CAP vs CAPE

To most people, the only difference in the two is the "E".  To weather geeks, the CAP defeats the CAPE.  Please allow me to explain.  A CAP is a layer of relatively warm air aloft which suppresses the development of thunderstorms. Air parcels rising into this layer become cooler than the surrounding air, and the rising air stabilizes. As a result,  thunderstorm development is inhibited even with extreme CAPE.  Which leads me to CAPE (Convective Available Potential Energy). This is a measure of the amount of energy available for convection.  CAPE is often attained through heating of the earth's surface and high humidity during the warm seasons.  Higher CAPE guidance values indicate greater potential for severe weather. The "magic" number I look for in the modeling is ~1,000 joules per kilogram for thunderstorm development.  However, as with ALL other numerical guidance, many other parameters must be analyzed, and there are no real threshold values above which feisty wx becomes likely. 
So why this academic discussion?  Because the persistent upper level cold air is being replaced by substantially much warmer air.  I like to use the 500 mb (18,000 ft) and the 850 mb (5,000 ft) maps for this.  The map below is the forecast for the 500 mb level for Sunday night.  As you can see, there is a nice 588 isobar over PA.  That little yellow blob over northern PA is the proverbial "fly in the ointment"!  This is a little spin in the upper atmosphere that could churn out a brief area of showers or thunderstorms as is moves in the flow to the SE.  That is basically our only chance of rain now through Wednesday afternoon!

Notice how by Decoration Day evening, the upper level high pressure has strengthened to 594 mb.  This further supports increased CAP and prevents convection from developing even with surface temps very hot and dewpoints quite humid!

This dynamic atmosphere in which we live will change however by Thursday as the air aloft cools thanks to the large upper level low over Quebec.  This will push cooler air towards PA both at the surface and aloft.  Thus, a cold front will develop and spread thunderstorms towards our area by Wednesday afternoon.  But not until we hit 90ºF for our anticipated "heat wave" of at least 3 consecutive days of 90ºF or higher temps! 

The map below shows another favorite of mine and that is the "thickness" map.  No, that does not describe my skull!  This is just a snapshot of again another ever changing parameter.  As heights lower, colder air aloft is often responsible, which leads to instability, and potentially precipitation.  Height falls are more exciting for me in January when snow possibilities can be determined from these thickness maps.  You can clearly see the front and its modeled precip from the Canadian maritimes back to Arkansas.  (Did you know that Arkansas is the only state mentioned in the Bible?  I believe it is in Genesis where it is stated that "Noah looked down from his ark and saw water everywhere....!........sorry I digress!)

 By next weekend, a stretch of very nice wx should be in store for us as a large high pressure system with lower humidity and cooler initial temps will settle in right over the mid-Atlantic region.  This should set the weather stage for our BEAUTIFUL WEATHER WATCH which by the next posting might very well be upgrades to a BEAUTIFUL WEATHER WARNING for next Friday-Saturday time frame!

On a side note, I would be remiss to not thank each and every one of you for actually taking the time to click on this "blog" and read my opinions about the weather, sports, and occasionally even some politics.  It is my goal to inform, educate, and even entertain through this electronic medium.  The counter to the right indicates over 1,000 hits and yes, I do notice it.  And I sincerely thank you all for "hitting" this site.  In fact, since we did go over 1,000 hits, all of you will continue to enjoy this site free of any subscription fees!  And speaking of hitting, the only thing that stopped those suddenly hot BoSox from hitting was of course what else....the weather (14-2 over Cleveland Wednesday and 14-1 over Detroit Thursday...wow!).  While I was writing this, CCR came on XM and asked in their 1970 song "Who'll Stop the Rain?".  Well, by reading this, y'all should now be able to tell John Fogerty that the CAP will stop the rain!  The video below is this 2.5 minute classic!

Happy Decoration Day!

Smitty

AA:  Heat wave this week followed by nice wx for the end of the week.  A cold front will pass through Wednesday evening with some storms, but they do not look too severe from this point!  Enjoy your holiday my friend.

Firecracker Hot for Memorial Day

Just a brief post to confirm my suspicions for a very hot Memorial Day 2011 as the modeling is suggesting at least a 15+ temp for a max on Monday.  Normal highs for Monday are ~77F and 15+ would get us to the low 90s at least.  Rain will also be out of the equation as we will have a strengthening high pressure at all levels of the atmosphere keeping a lid on any instability and subsequent convection that may even think about developing.  The map below indicates such an anomalous max temp for Monday.

But once the feel of summer makes it presences felt, the jet will allow for much cooler air to advect SE into the mid-Atlantic from our neighbors to the north.  When the air masses change next Wednesday afternoon, we are looking at the potential for some energetic storms to quickly move through our area.  But this is good news as we are then looking at the likelihood for some beautiful wx for the end of next week.  How does sunny and 75F sound?  In fact, I'm so tired of all of these nasty wx warnings, I'm going to issue a BEAUTIFUL WX WATCH for next Friday and Saturday.....of course this is only a watch.  But once we move into the shorter range, it is likely that this watch will be upgraded to a warning early next week!  The map below shows both the European and the GFS in agreement for a nice NW flow ushering in seasonable temps for early June. 

The max temp map for the 2nd week in June indicates near normal temps or even slightly below normal for our 1st week's end in June!  This suggests that baseball fans should have good wx to take in a PA baseball extravaganza of the Phillies clashing with the Pirates at PNC Park. In fact the map below lacks much heat at all for this time frame.

As I sit here and pound away at the keys as only my Econ colleague can so eloquently paint a graphic image of, I would be remiss in not mentioning thunderstorms and severe weather.  I am experiencing very heavy rainfall with vivid lightning and gusty winds at this time....so what else is new....right?  In fact, the light show out my picture window is much more entertaining than the Phillies ugly win over the Mets!  My other compadre suggested that this has been some of the worst weather that he can remember, and he is a geezer as he utilized Hurricane Hazel (1954) as his comparison!  Well, the graphic below shows that 2011 has been very active in terms of damaging wind reports.  In fact, we have essentially doubled our wind reports in the US to this point in the season compared to our 5 year mean of 2005-2010!  Astounding!

Thursday's storms were violet, but no confirmed tornadoes have been documented in PA to this point.  The graphic below does indicate how widespread the severe wx was for Thursday and how south central PA was most certainly in the cross hairs.

Many of my attendees today shared stories concerning their experience of the nasty weather they endured Thursday night.  The unifying factor shared by all was the fact that many were "scared" from the storm, and rightly so.  The darkness that overtook Etters at 6:30 pm had me thinking ONLY BRIEFLY that maybe Camping was just a few days early!  With the increased media presence espousing the awesome power of nature, many people, young and old alike, are becoming more aware of the incredible forces of nature.  Are these recent storms out of the ordinary in terms of the frequency and intensity?  To some extent yes, (last 100 years) but human records are but a blip on the timeline of how the wx has played out here on earth.  In fact, I often find myself wondering what the Little Ice Age would have to offer or what the day to day wx would have been like walking with Tyrannosaurus Rex!  I will share this snapshot taken by a student of the mammatus clouds he observed just after the storm became intense in the Harrisburg area.  Awesome photograph!  This could be used in a textbook describing these clouds.  These clouds remind me (in name only) of days gone by of a brief encounter following a canoe trip on the DE River in NE PA! 

I hope everyone enjoys their Memorial Day week's end and for those of you wishing for the heat, it's coming in spades!

Smitty

AA:  After some unsettled wx through Saturday, and possibly Sunday, it will be getting very hot for Mon-Wed then turning beautiful for the end of next week.  Beautiful Weather Watch for next Friday-Saturday!

We're Having a Heatwave

We're having a heatwave, a tropical heatwave, the temperature's risin', it isn't surprisin'.....I can just hear Elle Fitzgerald sing away describing the weather early next week.  A heatwave is defined as 3 consecutive days of 90F+ weather and I believe that will be attained by next Tuesday assuming we hit 90F on Sunday.  I'm concerned about some lingering showers and thundershowers for Sunday, but the bulk of the rain will fall now through Saturday evening.  Both the Euro and the GFS suggest the 850 mb temps will support surface temps at or above 90F as an upper air high pressure builds and strengthens over the Mid-Atlantic.  Below is the map for next Tuesday morning showing the 850 temps and the high pressure over our region.  In fact, with westerly winds downsloping off the mountains, KMDT should hit 90F Sunday through Wednesday.  Dewpoints will also be quite oppressive during this stint of hot weather.

By next Thursday, this surge of heat and humidity will be replaced by the low that is seen above over the northern plains, moving to the ENE and dropping a cold front down across PA late Wednesday and early Thursday.  If fact, if this moves faster than projected, then 90F will not be achieved Wednesday due to the clouds from advancing storms that will accompany the frontal passage.  The map below shows the 850 mb trough carrying cooler air towards PA thanks to the counterclockwise circulation around the low over Quebec.

By next weekend, it appears as if PA will be under a NW flow ushering in "normal" temps with low humidity, weather that would be described as ideal by many for this time of year.  However, once the heat comes up "over the top", another surge of "dry heat" may be moving in on NW flow which is not too unusual for the summer season.

As many of you are aware, there was yet another bout of severe wx here in PA Thursday evening.  In fact, 3 tornado WARNINGS were issued for our area Thursday afternoon and evening!  This is just some of the energy that ravaged the mid-west earlier this week as this potent storm grinds its way to the northeast and wreaks its weather havoc over the eastern 2/3 of the US!  The graphic below shows the severe storms report in the last 24 hours.  We will have some feisty storms yet again Friday afternoon.  This low level heat and humidity coupled with the cold air aloft and at the surface to our WNW (it was 48F in Chicago at 6 pm this afternoon) will once again do its dirty work and create heavy weather in our immediate area.  Unfortunately, I do believe that there will be numerous "lightning delays" at the state track and field meet both Friday and Saturday.

As for us this evening, Etters dodged the proverbial bullet, unlike the apple below.  We had some wind, heavy rain, but no hail, minimal lightning, and quite frankly were very lucky.  I hope all of you came through as unscathed as we did here in the metropolis of Etters, PA.

Enjoy your Memorial Day Week's end!

Smitty

AA:  Storms Friday and Saturday....maybe even Sunday, but getting hot and humid for Monday-Tuesday-Wednesday....then normal and "nice" wx for the end of next week!

Tough Call for Memorial Day Weekend

The modeling has been anything but consistent for this upcoming holiday weekend!  Numerical guidance often struggles with cut-off lows and a change in the pattern.  Both the Euro and the GFS have flip-flopped their solutions numerous times over the last couple of days.  Even when closely scrutinizing the individual ensembles from the GFS, they too are "all over the place" in terms of their solutions.  This is very typical as well in the summer months when timing of individual disturbances becomes very difficult as the wavelengths of the global Rossby Waves shorten and the embedded vort maxes are weaker.  One thing, however, that the modeling does agree upon is by the end of NEXT WEEK, a bona fide surge of heat and humidity will be ushered into the northeast thanks to a building and strengthening ridge.  Our first 90F looks to be VERY LIKELY by the 3rd or 4th of June!  The maps below show both the Euro and the GFS and their mostly agreed upon solutions:

If you look closely at the 2 above, you'll notice some differences, especially with the height of the ridge in the Pacific.  That does have major implications for the west coast of the US and potentially here in the east....but that can be a different story for a different day.

I am also attaching the total precip from the GFS for the next 8 days.  One can see the Ohio Valley is the hot spot for active storminess and some of that will spill into PA.  It appears as if the bulk of that precip will fall in our area in the Friday-Sunday time period, but again, the timing is very difficult to pinpoint as to which day looks to be the wettest.  I do feel confident, however, that as we progress through the weekend, the chances for precip will actually decrease but I could buy the fact that measurable rain will fall each of the days over the holiday weekend.

One way to look at the map above is that for areas in red, this is much above normal for precip.  For agricultural interests, this would cause planting and harvesting issues along with having yield implications.  So below are planting progress maps for both corn and soy in the heartland of the US.  It is clearly apparent that planting is behind the times as shown with the 5 year mean number.  Both corn and soy are about 10% behind normal planting progress.  Couple that with the idiotic mandate from the feds that bio fuels (ethanol) must be increased in gasoline over the next several years and this could lead to a quick futures commodity trade profit for those willing to take such a risk.  Again, please understand that this is for general information purposes only and those who do use it for investment purposes should check first their sanity and secondly their bank accounts.

 And now the soy map.....if I was any good with photoshop or GIS mapping, I would overlay the precip on both of these maps and you could compare the 2 as to precip coming and planting progress of the soft commodity.  But you'll just have to eyeball it the old fashioned way!

To me, and I'm sure you'll agree, the planting will be further delayed over the Ohio Valley and the bulk of the corn and soy belt thus producing a corn and soy opportunity for futures contract investments.......or not!  One thing to be sure, Chase Utley was back in the Phillies line-up last evening.  He had an 0-5 night at the plate (since he's on my fantasy baseball team!), but his presence in the line-up allowed the others to see more/better pitches and the Phillies looked like the team to beat for the remainder of the summer.

Have a good mid-week!

Smitty

AA:  Tough call on the weekend....looks like rain will threaten at almost anytime, and yes, even at states.  But, next week appears to have a surge of heat and humidity that would make mid-July proud!

Euro Modeling Paints Ugly Memorial Day Weekend

I will try to be brief.  Really!  The map below shows the GFS depiction of this upcoming weekend's upper air anomalies.  This run was from Saturday morning.  Note the area of "warm" colors over PA.

Now, 12 hours later, the GFS is hinting at a less than desirable solution as it begins to cut-off an upper air low over the lower Miss Valley.  This would lead to cooler and wetter than normal conditions for the upcoming holiday weekend.

Meanwhile, the Euro (seen below) is indicating a deep trough over the eastern US with just simply ugly sensible weather implications for the weekend.  The Euro had an even stronger trough in its previous run but nonetheless, a cut-off low from the main jet, which is scooting through southern O Canada, will make the weather here in PA ugly........AGAIN!

If the map below verifies, we are looking at a deep fetch of moisture from the tropical Atlantic which could lead to copious amounts of rainfall over the Memorial Day Weekend.  The 1st part of the weekend looks OK at best as a cold front will pass through on/about Friday.  Saturday could be the day to get the lawn mowed, garden weeded, state track & field events completed, etc. as by Sunday, the weather looks to quickly deteriorate.  The 850 mb low looks to be centered just to our west leading to a favorable low level jet region to give us ample opportunity for rainfall!

The last map is a 500 mb look for the same period.  It too shows the cut-off low over the Ohio Valley and portrays U-G-L-Y, you ain't got no alibi weather for us here in PA.  If it is any consolation, the Pacific NW will also be experiencing UGLY weather with a deep trough off the coast.  I was watching the SF Giants broadcast the other evening and the announcer stated that he can't remember a May that has been this wet and cold for them in SF!  It's that global warming thing you know!

And this rain will fall on already saturated ground!  Below is the soil moisture map:

Well don't shoot the messenger.....I'm just trying to give a possible "heads-up" to some potentially heavy rainfall and possible wet basements and flooding streams for the holiday weekend.  On a lighter note, no triple crown winner again this year.  But if you thought that Shackleford with his speed could be at the line first when the mile and 3/16 were completed and hold off all the closers, then you were smiling after Maryland my Maryland!  Note how clean the boy looks in the photo below as he and Flashpoint lead every call including the most important one with his wire to wire finish!

Have a good work week!

Smitty

AA:  Warm and summer-like with some T-storms early week, followed by cooler and damper as the week progress.  Saturday could be nice for states.  Could get quite ugly around here for next Sunday and Monday....and a few days beyond!