textproduct: State College

WHAT HAS CHANGED

* Tweaks to near term based on radar/sat trends * Flood watch considered, rejected for now

KEY MESSAGES

1) Rain moves to the south early tonight, but returns for Monday. Flood watch considered.

2) Rain potential continues for much of this week, although uncertainty remains in the details due to offshore low development possibilities. On the cool side as well.

DISCUSSION

KEY MESSAGE 1: Rain moves to the south early tonight, but returns for Monday. Flood watch considered.

Nebulous/broad sfc low pressure over the CWA at 18Z, seemingly centered somewhere within 40 miles of UNV. Several short wave troughs continue to roll into and over the Mid-Atlantic, but none have instability to work with north of the Mason-Dixon Line. PWATs remain high, touching the 2" mark in York/Lanc Cos. Flow is westerly and constant, but slightly confluent aloft. The closest thunder at 18Z is in ern OH and dropping steadily south enough that it will likely miss our CWA. But, occasional showers/rain continue to move in from upstream. QPF still looks low enough (<0.75") through midnight in the Laurels where the FFG is lowest (just under an inch in some places). That should be low enough in intensity/duration to keep any hydo problems minor and isolated. After collaboration with neighboring offices, we had low enough confidence in flooding-intensity rainfall to stay away from a Flood Watch at this point in time. But, the Laurels (particiularly Somerset Co) would be the place most-susceptible to any flooding into late this evening. Conditions are too dry farther east, and the bulk of the rain should stay south of I-80 for the rest of the day.

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KEY MESSAGE 2: Rain potential continues for much of this week, although uncertainty remains in the details due to offshore low development possibilities. On the cool side as well.

A fairly strong short wave trough currently over rolls in from lower LM late tonight. That should yield a renewal of rainfall in the Laurels. The system will still be working with 1.5-2.0" PWATs. But, it will arriving at an even more-stable time of day. The steady east and slightly northward spread of precip will only reinforce the stability (and keep temps chilly) Monday. Again, thunder cannot be ruled out, but would likely be elevated. It may remain dry (or just patchy drizzle) across the northern tier for much of the day. Models funnel the best moisture into the eastern half of PA Monday night, easing the flooding potential somewhat for the Laurels.

Extremely blocky pattern aloft yeilds very low confidence in sfc features and precip potential/placement beyond Tuesday. Low pressure tries to develop off shore (along the Gulf Stream) Wed, but may be shunted eastward through the second half of the week. The sure bet this week is for below normal max temps.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Scattered rain continues to plague the airspace this afternoon along with overcast skies and low clouds. Many areas will continue to see MVFR or lower ceilings through the remainder of this afternoon and into tonight. Rain will be likely across all airfields over the next 12 hours, and any site impacted by precipitation will see a reduction in visibility. Strength of these rain showers remains uncertain, but radar returns as of 18Z suggest rain is light overall. Timing out the main line of precipitation, it is expected to resume raining over the western Terminals of BFD and JST near 20Z.

Tonight lingering rain and low ceilings will keep flight conditions poor. There is some suggestion from the LAMP and NAM-MOS that a brief period of VFR is possible at IPT near 09Z, but confidence remains low with the more likely solution will be continued MVFR to IFR ceilings. Improvement Monday morning will be very slow, with clouds not expected to fully scatter to VFR conditions until the late morning/early afternoon.

Outlook...

Tue-Thu...Restrictions possible from -SHRA/BR and low ceilings, mainly S.

CTP WATCHES/WARNINGS/ADVISORIES

None.