Area Forecast Discussion
Issued by NWS Indianapolis, IN
Issued by NWS Indianapolis, IN
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
318 FXUS63 KIND 091625 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 1225 PM EDT Sun Jun 9 2024 .KEY MESSAGES... - Breezy Today. - Dry with near to below average temps through Wednesday. - Warming trend beginning Thursday. && .FORECAST UPDATE... Issued at 941 AM EDT Sun Jun 9 2024 Central Indiana is under the influence of high pressure but after a sunny start for the entire region...cirrus associated with the convective cluster to our southwest has overspread much of the southern half of the forecast area. 13Z temperatures were largely in the 60s. The cirrus shield will make for filtered sunshine near and south of I-70 in particular for the next several hours but expect cloud coverage to diminish as the afternoon progresses with the frontal boundary sagging further south into the Tennessee Valley. Increasing subsidence will contribute to a decrease in clouds as well...with breezy conditions again developing as mixing levels surge to above 8kft. Northwest winds will gust up to 25mph with dewpoints falling back into the 40s over much of the forecast area. The ultimate result will be another comfortably warm afternoon with highs in the upper 70s and lower 80s. Zone and grid updates out. && .SHORT TERM (Today and tonight)... Issued at 300 AM EDT Sun Jun 9 2024 Today... Radar and obs data were showing a fine line with diminishing very light returns from near a Muncie to Indianapolis to Sullivan line at 2 AM. Th fine line was coincident with a cold front that will move into Kentucky before daybreak. In the mean time, Goes-16 IR loop and obs were indicating there was a thick stratus deck spreading in from east central Illinois, in the wake of the front. These clouds will general sink southeast with the cold front this morning and leave behind plenty of afternoon sunshine. Would not completely rule out a shower or two over far south central Indiana, this morning. This area will be closer to the departed cold front and impulses in fast northwest flow that was located around the base of a southeastern Canadian upper low. Otherwise, Hi-Res soundings were showing the low levels drying as surface high pressure gradually builds in from the Plains, providing subsidence. This should lead to increasing afternoon sunshine and allow temperatures to climb back to the upper 70s to around 80 degrees. Last but certainly not least, Hi-Res soundings are showing the potential for 25 knot northwest winds to be mixed down from 5K feet, this afternoon. In addition, model winds look way too low, so raised them. It will once again be a breezy afternoon as has been the case the past few days. Tonight... The upper trough on the back side of the southeastern Canada and northern New England upper low, will pivot south to the lower Great Lakes tonight. This will send a surface trough across central Indiana as well. Hi-Res soundings are showing an increase in sfc-5K moisture tonight. However, they also were showing dry air aloft. With forcing weak and only limited low level moisture, skies should be mostly clear. The gusty winds will quickly die off near sunset as the diurnal mixing is lost. With northwest winds in place and upper 50s and lower 50s dew points, overnight lows will bottom out well into the 50s with good confidence. && .LONG TERM (Monday through Saturday)... Issued at 300 AM EDT Sun Jun 9 2024 A synoptic pattern characterized by flow with a predominantly northerly component will keep our weather quiet through the long range. Nevertheless, there are still a few things to talk about. First, a secondary shot of cold air looks to arrive Monday morning followed by surface high pressure. Some cloud cover may coincide with this frontal passage, but the overall dry nature of the continental air mass in place should limit this. The air flowing southward behind the front is quite cold. Temperatures at 850mb look to be between 0 and 5C, which corresponds to surface highs near 70 Monday afternoon. Additionally, as high pressure builds southward winds should diminish leading to ideal radiational cooling potential Monday night. Low temperatures by Tuesday morning may dip well into the 40s outside of urban areas. Second, a pattern change appears likely towards the end of the week. While flow aloft retains a northwesterly component, low-level flow takes on a more southerly component as surface high pressure shifts southeastward. Modest warm air advection should lead to a gradual increase in temperatures through Thursday. It is possible that highs climb into the upper 80s or even near 90 by Friday. However, there remains some uncertainty regarding this. Some members of guidance are insistent on bringing a cold front through the region Thursday night or early Friday. This would act to stunt any significant warm up, at least for a few days. Some precipitation may accompany the front depending on how quickly moisture can flow northward Wed and Thur. By the weekend, ensemble guidance continues to show substantial ridge-building over the eastern CONUS. NAEFS/ECMWF situational tables depict anomalous 250mb heights by Saturday/Sunday (ECMWF showing 99th percentile heights). In this scenario the polar jet is displaced well to the north across Canada, with weak flow through the column across the Midwest. Such a pattern supports above-normal temperatures with below-average precipitation. However, guidance is picking up on a plume of tropical moisture developing far to our south towards the end of the coming week. Should this lift northward into the ridge, then we may see a few more opportunities for rainfall than one would expect with such limited synoptic forcing. CPC`s official outlook echoes this, with above-average temperatures favored with near-average precipitation. && .AVIATION (18Z TAF Issuance)... Issued at 1225 PM EDT Sun Jun 9 2024 Impacts: - W/NW winds gusting up to 25kts this afternoon - MVFR ceilings possible mainly at KIND and KLAF Monday morning Discussion: Cirrus shield associated with convection over Kentucky and Tennessee continues to shift south of the region early this afternoon with mainly scattered high clouds expected for the rest of the day. Some diurnal cu development is expected as well with overall cloud coverage diminishing further into the evening as subsidence expands across the region. With the mixing layer expected to peak at 7-8kft this afternoon...winds will remain gusty for most of the rest of the day. A sharpening of the upper trough over much of the eastern part of the country tonight and into Monday will enable lower ceilings currently over the northern Great Lakes to progress south. MVFR stratus will make it to KLAF late tonight and KIND shortly after daybreak. Lower ceilings will gradually lift by Monday afternoon as drier air advects in from the north with gusty winds likely resuming as well. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ UPDATE...Ryan SHORT TERM...MK LONG TERM...Eckhoff AVIATION...Ryan