Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Charleston WV
605 am EDT Friday Aug 29 2014
warm front tonight. Turning hot and more humid Saturday in deep
southwest flow. Moisture increases in that flow...with an upper
level disturbance from the Gulf Crossing Sunday.
Near term /through tonight/...
no changes to the forecast this morning. Getting a little bit of
high cloud advection over the tri state area...which undoubtedly
helped prevent fog at heights this morning...along with a steady light
main challenge for the near term forecast is trying to nail down the
timing of an untrustworthy warm front which should spark some
evening convection as it moves into the tug Fork valley.
After this brief and modest cool down...a warm front returns to
bring the area back into very warm southwest surface flow. In the
upper levels...expect the dominating ridge over the southeast
Atlantic coast to drift slowly to the east...marking the transition
of the upper levels into a southwesterly flow. This will have more
of an effect in the short term even though the transition begins in
the near term.
Getting back to the warm front...using middle level frontogenesis for
timing brings chances into the southwest Virginia counties around
the 00z Saturday time frame. Always like to give a modest buffer on
the front of warm fronts as the models can have a tough time with
the speed of these features. Will be fighting a setting sun...so
this will not help the convection...and in the end...think a
scattered convection forecast is best. MOS guidance values over bkw
keep the chances under 40 percent.
Warm front lifts to the northeast overnight...but should see the
coverage of showers/storms decrease towards 12z. Probability of precipitation transition to
the north...and may be able to even clear much of the sky over the
tug Fork valley by dawn.
Temperature wise...even though a cold front came through and is
currently bringing cooler air...values rebound again tomorrow back
to the middle 80s over The Lowlands.
Short term /Saturday through Monday night/...
models continue to show an upper level feature and its associated
tropical like moisture lifting out of the western Gulf of Mexico
this Holiday weekend. The models are trending quicker with this
feature as it lifts northeast...well ahead of an approaching upper
trough in the westerlies. While differences remain among the models
as far as timing and amounts from this feature...HPC and the majority
of model guidance indicate the initial surge and greatest quantitative precipitation forecast with
this tropical like feature will be just west of our area...with the
best chance for rain in our area mainly Saturday night and
especially Sunday before the system lifts out of the Ohio Valley.
Thus...it looks like Saturday will be mainly precipitation free...but
warmer and more humid...as a warm front will have lifted north of
the area Saturday morning. But with the main upper trough and
attending cool front still to the west...will keep chance probability of precipitation in
for Monday. In general...the Holiday weekend looks unsettled. It
will be quite warm and humid...but lots of clouds and shower
activity will keep temperatures mostly in the 80s for highs and near
70 for lows.
Long term /Tuesday through Thursday/...
used wpc thinking with some tweaks. Westerly middle-level
flow...along with several middle-level disturbances...will result in
on and off chances of showers and storms through Tuesday. A cold
front will approach from the northwest Tuesday night...with this
feature expected to push southeast of the area by Wednesday
Wpc temperatures looked good and were generally used.
Aviation /10z Friday through Tuesday/...
after the fog mixes out this morning...VFR expected through the
day. Clouds on the increase from southwest to northeast after 21z
today with a warm front pushing into the tug Fork valley. Some
convection can be expected...but current forecast has chances less
than 40 percent...and cannot use in prevailing. Bkw would be the
only candidate as of now...but cannot eliminate chances for weak
convection this evening into tonight for all terminals.
Clouds and a light wind will prevent fog tonight. An exception
would be after rain at any terminal after 00z Saturday.
Forecast confidence and alternate scenarios through 12z Saturday...
Forecast confidence: medium to high.
Alternate scenarios: timing of the warm front could vary. May need
higher chances/prevailing rain showers/thunderstorms and rain at bkw.
Experimental table of flight category objectively shows consistency
of weather forecast office forecast to available model information:
h = high: taf consistent with all models or all but one model.
M = medium: taf has varying level of consistency with models.
L = low: taf inconsistent with all models or all but one model.
Date Friday 08/29/14
UTC 1hrly 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1hrly 04 05 06 07 08 09 10 11 12 13 14 15
crw consistency l l l l l M h h h h h h
heights consistency M l l l l h h h h h h h
bkw consistency h h h h h h h h h h h h
ekn consistency l l l l l M h h h h h h
pkb consistency l l l l l M h h h h h h
ckb consistency l l l l l h h h h h h h
After 12z Saturday...
IFR possible in showers/storms Sunday...and then in dense early
morning valley fog early next week.