Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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
110 FXUS61 KPBZ 092139 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 539 PM EDT Sun Jun 9 2024 .SYNOPSIS... Generally dry and seasonably cool weather is expected through Tuesday under the influence of an upper trough. Rising temperatures and dry weather will characterize the mid to late week period. Heat index vales Thursday and Friday will be well into the 80s. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... KEY MESSAGES: - Seasonably cool temperature will persist despite increasing overnight cloud cover ahead of the next system. -------------------------------------------------------------- The only change to the late afternoon - supper time update was to tweak clouds upward overnight given latest NCEP suite. This aligns well with the NBM on mostly cloudy conditions especially north of I70 arriving overnight. The rest is in fine shape with no changes. Previous discussion follows. Dry air and subsidence between upper level shortwaves will foster scattered cumulus and slightly below average temperature this afternoon. The next shortwave within the broad New England trough may combine with weak destabilization to generate isolated late afternoon to evening showers across northwest PA. Cloud coverage will increase overnight into Monday morning ahead of another upper level perturbation, which should mitigate further temperature falls and keep low values only 5 degrees below average. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... KEY MESSAGES: - Shortwave movement and additional cold front will create low probability light rain showers Monday. - Well below average temperature Monday is expected to become near normal by Wednesday as dry weather persists. ------------------------------------------------------------------- In response to ridge building just west of the upper Mississippi River Valley, another embedded shortwave will round the New England trough and cross the region Monday. Isolated light rain showers may develop along the associated surface cold front, but weak ascent and moisture origins mainly associated with Lake Erie should limit activity to the I-80 corridor and (later in the day) higher terrain. More notably, an uptick in cloud cover and additional cool advection will keep high temperature 10 to 15 degrees below the daily average while strong radiational cooling keeps similar temperature transparencies for the overnight low. Gradual height rises as the New England trough heads out to sea and flow out west becomes more zonal will rising temperature Tuesday into Wednesday. Surface high pressure will cross the region during this time as well, ensuring plenty of insolation and dry weather. && .LONG TERM /THURSDAY THROUGH SUNDAY/... KEY MESSAGES: - Increasing precipitation chances late Thursday into Friday with shortwave movement. - Upstream convective evolution will play role in timing and storm mode during that period. ------------------------------------------------------------------- The late week period will feature embedded shortwaves within fairly progressive zonal flow across the north central CONUS that will shirt towards the Great Lake region late Thursday into Friday. Ahead of it, confidence if high for above normal temperature with an uptick in warm, moist surface flow as the surface high shifts east. With it, the expectation is for an increased precipitation chances that generally favor northwest PA. There remains notable variation in timing/strength of the upper shortwave, with potential the prior convective evolution near the western Great Lakes may dictate the quickness of its eastward progression. Storm timing and strength of the upper trough will be key in accurately assessing any lightning potential, but severe weather appears unlikely as the probability for daytime SBCAPE values to exceed 1000K/kg are less than 10%. How quickly the shortwave traverse the area will dictate weather Saturday, but the general trend is for ridging to develop over the Ohio River Valley heading into the start of the next week. There is fairly high confidence in this pattern which would support dry weather and near to above 90 degree weather (75% probability of hitting 90+ on Monday 6/17 in Pittsburgh). && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... A scattered to broken cu field with VFR cigs is ongoing across the area under cool northwesterly flow in the wake of this morning`s cold front passage. This cu field will gradually diminish by 00Z with the loss of daytime heating and mixing, though models suggest a broken band of mid-level clouds from upstream convection passes overhead within that window. VFR conditions prevail through the remainder of the evening with winds settling after dark. Restrictions return overnight into early Monday morning as another weak cold front pushes through the area. Expect MVFR cigs to creep in from the north, first starting at FKL/DUJ around 06Z and reaching the I-70 corridor by 12Z. MGW may be the only terminal spared from MVFR as current guidance suggests cigs bottom out at low-end VFR that far south. Unfortunately, low cigs remain in place longer this time as the weak cold front brings a reinforcing shot of cold air that helps maintain the stratocu deck. Ceilings don`t lift and scatter until beyond the current 24hr TAF cycle (though improvement is reflected in the PIT 30hr TAF). There may be a brief, isolated shower or two up around FKL/DUJ in the 09Z-15Z timeframe, but confidence in that occurring is low and impacts (in addition to the ongoing MVFR cigs) would be minimal, so left mention out of the TAFs for now. Northwest winds will see a slight uptick from west around 4-7 kts ahead of the front to northwest around 7-10 knots with occasional gusts 15-20 kts behind the front. .Outlook... Ceiling restrictions linger through Monday afternoon before lifting and scattering Monday evening, giving way to VFR conditions under building high pressure Tuesday through Thursday. Showers and thunderstorms (and their associated restrictions) return Thursday night and Friday with another passing disturbance. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Frazier NEAR TERM...Frazier/McMullen SHORT TERM...Frazier LONG TERM...Frazier AVIATION...Cermak