Current Forecast Meet the Forecaster

Issued: 8pm on Sunday, October 24th 2021

Technical Forecast Discussion

Short Term (Sunday 10-24-2021 through Tuesday 10-26-2021)

Short term period is starting with incredibly active weather all across the lower 48 states, starting with severe weather outbreak back across Missouri and Illinois along with heavy rainfall for most of northern Ohio Valley region, we also have sub-950mb surface low over Pacific, few hundred miles west of Washington state, bringing in strong winds and heavy precipitation for west coast area. Locally speaking, WAA driven band of scattered showers and thunderstorms lifted northward past our area as warm front nears our area as of Sunday evening. Southerly flow behind the warm front will allow higher humidity to settle in our area and allow for mild conditions Sunday night into Monday afternoon as we will be in the warm sector of the surface storm to our west. Looking at the upper pattern, we actually have a slight upper level ridging out ahead of the short-wave, associated with the surface low over Kansas now, moving eastward right over the state of Ohio by Monday evening. Models shows this wave taking more of neutral tilt, this allows storms to form and there will be about 200-600 J/kg range of CAPE with plenty of shear for the storms to tap into for severe storms. Good thing is lapse rate is horrible along with weak instability which puts a damper on high severe chance, still the upper level dynamics is supportive enough for damaging winds and tornado threat for Monday afternoon/evening hours. As the cold front moves through, look for severe weather threat to end with cooler air settling in for us by Monday night. 2-day rainfall totals will be in 0.5″-1.0″ range, most of it falling on Monday. Our troughing pattern is going to stay in place for Tuesday as we remain on the back side of the storm, keeping in the chilly conditions with some clearing taking in place as high pressure will start to push into Illinois area. Due to sharper gradient between the surface high to west and low to east, we will see windy conditions during the daytime hours as winds will range in 10-15mph with gusts around 25mph. Temperatures during this period will feature our highs in mid-upper 60’s for Sunday and Monday which cool down to mid 50’s Tuesday with our lows dropping from mid 50’s Sunday night to mid 40’s Monday night and upper 30’s Tuesday night. Overall temperature anomalies will be in order of 2°F-4°F above normal with most of the departures coming from warmer nights.

Long Term (Wednesday 10-27-2021 through Saturday 10-30-2021)

Models show heights rising once again just past midnight Wednesday as an axis of upper level ridging temporarily forms over our area for the daytime hours on Wednesday and we will also have high pressure on the surface in response to the ridge. Our temperatures will recover to average values as of result under bright conditions. Looking further to the west over central plains, another sharp trough has moved into that region which will swing northeastward and intensity heading closer to our area between Wednesday night and Thursday. With this strong trough taking a negative tilt with the base of the trough over southeastern Missouri as of Thursday morning, expect surface storm to peak in intensity in the right exit region over eastern Missouri. Moisture from this storm will be pulled northward into our area as we will be under southeasterly flow so look for increasing rain showers risk during the daytime Thursday with better chances during overnight hours. Modeling for upper level pattern becomes rather interesting for Thursday night into Friday as we have another weak short-wave trough from northern Plains quickly dropping into the main trough located into southern U.S. which in turn deepens the main trough and we have “pin-wheel” effect with both troughs merging into one and swinging northward into central Appalachians region by Friday evening as of result. The translation of the pattern on surface, starting again on Thursday, after the initial surface low peaks in intensity in eastern Missouri, secondary surface low starts to develop just east of the Appalachians mountains by late Thursday night into early Friday morning period. What will happen is the energy transfer from the initial low will transfer to the new low and allow for relative quick intensification. This secondary low will end up being stronger of the two as models show it can deepen in high 980mb vs low 990mb for the initial one. As secondary storm will be on the northeast side of the main trough, this storm will also occlude and completely weaken by Friday night into Saturday. It is also important to note that since the surface low will be strong, rainfall will be somewhat wind driven during the whole event. Our main trough for eastern U.S. does not move much at all for Friday and Saturday so the surface low will also hang around Mid-Atlantic region and continue to generate rainfall for the eastern Ohio Valley into parts of Mid-Atlantic and northeast regions. Despite being about 4-6 days out, most models agree on the potential of significant rainfall amounts for our area with 1″-2″+ range not out the question between Thursday and Saturday afternoon before things dry out later in the day with clouds still hanging around. Our temperatures will likely be the warmest on Wednesday and Thursday for high temperature wise as low to mid 60’s expected with morning lows in mid-upper 40’s. Unsettled conditions on Friday and Saturday will keep our highs only in the upper 50’s with lows only dropping into middle 40’s. Overall temperature anomalies during the long term period will be about 1°F-3°F above normal.