Issued: 1pm on Sunday, November 7th 2021
Technical Forecast Discussion
Short Term (Sunday 11-7-2021 through Tuesday 11-9-2021)
Our short range period is starting out with classic fall weather where we have clear conditions with warm afternoon’s and cold night’s due to high pressure dominating our area over the past few days. Looking around the country, we have a trough for western U.S. bringing in series of precipitation in west coast with another area of weak “cut-off” trough just off southeastern U.S. so most of the precipitation is staying out of that area. A developing upper level ridge developing over middle of the country, as of Sunday morning, is what going to dictate our weather through out the short-term period. This ridge is expected to continue intensifying throughout the day while it gradually move eastward. In response to this developing ridge, our local upper-level heights looks to increase again which then allows warmer air to flow back into our area. By Monday, we have a general ridge pattern for most areas east of the Rockies with the main axis located right over Ohio Valley region. This type of a pattern will ensures the dominance of surface high pressure right over our region which would lead to additional days of clear conditions for our area. Moving forward into Monday night and Tuesday, there is a short-wave expected to quickly move eastward along U.S./Canada boarder, and we will see weakening of our ridge pattern. Our ridge does not completely break down given that this short-wave mostly takes a ride right over the top of the ridge instead of attacking it directly. Because of this shortwave, we will a frontal boundary which sags southward along I-90 corridor region of Illinois through Ohio which will allow some clouds to increase out ahead of this, but we lack moisture so there does not appear to precipitation chances associated this. Looking at our temperatures, highs during this period will be bit cooler in low 60’s on Sunday, but warming into middle 60’s for Monday and Tuesday. Morning lows are expected to gradually warming from low 30’s Sunday night to upper 30’s Monday night, and eventually in lower 40’s for Tuesday night. Our temperature anomalies during this period will be 2°F-5°F above normal.
Long Term (Wednesday 11-10-2021 through Saturday 11-13-2021)
As we head into longer range period, we start to notice models slightly diverge in their solution regarding the timing of a developing storm middle of next week and the timing of strong cold front moves through our area and if we could see secondary storm develop and move northward from Gulf regions into northeastern part of U.S. by the end of the week into start of next weekend. Starting with Wednesday, our initial ridge skips eastward and continue to weaken due to the shortwave right above it intensifying and breaking it down. While this is happening, another area of ridge is quick to develop over northern plains and midwestern region by Wednesday morning and then move eastward right over our region by afternoon and then quickly moving to our east during evening and overnight hours. Surface high pressure will continue to remain firmly over southern Appalachians region on the day of Wednesday which will continue to bring warm southwesterly flow in our area with and we should continue to see lot more sunshine on this day for our area before this high skips eastward and allows for increasing clouds by Wednesday night. As this ridge departs, we will note two developing areas of weak trough. First area is over Montana area associated with northern branch with other one in southern plains with southern branch. As we move forward with time, the energy over North Dakota as of Thursday morning takes over as the main energy due to it continuing to deepen (Intensify) over northern plains region. The southern branch will move out ahead of the northern side and phase together and become one large trough through Thursday morning. The negative tilt of the northern branch is what allows this phasing to happen aloft which on surface would translate to intensifying low pressure. By the end of the day, we will have a trough located between east of Rockies and west of Appalachians region. As mentioned above, this pattern on surface level will translate to genesis of a surface low over western Kansas/Texas panhandle area by Wednesday morning and quickly intensifying northeastward through eastern Kansas by Wednesday evening and continuing to move tri state region of Minnesota/Iowa/Wisconsin area by Thursday morning. This low pressure will continue to intensify and sit over northern plains as the main lobe of trough stalls out. There is some different model variations as to how things exactly evolve Wednesday into Thursday, but every models in general have the same idea on what happens so no real discrepancy. Warm front associated with this system will move trough our area by Thursday morning and we will have strong southerly flow in our area leading to increase in moisture out ahead of approaching cold front, but things continue to remain fairly mild out ahead. Look for rain chances to increase starting Thursday evening and then continue into Friday morning hours. Some modeling’s do suggest there maybe noteworthy rainfall totals, but most of suggest that there will be less. I am certainly leaning towards lower rainfall totals because it is the northern branch looks to be the stronger one compared to southern branch so moisture is not drawn more effectively initially and we would also have our low starting to occlude (weakening) as well. Colder air will eventually advect eastward into our area sometime Friday morning and continue through the day time hours so our official high’s likely peaks just after clock hits midnight Friday. Starting Friday afternoon hours is when all the weather models diverge rather significantly in their runs for what is expected regarding a potential secondary storm system. Weather models are having hard time figuring out on how the lobe of energy is going to oriented, same lobe as mid-week system, and where it is expected to be situated at. On the southern end of this trough, another wave of wind energy looks to be diving southward from northern Rockies down into southern plains area sometime by Friday evening, and trying to get out ahead of the main trough into Saturday morning. Some solution suggests that this new energy will be able to get ahead and phase with main trough as it lifts northeastward either along Appalachians or east coast region while others suggest that no phasing occurs and the whole thing shifts eastward together along with some in between solutions as well. If the phasing occurs, we may in a situation where another organized wave of low pressure forms and brushes through our area with more rainfall, or snowfall if things get cold enough, otherwise we will clouds hanging in place for Friday into Saturday. I am currently going with chance of scattered rainfall mixing with snow showers at times from late Friday night into Saturday evening for now and will certainly adjust as needed. Our temperatures during this period will start on warm note with highs in mid-upper 60’s Wednesday and Thursday before cooling down into mid 50’s Friday and eventually down to lower 40’s on Saturday. Morning lows in mid-upper 40’s Wednesday and Thursday night and dropping into lower 30’s Friday and Saturday night. Our overall temperature anomalies during this long term period remains about 1°F-4°F above normal.
