**February 2006 NC Weather Review**

**Overview**

February 2006 was highlighted by a return to more seasonable
temperatures. After several locations across North Carolina recorded one
of their warmest January's on record, February brought the typical cold
frontal passages and associated cool downs. As a result, the average
monthly temperatures for February 2006 turned out to be around 5 degrees
colder than those observed in January. Typically, January is the coldest
month of the year for North Carolina.

One thing that did not change was the continuation of the dry weather
during February. Just as in January, there were several fast moving,
moisture starved weather systems that affected the state in February.
The total monthly precipitation generally averaged between 1 and 2
inches across the interior of the state (35 to 50 percent of normal),
and 2 to 3 inches across the southern Mountains and along the Coast (65
to 90 percent of normal).

With the lack of significant precipitation in February, soil moisture
levels and stream flow slipped to well below normal levels by months
end. Local reservoir levels, aided by the extensive wet period between
November 15 and December 31, 2005, remained nearly steady. Most
reservoir levels were close to full pool or only slightly below full
pool level.

Figure 1 is the North Carolina drought monitor as seen on February 28,
2006. The Moderate drought classification was expanded to encompass
nearly all of central North Carolina. For the latest information
concerning the drought, visit <http://www.ncwater.org/drought/>

![](media/image1.png){width="5.280555555555556in"
height="3.301388888888889in"}

**Figure 1. North Carolina Drought Monitor as of February 28, 2006. Note
that moderate drought conditions had expanded to cover much of central
North Carolina.**

**Details**

**Temperatures**

The record setting warmth experienced in January 2006 did not linger in
February. February was dominated by frequent cold frontal passages that
limited the length of the mild conditions to a few days at a time.
Overall, the average monthly temperatures generally ranged within a
degree or two of normal. Monthly temperature readings averaged 1 to 2
degrees below normal near the coast to around 1 degree above normal in
the northwest third of the state. Normal February temperatures generally
range from 40 to 45 degrees, except 35 to 40 across and near the
Mountains. The February average temperatures are shown below in Figure
2.

The warmest period of the month occurred between February 15^th^ and
February and 17^th^, when high temperatures rose into the 60s and 70s.
Ironically, there were two snow events that occurred across portions of
the Mountains, foothills and Piedmont, which occurred before and after
the pronounced warm spell. This pronounced swing in temperatures
illustrates the highly variable temperature regime that was experienced
in February. The daily temperatures ranged from highs around freezing on
several of the coldest days, which was preceded or followed by a day
with temperatures in the 60s to lower 70s.

![](media/image2.png){width="6.989583333333333in"
height="3.2395833333333335in"}

**Figure 2. Average monthly temperatures during February 2006 across
North Carolina.**

Figures 3 and 4 shown on the following pages depict the daily maximum
and minimum temperatures observed at both Raleigh-Durham (RDU) and
Greensboro (GSO) during February 2006. The dashed lines represent the
normal maximum temperature (red) and the normal minimum temperature
(blue). The highly variable day to day temperature swings noted at both
sites are typical with frequent cold frontal passages.

![](media/image3.wmf){width="5.375in" height="3.1979166666666665in"}

**Figure 3. Daily maximum and minimum temperatures observed during
February 2006**

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

![](media/image4.wmf){width="5.333333333333333in"
height="3.1979166666666665in"}

**Figure 4. Daily maximum and minimum temperatures observed during
February 2006**

**at Greensboro (GSO).**

**February 2006 Precipitation**

Rapidly moving and moisture starved systems brought a distinct minimum
of precipitation over all of North Carolina during February. Rainfall
amounts of only 1 to 2 inches were common. The southern Mountains and
southeast coastal areas received the highest totals of around 3 inches.
These precipitation amounts were generally well below normal. The
northwest half of the state recorded only 30 to 40 percent of their
normal precipitation, while the southeast sections faired much better
receiving between 65 and 90 percent of normal precipitation. Figure 5
shown on the following page, is the estimated rainfall for February 2006
from selected National Weather Service reporting sites.

![](media/image5.png){width="6.989583333333333in"
height="3.3541666666666665in"}

**Figure 5. Estimated Rainfall for February 2006. Plotted data was
recorded by National Weather Service observation systems or cooperative
observers. February 2006 continued a dry trend that began in January,
raising concerns that another drought may be on the horizon.**

Figure 6 is a comparison of observed rainfall and the normal rainfall
for February 2006 at selected locations across North Carolina. Note that
all of these sites received less than normal precipitation for February.

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

**Figure 6. Comparison of observed precipitation and normal
precipitation for February 2006 at selected locations across North
Carolina.**

**Winter Weather Events During February**

There were no major winter storms over North Carolina during February
2006. Instead, there were several minor winter weather events across the
northern and western portions of the state. Precipitation during the two
significant winter weather events fell primarily as wet snow on February
11 and February 20. The wet snow accumulations were generally limited to
a trace to a half inch in locations across the northern Piedmont from
Winston-Salem to Roxboro. The snowfall accumulations increased to
between 2 and 3 inches over the northern Foothills and far northern
Mountains from Mount Airy to West Jefferson. Other light snow events
(Trace to a few tenths of an inch) occurred on February 9 and February
18.

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

December turned out to be the only month during the winter season
(December through February) that had colder than normal temperatures
across North Carolina. January averaged well above normal and February
averaged slightly above normal. Above normal monthly temperatures have
been recorded in 9 of the past 10 months at both Raleigh-Durham and
Greensboro. Temperatures have averaged above normal in 11 of the past 14
months at both sites dating back to January 2005. Only March, May, and
December 2005 averaged cooler than the 30 year normal. Figure 7
illustrates the annual monthly temperature departures from normals at
Greensboro and Raleigh-Durham. The unusually warm January, 2006
temperature anomaly stands out between the cold December, 2005 and the
near normal temperatures of February, 2006.

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

**Figure 7. Monthly temperature departures from normal at Raleigh-Durham
and Greensboro.**

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

After a six week rainy period, from November 20^th^ through December
31^st^, dry weather returned in January and continued through February.
There were only a few counties centered across the northern Piedmont
that remained in a moderate drought classification as of January 31,
2006. However, much of the central part of the state was upgraded to the
moderate drought classification again in mid February. The sub par
rainfall in February 2006 was the 8^th^ time in the past 13 months that
below normal rain has been recorded at RDU. Figure 8 depicts the
precipitation trends at RDU during the past 12 months.

![](media/image8.wmf){width="5.248611111111111in"
height="3.1534722222222222in"}

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

Greensboro has been even drier than Raleigh-Durham, as 9 of the past 13
months have brought sub par rainfall. Figure 9 depicts the monthly
precipitation totals and the departure from normal during the past 12
months at Greensboro.

![](media/image9.wmf){width="5.251388888888889in"
height="3.2395833333333335in"}

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

**North Carolina Water Resources Information**

The significant rains that fell in mid November through December reduced
the drought classification from severe (as classified last fall) to
abnormally dry (as classified in early January) across much of central
North Carolina. After bottoming out near record low levels last fall,
local reservoirs recovered to near full pool levels in January. The
reservoir levels began to slowly recede during mid to late February with
the lack of rainfall. The stream and river flows continued to decline
during February, which raised concerns that local reservoirs may again
begin to decline steadily unless significant rain returns before the
rapidly approaching warm season.

Figure 10 from the USGS illustrates the rapid decline of the water level
at Falls Lake in Wake County during the drought last fall. The water
level rose sharply with the heavy rain during late November and
December. Although the January rainfall was only 50 percent of normal in
the Neuse River basin, the reservoir level continued to slowly fill
during the month. The level began to tail off and then slowly fall again
in February. The water restrictions imposed by the local governments
around some of the Triangle region remained intact due to concerns of
the drought returning. This included the city of Raleigh and many towns
throughout Wake County.

![](media/image10.png){width="6.041666666666667in" height="3.78125in"}

**Figure 10. Falls Lake Water Level since March 2005. Data courtesy of
the USGS.**

**Water Resources Forecast**

If the recent trend of below normal rainfall that began in January
continues into February and March, there will continue to be a decline
in stream and river flows. Reservoirs would not show a decline
immediately, but with a lack of rain, they will likely show a decline
with the onset of the spring season. Conversely, if normal to above
normal precipitation through spring green-up is realized, local stream
flows, lake levels, and reservoirs would all show improvement.

**Climate Outlook for March, April, and May 2006**

The Climate Prediction Center released the latest 3 month climate
outlook recently. Details concerning this forecast can be found at:

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

**Precipitation outlook through April 2006 for North Carolina**

The precipitation outlook through April 2006 calls for equal chances of
above, near normal, or below normal rainfall across North Carolina.
There were no clear signals favoring any one forecast over another.

**90-120 Day Precipitation Outlook for North Carolina through June
2006**

According to outlooks from the Climate Prediction Center, there are
increasing probabilities of drier than normal weather across North
Carolina during the April through June outlook period. The dry weather
threat peaks in the May and June time frame (when probabilities reach or
exceed 40 percent for below normal rainfall during that 90 day outlook
period). Temperatures may also become a concern by late spring and
summer if the soils become dry. Hot weather will arrive much earlier
than normal, which would lead to increased evaporation rates and water
usage. Figure 11 is the 90 day precipitation outlook courtesy of the
Climate Prediction Center.

![](media/image11.png){width="4.623611111111111in"
height="3.5701388888888888in"}

**Figure 11. U.S. Seasonal Drought Outlook through June**

**Conclusion**

The recent and ongoing La Nina episode, recent dry trends, and soil
moisture forecasts support continued dryness over NC this spring.
Therefore, the amount of rainfall that we receive in March and April
will be critical in determining our drought and reservoir status by late
spring into the summer over central North Carolina.

Figure 11 is the U.S. Seasonal Drought Outlook from NOAA. The drought
over central North Carolina and southern Virginia may expand to cover
most of North Carolina and the southeastern U.S. from March through
June.

**NC Weather Review Team**

Phillip Badgett

Michael Strickler