NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS63 KLMK 040551 AFDLMK

Area Forecast Discussion National Weather Service Louisville KY 1251 AM EST Mon Dec 4 2023

Updated Aviation Discussion

Short Term
(This evening through Monday)
Issued at 240 PM EST Sun Dec 3 2023

================================================================ Key Messages

- Breezy this afternoon

- Cool Monday morning with a short period of light rain

================================================================

A deepening low pressure system will continue to lift off to the northeast across the Upper OH Valley and Great Lakes this afternoon and evening. Fast southwesterly winds and cold, dry air advection in its wake is resulting in a breezy afternoon. Wind gusts to 25-35 mph will be possible through mid-afternoon, mainly across the northern half of the forecast area. Stratus has mostly scoured out and lifted, resulting in partly to mostly sunny skies. Temperatures are running in the low to mid 50s.

Brief clearing will persist this evening into the first half of the overnight period. A slackening pressure gradient will help temperatures drop off rather quickly after sunset. Overnight lows should range through the 30s (near 40 along the TN border). A weak, compact area of low pressure will rotate ESE across the Mid-South Monday morning, bringing some quick-hitting light rain. Rain will diminish quickly from west to east Monday afternoon. Partly to mostly cloudy skies are anticipated Monday afternoon with afternoon highs in the upper 40s to lower 50s. Up to 0.1-0.2 inches of rain still looks possible Monday morning, though south-central KY will likely see less than a tenth of an inch.

Long Term
(Monday night through Sunday)
Issued at 301 PM EST Sun Dec 3 2023

==================================================================== Key Messages:

- A few chances of light precip Mon night and Tuesday

- Impactful weather system expected in our area next weekend

====================================================================

Monday Night through Wednesday Night...

Will be watching a shortwave trough axis moving towards the region Monday night into Tuesday. Moisture in the column is not overly impressive and is quite shallow. However, enough synoptic scale lift in advance of the wave should be sufficient to produce at least some light precipitation late Monday into Tuesday morning. P-type looks to be mostly rain showers given the multi-model forecast soundings. It's possible that a few snow flakes could mix in Tuesday morning where we're at the daily minimum on temps. Scattered showers will likely persist through the day with very light QPF amounts and the precip should diminish by Tuesday night. With an influx of colder air coming in behind the trough axis, a few snow flakes/flurries could mix in toward the end of the precipitation period. However, no impacts are expected as surface temps will largely remain just above freezing. Lows Monday night will be in the 33-38 degree range with highs on Tuesday in the 47-52 degree range. Lows Tuesday night will dip down into the 32-37 degree range with the colder spots being more limited to the deeper valleys.

Dry and cooler weather is on tap for Wednesday as we remain in a northwest flow aloft as ridging develops over the Plains. We're likely to see a gradient of temperature here for highs. Readings should top out in the upper 30s to the lower 40s over the Bluegrass region with mid-upper 40s west of the I-65 in southern IN and west- central KY. Lows Wednesday night should be a bit cooler across the area with a ridge/valley split likely. In the valleys, lows in the mid 20s are possible, with upper 20s to around 30 on the ridges.

Thursday through Sunday...

Mostly sunny skies are expected on Thursday as mid-level ridging moves into the area from the west. We'll see temperatures warm up here with a southwest flow. Current blended data suggests highs in the 55-60 degree range. Given the southwest flow regime, temps may end up over performing here, so a possible upward adjustment may be required in subsequent forecasts. Lows Thursday night should be a bit milder with readings in the upper 30s to the lower 40s. Dry conditions are expected for Friday, through we may see a bit more cloud cover as isentropic lift gets going. Highs Friday look to warm into the upper 50s and lower 60s. Scattered rain showers look to develop Friday night ahead of the next weather system with lows in the upper 40s to around 50.

As we move into the weekend, a fairly decent amplification of the upper level pattern is expected over the US. This amplification is due to a fairly strong jet streak that will exit east Asia in the next few days leading to non-linear wave amplification over the east Pacific/Western CONUS by next weekend. With strong ridging moving into the west coast, a large trough axis will get carved out across the Plains while moving eastward. The Euro and Canadian have been advertising this system quite well in the last few runs, with the GFS having the wave in some of its solutions, but it's pretty non-existent in todays 03/12Z run. Given the Euro/Canadian solutions, this system sure looks to give our region plenty of showers and perhaps a few thunderstorms depending on the track of the system. Taking the models explicitly, the best shear/instability still look to remain well south of the region and the higher risk of severe weather would likely stay across the deep south. Locally, soundings show a high shear/low CAPE environment. CSU machine learning progs keep the higher severe probs well southwest of here.
Overall evolution of the system suggest it will be fast moving and that could really limit the northward transport of moisture/instability, so the progressive nature of the flow aloft will need to be monitored. Highs Saturday will be in the lower 60s with highs on Sunday in the upper 40s to the lower 50s.

Some colder air will push in behind the system, but given the pattern preceding the system, we do not have a large reservoir of cold to the north to blast in here yielding a significant winter threat. The Euro solution is likely a bit overdone with the backside precip while the Canadian looks a bit more realistic.

Extended Forecast Discussion...

The teleconnection pattern at the end of the 7 day period looks to be in a -NAO/-AO/+EPO/neutral PNA set up. The Euro EPS suggests that the NAO and AO oscillations will be trending more neutral to slightly positive with time while the +EPO and neutral PNA pattern continue. The MJO pattern is forecast to be out in the phase 4/5 by this time. That overall teleconnection set up favors an increasingly mild pattern developing across the country which should persist into mid-late December. Not only will be mild, but the pattern looks to produce above normal precipitation across much of the country.

Towards the holidays, there continues to be strong indications that the upper level pattern will translate into one that should become colder. Most dynamical models suggest the MJO will orbit through phase 5/6 and possibly reach phase 7/8 (colder) towards the Christmas holidays. However, the ensemble spread within those runs remains quite high with many ensemble members showing larger orbits in the RMM phase diagrams which could slow the progression down by a week or two. The CFSv2 ensembles have been rather consistent over the last couple of weeks with larger orbits through the warmer phases and have been delaying the phase 7/8 arrival until around New years. The Euro weeklies have continued to show height anomalies over the eastern US to become more negative by the end of the month. However, while the weeklies attempt to pop a ridge over the western US, the pattern still has a rather +EPO pattern (troughing over AK) to it and the Pacific jet remains rather strong and extended which could end up supplying modified Pacific air to much of the nation. Bottom line, while a pattern change to one that is colder has decent model support, the timing of pattern change remains quite uncertain.

Aviation
(06Z TAF Issuance)
Issued at 1249 AM EST Mon Dec 4 2023

Cirrus is moving into the region. Our next small system is advancing towards the region from the west. This will continue to slowly lower ceiling overnight. Light rain with limited duration will begin impacting area TAF sites around sunrise. LEX, farther east, will be impacted a few hours later. Winds will remain fairly light, but will be variable through the period.

LMK WATCHES/WARNINGS/ADVISORIES
IN...None.
KY...None.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Louisville, KY,