WEATHER CONDTIONS FOR THE GREAT

AMERICAN ECLIPSE 21 AUGUST 2017

based on the data SUNDAY AFTERNOON 8/13/17

SUMMARY

Over the past few days I have been issuing daily forecasts with regard to the great American eclipse on Monday August 21. If you do not

know by now Solar Eclipse will occur across much of the country with a spectacular long lasting totality sweeping across the country from

the Pacific Northwest to the Southeast US on the 21st. It will begin Monday late morning and last through the midday hours into the

afternoon. Obviously the main concern is going to be weather conditions. Some of you may be looking at various web sites on the Internet

or your smart phone or social media to get weather information. As a professional meteorologist of more than 25 years experience, I

can tell you that the weather information you get on your smart phone, social media or on various web sites which contain

temperatures, cloud cover, winds and precipitation beyond day 3 or 4 days is pretty much useless Crap. .

For those of you that did not know me .. I am a Grain or agricultural meteorologist. This means I deal in the commodity markets

quite extensively and if you know anything about the commodity markets or agricultural weather in general, then you know that

what matters is not the forecast for today or tomorrow. What matters is the forecast 3 days, 5 days, 8 days, 12 days 30 days

out into the future. As a result I spent my entire time forecasting behind the next 48 hours and I am very good at

This is important because the fact of the matter is that your local NWS forecast office gives the " extended forecast" the lowest priority

and effort of any of their forecast products . And the dirty little secret from the TV weather world is that most TV weather personalities and

meteorologists would rather not do 5 day or 7 day forecast. The only reason they do so because the news directors demand that they do

so. Most of TV weather folks (not all most) do not like making extended forecasts and they are not very good at it. (why exactly the

not very good at it is a whole different kettle of fish).

For this forecast I have divided the country up into several sections based upon geography and climate and the current weather

pattern. This makes it easier to break the forecast down into a readable format so that you, the average person, can understand what is

going to happen on August 21. Hopefully these forecasts will enable you and others to understand which areas of the country are likely to

see spectacular conditions for the solar eclipse , which areas are likely see so so conditions, and which areas are likely to have real

problems.

There are images and model data out there which can be presented which shows the overall cloud cover for Monday midday across the

continental US (conus) . However these are model projections from forecasts which are 8-9 days away and not very good. The model

guidance should be looked at but there is more to making a extended forecast than simply looking at whatever the model data is showing.

These forecasts rejections are based upon the model data from Sunday afternoon mainly the European model at 12 the but there is

some input from the Canadian GFS models.

Image #1 one refers to the overall Upper air pattern Sunday night August 20. I have highlighted two important aspects to the overall pattern

without getting too scientific. First is Feature A which represents a strong trough over southwestern Canada which is trying to push towards

the U.S./ Canadian border. I have highlighted a portion of the jet stream which is moving down from Canada across the Idaho Montana and

North Dakota. This trough and the Jetstream associate will bring increased cloudiness to portions of Idaho and Montana and possibly

into during the day on August 21.

FEATURE B is a strong UPPER LOW which is situated over the Southeastern U.S. In addition because there will be a fairly strong

western Atlantic Ridge (also known as the Bermuda HIGH) there will be a strong inflow of Southeasterly winds bringing moisture and

increased likelihood of significant showers and thunderstorms from Georgia to Virginia and into Pennsylvania and southern New Jersey on

August 21. Unless this change, this is likely to impact the viewing conditions across the Carolinas significantly.

IMAGE #2 shows the overall pattern on Monday morning August 21. Both features A and feature B are still there. In addition there

are small additional pieces of energy moving into this upper level disturbance from Missouri . As a result the European model forecast

maps show enhanced showers and thunderstorms on Sunday morning stretching from Maryland down to Georgia. Given the high level

inflow of humidity, and high dew points, it is quite likely that most of the Southeastern states will be overcast throughout the day on Monday,

August 21 which will greatly impact viewing conditions.

Indeed the European model total cloud cover image shows this quite nicely.

Over the central portions of the country there will be a weak cold front associated with that trough over south central Canada which will

cause some clouds across the Dakotas and Minnesota but for the central portions of the country this feature should not have any real

threat to blocking out good viewing conditions .

Over the Rockies however the jet stream associated with the trough over south central Canada will cause the areas of significant cloudiness

for some locations. But it will not be widespread overcast and they will be breaks the clouds and some areas could see 50 to 60% sunshine.

By Monday afternoon at the height of the eclipse the European model continues to show significant showers and storms stretching from

Maryland to Georgia. This is not good for those hoping to see optimal the viewing conditions over the Carolinas. West of the Appalachian

Mts a viewing conditions will be much better because the low level moisture coming in from Southeastern states will have great difficulty

in crossing the Appalachians.

As a result of viewing conditions in areas such as Tennessee and Kentucky could do significantly better than what we see over the

Carolinas.

ACTUAL FORECASTS

First keep in mind that because THIS solar eclipse will occur during the middle portions of the day... clouds

conditions near the horizon or at the lower portions of the sky will not have much of an impact upon viewing conditions

when eclipse conditions get underway. This may seem obvious but keep in mind that there are many solar eclipses

which occur near / close to the horizon during the morning or late afternoon hours. In this case that will not be issue.

That being said we are using 4 categories for viewing conditions with regard to eclipse

OPTIMAL 85% of the time will overhead sky conditions will see either no clouds or a few small minimal clouds during the time

of the solar eclipse

GOOD 60 to 85% of the time will overhead sky conditions feature either no clouds a few clouds that could interrupt

otherwise near ideal viewing conditions during the time of the solar eclipse. That also means 15-40% of the time there will be

some clouds that could cause interruptions for a few minutes

MARGINAL 35-60% of the time will overhead sky conditions feature good viewing conditions. There will be intervals of a

few intervals of sun and no or few clouds around the sun but these intervals wont last long and will not be very common. This

also means 40-65% of the time there will be clouds over the central portions of the sky that could cause several minutes (or

longer) of interruptions for viewing the eclipse.

POOR only 5 to 30% of the time will over head sky conditions will feature good viewing conditions . There could be a few

intervals of breaks in the clouds around the sun which will allow for a good view of the eclipse but these intervals wont last

long and will not be very common. Most of the time the eclipse will not seen. 70-95% of the time there will be clouds over the

central portions of the sky that could cause several minutes (or longer) of interruptions for viewing the eclipse.

OREGON IDAHO

Viewing conditions in Oregon for most areas should be in the GOOD category. Locations on the southern half of the path of totality may

have slightly better conditions -- areas such as Corvallis and Eugene Redmond and Baker City and La Grande

IDAHO

Viewing conditions in Idaho will vary between GOOD and MARGINAL. The data clearly shows there will be some cloud cover over central

and southern Idaho but it may not be particularly dense/ heavy.

WYOMING

As we move into Wyoming the the track of the solar eclipse begins to bend to the southeast which means we are moving away from the

strong jet stream over the Pacific Northwest. This means that the eastern areas of Wyoming will probably have GOOD to OPTIMAL view of

conditions while the western portion of Wyoming close to the Idaho border will have GOOD to MARGINAL viewing conditions.

NEBRASKA

Based upon the current data Sunday afternoon it looks like Nebraska maybe one of the best places to see the eclipse with the few if any

clouds and OPTIMAL conditions. But conditions in far northeastern Kansas far southern Illinois and Missouri will also pretty darn GOOD

as well. All the data that I see keep most of northeastern Kansas and central Missouri into southern Illinois to be clear of any significant

clouds during the time of the maximum solar eclipse.

KANSAS MISSOURI southern ILLINOIS

Based upon the current data Sunday afternoon it looks like Nebraska maybe one of the best places to see the eclipse with the few if any

clouds and OPTIMAL conditions. But conditions in far northeastern Kansas far southern Illinois and Missouri will also pretty darn GOOD

as well. All the data that I see keep most of northeastern Kansas and central Missouri into southern Illinois to be clear of any significant

clouds during the time of the maximum solar eclipse.

KENTUCKY TENNESSEE

Things get a little tricky in eastern Tennessee but still look pretty good in western Kentucky and western Tennessee. The further west you

are, the better viewing conditions you will have. There is going to be rain and clouds across the Southeastern states up into Virginia

Maryland Delaware Pennsylvania New Jersey on Monday, August 21. Some of the cloud cover from that rain will probably push across the

Appalachian Mts and impact viewing conditions in portions of EASTERN Tennessee. Again the further west you are the less clouds and

the further east you are the more clouds. based on the current data, eastern Tennessee is the most difficult area to forecast. Right now

most of the model data keeps eastern Tennessee in GOOD viewing conditions but it is possible conditions could worsen if the clouds

push across the mountains. Western Tennessee and West Kentucky look to be in either GOOD to OPTIMAL viewing conditions.

SOUTH CAROLINA NORTH CAROLINA GEORGIA

Viewing conditions here look POOR... In fact they look downright awful. The position of the Upper Low as well as HIGH pressure off the

Southeast coast will set up southeast winds feeding moisture into Georgia, the Carolinas, Virginia, Maryland, Delaware. and up into

Pennsylvania and New Jersey. Some of the data suggest it could be overcast and rain most of the day over the Southeast. It is still

possible that this portion forecast could change or they may be some breaks in cloudy conditions over the mountains of North Carolina but

this is clearly the least favorable area for for viewing the eclipse across the continental US.

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