Flash Flood Warning 12, NWS Pittsburgh, PA

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
932 PM EDT Tue Jun 18 2019

.SYNOPSIS...
Periodic showers will continue through the week as a frontal boundary
remains stalled in the region and several disturbances cross the
upper Ohio Valley.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Convergence along a quasistationary frontal zone has sustained
shallow but efficient rain showers especially from UCP-PHD-TZR. As a
result of persistent rainfall saturating the ground over recent days,
very high PWAT value and high freezing level supporting warm rain
processes and slow convective movement, flooding/flash flooding
remain the main risks as even modest-looking showers are proving to
be very efficient rain producers.

Convection will taper off tonight as daytime heating is lost, which
will help end the immediate threat of flash flooding. The current
Flash Flood Watch remains in effect until late tonight, at which
point its tenure will be evaluated.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Diurnal heating plus sfc convergence along the lingering stationary
boundary will yield more convection late Wed morning into the
afternoon. This initial convection will favor areas south of I-80
where lift/convergence within swly flow aloft will assist development.
Though PWAT will remain high and storm movement will be slow, the
overall flash flood risk will be less during the day due to the lack
of sufficient areal coverage and the expected weaker intensity of
storms.

Two shortwave troughs will swing through the region Wed night
through Thu, with a sfc cold front moving through Thu night as the
second wave exits. Better upper-level support will make showers and
thunderstorms more widespread and heighten the threat of flash
flooding, especially near the sfc boundary that is expected to be
near the I-80 corridor. The period of heavy rain will be Thu
afternoon and evening when the second wave becomes a positively-
tilted closed low, which will enhance mid-level frontogenesis and
lead to widespread convection with deeper updrafts.

A flash flood watch may be needed for this system, but will defer
any issuance until the current watch is dispatched and subsequent
shifts can better identify the geographical scope of threat.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Drier and cooler air will arrive Fri morning in the wake of the cold
frontal passage and will persist through the day under nwly flow.

A ridge is expected to build ewd through the rest of the weekend to
keep dry weather in place, but there are hints that upstream
convection may round the ridge and impact a portion of our area both
Sat and Sun mornings. Regardless, the ridge will provide a rebound
in temperature for the region.

Wet weather will return by the start of the work week with another
series of disturbances aiding storm development across the area.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Coverage of showers will wane this evening with the departure of an
upper-level wave and the loss of diurnal heating. For the remainder
of the afternoon, conditions are expected to be relatively steady-
state, with showers along and south of a frontal zone from near FKL
to near OSU. Once showers and their attendant restrictions dissipate,
cigs will lower overnight to IFR or lower in the stagnant near-
saturated airmass. Restrictions to vsby also are expected as fog
develops late.

Restrictions should lift to MVFR-VFR diurnally, with showers and
storms renewing by late morning. With the airmass remaining in place,
all terminals are expected to see convection nearby through the day,
which will be capable of heavy rain and consequent restrictions.

.Outlook...
Periodic restrictions are possible through the week as a frontal
zone sags over the region and interacts with crossing disturbances to
produce frequent showers and storms.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...Flash Flood Watch until 2 AM EDT Wednesday for MDZ001.
OH...Flash Flood Watch until 2 AM EDT Wednesday for OHZ039>041-048>050-
     057>059-068-069.
PA...Flash Flood Watch until 2 AM EDT Wednesday for PAZ013>016-020>023-
     029-031-073>076.
WV...Flash Flood Watch until 2 AM EDT Wednesday for WVZ001>004-012-021-
     509>514.

&&

Update...Kramar

Hazardous Weather Outlook...UPDATED
National Weather Service Pittsburgh PA
934 PM EDT Tue Jun 18 2019

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ013>016-020>023-029-031-
073>076-WVZ001>004-012-021-509>514-200145-
Garrett-Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-
Jefferson OH-Muskingum-Guernsey-Belmont-Noble-Monroe-Lawrence-Butler-
Clarion-Jefferson PA-Beaver-Allegheny-Armstrong-Indiana-Washington-
Greene-Westmoreland-Westmoreland Ridges-Fayette-Fayette Ridges-
Hancock-Brooke-Ohio-Marshall-Wetzel-Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
934 PM EDT Tue Jun 18 2019

...FLASH FLOOD WATCH IN EFFECT UNTIL 2 AM EDT WEDNESDAY...

This Hazardous Weather Outlook is for western Maryland, east
central Ohio, southwest Pennsylvania, west central Pennsylvania,
western Pennsylvania, northern West Virginia and northern panhandle
of West Virginia.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Flash Flood Watch.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

A series of disturbances will bring increased coverage of showers
and thunderstorms late Wednesday through Thursday. As a result of
saturated ground from recent rainfall, these storms will be capable
of producing heavy rain that could cause flash flooding.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.

PAZ007>009-200145-
Mercer-Venango-Forest-
934 PM EDT Tue Jun 18 2019

This Hazardous Weather Outlook is for northwest Pennsylvania.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

A series of disturbances will bring increased coverage of showers
and thunderstorms late Wednesday through Thursday. As a result of
saturated ground from recent rainfall, these storms will be capable
of producing heavy rain that could cause flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Kramar