Area Forecast Discussion
Issued by NWS Paducah, KY
Issued by NWS Paducah, KY
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
137 FXUS63 KPAH 221042 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 542 AM CDT Sun Sep 22 2024 .KEY MESSAGES... - A cold front remains on track to brings waves of showers and storms this morning through Monday night. The risk for severe storms is marginal for today and Monday. The main concern is for isolated damaging winds and perhaps some large hail during peak heating. Between 0.5 to 2.0 inches, with locally 3.0 inches of rainfall along the I-64 corridor remains possible. - Behind the cold front, cooler and less humid conditions are expected for the rest of the week with highs only in the mid 70s to low 80s. - Returning rain shower chances are becoming more likely towards the second half of the week into next weekend. Forecast confidence is below average in how a potential tropical system down in the Gulf of Mexico may interact with a disturbance in the vicinity of the region and anything that would be more impactful. && .DISCUSSION... Issued at 319 AM CDT Sun Sep 22 2024 An unsettled period of weather remains on track as a 500 mb trough over Colorado lags behind a cold front slowly transversing southeast across Missouri. Increasing height falls will mean ample rain chances along with cooler temps as potentially 4 waves of pcpn will impact the FA through Monday night. The first round of convection is currently moving downstream from central Missouri and is on track to bring a round of showers and storms later this morning, mainly across southern Illinois and southwest Indiana. These storms should be mainly elevated with heavy downpours and lightning being the main concern. It is worth nothing that enhanced cloud cover will likely mean temps struggle to reach 90 today across most of the FA. For this reason, leaned below the NBM as highs are now likely to range from the lower 80s to upper 80s from north to south. After the initial wave pushes east by the afternoon, isolated activity still remains possible at any given time; however, CI associated with the second wave likely occurs late this afternoon into the evening as the aformentioned cold front approaches from the west. These storms are likely to be more scattered versus what will be a cluster of storms this morning, but will pose a marginal risk of severe weather as indicated in SPCs D1 convective outlook. The risk will be contingent on how much destabilization occurs this afternoon as it will depend on how much cloud cover debris there is from the morning convection. Should the parameters come together, the general consensus is for about 1500-2000 J/kg of MLCAPE and 30-35 kts of effective bulk shear combined with 7.0-7.5 C/km sfc-3km lapse rates. This would support mainly a isolated damaging wind risk and large hail. The severe risk should quickly wane after sunset with the loss of heating, but additional isolated to scattered storms remain possible through the overnight. As the cold front stalls over the FA Monday morning, increased sfc convergence and mid level forcing will support a third round of showers and storms, followed by the final round late Monday afternoon into Monday night. The last round will once again pose a similar marginal severe risk to today, but again is contingent on how much destabilization is able to occur due to cloud cover. Given that the forcing will be more robust, the risk has the potential to be slightly greater on Monday if all the ingredients are able to come together. Otherwise, a few rain showers may linger into Tuesday as the cold front pushes southeast of the FA. Total rainfall amounts through Tuesday generally look to be between 0.5 to 2.0 inches, with localized higher amounts near 3.0 inches favored along the I-64 corridor. Given that the rainfall will occur over a long duration, any flash flooding concerns should be limited to mainly runoff on roadways where heavy downpours occur. Behind the front, highs are now progged to range from the mid 70s to low 80s through the end of the week. The synoptic flow turns highly amplified with a deep 500 mb trough that will begin to dig into the lower Ohio Valley on Wednesday. This is when the forecast challenges begin as there is more support from the latest 0z model guidance for conditions to turn rather wet to end the week, while some guidance still would support mainly dry weather. The deterministic ECMWF/CMC are in decent agreement in showing a 500 mb cutoff low developing in the vicinity of the FA by Wednesday morning, and remaining nearly stationary with robust cyclonic flow through the weekend. This scenario would result in daily rain chances returning quickly in the middle of the week and continuing right through the weekend. The one caveat is how the potential Gulf of Mexico tropical system eventually interacts as this scenario would also potentially mean quite a bit of heavy rainfall and possibly some wind. Meanwhile, the GFS is much more progressive with the evolution of the 500 mb low and would mean mainly dry weather into the weekend. It is worth noting the ECMWF/CMC have much stronger support for the 500 mb low by its ensembles, similar to what the ECMWF AIFS has been showing. Meanwhile, the GFS lacks much support from the GEFS, and is why the deterministic runs have been very inconsistent. Given the latest trends, would lean towards there being at least returning rain shower chances later in the week. Until the tropical system develops in the northwest Caribbean, substantial changes are still likely to occur for anything that would be more impactful. For this reason, forecast confidence remains below average. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 540 AM CDT Sun Sep 22 2024 The next round of convection is now entering the region from the northwest and will impact terminals KMVN/KEVV/KOWB through this morning. Brief cig & vsby reductions are possible during heavy downpours. Otherwise, mainly VFR in the afternoon with SCT-BKN mid-level clouds before the next round of storms arrive late this afternoon into the evening. Unlike the morning round, additional pcpn will be more scattered versus a cluster. There is slightly higher confidence in seeing impacts at KCGI/KPAH, but overall these will likely be hit or miss in nature at any given location. Any storms that do develop will be capable of turning severe with isolated gusty winds and large hail. Following storms this evening, there will likely be a lull tonight before yet another round arrives towards the end of the TAF period. However, MVFR/IFR cigs & vsbys will be the main concern overnight as the column turns extremely saturated. Some of the model guidance is hinting at BCFG at KCGI again Monday morning, but would lean towards this being just low-stratus clouds. Winds today will be light out of the SW-W around 5-7 kts before turning light & variable again after sunset. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ DISCUSSION...DW AVIATION...DW