Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
822 PM EDT Thursday Jul 2 2015
unsettled weather to continue as a frontal boundary waffles across
the area...and waves of low pressure move through at times. The
weather may settle down a bit on the 4th and into early next week.
Near term /through Friday/...
8 PM update...confined chances for showers in the southwest third
of the area overnight...before lifting back north on Friday. Took
most of the thunder out.
another challenging day here on the near term desk. One round of
downpours moving through areas along and S of i64 this afternoon. Behind
this system over Kentucky...the sun is poking through and some bl heating
is being realized. Expect some convection to develop along quasi
stationary boundary in the vicinity of the Ohio River which may
propagate into west zones late this afternoon and early evening. Confidence
on that panning out is not particularly high. Do think a general
lull will be realized over much of the area overnight before the
downpours redevelop on Friday as a baggy surface low makes a run into the
area. Despite the deeper moisture convergence and decent
instability remaining S of the County Warning Area Friday...think the rain showers/thunderstorms and rain that
do develop with the low and along the frontal boundary will be
efficient rain producers as precipitable waters make a run to 2 inches. Given
what has fallen over the past 24 hours and what is expected
tomorrow...went ahead and hoisted a Flash Flood Watch for areas
along and S of i64 corridor through 00 Sat. This may have to be
extended in time through tomorrow night depending on progression of
the low pressure and short wave trough.
Short term /Friday night through Saturday night/...
a surface low pressure system will cross the area from southwest to
northeast Friday night into Saturday. Rounds of showers and storms
are likely south and east of the area...with chances over the
reminder west and north. NAM suggest precipitable waters from 1.9 inches Friday
night to 1.7 inches Saturday. Some h200 divergence...middle level Omega
and h850 to h700 Theta-E around 330k suggest heavy or prolonged
periods of heavy rain are possible Friday night into Saturday.
Therefore...will continue mentioning excessive rainfall and
possible water issues in the severe weather potential statement.
Comfortable afternoon temperatures...generally around 80 lowlands to
the upper 60s higher elevations...with lows in the 60s are expected
through Saturday night. A bit warmer temperatures can result Sunday
per less cloud cover spreading from north to south as a high
pressure builds from the north.
Used a combination of consensus MOS and all blend for temperatures
through the period.
For the 4th of July...precipitation will gradually exit to the east with
drier conditions spreading from northwest to southeast into
Saturday night. So kept chance probability of precipitation roughly from heights to pkb with
slight chance and drier across southeast Ohio spreading southeast.
Long term /Sunday through Thursday/...
weak high pressure builds to our north Sunday to bring drier
conditions at least over the northern half of the area through
Tuesday night. A frontal boundary remains south of the area. With
weak middle level disturbances passing by...a chance for afternoon
showers and thunderstorms each day will continue with afternoon
heating mainly extreme southern sections through Tuesday.
A cold front approaches from the northwest Wednesday...crossing
Wednesday night into early Thursday. Coded high chance probability of precipitation with
this feature for now. Another weak high pressure should develop
behind the front Thursday into the end of the period.
Went with HPC guidance for temperatures through the period.
Aviation /00z Friday through Tuesday/...
00z Thursday through 00z Friday...
weak east to wet frontal system remains draped across the
southern portion of the area overnight. Still expect showers
overnight south of a heights-crw-bkw line...but most of the thunder
out as previous rains have somewhat stabilized the atmosphere.
Otherwise...rather similar to last night with any early VFR
becoming IFR/LIFR at major terminals....mainly after 06z.
Conditions improve to MVFR after 12z...but then an organized area
of showers and storms lift northeast across the area with a wave
of low pressure...again reducing at times to IFR conditions.
Forecast confidence and alternate scenarios through 18z
Forecast confidence: low to medium.
Alternate scenarios: spatial extent of fog and stratus in
question tonight. Timing and extent of downpours tomorrow may
After 18z Friday...brief IFR possible in thunderstorms this
WV...Flash Flood Watch through Friday evening for wvz005-006-
Kentucky...Flash Flood Watch through Friday evening for kyz101>103-105.
Virginia...Flash Flood Watch through Friday evening for vaz003-004.