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
848 FXUS63 KPAH 170447 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 1147 PM CDT Thu May 16 2024 .KEY MESSAGES... - A few strong to severe thunderstorms are possible late this afternoon and this evening mainly over southeast Missouri and adjacent portions of southern Illinois and west Kentucky. Large hail and damaging winds will be the primary threats. - A Flood Watch for flash flooding is in effect from 7 PM tonight through 7 PM Friday over southern portions of southeast Missouri, the southern tip of Illinois and the Purchase Area of west Kentucky - Very warm conditions will return Sunday through Tuesday with daily high temperatures in the upper 80s. A few 90 degree readings will be possible. - A cold front will bring a good chance of thunderstorms to the region Tuesday night into Wednesday. At this time locally heavy rainfall and lightning are the primary hazards. && .UPDATE... Issued at 1135 PM CDT Thu May 16 2024 Updated aviation discussion for 06z TAFs. && .DISCUSSION... Issued at 327 PM CDT Thu May 16 2024 SPC mesoanalysis indicates that there is 1000 J/kg of mixed- layer CAPE over western portions of southeast Missouri as of 19Z. This could spread farther east with additional heating late this afternoon. Effective bulk shear of 30-35kts could support multicell thunderstorms with mainly a damaging wind risk. Mid- level lapse rates are weak, but low-level lapse rates are pushing 8C/km. The steep low-level lapse rates, coupled with downdraft CAPE approaching a 1000 J/kg certainly supports a damaging wind threat. A Flood Watch for flash flooding has been issued for southern portions of southeast Missouri, the southern tip of Illinois, and the Purchase Area of west Kentucky for tonight and Friday. Please consult the hydrology section of this discussion for details. An upper trough over the southern Rockies today will push gradually eastward to the southeast states by Sunday. Disturbances will lift northeast over the Quad State tonight through Friday, leading to the heavy rainfall concern. As the main trough passes to the south of the area Saturday, more showers and even some thunderstorm may linger over the eastern half of the region. The GFS even hints at some showers lingering into Sunday in the southeast. The upper trough will be stubborn over the southeast, and that will eventually result in a pesky upper ridge over the Quad State. The ridge will hold overhead into Tuesday, effectively deflecting disturbances northeast from the Plains to the upper Mississippi Valley early next week. Eventually a disturbance is expected to push more to the east and bring a weak cold front through the Quad State along with a good chance of more showers and storms Tuesday night into Wednesday. At this time, the best lift and wind fields look to be to our west, so for now will just advertise locally heavy rainfall and lightning with this event. With zonal flow developing aloft, there is potential for the front and associated convection to linger in our vicinity into next Thursday. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1135 PM CDT Thu May 16 2024 A band of showers with a few rumbles of thunder has now developed over SEMO and will impact terminals KCGI/KPAH through the morning. Heavy downpours and MVFR vsby reductions will be possible. Lighter scattered showers are anticipated across the rest of the terminals before gradually diminishing from west to east in the afternoon. The other concern will be for MVFR/IFR cigs that are progged to spread across the region from the southwest by 11-15z. The low cigs will gradually scatter out by the evening across western terminals, but likely remain in place at KEVV/KOWB due to low level saturation. Light & variable winds become S-SE between 5-10 kts after daybreak. At night, calm winds are expected. If skies are able to clear out in time, conditions may be favorable for fog development towards the end of the TAF period across portions of the region. && .HYDROLOGY... Issued at 327 PM CDT Thu May 16 2024 It is pretty simple sometimes. The convection from early this weak resulted in a couple of swaths of very heavy rainfall. One from near the OH/MS confluence northeast along the Ohio to the Evansville/Henderson areas, and the another along the TN/KY border from the Lakes eastward. In southern Illinois yesterday, creeks were at bankfull and there remained considerable field flooding. WPC QPF has 2-3" of rainfall forecast from late this afternoon through Friday. Most of this will fall in two waves, one through this evening and another from pre-dawn through Friday morning. The footprint of this expected heavy rainfall overlaps much of the previous heavy rainfall, and it is in those water- logged areas where we have the greatest concern for renewed flash flooding. Instability is not great, but will be maximized in the Watch area. Precipitable water values will be near the 90th percentile, so efficient rains are a good bet. If we had better instability and a better defined surface boundary to focus convection, confidence would be higher, but with the antecedent rainfall, there was little reason not to issue the watch this afternoon There is potential for the heavy rains to spread farther east across the Quad State and that could lead to an expansion of the Flood Watch at some point tonight or Friday morning. Stay tuned. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Flood Watch through Friday evening for ILZ088>090-092>094. MO...Flood Watch through Friday evening for MOZ108>112-114. IN...None. KY...Flood Watch through Friday evening for KYZ001>009. && $$ UPDATE...DW DISCUSSION...DRS AVIATION...DW HYDROLOGY...DWS