From the cold 40s, rain and even snow last weekend across New England, 50s and 60s from Boston to DC, it’s now all about the HOT, HAZY and HUMID with highsd into the 90s! What a way to commence June and the official start to meteorological summer 2013 after a downright cold spring.

What a difference a week makes. Remember back to last Saturday when as much as 36 inches of snow fell at New York’s Whiteface Mountain, over a foot fell at Mt Mansfield, VT while there was over 6 inches of rain fell in Burlington with roads washing out with the 2 month’s worth of rain in 5 days. Burlington by the way may top 90 today after a high of just 46 last Saturday. It reached 88 there yesterday.

Speaking of wild temperature swings, Mt Mansfield, which saw it’s biggest snow so late, on record, recorded a high of just 31 last Sunday. The high there yesterday reached 70 and today may push 80.

New York City last Saturday was stuck at 50 degrees at noon. Today at noon it will be close to 40 degrees warmer as the high pushes 91-93 in the park!

Differences between last Thur, Fri and Sat and yesterday and today.

Last Thu/Fri/Sat         Yesterday             Today

Burlington, VT                       46                            88                       90

Syracuse, NY                          50                            87                        90

Boston, MA                             54                            88                       92

New York, NY                         54                            90                       92

Philly, PA                                 64                            93                       94

Baltimore, MD                        65                            92                       92

Here’s the difference between last weekend and today with the ECMWF upper chart and 5,000ft temperatures.

Last weekend.

Today.

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Complete turnaround. It’s like the Northeast has went from the winter that doesn’t want to quit, straight to summer in just 5 days.

Here are yesterday’s highs across the country.

As the trough slides slowly east into the Ohio Valley with a line of strong storms rumbling northeast along the front and a heat core centred over the Mid-Atlantic coast, you’ve got a strong SW flow which should raise temperatures over the Big Cities today beyond those of yesterday. Philadelphia may push 94, New York 93 and Boston where it got up to 88 yesterday, may approach 93 today. The typical urban-induced hot spots of Newark and LaGuardia may reach 95 today.

However, while summer is off to the races in the Northeast, fall-like cloud, rain and temperatures will make for a dreary day over the western Dakotas and much of Montana.

Here’s today’s surface/precip chart off the GFS.

Note the heavy precip along the front where severe weather will erupt this afternoon into this evening. A low centred on the North and South Dakota line with pressure down to 992mb is drawing chilly air out of Canada and as you can see, also a lot of rain on the north and west side. The cloud, chilly winds and rain will hold afternoon readings in the upper 40s, low 50s across eastern Montana and the western Dakotas. 60s on the east side of the low in cities such as Fargo.

Here are today’s highs forecasted by The Weather Channel.

Northeast

Northern Plains

Temperature departures from normal.

Severe weather remains ongoing across the Plains and today we’ll see a heightened risk from Oklahoma City up towards St Louis with even a risk up into the Chicago area.

Here’s today’s risk according to the SPC.

The risk drifts east through this weekend as the front continues it’s eastward march. Eventually the front will reach the Big Cities Sunday afternoon but perhaps not before temperatures make it into the 90s for a 3rd straight day in New York City.

Here’s tomorrow severe risk.

Sunday

Notice the heightened risk over the Northeast.

As you would expect, rain totals will be high over the ‘storm corridor’.

Here’s the latest QPF chart for just the next 72 hours.

This weekend will see the cool air drop into the trough which deepens and drops down over the Great Lakes. This cool, dry air mass will eventually reach the Northeast and the DC to Boston corridor should enjoy 70s and low 80s by Monday.

Interestingly the GFS surface/precip chart is SLOW with the front reaching the I-95 corridor as the bulk of precip remains to the west late Sunday and even by Monday morning.

Before the boundary arrives and cleans the air out, we’re likely to see pre-frontal showers and storms which will locally cut down the heat but Sunday could well be another hot one from DC to Boston with an increase in storm activity. Notice the clear out of the atmosphere over the central part of the country.

Skipping out to next Wednesday and notice the difference over the Northeast once the front clears the coast. A nice refreshing air mass returns.

Major Heat Builds Over Southwest

While the atmosphere over the Central and eventually Eastern half of the country gets cleared out, a ridge will build this weekend over the Southwest. The hottest air mass of the season will build with upper heights rising towards 584-588dc. This depth of sink and the dry air over the desert should support surface temperatures this weekend to reach record or near record levels over southern and central California east through the Desert.

How hot may it get?

The heat builds Saturday through Monday but at it’s peak, I believe Downtown LA should see a couple of days in the 90s, 98-102 in coastal valleys of SOCAL, 100-105 in the central valley, 108-112 for the low desert including Palm Spring, Thermal and Phoenix, 103-106 in the upper desert including Barstow and Las Vegas and a sweltering 118-121 in Death Valley.

This heat will extend into early next week but should get tempered as low pressure swings into the PNW which shall trim heights back over the Southwest.

Tropical Development In The Gulf Late Next Week?

After enhancing heavy rain and storms over Mexico much of next week, a feature pushes out over the warm waters of the Bay of Campeche and modelling shows development. In a recent post looking more closely at this, I showed the favourable MJO pulse which makes this scenario very plausible with lowering pressures throughout the Caribbean and Gulf and the enhanced convection.

Development later next week is looking more and more likely. See my post which looks at the current conditions which favour an early season system in detail.

Here’s the latest GFS which shows low pressure forming over the central Gulf next Friday.

This is 192 or next Saturday.

By 216 or next Sunday, the GFS takes the system into the Fla Panhandle perhaps as a depression or even a weak storm. This would be a significant rain producer if anything.

One must also consider the possibility of an Appalachain/East Coast heavy rain and flood event if this thing were to run north.

Hope to have a detailed write-up on this situation later. Stay tuned.

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Tags: Gulf tropical development, May Heatwave, Meteorological Summer 2013, northeast heatwave, Southwest Heatwave, Tropical weather, us weather