The weather headlines of 2007 in the Tennessee Valley were:

• Development of exceptional drought conditions across most of the area
• Hot weather in August and overall above normal temperatures for the year
• Minor snow event in early February
• Mild, dry weather in March followed by a hard freeze in early April

Narrative Climate Summary for Huntsville

2007 got off to a mild start at Huntsville. Temperatures averaged above normal for the first couple of weeks of January, culminating in a record tying high temperature of 71 on the14th. Warm southerly winds wrapping around the western side of a large Atlantic sub-tropical ridge were responsible for the unusually mid weather. This ridge lost influence over our weather as it was shunted off to the east. It was replaced by a series of cold high pressure systems from the north, leading to mostly below normal temperatures for the remainder of the month. The first part of the month was mild enough however, to offset the cooling trend later in the month, and January temperatures ended above normal overall. Precipitation finished just over half of normal for the month, continuing the trend from the previous year. Amazingly, not a single month in 2007 would end with above normal precipitation for Huntsville.

Much below normal temperatures occurred on the last day of January, setting the stage for a cold start to February and the area's first and only measurable snowfall of the year. One inch of snow was officially reported at Huntsville on February 1st as temperatures dipped just below freezing that morning. Minor light snow and flurries occurred around the middle of the month as well, but these only added up to trace amounts. A series of cold fronts followed by cold high pressure systems kept temperatures below normal for most of the month through the 19th. Then a reversal in the trend occurred with temperatures remaining above normal from the 20th through the end of the month. Nevertheless, temperatures overall averaged more than three degrees below normal during the month. Just as in January, precipitation was just over half of normal for February.

The mild end to February continued into March, with temperatures soaring into the 70s during the second week. Temperatures by the last week of the month had even climbed into the mid to upper 80s. New record highs of 88 degrees were set on the 26th and 29th. March finished with an average temperature of 60.0 degrees, which was 7.7 degrees above normal and enough to rank as the third warmest on record. Accompanying the unusual warmth were abnormally dry weather conditions. In what is normally the wettest month at Huntsville, March 2007 finished with a paltry 1.12 inches of precipitation, well below the normal of 6.68 inches, and enough to rank it as the 3rd driest March on record. In spite of the abnormally dry weather, the early warmth was sufficient to lead to an early bloomage of vegetation across the area. This would prove to be devastating, as Old Man Winter had some surprises in store for April.

April started off deceptively mild with afternoon high temperatures in the 70s and 80s for the first three days. Overnight low temperatures on the 1st and 2nd were warm enough to set new records, at 63 degrees and 61 degrees, respectively. However, a strong late season cold front swept through the Tennessee Valley late on the 3rd, heralding an end to the unusually mild weather, and setting the stage for a pronounced hard freeze across the region. A reinforcing shot of cold air moved into the area, dropping temperatures to record setting levels in the mid 20s on the mornings of the 7th and 8th. The severe late season cold was enough to cause devastating losses to crops and vegetation. These losses never fully recovered for the remainder of the growing season as the drought continuted to intensify into the summer months. It is not clear the extent to which these losses had on the drought and the subsequent heat wave that affected the area during the month of August, but the lack of water transpiring flora did appear to play some role. Weather conditions did moderate eventually, with temperatures fairly close to normal for the latter half of April.

Precipitation continued to be well below normal for May, June and July. Meanwhile, temperatures were above normal for May and June, but a series of unusual mid-Summer cold fronts brought seasonably cool temperatures to the area during portions of the month of July. The 0.78 inches of rain that fell in May was 4.46 inches below normal, and the second lowest in the history of that month. Thunderstorms only occurred on one day during the entire month of May, but visited the area several times during June and July. Precipitation for July was very close to normal, but remained just below with a deficit of only 0.08 inches. Still, the streak of consecutive below normal precipitation months, ongoing since November 2006, remained alive and well.

Dry weather would return for the first half of August, with only a trace of precipitation occurring during the first 16 days. Perhaps more memorable though, was the intense heat wave that affected the area during the month. One of the worst heat waves on record to grip the area had its roots in the last few days of July as temperatures slowly began to edge above normal. By the first of August, daytime high temperatures were in the 90s with overnight lows in the 70s, not entirely unusual for this area this time of year, but the worst was yet to come. A large and unusually strong high pressure cell, normally situated in the western Atlantic, built into the southeastern U.S. during the month. This combined with a weakened vegetative state and dry soil moisture conditions lead to unsually hot weather, and what would become the hottest month at Huntsville since temperature records began in 1907. Temperatures climbed to 101 degrees on the 8th, establishing a 10 day streak of 100+ days that would go down in the history books. Temperatures during this period reached a maximum of 105 degrees on the afternoons of the 15th and 16th. If the daytime heat weren't enough, temperatures remained above normal at night too, mainly in the 70s. Temperatures climbed into the mid and upper 90s on the 18th through the 21st, then broke through the century mark once again on the 22nd, 23rd, and 24th. Temperatures then fell a little, but remained above normal for the rest of the month. In fact, every single day during August 2007 experienced above normal temperatures. A total of 15 record high temperatures, whether record daily maximums or minimums, were set during the month. The heat wave was certainly extreme, but not unprecedented. A similar streak of 100+ days also occurred during the latter half of July 1952. Nevertheless, the average temperature for the month of August was 85.8 degrees, incredible not only in that it was 7.1 degrees above normal, and that for a summer month, but also in that it broke the previous record hot month, July 1930, by some 1.9 degrees.

Above normal temperatures would continue through much of September and into the first 10 days of October as rainfall remained well below normal. Fall-like temperatures would finally come to the Huntsville area on October 11th, as a cold front passed through the Tennessee Valley, dropping high temperatures into the 70s. A series of cold fronts moved through the area during the latter half of October, but did not bring enough rain to put the month into the surplus category.

Temperatures averaged slightly above normal for the month of November, but the precipitation deficit grew worse again. Measurable precipitation did not occur until the 13th when a cold front brought thunderstorms to the area. Other frontal passages later in the month brought more rounds of precipitation to Huntsville, but amounts were relatively light. The precipitation deficit for the month was 2.44 inches...impressive, but not as impressive as the 3.85 inch deficit that would occur in December. December temperatures averaged above normal too, but with a much higher anomaly than that which occurred in November. Temperatures averaged around 20 degrees above normal as daytime highs soared into the 70s on the 8th through the 12th with overnight lows only dropping into the mid to upper 50s. A record high of 73 degrees was tied on the 9th, with new record highs of 76 and 77 being established on the 10th and 11th, respectively.

Overall, the year ended as the driest on record and the 2nd warmest on record. The annual precipitation of 28.65 inches shattered the previous record low annual precipitation of 37.18 inches, which was set in 1925. Twenty-six record high temperatures were set or tied for the year, including five record lows. Interestingly, the only daily precipitation record set for the year, was the 1.0 inch snowfall that occurred on February 1st. This tied a previous snowfall of 1.0 inch snowfall on February 1st 1951.

Narrative Climate Summary for Muscle Shoals

Although not as warm and dry as Huntsville...weather conditions at Muscle Shoals for 2007 were certainly drier and warmer than normal. In fact...2007 ranks as the 2nd warmest and 3rd driest year on record there. The average annual temperature for Muscle Shoals was 63.7 degrees…which was 2.7 degrees above normal. Rainfall for the year totaled 38.25 inches...which was a considerable 17.55 inches below normal.

In similarity to Huntsville...unusually dry and warm weather in March was followed by subfreezing temperatures in early April. High temperatures soared into the mid 80s in late March...setting records on the 26th and 29th. Less than two weeks later...a strong cold front moved through the Tennessee Valley....bringing subfreezing temperatures to the region. Early morning low temperatures of 26 degrees occurred on the 7th and 8th of April...setting new records for each date.

Heavy thunderstorms that moved through northwest Alabama on the 5th and 6th of July brought copious rainfall to the area. 3.01 inches fell on the 6th...setting a precipitation record for the date. Interestingly...the 4.08 inches that fell on these two days (the 5th and 6th) represented more than 10.5% of the rainfall that occurred during the entire year. A few more thunderstorm events that occurred during the month brought the July total for Muscle Shoals to 7.64 inches...which ranked as the 10th wettest July on record. This was the first month since November 2006 in which precipitation was above normal. Precipitation would continue to be above normal at the Shoals in August and again in October. However...precipitation deficits in the driest months...would be sufficient enough to cast this as the 3rd driest year on record.

Although precipitation was above normal during the month of August...unusually hot weather occurred just as in Huntsville and the rest of the Tennessee valley. The average temperature for August was 85.5 degrees...which was an incredible 6.4 degrees above normal...and enough to rank as the warmest August and the warmest month on record at the Shoals. Temperatures reached or surpassed the century mark on twelve consecutive days...beginning August 7th and ending August 18th. This tied with a similar period in July 1980 as the longest streak of 100+ consecutive days on record. Temperatures then climbed above 100 degrees again on the 21st through the 24th...making a total of 16 days during the month in which temperatures reached 100 degrees or higher. June 1914 stands as the only other calendar month in which this has occurred. In addition...13 record highs (daily max or min) were set or tied during the month. The 107 degree record-setting high on the 15th was the hottest temperature to occur at the Shoals since August 8th 1930. Interestingly...2.38 inches of rain occurred on the 24th...which was a new precipitation record for the date and the last day in which temperatures reached the century mark for the month.

With the exception of October...precipitation was below normal through the remainder of the year at the Shoals. The record-setting 2.85 inches that fell on the 22nd of October was enough to propel that month into the above normal category...but was not enough to keep the fall season from averaging below normal for precipitation.

The above normal temperature trend that was reestablished in August continued through the end of the year. Record high temperatures did not occur at the Shoals, however, until the second week of December. High temperatures soared into the mid 70s on the 9th...10th and 11th...breaking or tying records for each date.