• Category Archives GFS
  • Model Data Remains Consistent On A More Active Pattern Returning…

    Today’s 12z model suite is in and it remains consistent on a more active weather pattern returning to the delight of many Hoosiers! A blend of the GFS and European 10-day rainfall numbers print out 2″ for Indianapolis.  The GFS ensemble ‘mean’ (a blend of 21 individual members) agrees.

    Best overall coverage of showers and thunderstorms should come in (3) waves over the upcoming 10-day period:

    • Wednesday into Thursday
    • Saturday into Sunday
    • Middle parts of the following week

    While we don’t see any sort of uniform type rains in the upcoming period, the “smattering” of storms should help most neighborhoods get in on the rainy “goods” at one time or another over the upcoming week and a half.  Keep in mind, we’re in mid-June now and it’s mighty difficult to ask for anything much more than scattered storms this time of year on through late-summer…unless a tropical entity gets involved.  That’s just the way this time of year is.  With that said, localized torrential downpours are a very good bet from time to time, beginning as early as mid-week, as precipitable water values approach, or exceed, 2″ (about as moisture-rich as you can ask the air mass to get around these parts) into the upcoming weekend.

    As I type this outside on the back porch this evening, I hear the sounds of sprinklers in full-force through the ‘hood.  Thankfully, Mother Nature will help save on the water bill later this week.  Longer-term, you’ll hear us use the word “transient” many times this summer when discussing the overall weather pattern.  Thankfully that tends to result in a fairly busy time of things.  Before you know it, college football season will be back (83 days until my beloved Auburn Tigers kick-off), those wetter autumn storms will return, and thoughts will begin to shift to winter (they may have already started here :-))- not that we’re trying to rush summer away or anything…


  • Developing Hot Pattern Doesn’t Last; Cooler And Wetter Times Loom…

    Through the short-term, there are two words that will sum up Indiana’s weather: Dry and Hot.  We’re entering a stretch where the overall weather pattern will promote an expanding hot dome in the coming days, and put many communities across the state solidly in position to break the 90° mark on multiple days.

    Expanding upper ridge means hot times loom late weekend into early next week.

    However, this increasingly hot and dry pattern will be a transient one.  This morning’s European model shows the evolution to cooler and increasingly wet, unsettled times nicely as we progress into the 6-10 day period.

    The GFS ensemble would also agree in the overall pattern shift back to cooler and unsettled conditions as early as mid-late next week.

    The 10-day GEFS ‘mean’ is a beautiful sight as moisture returns.

    Updated 7-day out later this afternoon!  Enjoy a beautiful Saturday, friends!


  • February Tug Of War…

    With data only encompassing the first couple days of the month, February has gotten off to a warm start.  As we know, the trend over the past 24 hours has been colder and this will continue as we open up the weekend.

    conus_mtd_t2max_anom_2017However the cold air won’t last and milder times will return by the second half of the weekend.  This back and forth “tug of war” type regime will remain as cold and warmth (relative to average) continue to battle over the upcoming couple weeks.  The latest European ensemble shows this nicely.

    EPS2317This also favors a rather active pattern and confidence is high on a wetter than average period upcoming over the next couple weeks.  See the GFS ensembles support this idea.  A couple strong storms are also possible Tuesday.

    gfs-ens_apcpna_us_4Unfortunately for snow lovers, the majority of significant moisture should fall as rain.  Best snow chances appear to come with “backlash” wrap around snow showers and squalls Tuesday night into Wednesday morning.  Accumulating snow is possible, but most amounts should be light.  We’ll keep an eye on it.

    gfs_ptype_slp_conus2_19Longer-term, the fight continues deeper into the month.  As mentioned this morning, teleconnections and analogs would suggest cold and wintry conditions, but modeling sure isn’t going in that direction as of yet.  The battle rages on and given the trends of the winter, it’s hard to bet against the warmer solutions, albeit with lower confidence than we’d like to have from this distance.


  • Confidence Increasing On Leader-Follower Event; But Details Murky…

    A look over model data from overnight suggests we need to focus on a “leader-follower” event for the upcoming weekend.

    We’re confident the “leader” player is a rain maker for IN in the Thursday afternoon-Friday time frame (.40-.70 rainfall potential).

    Source: Tropicaltidbits.com
    Source: Tropicaltidbits.com

    As we progress into the second half of the weekend, details get quite murky on the specifics with the secondary (follower) area of low pressure that develops along a pressing arctic front.

    As we’ve been discussing, model solutions will vary within each respected model (GFS, Euro, GEM, etc.) in a run-to-run fashion.  Stack them up against one another, and we’ll likely continue to have as many different solutions as we do models that we’re looking at.  It’s a byproduct of a pattern transition and that crashing SOI (which is still crashing this morning, btw).  Case in point, note the various options below for Sunday.

    The GFS takes a low from southern AL into the coastal plain of NC. Source: Tropicaltidbits.com
    The GFS takes a low from southern AL into the coastal plain of NC. Source: Tropicaltidbits.com
    The Canadian is a blend of the GFS and European as it tracks low pressure from eastern LA into the central Appalachians. Source: Tropicaltidbits.com
    The Canadian is a blend of the GFS and European as it tracks low pressure from eastern LA into the central Appalachians. Source: Tropicaltidbits.com
    The European is most aggressive in the west track as it takes low pressure from the MO bootheel into northern IN. Source: Tropicaltidbits.com
    The European is most aggressive in the west track as it takes low pressure from the MO bootheel into northern IN. Source: Tropicaltidbits.com

    Past experience with similar patterns certainly leads us to lean more towards the European/ Canadian solution over the GFS from this distance.  We know that models have their own biases though.  Time and time again the GFS bias is to rush things along a bit too much from this distance and become too progressive.  On the flip side, the European is notorious for dragging it’s heels a bit and, at times, can be too slow with bringing energy out of the west.  This in return impacts things downstream…

    From this distance, we still can’t be too specific with snow/ precipitation prospects Sunday.  While confidence is increasing on at least some sort of snow to contend with, the significance of such isn’t possible to iron out at the moment.  Much fine tuning will be required.  Stay tuned.


  • Periods Of Heavy Rain…

    Saturday will dawn dry across the region, but that will quickly begin to change as morning progresses into afternoon. Moisture is streaming north and a “wavy” frontal system will remain draped across our region through the weekend into early next week before a surface low finally sweeps a cold front through here Monday evening.

    Forecast radar, courtesy of Weatherbell.com, shows rain expanding in coverage this afternoon.

      
    Periods of heavy rain will fall across the region between this afternoon and Monday. 

       
       
    We note precipitable water reaches in excess of 1.5″ and adds to our confidence of heavy rain coming. Note also the true GOM connection with this storm system.

      
    Models agree on heavy to excessive rains falling with widespread storm totals between 3″-5″.

       
       
    The storm system will finally begin to pull away Monday night, leaving drier, breezy, and cooler air in it’s wake. 

      
    The true push of cold air awaits until the end of the week.

    Your full 7-day outlook can be found here.


  • Where We Stand…

    Some are beginning to grow tired of the seemingly unending warmth and lack of snow, particularly with an above normal stretch of weather coming that includes the Christmas holiday (though not nearly as warm as the European suggested as soon as only a few days ago).

    Month-to-date, December has been a warmer than normal month for most of the country. Source: Weatherbell.com
    Month-to-date, December has been a warmer than normal month for most of the country. Source: Weatherbell.com

    Our winter outlook stated we thought we’d get off to a warmer than normal start, but we were also very clear in stating we thought a rather marked shift to more sustained wintry conditions loomed for mid and late winter.  That period is drawing closer by the day and it’s time to “put up or shut up.”  By “mid winter” we mean mid January.  Yes, that means three weeks out.  Without holding back any punches, we’re fully expecting a colder than average period developing by then (and with staying power), along with plenty of opportunities for wintry precipitation.

    You can read our full winter outlook (published in October) here.

    The reasoning for our thinking has been outlined in previous posts and in our winter outlook, but, in short, it’s built on the idea of a weakening El Nino and a mean winter upper air pattern that includes W NA ridging (positive PNA regime).  Later in the season, a more sustained negative AO and NAO should establish itself that could carry the wintry regime into meteorological spring.

    Current Sea Surface Temperature Anomalies
    Current Sea Surface Temperature Anomalies

    We think we begin to progress into a “step down” process to the pattern explained above through the early stages of January, and the ensemble data is beginning to support this.

    GFS ensembles for early January. Source: Tropicaltidbits.com
    GFS ensembles for early January. Source: Tropicaltidbits.com

    The modeled W NA ridging is a far cry from what we’ve been dealing with over the past month.

    Now we caution that the initial step down to a more sustained wintry pattern won’t occur overnight.  We label it “step down” for a reason.  All the while, it’s a start in shifting away from the anomalous warmth we’ve been dealing with through the month of December.  Initially, cold air will only be marginal, but as things align into the mid/ late winter pattern and we expand snow cover, arctic air will grow in a more widespread fashion.  Something else we’ll begin to have to keep a close eye on?  A potentially active NW flow that features several clippers plenty capable of producing accumulating snow.  We note central-based Ninos are notorious for the clipper parade during the mid and late winter stretch.

    In the shorter term, a rather unsettled Christmas week looms.  Modeling will continue to “sure up” the handling of a rather complex storm system after Christmas, as well.  We note runs that have pumped out copious rain numbers and others that suggest wintry precipitation may fall as the cold upper low ejects northeast.  We’ll continue to monitor.

    In the meantime, gear up for a rather wet Monday.  We think one half inch is a good bet across the area, with locally heavier totals.  Our updated 7-day in the morning will be a rather busy one.  Talk with you in the AM!

    hrrr_t_precip_indy_16