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Issued: 10am on Sunday, October 3rd 2021

Technical Forecast Discussion

Short Term (Sunday 10-3-2021 through Tuesday 10-5-2021)

Our short term period is starting off with line of scattered showers with embedded thunderstorm moving through our area as of 10am Sunday. These showers/storms are associated with a weak short-wave trough lifting into western Illinois area and interacting with strong plume of Gulf of Mexico moisture under southerly flow. As we continue to move through the day today into Monday, this weak short-wave will mainly retrograde southwestward over central Arkansas region, but there is a small piece of that wave which still hangs back over tri-state region of OH/IN/MI. This pattern on surface translates to surface low moving eastward over northern Michigan with a cold front trailing down into Illinois moving eastward. As the low pressure weakens out by Monday, the front will be stuck in central Ohio region. This pattern will result in high chances of showers/storms through the day Sunday, but look for overall precipitation risk to decrease by late Sunday night into Monday before precipitation ends. Rainfall totals by Monday will be around 0.5″ inch with isolated amounts near 1″. As we continue to progress into Monday night and Tuesday, short-wave will start to intensify and remain still over Arkansas. Our area will get reprieve from rainfall on Tuesday with decreased cloud coverage in our area. Expected temperatures during this period to be in low-mid 70’s for highs Sunday and Monday, drier and warmer on Tuesday with upper 70’s for highs, and lows will remain lower 60’s under overall humid conditions. These temperature anomalies are about 3°F-6°F above normal for highs and 14°F-18°F above normal for lows with overall 9°F-12°F above normal departures.

Long Term (Wednesday 10-6-2021 through Saturday 10-9-2021)

Long term period resumes with upper level low continuing to remain stationary over central Arkansas as it’s blocked from moving north due to quickly intensifying upper level ridge, which is centered over far northern Michigan, dominating most of Ontario/Québec along far northern sections of continental U.S.. As our area is under continued southerly flow, look for scattered to numerous showers and storm associated with ULL to move back into our area form Wednesday into Thursday. As we progress Thursday into Friday, 500H ridge will shift eastward and weaken down a little, the ridge axis shifts form northwest-southeast to more north-south over western Québec region. At this same time, our short-wave trough will finally lift northward and weaken as it moves into Illinois and Indiana by late Friday. Given that there still be some forcing in our area on Friday along with high PWAT values, we cannot complete rule out chances of isolated showers, but chances are expected to be significantly lower compared to Wednesday/Thursday. Weather conditions by Saturday are looking to be warm with continued drying trends. High temperatures during the long term period will remain in low-mid 70’s for highs with lows only dropping in upper 50’s to lower 60’s. Overall temperatures departures will continue to remain about 9°F-12°F above normal with highest departures coming from warm mornings due to continued presence of high humidity for this time of the year.