Scientific Forecaster Discussion
fxus61 kctp 180954
Area forecast discussion
National Weather Service State College PA
554 am EDT Tue Jun 18 2019
an unsettled and stormy weather pattern is expected this week
thanks to the close proximity of a slowly meandering stationary
front. There will be multiple rounds of heavy downpours with the
potential for flooding. Temperatures will not be too far from
normals through the period, but could be a little cooler than
normal Friday and Saturday in the wake of a cold front.
Near term /until 6 PM this evening/...
front seems to be over duj and oym where the pressure is
falling. It is lifting ever so slightly to the north at this
moment in response to the minor short wave/vort Max lowering sfc
pressures over wrn PA. The low is progged to roll east along or
just north of I-80 this morning. By noon, it will be pushing
east of ipt. It will drag the front back to the south as it
moves to the east, and with it, the threat of heavy
rain/flooding. Much of the northwest received heavy precipitation less
than 36 hours ago. The lowest ffg is over Clearfield and Elk
counties. The quantitative precipitation forecast thru this aftn is roughly an inch or more for
this stripe of counties, with the hrrr (07z run) generating
point amounts of 2+". And this seems reasonable with the pwats
high/above normal. The Flash Flood Watch segment for the
northern stripe will die off at 18z, while the srn half of the
County Warning Area will have it continue into the first part of the night to
allow for all the convection to drop to our south. While some
additional pinpoints of convection may bubble up over the NC
mtns late today, the threat for flash flooding should be over
Short term /6 PM this evening through 6 PM Wednesday/...
the threat of flash flooding continues into late evening or
early tonight over the southern tier. A good shot of 0.5-1" of
rain just occurred north of the Turnpike. But, that area has
been much drier than expected the past two days - this is the
heaviest rain for many places these last few days. Deep
convection and heavy rain remain possible thru much of the
valid period of the watch. The most likely scenario is that one
or two spots in the south will get heavy rain late today as the
front is pushed back to the south and into the soupiest air.
Plus, that area could try to get some peeks of sun through the
clouds. Storm Prediction Center does have a marginal risk there, but main threat today
is excessive rain. Little consensus exists among the model quantitative precipitation forecast
for later today and this evening over the south. Thus, without a
clear signal either way to tip the scales, we will ride the
watch. Ending time of 06z looks good.
Consensus forecast is for the convection to die down and slide
south of the area for the balance of tonight. A few isolated
cells may pop up again over the north central mtns later in the
day if the sun can break through there in the aftn. The NAM and
a few cams play this out. Have nudged pops below 30pct for the
second half of the night. Little clearing is expected tonight
except in the north. If it does clear out, fog will develop
again. Lows will stay several degs above normal.
Wed will be without forcing of any note until very late in the
day as a wave moves into the west after sunset. Clouds in the
morning will probably break for a bit, which should crank up the
cape and allow sct convection to fire up. But, the daylight
convection will not be as robust as it could be without
additional lift. Pops will be highest in the south, but a thunderstorms and rain
is possible just about anywhere on Wed as the front makes a push
to the north again. Maxes generally 75-80f will be spot on
Long term /Wednesday night through Monday/...
wet pattern with repeat rounds of rain along nearly stationary
frontal zone will continue to bring an increased flood risk to
south central PA through midweek.
A strong low pressure system for June will track across the area
on Thursday, and could bring a significant threat of severe
storms and flash flooding.
Breezy and drier conditions will arrive into Friday as the
system continues to deepen as it moves away from the area.
The latest guidance favors a dry start to the weekend before
more showers and storms return to the forecast on Sunday.
Persistent cloud cover suggests highs running a bit below
average through midweek while higher dewpoints favor muggy
nights/above avg lows. Near normal temps are forecast through
Aviation /10z Tuesday through Saturday/...
updated the tafs here just before 530 am.
Clusters of showers and isolated storms lifting to the northeast
the next few hours.
Expect a wide range of conditions through the mid to late
morning hours. Some areas like the office here have fog, others
have brief heavy downpours.
Abundant low level moisture and light wind in vicinity of a
stalled frontal boundary will lead to low ceilings at times today
into Wed. Also an isolated rumble of thunder.
Wed...am rain/low cigs possible. Scattered PM tsra impacts
Thu...am rain/low cigs possible. Scattered PM tsra impacts
Fri...am low cigs possible west mtns.
Sat...no sig wx expected.
astronomical Summer (solstice) begins Friday, June 21st at
1154am EDT (1554 utc).
Flash Flood Watch until 2 PM EDT this afternoon for paz010>012-
Flash Flood Watch through late tonight for paz017>019-024>028-