Area Forecast Discussion

WHAT HAS CHANGED

* Adjusted timing for storms Sunday.

KEY MESSAGES

1) More storms expected for central PA Sunday afternoon and evening. 2) Valley fog in the north should dissipate shortly after sunrise.

DISCUSSION

KEY MESSAGE 1: More storms expected for central PA Sunday afternoon and evening.

AFter a fair and dry day and night, the air will get muggier on Sunday, especially in the Lower Susq. Dewpoints 65-70F are expected by mid-afternoon. Upper trough crossing the Great Lakes will drive strong forcing across during the peak heating and early evening. SPC outlook for Sunday paints a risk of tornadoes across the SE, where hodographs are slightly curved and helicity exceeds 200. CAPE at LNS is not all that fat, but nears 1100J/kg in the mid-aftn with deep layer (0-6km) shear of 40KT. LCLs are low there, too. But, the rest of the CWA will probably realized less CAPE due to lower dewpoints. UNV CAPE almost non- existent, but shear just slightly higher. BFD has a significant cap overhead until mid-aftn, but the lift from the nearing front and falling heights work. Thus, there could be two areas of convection develop simultaneously (W and SE), then the western convection should slide east and impact some of the central zones. However, the instability does look limited in the central zones. SPC SLGT risk of svr tstms covers most of the CWA and the WPC ERO MRGL risk are also touches the wrn mtns. Some convection should hang on after sunset until a cold front pushes through (00Z NW - 04Z SE), but it should be out of the CWA around 11 PM. The main action will be out ahead of the front during peak heating.

KEY MESSAGE 2: Valley fog in the north should dissipate shortly after sunrise.

The cool temps across the nrn mtns have allowed the valleys to fog up. The fog is developing, but the dry air that has moved in should help limit the spread away from the rivers/streams. However, we'll continue to monitor it for possible fog advy if it gets more widespread this morning.

AVIATION /09Z SATURDAY THROUGH WEDNESDAY/

Unlike most mornings here this Spring, a really nice sunrise at the office, with very clear skies. This in part due to the really dry air aloft.

The patch of lower clouds near JST did not hold up well overnight. Some fog at BFD at times, but fog there not there all the time.

More information below.

A west to northwest flow of drier air will keep dry weather and VFR conditions across the area today into Sunday morning.

Still some hints on radar at 11 PM of maybe a few lower clds and even a drop of rain across the southwest, which could work into JST over the next few hours. Otherwise today will feature VFR conditions.

A cold front dropping southeast late Sunday will bring the potential for strong storms to the area later Sunday.

With a large upper level low to the north next week, there will be a tedency for weak cold fronts and troughs to result in showers and storms at times. Timing will be tricky with this type of flow pattern.

Outlook...

Sunday...VFR favored early, with restrictions possible as FROPA brings chance of -SHRA/-TSRA later in the day.

Monday...Mostly VFR with isolated -SHRA possible.

Tuesday...Mostly VFR with isolated -SHRA/-TSRA possible.

Wednesday...-SHRA/-TSRA chances increase ahead of low pressure system.

CLIMATE

The high temperature on Friday at Harrisburg reached 94 degrees. This broke the old record of 92 degrees, last set in 2017.

CTP WATCHES / WARNINGS / ADVISORIES

None.