Area Forecast Discussion
Issued by NWS Mt. Holly, NJ
Issued by NWS Mt. Holly, NJ
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --389 FXUS61 KPHI 200716 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 316 AM EDT Thu Jun 20 2024 .SYNOPSIS...-- Changed Discussion --Bermuda high pressure remains in control through the weekend. A back door cold front will move in from the north on Friday and will stall over the area on Saturday before returning north as a warm front. A stronger cold front will pass through the region Sunday night, then lingers over the area through Monday. High pressure returns on Tuesday, followed by another front for Wednesday.-- End Changed Discussion --&& .NEAR TERM /THROUGH TONIGHT/...-- Changed Discussion --The Heat Advisory continues for today for most of the region. Temperatures will be a touch higher compared to yesterday with heat indices of 93-98 within the Heat Advisory. Limit outdoor time today and if you have to be outside, take frequent breaks and stay hydrated! A strong 597-598 dam ridge will retrograde to the west today, though it will remain the dominant feature influencing the pattern. Bermuda high pressure remains offshore, fostering a light south/southwesterly flow. The result will be another hot day, and temperatures will be slightly higher compared to yesterday. Looking at low 90s within the Heat Advisory, with heat indices climbing into the mid to upper 90s. Areas near the coast will be a touch cooler, similar to previous days, with upper 80s expected within South Jersey and lower Delmarva. A sea breeze (and bay breeze where applicable) will develop, keeping things cooler near the coastline. Given some impressive records for today (see climate section below), not expecting any record highs to fall. Mount Pocono has a chance, but they are the only site with forecasted highs within 5 degrees of their record. For tonight, a mild and muggy night is expected. Lows will fall into the mid to upper 60s/low 70s with dewpoints in the 60s. Not much relief expected overall.-- End Changed Discussion --&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...-- Changed Discussion --Hot and increasingly humid conditions remain in place for the end of the week. The Heat Advisory remains in effect for Friday for southeast Pennsylvania, most of New Jersey, and northern Delaware as highs will get in the low to mid 90s along with surface dew points in the mid to upper 60s. This will yield max heat index values in the upper 90s to around 100 in the Advisory area and in the low 90s elsewhere. A broad almost 600 dam 500 mb high over the Ohio and Tennessee Valleys, Gulf Coast states, and southern Plains will sag a bit to the southwest. As a result, 500 mb heights will fall from around 593 dam to around 590 dam as a back door cold front slides in from the north. Showers and thunderstorms will develop across areas mainly north and west of the Fall Line, with showers and thunderstorms becoming likely over portions of Carbon and Monroe counties in Pennsylvania and Sussex county in New Jersey. For most of the area north and west of the Fall Line, SB CAPE values will be upwards of 1500 to 2000 J/kg and DCAPE values will be from 800 to 1000 J/kg. 0- 6 km Bulk Shear will be minimal at generally less than 15 kt, and PWATs will be 1.75 to 2 inches. Slow-moving thunderstorms will produce heavy rain and localized flooding, especially in these far northern zones. Localized severe thunderstorms will be capable of damaging wind gusts. The Storm Prediction Center has a Marginal Risk (1 out of 5) for portions of the southern Poconos, northern New Jersey, and Lehigh Valley. Warm and humid Friday night with showers and thunderstorms tapering off. Should be humid enough for patchy fog, especially in areas where thunderstorms occur. That front remains over the area, mainly along the Fall Line, on Saturday. As a result, high temperatures will be in the upper 80s for the southern Poconos and in the low to mid 90s for northern New Jersey and the Lehigh Valley. A slight onshore component to the winds along the coast, as well as local sea breezes, should keep temperatures in the 80s along the coasts as well. Going inland, however, and highs will get into the mid and upper 90s, with the highest temperatures along the I-95 corridor and in Delmarva. With southerly flow now taking hold and increasing, surface dew points will climb into the upper 60s and low 70s. Max heat index values will be in the upper 90s to around 105. Will keep the Excessive Heat Watch in effect for now. Some shortwave energy approaches from the west in the afternoon and interacts with the front bisecting over the area. Another round of showers and thunderstorms will develop in the afternoon and evening, with chance PoPs down to the I-95 corridor. Again, locally heavy rain and damaging wind gusts are possible. Even warmer and more humid Saturday night.-- End Changed Discussion --&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...-- Changed Discussion --Excessive Heat Watch remains in effect for Sunday, and the trend has been back hotter and more humid. NBM max temperatures are 100 to 101 for Philadelphia and along the I-95 corridor. However, this may be a bit too high for several reasons. A cold front will approach from the west. With increasing clouds over the area with the approach of that front, the cloud cover may keep temperature from getting as hot. The other thing is convection associated with that front, as showers and thunderstorms will knock temperatures down and, depending on the timing, could keep areas from reaching forecast highs. That said, high temperatures should get up into the mid and upper 90s, though just shy of 100, for most of New Jersey, the Lehigh Valley, southeast Pennsylvania, and Delmarva, with the hottest temperatures along the I-95 corridor and in Delmarva. Surface dew points will also be in the low 70s, which results in max heat index values generally from 100 to 105, and possibly up to 110 in Delmarva. As a result, will expand the Excessive Heat Watch to include the whole area, though if 110 heat index values do not occur in Delmarva and extreme southeast New Jersey, that Watch could be converted to a Heat Advisory. Now, with all of this heat and humidity, that sets the stage for a potential severe weather outbreak Sunday afternoon and evening as a strong cold front approaches from the west. SB CAPE values will be up around 1500 to 2000 J/kg, DCAPE values will be up around 100 J/kg, 0-6 km Bulk Shear will increase to 25 to 30 kt, and PWATs will be up around 2 inches. The question is if the highest shear values will line up with the highest CAPE values, and that will depend on the timing of the front. Damaging winds and heavy rain with localized flooding will occur in the strongest storms. Showers and thunderstorms will continue through Sunday night before tapering off Monday. The front will be hung up over the area and will not move offshore until Monday night. Weak high pressure builds back into the region Tuesday, followed by another front on Wednesday. Temperatures will not be as hot, but will still be above normal on Monday and Tuesday with highs in the upper 80s to low 90s. Highs on Wednesday will be in the low to mid 90s. Fairly humid on Monday with highs in the upper 60s before drier air builds into the region Tuesday. Humidity returns on Wednesday.-- End Changed Discussion --&& .AVIATION /07Z THURSDAY THROUGH MONDAY/...-- Changed Discussion --The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Through 12z...Prevailing VFR for much of the night. Some patchy fog at KACY possible around daybreak, reducing visibilities to MVFR levels briefly. Fog should mix out by 11z though. Everywhere else should stay VFR with south/southwest winds at 5 kt or less. Moderate confidence. Today...VFR Winds increase out of the south to southwest 5-10 knots. More southerly winds expected yet again at KMIV/KACY this afternoon with the passage of the sea-breeze. Funneling up the Delaware Bay will result in a south/southeast wind at KILG as well. High confidence. Tonight...VFR. Winds out of the south/southwest 5 kt or less. High confidence. Outlook... Friday through Saturday...Overall, VFR. Afternoon evening SHRA/TSRA with sub-VFR conditions possible at KRDG/KABE/KTTN/KPNE/KPHL Friday and Saturday. Sunday through Monday...Generally VFR Sunday. SHRA/TSRA developing Sunday afternoon, continuing through Sunday night before tapering off on Monday will result in sub-VFR conditions.-- End Changed Discussion --&& .MARINE...-- Changed Discussion --No marine headlines expected through tonight. Light winds this morning will increase to around 10-20 kt out of the south. Seas 2 to 4 feet. Outlook... Friday through Saturday...Sub-SCA conditions, though persistent 15 to 20 kt winds may develop at northern NJ ocean waters each afternoon. Sunday through Monday...SCA conditions may develop with S winds 15 to 20 kt with 25 to 30 kt gusts and Seas building to 3 to 5 feet. Showers and thunderstorms will develop Sunday afternoon and continue through Sunday night before tapering off on Monday. VSBY restrictions in heavy rain and damaging wind gusts possible. Rip Currents... Thursday...Southerly winds around 10 mph and breaking waves will be around 1-3 feet. Portions of the southern NJ coast will keep an onshore component of the wind, in addition to the Full Moon on Friday. For this reason, have maintained a MODERATE Risk for all New Jersey beaches except Monmouth County. For the Delaware Beaches and Monmouth County, maintained the LOW Risk of dangerous rip currents. Friday...Similar weather conditions are expected on Friday in addition to the occurrence of a Full Moon. With this in mind, saw no reason to change Rip Risks for NJ/DE beaches from what is currently posted for Thursday. Rip currents occur often in the vicinities of jetties and piers. Utilize any guarded beaches if venturing out into the water. For specific beach forecasts, visit weather.gov/beach/phi-- End Changed Discussion --&& .CLIMATE...-- Changed Discussion --Record high temperatures Today. Location Record High (6/20) Philadelphia, PA 98/1931 Allentown, PA 100/1923 Reading, PA 101/1923 Mount Pocono, PA 89/2012 Trenton, NJ 98/1923 AC Airport, NJ 95/2012 AC Marina, NJ 90/1908 Wilmington, DE 97/2012 Georgetown, DE 98/2012 Record high temperatures Friday. Location Record High (6/21) Philadelphia, PA 99/1923 Allentown, PA 100/1923 Reading, PA 99/1923 Mount Pocono, PA 90/1953 Trenton, NJ 97/1923 AC Airport, NJ 97/1988 AC Marina, NJ 94/2012 Wilmington, DE 98/2012 Georgetown, DE 99/2012 Record high temperatures Saturday. Location Record High (6/22) Philadelphia, PA 100/1988 Allentown, PA 95/1941 Reading, PA 96/1921 Mount Pocono, PA 90/1908 Trenton, NJ 99/1988 AC Airport, NJ 100/1988 AC Marina, NJ 92/1949 Wilmington, DE 98/1988 Georgetown, DE 97/2012 Record high temperatures Sunday. Location Record High (6/23) Philadelphia, PA 97/1888 Allentown, PA 95/1965 Reading, PA 96/1908 Mount Pocono, PA 90/1908 Trenton, NJ 97/1894 AC Airport, NJ 98/1988 AC Marina, NJ 91/1909 Wilmington, DE 100/1894 Georgetown, DE 100/1988-- End Changed Discussion --&& .PHI WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --PA...Heat Advisory until 6 AM EDT Saturday for PAZ054-055-060>062- 070-071-101>106. Excessive Heat Watch from Saturday morning through Sunday evening for PAZ054-055-060>062-070-071-101>106. NJ...Heat Advisory until 6 AM EDT Saturday for NJZ001-007>010-012- 013-015>020-027. Excessive Heat Watch from Saturday morning through Sunday evening for NJZ001-007>010-012-013-015>020-027. Excessive Heat Watch from Sunday morning through Sunday evening for NJZ014-021>026. DE...Heat Advisory until 6 AM EDT Saturday for DEZ001. Excessive Heat Watch from Saturday morning through Sunday evening for DEZ001. Excessive Heat Watch from Sunday morning through Sunday evening for DEZ002>004. MD...Excessive Heat Watch from Sunday morning through Sunday evening for MDZ012-015-019-020. MARINE...None.-- End Changed Discussion --&& $$ SYNOPSIS...MPS NEAR TERM...Hoeflich SHORT TERM...MPS LONG TERM...MPS AVIATION...Hoeflich/MPS MARINE...Hoeflich/MPS CLIMATE...