Sunrise 6:20 AM   Sunset 7:48 PM Moonrise 1:51 PM   Moonset 3:16 AM

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ANZ530 Chesapeake Bay North Of Pooles Island- 941 Pm Edt Thu Apr 18 2024
.small craft advisory in effect until midnight edt tonight - .
Rest of tonight - E winds 10 to 15 kt. Gusts up to 20 kt late this evening and early morning. Waves 1 to 2 ft. Fri - SE winds 5 to 10 kt. Waves 1 ft. Fri night - SE winds 5 to 10 kt - .becoming W late. Waves 1 ft. A chance of showers. Sat - NW winds 10 to 15 kt. Waves 1 ft. Sat night - NW winds 10 to 15 kt. Waves 1 ft. Sun - NW winds 5 to 10 kt. Waves 1 ft. Sun night - NW winds 5 to 10 kt. Waves 1 ft. Mon - NW winds 5 to 10 kt - .becoming sw. Waves 1 ft. Tue - S winds 10 to 15 kt. Waves 1 to 2 ft. A chance of showers through the night.

ANZ500 941 Pm Edt Thu Apr 18 2024
Synopsis for the tidal potomac and md portion of the chesapeake bay -
a cold front will move through the region Friday night into Saturday morning. High pressure gradually pushes in from the west by late in the weekend. Small craft advisories may be needed at times this weekend.

FXUS61 KCTP 182309 AFDCTP

Area Forecast Discussion National Weather Service State College PA 709 PM EDT Thu Apr 18 2024

SYNOPSIS
-Partly sunny over Central and Western PA and cloudy east of the Susquehanna Valley late this afternoon and evening.
-Becoming cloudy overnight.
-A few periods of rain showers precedes and accompanies a weak cold front that will cross the region Friday afternoon and evening.
-Cooler conditions for the weekend with a gusty west breeze on Saturday.
-Frost/freeze risk for Sunday & Monday mornings.

NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
North-south oriented occluded front is stuck over the Susquehanna Valley and will likely retreat westward by about 100 NM overnight as vertical mixing wanes west of it and boundary layer decoupling/and the llvl east/west P-gradient enhances the near sfc easterly flow.

The persistent stratus deck based AOB 1000 ft agl will show a steady WWD push and bank itself up against the Alleghenies (possibly as far west as the RT 219 corridor) late tonight through the mid morning hours Friday.

Min temps will be in the 40s and only span a range of about 5 degrees F across the CWA, though the range will be slightly greater if we account for some cool spots across the higher terrain of Schuylkill and Sullivan Counties.

The moist east to southeast upslope flow will create some patchy drizzle and fog later tonight and early Friday, especially to the east of the Susq Mainstem.

Showers associated with an approaching cold front could reach the extreme western part of the CWA by daybreak Friday, but most likely hold off until after 12Z. Lows will range from around 40F on the ridgetops in Schuylkill & Sullivan County to 50F over southwest Somerset County.

SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
A few bands of light to briefly moderate rain showers will precede and accompany a weak cold front as it drifts east across the CWA Friday afternoon and evening.

PWs peak around 1" ahead of the front over far south central PA where some mdt to briefly heavy downpours/embedded t-storm cannot be ruled out.

Mean MU CAPE via the HRRR may push 500 J/KG across a small portion of Scent PA and the Laurel Highlands during the mid to late afternoon hours Friday, which could support a few relatively low-topped TSRA. Elsewhere, very minimal CAPE values will negate TSRA formation and lead to lighter QPF of generally around 0.10 of an inch.

Conditions gradually improve Friday night and early Saturday with sharply falling sfc dewpoints/PWATs.

LONG TERM /SATURDAY THROUGH THURSDAY/
Cooler and drier air will arrive in CPA behind the cold front to start the weekend, directed by a west wind gusting 25-35 mph.
A shortwave trough crossing the eastern Great Lakes may touch of an isolated shower over north central PA late Sat morning into the afternoon. Sfc ridging will ensure dry weather Saturday night as focus shifts to frost and freeze risk.

The setup for frost Saturday night is uncertain, depending on the timing and coverage of low clouds that may develop in a thin layer of upslope moisture beneath the low level inversion. If more clouds develop earlier in the night, Saturday night could be more of an advective marginal cold freeze setup (vs. more favorable radiational/decoupling frost pattern.) But for now, models suggest there could be at least a few hours of mostly clear skies and light winds before the clouds develop, during which frost can form. Low temps are fcst in the 30-35F range over the northwest half of the CWA which could impact counties activating the growing season April 21 along the US220/I99/I80 corridor.

The bulk of model guidance supports dry conditions Sunday through through Tuesday morning as high pressure builds into the area. Upper-level troughing does support below-average temperatures for the majority of the period.

The combination of light winds, dry air, and mostly clear skies associated with the surface ridge is likely to result in more widespread frost Sunday night into Monday morning. The greatest risk of frost is over the northern mountains where the growing season is not active, but areas in the growing season further south could also be affected.

Temperatures are expected to warm Monday into Tuesday with the surface high pressure shifting eastward off the east coast and an approaching shortwave bringing the next chance of showers.
Ensemble plumes indicate the best chance for precipitation will come Tuesday PM, with scattered showers lingering into Wednesday. Another shot of cold air will follow for Wed night into Thu morning, with temperatures taking another dip below the freezing mark across the northern tier.

AVIATION /22Z THURSDAY THROUGH TUESDAY/
A north-south quasi-stationary front lies across the Susq Valley early this evening, with mostly clear skies to the west of it and low cigs/stratus covering most locations east of the boundary. Models indicate this boundary will shift west overnight, resulting in deteriorating flying conditions over Central PA, as a wind shift to the east draws increasing low level moisture into the area.

Latest model RH time sections and ensemble prob charts support predominantly MVFR cigs across the lower elevations of the Susq Valley tonight. Further west, expect a fairly rapid transition from VFR to IFR cigs between 06Z-10Z, as the increasing moisture is forced to ascend the higher terrain of the Appalachians.
Upon examination of the latest model soundings have removed earlier mention of LLWS for the overnight. However, a brief period of LLWS does look possible over the NW Mtns (KBFD)
between 12Z-16Z associated with increasing winds aloft ahead of a cold front approaching from the Grt Lks.

Very little improvement is expected Friday, as a moist southeast flow off of the Atlantic remains in place. Diurnal heating is likely to result in a very modest increase in cigs, with VFR possible across the Lower Susq Valley (MDT/LNS) by afternoon but borderline IFR/MVFR cigs likely holding on along the spine of the Appalachians. In addition to the low cigs, a few showers will move into the region during the late AM and afternoon hours in advance of the approaching front.

Outlook...

Sat...Pre-dawn low cigs/showers possible Eastern PA.

Sun-Mon...No sig wx expected.

Tue...Slight chance of evening showers/cig reductions NW Mtns.

CTP WATCHES/WARNINGS/ADVISORIES
None.

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Port Deposit
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Thu -- 03:08 AM EDT     0.98 feet Low Tide
Thu -- 04:14 AM EDT     Moonset
Thu -- 06:21 AM EDT     Sunrise
Thu -- 07:29 AM EDT     2.30 feet High Tide
Thu -- 02:50 PM EDT     Moonrise
Thu -- 03:00 PM EDT     0.66 feet Low Tide
Thu -- 07:46 PM EDT     Sunset
Thu -- 08:25 PM EDT     2.39 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Port Deposit, Susquehanna River, Maryland, Tide feet

Havre de Grace
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Thu -- 01:27 AM EDT     0.59 feet Low Tide
Thu -- 04:14 AM EDT     Moonset
Thu -- 06:21 AM EDT     Sunrise
Thu -- 07:02 AM EDT     1.91 feet High Tide
Thu -- 01:01 PM EDT     0.72 feet Low Tide
Thu -- 02:50 PM EDT     Moonrise
Thu -- 07:05 PM EDT     2.21 feet High Tide
Thu -- 07:45 PM EDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Havre de Grace, Susquehanna River, Maryland, Tide feet

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