DISCUSSION: Earlier this year during the spring months, portions of Arkansas and southern Missouri experienced record flooding. Details on this previous event can be found here. Currently, a few months later, these same places are now considered to be in a moderate to severe drought, as shown by the US drought monitor image, but possibly not for long.
Current conditions show an elongated frontal boundary with a weak wave of low pressure moving northeast as the precipitation follows suit. A general 0.5 – 1 inches with up to 2+ inches of precipitation fell yesterday, December 22nd, into the overnight hours across southern Missouri and Arkansas with precipitation stretching into Louisiana as this front brought thunderstorm type activity last night. This precipitation yesterday evening shows up well when looking at the synoptic scale features that were in play alleviating some of these drought conditions.
The 850 mb map shown below, which plots heights (dam), isotherms (degrees C, dotted yellow), and dew point temperatures filled (degrees C), valid 12/23/00Z, shows southerly winds bringing warm air advection, which leads to upward vertical motion, across Arkansas and working its way into southern Missouri. Gulf of Mexico moisture is being advected into the region moistening up the atmosphere enhancing the heavy precipitation threat. Accompanied with this, favorable upper level jet dynamics are present enhancing divergence (yellow contours) in the upper levels (streamlines and isotachs in knots are also plotted) of the atmosphere as shown in the 300 mb analysis valid 12/23/00Z. This enhances the rising air in this region and the chance for precipitation.
These factors come together nicely when looking at the radar imagery from yesterday evening shown below, which illustrates a nice area of precipitation where it was expected in the drought areas based on this synoptic scale analysis.
Stay tuned for future updates here across the Mississippi Valley to see if more drought alleviation is on the way!
©2017 Forecaster Joseph DeLizio