Forecast Discussion
Summary
SYNOPSIS
... Dry weather through tonight courtesy of high pressure. Another system arrives Friday into Saturday with rain and very strong winds. Much warmer by early next week.
NEAR TERM /THROUGH FRIDAY/... As of 725 PM Thursday...
Other than tweaking wind and wind gust parameters slightly, the forecast is unchanged and on track. Timing of precipitations is also unchanged even with analyzing newer model data.
As of 230 PM Thursday...
Surface high pressure is traversing across the region today providing for abundant sunshine amid seasonable temperatures. High temperatures will top out in the mid 50s to low 60s across the lowlands, with 40s to low 50s for the mountains. Given a rather deep mixed layer today, Min afternoon and early evening RH values will generally be in the 20-30% range, but with much calmer surface flow than yesterday.
Quiet weather persists tonight amid increased upper level clouds as the next disturbance approaches. Temperatures will likely fall rather quick after sunset given the dry airmass in place, then level off or even rise (mainly west) as boundary level flow increases ahead of the next disturbance and a warm front quietly lifts north across the region. Low temperatures will be in the mid 30s to mid 40s for the lowlands, with 30s to low 40s for the mountains.
Scattered rain showers quickly move into western locations near or slightly after dawn on Friday as a strong low level jet begins to move over the area. Rain showers will progress eastward across the CWA throughout the morning into the afternoon, with some drying likely taking place from W to E throughout the afternoon. Up to half an inch of rain is possible, with the heavier amounts likely across northern/western locations. A few isolated thunderstorms are also possible. High temperatures are progged for the upper 50s to low 60s for the lowlands, with 50s for the higher terrain. Wind gusts of 15-25+ mph are possible areawide tomorrow.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 250 PM Thursday...
Key Points: * Breezy, with rain showers and thunderstorms on Friday. * Some storms may be strong to severe late Friday into Friday night. * Strong, gusty winds are expected area wide on Saturday. * More tree damage and power outage issues likely.
Any early evening reduction in precip across the area will quickly end as the front moves in from the west, bringing what is likely a fairly solid band of showers and thunderstorms across the area. While the better chance for severe storms will definitely be to our west, a few storms could still contain severe winds as the move in ahead of and with the front. Even outside of any thunderstorms, winds will still be gusty ahead of the front, with gusts of 35-45mph possible ahead of it.
Once the front goes through, aside from any gusts right with the front, winds may drop briefly behind the front late night into early Saturday morning. However, with the expectation of a substantial dry slot and clearing skies Saturday morning into the afternoon, once some mixing gets going by mid-morning, gusts will pick up rapidly. Soundings show the potential for tapping into 50kt+ gusts over much of the area, and the High Wind Watch was expanded substantially to include much of the lower elevations of West Virginia. With up to an inch of rain possible across much of the area ahead of the system, and advisory to warning level winds and gusts, another round of substantial tree damage and power outages is possible on Saturday.
Winds could stay gusty well into the night in the mountains, where the pressure gradient may stay pretty tight, but should eventually start to relax heading towards sunrise Sunday morning.
LONG TERM /SUNDAY THROUGH THURSDAY/... As of 1213 PM Thursday...
High pressure will build in on Sunday bringing any remaining precipitation to an end. The High will then push off the east coast Sunday night which will allow a cold front to approach the area from the northwest. The combination of the front and a weak shortwave passing by to our south will bring rain chances back to the area by late Monday.
The front is expected to become stationary north of our area before pushing back north as an area of low pressure moves from the southwest US into the northern Mid-Mississippi Valley by mid week.
Models have differences with the track of the low and associated cold front. The ECMWF is faster with the cold front pushing east of the area early Thursday with the GFS pushing the front east later Thursday into Thursday night.
Whichever of these model verifies, precipitation chances will increase and then remain in the forecast into Thursday. Model blend shows this thinking.
Temperatures should be below normal Sunday with readings generally in the 50s and a few 40s in the higher elevations. Southerly winds will result in warmer temperatures Monday through Wednesday with readings potentially reaching highs in the upper 70s to mid 80s in the lowlands and mid 60s to 70s in the mountains on Wednesday. Clouds, precipitation and the front should hold temperatures down Thursday. However, readings should still be as much as 5 to 10 degrees above normal.