I can’t get going on a Monday without coffee, so yesterday I clicked onto Weatherbell Site to look at Dr. Ryan Maue’s  temperature maps from the GFS model, and clicked on South America to see if the forecasts were right, and they had frost on Sunday morning. The pink in the very south of Brazil shows they did.

Brazil 1 gfs_t2m_samer_1

This is news because it is only the start of Autumn down there. It is more usual to get frost in the middle of their winter, which is July. This is like the orange groves of Florida getting frost in October, rather than January.

I got curious about the GFS forecast, so I clicked ahead through the next few days, and could see the early cold snap faded away. New Antarctic cold threatens at the bottom of the maps, but is curved to the east by the roaring Antarctic westerlies.

MONDAY MORNING  Brazil 2 gfs_t2m_samer_5TUESDAY MORNING  Brazil 3 gfs_t2m_samer_9WEDNESDAY MORNINGBrazil 4 gfs_t2m_samer_13

It has been suggested some of the farmers in Brazil have tried to grow coffee too far south. The same thing happened in the USA when some tried to grow oranges too far north in Florida, and even in Georgia. So one needs to check the map to see if this frost actually reached north to where coffee grows. Brazil 5 brazil-coffee-screen-shot-2013_07_17-at-8_35_50-am

It looks to me like the frosts were  just south of where the coffee is grown. But, if Global Warming was real, they should be able to grow coffee further south. Frost on the first of May, when the trees are just blooming, seems a good reason to avoid planting further south.

Something to think about, as I sip my second cup.



LOCAL VIEW –No Frost; No Fires–

It is a chilly morning, but not as cold as the GFS model threatened. The winds never fully died down, and out on Main Street I could see the Memorial Day flags slowly flapping on the electrical poles before dawn, making waving shadows on the street in the light of the street lights above. There were also some scattered clouds, and radar showed a few scattered sprinkles (not flurries) in the mountains to our north. The coldest temperature I could find in southern New Hampshire was 35° (+1.7° Celsius) in the low flats of Keene, well to our west. It was around 40° (+4.4° Celsius) here.

May 21 Frost gfs_t2m_b_boston_2

(A Dr. Ryan Maue map from Weatherbell. Pink areas represent freezing.)

By tomorrow the storm south of us will grow, but slip out to sea.  The weak storm northwest of us will be drawn into it.

20150521 satsfc

As the storm passes out to sea the rain will once again miss us, staying south over Cape Cod.

May 21 Frost gfs_ptype_slp_boston_7

The northeast winds will be cold, but keep the overnight temperatures less cold.

May 21 Frost gfs_t2m_b_boston_6

But after the storm passes, the back-side winds will drag down another shot of very cold air from the ice-covered waters of Hudson Bay, and I’ll worry about frost again. There’s a chance this might be record-setting cold.

May 21 Frost gfs_t2m_b_boston_10

After that the warmer airs will start to slide in, as west winds replace the north winds. I’ll be able to shift my frost-worries to drought-worries. The first chance of rain looks like it will be Tuesday, as warmer and muggier air pushes a warm front north.

May 21 Frost gfs_ptype_slp_boston_20

It looks like we might even get a half inch, which sure would be nice. Even towards the coast in Boston, which has received coastal rains and snows that missed us, they have had very little water since a drenching in December, and basically nothing in May.

May 21 Frost sn72509_1yr(2)

One odd thing I note this morning is that, despite the chill, not a single chimney in town is puffing smoke. If this was September, and temperatures were first dipping into the thirties, you can bet everyone would be getting into winter-mode, and the first fires of the fall would be cheering hearths. Now, however, no one can bother with such blazes. Everyone knows the sun will be summer-high by mid morning, and so they don’t worry about a bit of chill.

I think I am going to follow their example, and skip worry for the rest of the morning. Outside the chorus of birdsong is like a sheer gushing of noise, an avalanche, a little like someone spilled buckets of glass bottles but none of them broke.

The birds don’t seem all that worried. A small and jaunty bird is pestering a meditative crow that is trying to watch the sunrise, silhouetted atop a tree to the orange east.


LOCAL VIEW –Frost and Fire Warnings–

A secondary cold front slid past today, and temperatures fell despite the bright sun. The wind was gusty and very dry. Despite some talk of big thunderstorms yesterday, the primary front passed without much ruckus, and in all we only got a tenth of an inch of rain. That barely made any puddles, and dried up with somewhat amazing speed. The swift evaporation created a shallow overcast of flat, purple cumulus, and robbed us of our warming sun. As I shuddered in the garden I figured I’d best zip home and see if we are in for a frost.

The map’s isobars seem to show a flow straight down from Hudson bay.

20150520B satsfc

Hudson Bay is still nearly entirely ice-covered.

Hudson Bay May 20 CMMBCTCA

The most recent storm even laid down a swath of snow-cover across Ontario. Most of the smaller lakes are still frozen up there, and there is even a bit of ice left in the easternmost part of Lake Superior, though it is nearly June. No warmth is in winds from up there.

May 20 ims2015139_usa

Usually the fact the foliage is out does something that prevents frost. The leaves exude moisture when the winds die, or some such thing. So usually I’d ignore the GFS-based NWS forecast, which has a frost warning. They tend to be too cold. However it is so bone dry that I’m nervous. The thirsty trees may have less ability to resist frost than usual.

The air temperatures are still up in the mid 50’s, (12.8° Celsius) but the dew point is down to 36°, which reduces the relative humidity to around 30% . That is so dry my skin feels sort of chapped by the wind. New Hampshire has a class three fire danger, which is high. The very afternoon you might like a fire to warm by you’d be a Tom Fool to start one, because the wind could whip across the field into the neighbors yew bushes, and I don’t think they’d like that.

I’m not going to take any chances. I have piles of grass clippings in the garden, from mowing the lawn, and I think I’ll bury my tomato plants in the dry grass, just to be on the safe side. I’d complain about the extra work, but it’s my own fault for trying to get away with putting tomatoes in early. The old-timers are laughing at me from the clouds they sit on, as they never trusted New Hampshire springs, and never bothered much with their gardens until May 31.

Its odd to hear fire dangers and freeze dangers in the same forecast. The only good news is that over at the Weatherbell Site Joseph D’Aleo sees signs the pattern will get wetter next week.  I don’t see a sign of it yet, but here’s to hoping.