Areal Flood Warning 18, NWS Philadelphia/Mount Holly

Area Forecast Discussion
National Weather Service Mount Holly NJ
940 AM EDT Mon May 1 2023

.SYNOPSIS...
Surface low pressure will exit north of the region today, but a
lingering upper low across the Great Lakes will keep cool and
unsettled weather with daily chances for scattered showers
across the region for much of the upcoming week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Low pressure will exit off to our northeast this morning. In
its wake, cooler and drier air will build in under westerly flow
which will eventually back to southwesterly in the late
morning. Aloft, a closed low extending all the way up to 250 mb
will continue to meander east across the lower Great Lakes. An
upper jet streak will traverse the base of the low as will
rounds of shortwaves. With a thermal trough extending out of the
upper low, expect some mid- level clouds around for most of the
day. As surface heating commences, low- level lapse rates will
approach dry adiabatic and, coupled with the broad ascent from
the upper level features, expect scattered showers to develop in
the afternoon. As a result of the steep lapse rates extending
up to near 750 mb, expect that some of the showers could contain
graupel at times. Highest coverage should be north and west of
the urban corridor.

Winds will again increase as mixing commences as well. 850 mb
sustained winds will be 25-30 knots and with the steep lapse
rates these should fairly easily mix to the surface. Winds will
be southwesterly 15-20 mph with periods of gusts to 25-30 mph.
Looking for highs in the mid upper 50s, possibly touching 60 in
some spots.

There may be a brief break in the clouds and showers tonight as
diurnally driven mixing ceases, though it will be short lived
as another more potent shortwave moves around the upper low and
reintroduces clouds and showers in the latter portion of the
overnight hours Monday night into Tuesday morning. Overnight
lows will fall into the 40s, with low 50s along the coast, and
mid 30s in the Poconos. With temperatures in the 30s and cold
air aloft, it is not a lock that precipitation type across the
highest elevations of the Pocono Plateau will be solely rain,
though BUFKIT soundings are suggesting that the majority of the
moisture within the column will be below -10C, thus a cold rain
as opposed to a mix of snow with ice crystal production limited.
Will be worth monitoring trends through the day today, but
can't entirely rule out a few snowflakes mixing in in the
highest elevations with no impacts expected. The temperatures in
the mid 30s also warrant the mention of frost potential which
should be very low; winds will remain elevated (5-10 mph)
overnight and this should preclude any frost development.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A very evident omega block will set up with a deep low in the
Pacific Southwest, a ridge across the central CONUS, and the
stubborn low across the Northeast. The result will be a stagnant
pattern resistant to evolution. The upper low will very slowly
slide southeast Tuesday - Thursday, likely right overhead
Wednesday evening, and rounds of shortwaves will continue to
traverse it. At the surface, lingering weak low pressure will
meander under the closed upper low and the omega block will hold
surface features in place as well. The result will be
maintaining scattered shower chances through the entirety of the
short term period, though don't expect that any part of the
period will be a complete washout. As the core of the low moves
overhead, expect overall chance and coverage of showers to
diminish as we briefly lose the synoptic forcing. Some graupel
may mix in at times with the showers owing to cold air aloft
from the upper low and steep low level lapse rates, and coverage
should be the highest in the afternoons.

For Tuesday night, cannot entirely rule out the possibility of
some snowflakes mixing in in the highest elevations of the
Pocono Plateau as lows will again fall to the mid 30s. Forecast
soundings show a similar profile to that of Monday night with
most of the moisture holding below -10C and thus not cold enough
for prime crystal growth, so if some wet flakes do mix in, no
impacts are expected (besides asking yourself "isn't it May?").
Winds will remain elevated enough to again likely preclude frost
formation as well.

Highs will be in the mid-upper 50s Tuesday and Wednesday.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A similar pattern to the short term period will continue on
Thursday as the upper low begins to exit. The only notable
difference will be highs nudging slightly warmer on Thursday as
850 mb temperatures increase a few degrees. Ensembles are the in
generally good agreement that the omega block gives way on
Friday and thus the departure of the upper low. Associated
precipitation chances will diminish as a result. Some lingering
vorticity advection on the back end of the low may act to hold
clouds around on Friday, but high pressure nudging down from the
north will help to suppress precipitation development. As of
now, the weekend looks to be mostly dry. Ensemble patterns
suggest upper ridging building in for Saturday as the omega
block releases its grip. At the surface, ensemble members
suggest high pressure centered somewhere north of Lakes
Superior/Huron extending a ridge to the southeast and nosing
into our area. The rising heights will support a warming trend
into the weekend and the ridge should help to keep us mostly dry
with highs likely returning closer to climatological normals
(upper 60s), but still a few degrees below.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.

Rest of Today...VFR. SCT to BKN CIGs around 5-8kft. Some
scattered showers around from late late morning through early
evening. Showers may mix with graupel at times. Southwesterly
wind 10-15 knots with gusts to 25 knots. Moderate confidence.

Tonight...VFR. Clouds may break for a brief period around 04z.
Showers ending in the evening before returning closer to
daybreak Tuesday. Southwesterly wind 5-10 knots.

Outlook...

Tuesday through Thursday...Predominantly VFR. Brief periods of
MVFR ceilings possible each afternoon with scattered showers.
Southwesterly to westerly wind 10-15 knots with gusts to 20
knots. Moderate confidence.

Friday...Predominantly VFR. Brief periods of MVFR ceilings
possible with scattered showers. Northwesterly wind 5-10 knots.
Moderate confidence.

&&

.MARINE...
Small Craft Advisories remain in effect for the Delaware Bay
through 6PM this evening and for all of the ocean waters through
6PM Tuesday. Expect southwesterly wind 15-20 knots with gusts
to 25-30 knots diminishing to 10-15 knots in the Delaware Bay
tonight. An additional SCA may be needed for the Bay Tuesday
afternoon. Seas 6-8 feet, diminishing to 4-6 on Tuesday.

Outlook...

Wednesday through Friday...No marine headlines expected. A
brief period of SCA wind gusts possible Wednesday night into
early Thursday morning. Southwesterly/westerly wind 10-15 knots
Tuesday and Wednesday becoming northwesterly on Thursday with
gusts to 20 knots.

&&

.HYDROLOGY...
We have a number of gauges in flood stage across SE PA into New
Jersey due to the recent heavy rainfall of generally 2 to 6
inches. This includes many of our sensitive points across the
Raritan, Passaic, and Rancocas basins. Fast responding creeks
and streams have already crested or will crest this morning and
then fall below flood stage. However slower responding rivers
such as the Passaic at Pine Brook will not crest until Tuesday.
The good news is that while the weather pattern will remain
generally unsettled with some scattered showers around most days
this week, we don't expect any additional heavy rainfall
through the week.

&&

.TIDES/COASTAL FLOODING...
The Coastal Flood Advisory for Ocean County is in effect until
6 PM. Flooding here is expected to be confined to the Barnegat
Bay area due to the combination of tidal flooding and
freshwater input from heavy rainfall. Elsewhere, we are not
expecting tidal flooding.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...Coastal Flood Advisory until 6 PM EDT this evening for NJZ020-
     026.
DE...None.
MD...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ430-
     431.
     Small Craft Advisory until 6 PM EDT Tuesday for ANZ450>455.

&&

SYNOPSIS...Brudy
NEAR TERM...Brudy
SHORT TERM...Brudy
LONG TERM...Brudy
AVIATION...Brudy
MARINE...Brudy
HYDROLOGY...Staff
TIDES/COASTAL FLOODING...Staff

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
624 AM EDT MON MAY 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0601 AM     FLOOD            2 SW RARITAN            40.55N 74.66W
05/01/2023                   SOMERSET           NJ   PUBLIC

            RIVER ROAD IN HILLSBOROUGH IS CLOSED ALONG
            THE RARITAN RIVER DUE TO FLOODING.

&&

MLB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1021 AM EDT MON MAY 1 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1000 AM     HAIL             LEESPORT                40.45N 75.97W
05/01/2023  E0.25 INCH       BERKS              PA   TRAINED SPOTTER

&&

DI