to the majority of reporting
stations. This event occurred on February 25.

Snowfall was well below normal throughout North Carolina during
February. The only system of substance came on February 1, when light
snowfall accumulations were observed across much of the state. Although
the temperatures were cold enough for snow to accumulate, the
precipitation amounts turned out to be light. Figure 8 is a depiction of
the snowfall accumulations across the state during the February 1, 2007
snowfall event. Note that there were totals of 2 to 4 inches over the
southwest Mountains, including Murphy, Bryson City, Franklin, and
Cullowhee. However, accumulations to the east and north were very light.
A case event summary for this February 1, 2007 light snow event can be
found at:

<http://www4.ncsu.edu/~nwsfo/storage/cases/20070201/>

The only other snow events in February occurred in the northwest upslope
snow regions of the northern Mountains, in the wake of strong cold
frontal passages.

![](media/image7.wmf){width="5.583333333333333in"
height="3.8020833333333335in"}

**Figure 7. Comparison of observed precipitation and normal
precipitation for February 2007 at selected locations across North
Carolina.**

![](media/image8.png){width="6.947916666666667in"
height="3.4583333333333335in"}

**Figure 8. Snowfall accumulations observed during the February 1, 2007
light snow event.**

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

The colder than normal temperatures in February broke a string of three
straight months with above normal temperatures at both Raleigh and
Greensboro. Three of the past six months have been warmer than normal at
Raleigh and Greensboro. However, 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 9 illustrates the monthly temperature departures from normal at
Raleigh-Durham and Greensboro. Note that seven of the past twelve months
have been warmer than normal at Raleigh-Durham. Eight of the past twelve
months have been warmer than normal at Greensboro.

![](media/image9.wmf){width="5.59375in" height="3.59375in"}

**Figure 9. Monthly temperature departures from normal at Raleigh-Durham
and Greensboro from February 2006 through February 2007.**

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

The below normal precipitation recorded during February marked the third
consecutive month of below normal rainfall at Raleigh-Durham. However,
the rainfall deficit during the past three months only totaled 2.67
inches. This marked the 4^th^ time in the past 7 months where rainfall
averaged below normal at Raleigh. RDU finished 2006 with a 12 month
surplus of 10.64 inches. Figure 10 depicts the precipitation trends at
RDU during the past year. The dry pattern 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 three. It also marked the 4th month in the past 7 months with
sub par rainfall at Greensboro. 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 11 depicts the monthly precipitation totals and
the departure from normal during the past year at Greensboro.

![](media/image10.wmf){width="5.416666666666667in" height="3.3125in"}

**Figure 10. Semi-annual and annual precipitation trends at
Raleigh-Durham (RDU).**

![](media/image11.wmf){width="5.447916666666667in"
height="3.3645833333333335in"}

**Figure 11. 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 two months of 2007 have brought back discussions of drought
potential. 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
developed over this region of the state, with stage one drought
conditions being observed upstream in the Tennessee Valley region. East
of the continental divide, the lighter precipitation totals in the past
two months have had little affect on streams, rivers, lakes, or
reservoirs. Most reservoirs that supply water to the major cities in the
center of the state were near normal on March 1, 2007. The latest
Drought Monitor can be viewed in Figure 12. For the latest information
concerning the drought, visit <http://www.ncwater.org/drought/>

![](media/image12.png){width="6.876388888888889in"
height="5.124305555555556in"}

**Figure 12. U.S. Drought Monitor as observed on February 27, 2007.**

**Climate Outlook for the spring 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 was centered on the recent rapid
demise of the El Nino conditions in the equatorial Pacific, and the
possible development of a La Nina. Moderate El Nino conditions,
characterized by sea surface temperatures 0.5°- 1.0° Celsius warmer than
normal, were observed in the critical regions of the Equatorial Pacific
in December. These conditions did not last as long experts felt they
would - The El Nino conditions rapidly diminished by the middle of
January. Near neutral Enso conditions are now forecast through the
spring and summer seasons. The bottom line for North Carolina, El Nino
will no longer be a factor in the climate outlook for the spring season.
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 now 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 3 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 Figures 13 and 14.

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/image13.png){width="4.998611111111111in"
height="3.040277777777778in"}

**Figure 13. Precipitation outlook from the Climate Prediction Center
for the spring 2007.**

![](media/image14.png){width="5.752083333333333in"
height="3.484722222222222in"}

**Figure 14. Temperature outlook from the Climate Prediction Center for
the spring 2007.**

**NC Weather Review Team**

Phillip Badgett

Michael Strickler