**December Number range CHAPTER2005 NC Weather Review**

**Overview**

December 2005 was highlighted by widespread rain that brought relief to
the drought conditions affecting portions of North Carolina. Widespread
precipitation events continued to bring much needed rainfall to North
Carolina throughout the month. Monthly rainfall totals generally
averaged between 4 and 5 inches, with localized amounts of 6 to 7 inches
over portions of the southern Foothills. These rainfall totals were
generally 1 to 2 inches above the December 30-year averages. All the
rain was very welcome news for the drought parched Piedmont, where a
severe drought had gripped the region since August.

The welcome rains in December were actually a continuation of a wetter
than normal trend that began around November 20^th^. Many areas over the
drought stricken Piedmont region received between 7 and 10 inches of
rainfall (150 to 250 percent of normal) during this six week period
ending December 31, 2005. This wet period was in stark contrast to the
previous six week period, when hardly a drop of rain fell and local
reservoirs crashed to near record low levels.

Due to the extensive wet period during the past 6 weeks, drought
conditions appear to have peaked in the fall of 2005. Soil moisture
levels, stream and river flows, and local reservoir levels improved
greatly as the month progressed.

Figure 1 is the North Carolina drought monitor from December 27, 2005.
The severe drought classification, depicted over the central Piedmont in
October and November, had been trimmed back to moderate drought
conditions for only a handful of counties at the end of December.
Elsewhere, conditions had improved enough that they were no longer
considered in a drought. For the latest information concerning the
drought visit <http://www.ncwater.org/drought/>

![](media/image1.png){width="5.28125in" height="2.7083333333333335in"}

**Figure 1. North Carolina Drought Monitor of December 27, 2005. Note
that drought conditions were now categorized as "Moderate" over portions
of central North Carolina.**

**Details**

**December 2005 Precipitation**

The final monthly rainfall tallies were quite impressive, especially
when considering much of the area had been in a severe drought since
August. There were two widespread heavy precipitation events that
occurred during the first two weeks of December. They occurred on
December 4-5, 2005, and December 14-15, 2005. Each of these events
brought widespread rainfall amounts of 1 to 2 inches, with localized
amounts as high as 3 inches. There were four additional (lighter)
widespread precipitation events that affected the state in December.
These additional systems brought a general 0.25 to 0.50 inches of rain
with them.

Some of the heaviest monthly rainfall totals extended from southwest to
northeast across the Piedmont of North Carolina. This included areas
that had been in a severe drought classification to begin the month.
Rainfall reports from Salisbury, Randleman, Burlington, Chapel Hill,
Raleigh, Durham, and Henderson were all in excess of 5 inches. The
lightest monthly amounts occurred over the far western Mountains,
especially in the French Broad River Valley region. Hot Springs for
example, only reported 1.63 inches. Figure 2 is the estimated rainfall
for December 2005 from selected National Weather Service reporting
sites.

![](media/image2.png){width="6.493055555555555in"
height="3.1847222222222222in"}

**Figure 2. Estimated Rainfall for December 2005. Plotted data was
recorded by National Weather Service observation systems or cooperative
observers. December 2005 brought above normal rainfall amounts to much
of North Carolina, helping alleviate the ongoing drought.**

Figure 3 is a comparison of observed rainfall and the normal rainfall
for December 2005 at selected locations across North Carolina. Note that
all these sites recorded rainfall that was above the 30 year normal for
December.

![](media/image3.wmf){width="5.604166666666667in"
height="3.5104166666666665in"}

**Figure 3. Comparison of observed precipitation and normal
precipitation for December 2005 at selected locations across North
Carolina.**

**Temperatures**

In addition to the return of beneficial rain, cold temperatures were
also felt over much of North Carolina during December. The overall
monthly temperatures averaged below normal at many locations including
Greensboro and Raleigh. The colder than normal temperatures observed at
both GSO and RDU snapped a string of 7 straight months in which the
temperatures averaged warmer than normal. The temperatures were cold
enough to support a major ice storm that impacted portions of western
North Carolina on December 14-15, 2005.

The December 2005 average monthly temperatures across the state
generally ranged between 2 and 4 degrees below normal. Average monthly
temperatures generally ranged from 35 to 45 degrees, with colder
readings over the northern Mountains, and warmer readings along the
immediate coast. The average monthly temperatures across North Carolina
are shown in Figure 4.

![](media/image4.png){width="6.493055555555555in"
height="3.0868055555555554in"}

**Figure 4. Average monthly temperatures during December 2005 across
North Carolina.**

Figures 5 and 6 depict the daily maximum and minimum temperatures
observed at both Raleigh-Durham (RDU) and Greensboro (GSO) during
December 2005. The dashed lines represent the normal maximum temperature
(red) and the normal minimum temperature (blue). The colder than normal
temperatures were quite noteworthy during much of the month, with a
decided milder trend during the last week of the year. There was a
string of 18 straight days of below normal temperatures between December
4^th^ and December 21^st^. This was followed by 10 straight days with
above normal temperatures to end the month.

![](media/image5.wmf){width="5.427083333333333in"
height="3.1979166666666665in"}

**Figure 5. Daily maximum and minimum temperatures observed during
December 2005 at**

**Raleigh-Durham (RDU).**

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

**Figure 6. Daily maximum and minimum temperatures observed during
December 2005 at Greensboro (GSO).**

**Winter Storms that affected North Carolina during December**

Cold air allowed a good deal of the precipitation associated with the
December 4-5 and the December 14-15 storm systems to fall as freezing
rain over western North Carolina. An ice storm crippled portions of the
eastern slopes of the Blue Ridge Mountains and Foothills along with the
western Piedmont region of the state on December 14-15. Freezing rain
accruals ranged between 1/4 and 1/3 of an inch over these areas with
local amounts of nearly 1/2 inch reported. This icing was responsible
for downing numerous trees, tree limbs, and power lines. The freezing
rain accruals from the December 14-15 storm are depicted in Figure 7.

![](media/image7.png){width="6.989583333333333in"
height="3.5104166666666665in"}

**Figure 7. Freezing Rain totals from December 14-15, 2005 Winter
Storm**

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

The colder than normal December bucked the recent trend of warm
temperatures across the state. The string of seven straight months with
above normal monthly temperatures was broken at Greensboro and Raleigh.
However, the temperatures have averaged above normal in 9 of the 12
months at both sites during 2005. Only March, May, and December averaged
cooler than the 30 year normal. Dating back to 2004, both Greensboro and
Raleigh-Durham have recorded warmer than normal monthly temperatures in
13 of the past 16 months. Figure 8 illustrates the annual monthly
temperature departures from normal as observed at Greensboro and
Raleigh-Durham.

![](media/image8.wmf){width="5.59375in" height="3.59375in"}

**Figure 8. Monthly temperature departures from normal at Raleigh-Durham
and Greensboro.**

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

The six week rainy period from November 20^th^ through December 31^st^
was in stark contrast to the previous six week period when there was
generally less than a half inch of rainfall recorded. This is typically
the period of time when water levels at local reservoirs in the northern
Piedmont reach their annual lows. Each of the precipitation producing
systems in late November through December slowly chipped away at the
severe drought over the central part of the state. By the end of 2005,
the severe drought conditions had been eliminated. There were only a few
counties over the northern Piedmont that remained in a moderate drought
classification.

As of January 1, 2006, it was expected that it would still take several
additional widespread soaking rain events in the coming weeks before the
moderate drought can be eliminated from remaining Piedmont counties.

The total precipitation for the calendar year 2005 at Raleigh-Durham
(RDU) still ended well below normal. The final total was 37.55 inches,
which is 5.50 inches below normal. There was sub par rainfall during 7
of the past 12 months at RDU. Figure 10 depicts the monthly
precipitation totals and the departure from normal during this period at
Raleigh-Durham (RDU).

![](media/image9.wmf){width="5.46875in" height="3.3333333333333335in"}

**Figure 9. Semi-annual and annual precipitation trends at
Raleigh-Durham (RDU).**

Greensboro ended 2005 on an even drier note. The calendar year total was
only 33.68 inches, which is 9.46 inches below the annual average. Eight
of the past twelve months have been drier than normal at Greensboro.
Figure 10 depicts the monthly precipitation totals and the departure
from normal during this period at Greensboro.

![](media/image10.wmf){width="5.447916666666667in"
height="3.3645833333333335in"}

**Figure 10. Semi-annual and annual precipitation trends at Greensboro
(GSO).**

**North Carolina Water Resources Information**

What a difference significant rain events can make! During the extensive
dry spell from August into mid November, local reservoir levels dropped
to near record low levels. Local municipalities around the Piedmont area
tightened water restrictions for numerous cities and towns. The water
level drop in Falls Lake during this time span, the water supply for the
city of Raleigh and many other communities in Wake County, was alarming.
The Falls Lake level dipped to 243.07 feet on November 20, 2005 (8.43
feet below the normal pool level of 251.5 feet). This was only 0.29 of a
foot from the record low of 242.78 feet recorded November 27, 1993.
Then, like turning on a switch, the rain started falling. The lake
levels including Falls Lake began to be replenished with each successive
significant rain event from late November through December.

Figure 11 illustrates the lack of rain and the corresponding rapid
depletion of the water in Falls Lake from mid August through mid
November, and then the rapid improvement in December, as several rain
events soaked the region. Although the streams, lakes, and reservoirs
saw major improvement, the water restrictions imposed by the local
governments around some of the Triangle region remained intact,
including the city of Raleigh and many towns throughout Wake County.

![](media/image11.png){width="6.427083333333333in"
height="4.510416666666667in"}

**Figure 11. Falls Lake Water Level and Rainfall since the January 2005.
Data courtesy of the U.S. Geological Survey.**

**Climate Outlook for January, February, and March 2005**

The Climate Prediction Center released its most recent 3 month 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>.

A continued improvement in the recent drought conditions over central
North Carolina is expected through the month of January. Those counties
still experiencing moderate drought conditions as of January 1, 2006 are
expected to see a gradual improvement through January and into February.
It is expected that it will take 2 to 3 additional significant
widespread soakings (1 to 2 inch rainfalls) during the next month to
ameliorate the moderate drought over the north central Piedmont.

Current indications are that there is a better than equal chance of
above normal precipitation during January 2005. It is expected that the
current parade of storm systems, associated with a very active Pacific
Jet Stream, will continue to bring North Carolina an increased chance of
above normal rainfall. This pattern of Pacific Storm systems moving
rather rapidly eastward across the United States also favors above
normal temperatures as long as the pattern persists.

Currently, the 90 day outlook including February and March, indicates
equal chances of above median, median, and below median rainfall and
precipitation. Due to the current and expected weak La Nina conditions
in the equatorial Pacific, there are expected to be several pattern
changes throughout the winter season. These pattern changes are expected
to bring North Carolina periods of warm and cold weather along with
highly unpredictable precipitation anomalies, especially in late January
through March.

**NC Weather Review Team**

Phillip Badgett

Michael Strickler