Monitoring Prospects For Heavy Weekend Rain…

A combination of ingredients are coming together to offer up the potential of heavy rain for portions of the region this weekend.

An approaching cold front will drop slowly southeast out of the Plains while a tropical low moves inland from the central Gulf Coast.

Wknd8:13The precise placement of the front will serve as the focal point for heavy weekend rains.  As we’d expect from this distance, modeling disagrees on the all-important specifics.  Using a model blend, central Indiana is on the table for heavy late week-weekend rain as of now.  Precipitable water values (PWATs) will be above 2″ and suggest the threat of torrential downpours, including localized flash flooding across the Ohio Valley.  Eventually, the cold front will sweep the tropical-rich moisture away from the region and cooler, much less humid air will press in by this time next week.

We still have time to watch the evolution of things play out as we progress through mid week. Stay tuned as we “sure-up” the details and hone in on the area where heavy rain is likely.

Thursday Evening Rambles…

1.) A big ole ridge will supply oppressive heat and humidity across the Mid West this weekend.  Unseasonably hot temperatures will combine with downright “soupy” air to create heat indices between 105-110 degrees across central IN this weekend.  Take it easy and implement frequent breaks if your plans take you outdoors.

HeatIndex

2.) Similar to what we’re seeing on radar this evening, thunderstorms will also make an appearance from time to time for some.  With an atmosphere loaded with moisture, any storm that develops will be plenty capable of producing “frog straggler” type rainfall rates.  Perhaps there will be a couple periods of more concentrated storm activity, focused on late tomorrow night and early Saturday, and again late Saturday night-Sunday morning.  We’ll keep an eye on things.

LateFriNight

3.)  The pattern is one (as has been the case all summer) that’s transient and the situation that develops to wrap up July and open August is an all-too-familiar look around these parts: NW flow aloft that offers storm potential, along with seasonal to slightly warmer than average.  It’s a wet look, overall.

WetPattern

10-Day GFS rainfall numbers are impressive across the Mid West. Soaking rains for many. Courtesy Weatherbell.com
10-Day GFS rainfall numbers are impressive across the Mid West. Soaking rains for many. Courtesy Weatherbell.com

This is what the upper air pattern should look like as we close July- 10 days from now (hard to believe)!

July31st

4.)  Looking further ahead, the latest JMA Weeklies continue to suggest the most sustained hot pattern should remain across the west as we rumble deeper into August.  That’s not to say we won’t deal with periods of hot weather here at times, but sustained heat will be hard to come by with such a pattern…

Screen Shot 2016-07-21 at 7.48.29 AM

Screen Shot 2016-07-21 at 7.48.39 AM

Heat Builds Late Week, But Doesn’t Last…

The pattern remains in a transient state.  An upper ridge will build over the region late week into the weekend.  With this will come the hottest air of the season (multiple days of lower to middle 90s starting Friday, continuing into early next week).  The hottest days appear slated for Friday and Saturday.  Heat indices will approach 105 degrees.

However, just as fast as the ridge builds over the area, we see the “want” to position itself over the Rocky Mountain region.

Hot dome will provide a couple days of highs in the middle 90s Friday-Saturday. Image courtesy of Tropicaltidbits
Hot dome will provide a couple days of highs in the middle 90s Friday-Saturday. Image courtesy of Tropicaltidbits

3

 

Note the difference of the ridge position by Day 10. Courtesy of Tropicaltidbits
Note the difference of the ridge position by Day 10. Courtesy of Tropicaltidbits

4While some oppressive heat and humidity will impact our local area to wrap up the work week and head into the weekend, this is a pattern where it’s incredibly difficult to deal with any sort of one particular weather pattern for any time of substance.  Looking forward to August, we don’t see this changing.  Remember that word we leaned on to begin summer? “Transient” remains the best way to describe the pattern moving forward, as well.

Additionally, this is a pattern that should result in a return of wet and active times as we put a wrap on July and welcome August.  It’s impossible to nail down the precise details of any one particular neighborhood’s rainfall numbers from this distance, but understand the pattern is one that should yield more locally hefty rains in the weeks ahead.

WetTo close, we’ll leave you with a look at the latest PNA pattern.  This has been the primary driver of our weather this summer, and it also argues any sort of dry, hot weather doesn’t last.  Note the positive PNA returning to close July.  This also lines up well with our idea of unsettled times returning…

Screen Shot 2016-07-18 at 5.58.35 PM

PositivePNA

Hot, Drier Pattern Awaits…

We’ve been relatively spoiled so far this summer- both in regards to temperature and precipitation.  That said, as we approach the second half of July, things appear to be changing for the hotter and drier side of things.

July, so far, has been very pleasant, locally.  BTW- another push of drier air is inbound that should lead to a nice weekend, including low humidity values.

1Ensemble data continues to suggest that the mean ridge position (hot dome) develops over the eastern portion of the country early next week before slowly retrograding northwest with time.

2By the middle and latter portions of next week, the hot dome is set up in a position that will yield an extended stretch of hot temperatures across the state, including multiple mid-90 degree highs across central IN.

3

4Given the current look of the ridge position, this would also be a rather dry pattern, as well, as the storm and rain track would shift north across the Canadian border into the northern Great Lakes states.  (Follow that 588 line above for a good indicator of the storm track).

gfs-ens_apcpna_us_8One always has to be careful in trying to predict the timing of the ridge breaking down/ overall placement this time of year (models can struggle), but for now it appears as if we really heat things up and dry things out as we move through next week- especially the middle and latter portions of the week.