Sugar Mountain

Forecast Discussion

Summary

chance will be across the mountains but with a better chance across the foothills than recent days. Moderate instability expected once again although with continued meager lapse rates. Mid level dry air and DCAPE values will not be as great as previous days, but will be high enough to keep the potential for isolated damaging downbursts in place. Hot and humid conditions continue as well. There may be less mixing than previous days, but still expect a nearly normal diurnal trend to dew points. This should keep heat index values below 105 but above 100. Will not issue a heat advisory at this time, but one may be needed if dew points don`t mix as expected.

SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 200 PM Fri: The pattern will change little Saturday night into early Sunday. Weakly cyclonic flow aloft will exist over our area, and decent lapse rates will persist just above the boundary layer. The GFS and SREF expect some convection will continue overnight in the mountains in response to these conditions, but the opnl NAM is dry. The forcing however just looks too weak to expect convective initiation. PoPs thus wane and fall below the mentionable threshold in all zones.

Heights fall slightly thru Sunday as a shortwave moves across the northern Great Lakes. The associated cold front should remain to our north and west during the day, but slightly higher convective chances are warranted with slightly higher dewpoints and the potential for activity to propagate off of the front and south into the area. With somewhat increased shear and the focusing mechanism, last night SPC included our northern zones in a marginal risk on Day 3. Damaging outflows and perhaps marginally severe hail are within reason. Max temps should be 2-3 degrees cooler owing to the reduced thickness and more cloud cover. This will mitigate any excessive heat concerns that could otherwise arise with the juicier dewpoints.

Some guidance, namely NAM, expects that as the front sags further south Sunday night, additional rounds of convection could develop. Hence PoPs will be kept at slight chance or better into morning. Whatever is left of the frontal boundary appears to wash out over the area Monday; temps and dewpoints will top out another degree or two cooler. Nonetheless models depict similar convective coverage south of I-40. Shear will be sufficient to expect clusters of storms producing gusty winds, but at this time it does not look particularly likely they would be severe.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 150 PM Friday: The models show in the 500mb pattern Monday evening a trough over NY and PA with axis roughly down the Appalachians. This trough pushes off the New England coast Tuesday night with the associated cold front lying west to east across TN and the Carolinas early Tuesday. This front may even push south across Georgia Wednesday then linger over our region into late week as it slowly dissipates. The 06Z run of the GFS had an upper ridge centered over New Mexico and the TX panhandle having a significant influence in mid week to the Carolinas. The new 12Z GFS returns the suppression of the ridge to the SW and gives the eastern trough the greatest influence. With the ridge to our west and an upper NW flow of weather from the top of the ridge to our region, there is the potential for one or two weakening MCSs to reach our area in the mid to late week. The dissipating front will provide the focus for convection each day. Instability should be best on Tuesday afternoon. Max temperatures near normal Tuesday and again Friday but a little below normal Wed and Thursday. Min Temperatures near or slightly above normal each day.