The first half of October was very active with several precipitation events occurring through the 15th which coincided with below normal for temperatures. In contrast, the latter half of the month remained relatively dry and above normal for temperatures (See Figures 1 to 4).
Figure 1: Accumulated precipitation percent of normal from October 1 to 15, 2014. The southern to eastern portions of the state were well above normal for precipitation during this period. Image courtesy MRCC.
Figure 2: Accumulated precipitation percent of normal from October 16 to 31, 2014 when the majority of the state remain below normal for precipitation. Image courtesy MRCC.
Figure 3: Average temperature during the first two weeks of October 2014 were below normal across the entire state of Iowa. Image courtesy MRCC.
Figure 4: The average temperature across Iowa the last two weeks of October 2014 resulted in being above normal. Image courtesy MRCC.
Figure 5: October 3-5, 2014 average temperature departure from normal.
The average temperature for the state of Iowa was 51.2°F or 0.4°F above normal, while the average temperature for the DMX CWA was 52.3°F for the month of October 2014. October 2014 ranks as the 64th coolest out of 142 Octobers. The majority of the first two weeks remained near or below normal for temperatures. The coldest stretch was from the 3rd to the 5th, with another cold snap from the 9th to the 12th (See Figures 5 & 6). Several places were 10 to 11 degrees below their daily average temperature on the 3rd and 4th with a few areas even receiving a little frost and freezing temperatures on the morning of the 4th.
Figure 6: October 9-12, 2014 average temperature departure from normal.
However, the most widespread hard freeze occurred on the 11th as several locations across northern Iowa dropped into the 20s for low temperatures. The reason the 3rd to 5th stretch was a little cooler than normal, compared to the 9th to the 12th, was the high temperatures during the middle of the month were warmer overall, resulting in a warmer average daily temperature. Halloween resulted in being the coldest day of the month as temperatures fell into the upper teens and lower 20s the final hours of October. The coldest temperature of the month came on the 31st when Spencer dropped to 17°F.
Several cloudy and rainy days affected the first couple of weeks of October. The statewide average precipitation was 3.22 inches resulting in being 0.61 inches above normal. Waterloo reported a trace of snow on October 4th which was the first time snow had occurred at that location on that date since keeping records back to 1895. Otherwise, the bulk of the precipitation accumulated in the southeastern half of the state and much of that occurred on the 14th. A widespread swath of 1 to 2 inches with a few locally higher amounts to over 3 inches accumulated over southern to eastern portions of Iowa on October 14th (See Figure 7). Newton received 2.25” and Knoxville received 3.20” on the 14th. In fact, a new daily precipitation record of 1.78” occurred at Ottumwa on the 14th. This broke the previous record of 1.47” set in 2012. The active weather pattern dried out the last couple of weeks with only a couple days were measurable precipitation occurred. All the precipitation caused a significant increase in flow along major and minor river basins in central Iowa resulting in well above normal flow for October (See Figure 8). It also contributed to a foggy weather pattern late in the month, when a few mornings dense fog developed and caused some significant visibility. The most widespread fog occurred on the 24th of October (See Figure 9).
Figure 7: Accumulated precipitation on October 14, 2014.
Figure 8: Many of the river levels across central Iowa during October 2014 were well above their normal flow. Image is courtesy of USGS.
Figure 9: Visibility across Iowa on the morning of October 24, 2014. Image is courtesy of IEM.
Blog post by Kenny Podrazik – NWS Des Moines