


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
497 FXUS61 KPBZ 140731 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 331 AM EDT Mon Jul 14 2025 .SYNOPSIS... Scattered showers and thunderstorms associated with a slow-moving boundary, bring a risk of isolated areas of flooding, are expected this afternoon and evening. Relatively drier conditions Tuesday. By midweek, heat, flooding and severe weather concerns return to the region. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - A weak front approaches the area today from the west. - Isolated to widely-scattered morning showers, followed by scattered afternoon thunderstorms mainly south of Pittsburgh. - Seasonal daytime high temperatures followed by warm and humid nighttime lows. --------------------------------------------------------------- A shortwave trough is still slated to cross the region today, bringing a weak surface boundary with it. The trend in hi-res models finally appears to more accurately resolve the slower- than-originally-expected movement of the shortwave and associated front. The result is higher rain chances farther north and west than originally forecast. Expect a wave of scattered showers to develop across most of the area along and south of I-80 this morning, followed by a higher concentration of thunderstorm activity near and southeast of Pittsburgh in the afternoon/evening as the front begins to finally make its way through. We continue to see anomalously moist atmospheric conditions ahead of the front, with NBM mean PWATs around 1.9" while the 25th and 75th percentiles are near 1.8" and 2.0", respectively. This, coupled with slow storm motions, will support another low- end flooding risk mainly south and east of Pittsburgh this afternoon/evening where the greatest thunderstorm coverage and heaviest downpours are expected. Meanwhile, instability and DCAPE remain respectable enough to support a low-end downburst wind threat in the strongest storms, again mainly south and east of Pittsburgh this afternoon and evening. Thunderstorm activity should wane after sunset with the loss of daytime heating, though some isolated showers could continue (primarily along and south of the slow- moving front) Monday night. Seasonable afternoon high temperatures reach the mid 80s, although sticky dewpoints near or above 70s will help heat indices climb to around 90. The warm and humid overnights continue Monday night, with lows staying in the upper 60s to around 70. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... KEY MESSAGES: - Warmer Tuesday with lower precipitation chances - Heat Wednesday and Thursday ---------------------------------------------------------------- The weak front may have trouble clearing our region by Tuesday, hanging up to the south of Pittsburgh in weak flow aloft. This may result in another round of scattered diurnal convection along the Appalachian Mountains in Fayette, Westmoreland, Preston, and Tucker counties as well as other areas in northern West Virginia where PoPs are around 35%-45% in areas where better low-level convergence is suggested. Low end severe/flood risk may remain, if a bit lower than Monday. North of the stationary front, 500mb heights are forecast to build back above 590dm warming temperatures. In these areas, NBM shows a general 30%-50% chance of highs of 90 or higher, with 50%-70% chance in valleys/urban areas. Heat index values may rise into the mid to upper 90s as a result in these warmer locations. This will be followed by another night with little relief from the warmth after convection fades again, with most overnight lows/dewpoints 70F or a bit higher. Wednesday is expected to feel like the hottest day of the week as it stands with the greatest extent of upper ridging an. There is a d the strongest southwesterly flow. This will bring in moisture hiking up the dew points which will increase the heat index. This explains why the heat risk on Wednesday generally maximizes in the moderate/major category, however, this threat will require no afternoon rain/storms in any given area. For areas that do see rain, there is some severe potential. On Wednesday, subsidence in the upper-levels is undercut by warm, moist southwest flow during a low to mid-level shortwave passage south of the main surface front which may allow for a downburst wind threat. This is highlighted in roughly 30% chance of severe within 70 miles of a point in CIPS analogs, however, CSU machine learning is a bit less bullish in probabilities. As for flooding, PWATS will be near the 90th percentile, though sfc to 500mb mean flow of 15kts may hit that realizing a flood threat will rely on training. Environmentally, the area will remain quite similar on Thursday. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... KEY MESSAGES: - Frontal passage on Friday will bring more seasonable temperatures. - Forecast uncertainty increasing into the weekend. ------------------------------------------------------------------- Friday`s environment will remain quite similar to Thursday before the main cold frontal passage. This will support non-zero severe threats, and multiple rounds of diurnal storms will also increase the flooding risk slightly. Ensembles seem to be in relatively good agreement with a 500mb trough moving across the region Friday. This will bring a cold front with a more organized band of showers and thunderstorms through the region Friday afternoon. As a result, high temperatures are expected to cool closer to (but slightly above) the seasonal average and low temperatures will drop below 70F. There are some uncertainties in the strength and timing of this 500mb trough with ensembles showing the potential for it to be weaker and slower than the mean flow. A weaker trough would bring warmer temperatures while a slower trough could bring a higher probability for precipitation. Currently, high temperatures should remain in the mid-80s while low temperatures should stay below 70F with precipitation remaining diurnally driven. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... Beginning to see pockets of SCT/BKN stratocu form around the area with cigs ranging from 3.5kft to 6kft AGL. Expecting at least patchy fog to develop around 08z-12z and possibly for these cigs to drop during that time as well. If this occurs, IFR restrictions will be possible, especially in areas that saw rainfall on Sunday. Additionally, seeing a few very isolated showers form that could wander near or over a terminal or two before sunrise, though impacts would be minimal and very brief in nature based on recent obs from locations within these showers. The isolated to scattered convective activity continues on Monday as a front very slowly makes its way into the local area from the west. Increasing chances for scattered showers will develop west to east after sunrise, followed by thunderstorm potential in the late morning and afternoon. There`s still low confidence in how much coverage we will see, but latest guidance continues to suggest the best rain chances are along and south of the I-70 corridor with a more sparse coverage farther north towards I-80. Local restrictions can be expected in and around instances of heavy rainfall, but otherwise VFR will prevail outside of convection throughout the day. Patchy fog will once again be possible Monday night, especially in any places that see rainfall in the afternoon and evening. Outlook... Scattered diurnal convection now appears likely again on Tuesday, potentially leading to brief restrictions during the afternoon/evening hours. Localized morning fog also can`t be ruled out. Precipitation and restrictions become more widespread on Wednesday and Thursday as southwest flow and moisture increase. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...CL/Lupo NEAR TERM...Cermak SHORT TERM...CL/Lupo LONG TERM...Lupo AVIATION...Cermak