July 2012: hottest month in U.S. history

By: Dr. Jeff Masters , 7:16 PM GMT on August 10, 2012

During the 1930s, a series of epic heat waves gripped the U.S., drying up the soil in an unprecedented drought that brought about the great Dust Bowl. The most intense heat hit during July 1936, which set a record for hottest month in U.S. history that stood for 76 years. That iconic record has now fallen, bested by 0.2°F during July 2012, which is now the hottest month in U.S. history, said NOAA's National Climatic Data Center (NCDC) this week. So far in 2012, we've had the warmest March on record, 3rd warmest April, 2nd warmest May, and warmest July. These remarkably warm months have helped push temperatures in the contiguous U.S. to the warmest on record for the year-to-date period of January - July, and for the 12-month period August 2011 - July 2012. Twenty-four states were record warm for that 12-month period, and an additional twenty states were top-ten warm. The past fourteen months have featured America's 2nd warmest summer (in 2011), 4th warmest winter, and warmest spring. The summer of 2012 is on pace to be a top-five warmest summer on record, and could beat the summer of 1936 as the warmest summer in U.S. history.


Figure 1. When the temperature peaked at an all-time high of 108° in Minneapolis, Minnesota on July 14, 1936, the want-ad staff at the 'St. Paul Daily News' was provided with 400 pounds of ice and two electric fans to cool the air in the press room. Photo from the Minnesota Historical Society.


Figure 2. Year-to-date temperature, by month, for 2012 (red), compared to the other 117 years on record for the contiguous U.S., with the five ultimately warmest years (orange) and five ultimately coolest years (blue) noted. The 2012 data are still preliminary. The year-to-date period of January - July was the warmest on record by a huge margin--1.0°F. Image credit: NOAA/NCDC.


Figure 3. For the fourth consecutive month, a new U.S. record for hottest 12-month period was set in July 2012. Five of the top-ten warmest 12-month periods in the contiguous U.S. since 1895 have occurred since April 2011. Image credit: NOAA/NCDC.

Most extreme January - July period on record
NOAA's U.S. Climate Extremes Index (CEI), which tracks the percentage area of the contiguous U.S. experiencing top-10% and bottom-10% extremes in temperature, precipitation, and drought, was 46% during the year-to-date January - July period. This is the highest value since CEI record-keeping began in 1910, and more than twice the average value. Remarkably, 83% of the contiguous U.S. had maximum temperatures that were in the warmest 10% historically during the first seven months of 2012, and 74% of the U.S. of the U.S. had warm minimum temperatures in the top 10%. The percentage area of the U.S. experiencing top-10% drought conditions was 20%, which was the 16th greatest since 1910. Extremes in 1-day heavy precipitation events were the 24th greatest in the 103-year record.


Figure 4. NOAA's U.S. Climate Extremes Index (CEI) for January - July shows that 2012 has had the most extreme first seven months of the year on record, with 46% of the contiguous U.S. experiencing top-10% extreme weather.

Little change to the U.S. drought during the past week
The great U.S. drought of 2012 remained about the same size and intensity over the past week, said NOAA in their weekly U.S. Drought Monitor report issued Thursday, August 9. The area of the contiguous U.S. covered by drought dropped slightly, from 63% to 62%, and the area covered by severe or greater drought stayed constant at 46%. The area of the country in the worst drought categories (extreme to exceptional drought) doubled from 10 percent last month to 22 percent this month. The extreme dryness and excessive heat devastated crops and livestock from the Great Plains to Midwest. During July, the area of the U.S. covered by moderate or greater drought was 57%, ranking as the 5th largest drought in U.S. history:

1) Jul 1934, 80%
2) Dec 1939, 60%
3) Jul 1954, 60%
4) Dec 1956, 58%
5) Jul 2012, 57%



Video 1. This is Not Cool: Peter Sinclair's July 2012 video from the Yale Forum on Climate Change and the Media couples historical footage with contemporary clips and news segments. In one of the latter, for instance, NBC anchor Brian Williams opens the network’s flagship news program with the words: “It’s now official. We are living in one of the worst droughts of the past 100 years.” NASA scientist James Hansen is featured testifying about risks of “extreme droughts” in the nation’s breadbasket, and I'm featured in a few clips talking about the drought of 2012.

I'll have a new post by noon Saturday.

Wunderground's weather historian Christopher C. Burt has a post looking back at the great Heat Wave of July 1936.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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Quoting Progster:
Latest (00Z) CMC ensemble takes the next E Pac storm and drives it N into LA next weekend. Normally, i'd LOL that off, but it is an ensemble...

Link

That might be Ernesto.
Member Since: December 31, 1969 Posts: Comments:
Latest (00Z) CMC ensemble takes the next E Pac storm and drives it N into LA next weekend. Normally, i'd LOL that off, but it is an ensemble...

Link
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1592. Msdrown
Quoting lovemamatus:
Any updates on the enormous gash in the sun? I've really come to love the sun, electricity, water, and food over the years. Would hate to go without them.


Not sure what you mean?? There have been reports lately about solar flares and CME's. Someone on here late last night was talking about this who seemed very knowledgable.
Member Since: December 31, 1969 Posts: Comments:
well it looks like the 1st TD of the season too bust
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1589. DDR
Good morning
Major flooding and land slips in north western Trinidad after 2 hours of heavy rains.

Met office
Trinidad and to a lesser extent Tobago have been
experiencing cloudy to overcast conditions with
showers and thundershowers over the last few
hours. This is attributed to an active Inter
Tropical Convergence Zone or ITCZ.
This inclement weather is expected to persist
throughout the day over both islands with showers
and thundershowers as well as periods of rain.
Some improvement is expected by this evening.



Showers and thundershowers can be moderate to
heavy and may be accompanied by gusty winds and
street/flash flooding. There is also the
possibility of landslides/landslips. Seas can
become choppy in the vicinity of thundershowers.

Citizens are advised to be vigilant and cautious
as they conduct their daily activities given the
forecast conditions. Be alert to electrical
discharges from thundercloud activity.
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1588. Msdrown
Quoting AussieStorm:
Evening all.....

the Hurricane Hunters are like this with TD-7


Also in other news.
Region: NORTHWESTERN IRAN
Geographic coordinates: 38.324N, 46.759E
Magnitude: 6.4 Mwp
Depth: 9 km
Universal Time (UTC): 11 Aug 2012 12:34:35
Time near the Epicenter: 11 Aug 2012 16:04:35
Local standard time in your area: 11 Aug 2012 12:34:35

Location with respect to nearby cities:
48 km (30 miles) NE (56 degrees) of Tabriz, Iran


Thats funny.
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1587. hydrus
Quoting kmanislander:
Another sign of a system that is starting to open up.
The vort has now become very elongated to the SW

Yes. Looking very disorganized. What are your thought about the activity in the Western Caribbean.?
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Quoting Msdrown:



I think they only give you a small file once a day and not a constant up date. When it does come up check the date and the running clock top right. You will see a very limited time span.


This is what I get from Cuba Radar
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Quoting lovemamatus:
Any updates on the enormous gash in the sun? I've really come to love the sun, electricity, water, and food over the years. Would hate to go without them.


Gash? Where? Link

Nothing mentioned on Spaceweather.
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1584. Msdrown
Quoting kmanislander:


I just pulled up Cuban radar and got a red "x".

Perhaps it is offline now



I think they only give you a small file once a day and not a constant up date. When it does come up check the date and the running clock top right. You will see a very limited time span.
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Quoting barbados246:



Morning Lemmie, Ryan & Julie guess we're going to get some showers today? any idea when the TD will pass?


Morning Barbados246, I'm guessing we could start to see something about 11am. Not entirely sure what that something is though as there are all sorts of reports.

Trinidad is completely flooded out right now, its reported about 3" of rain so far. Vehicles under water etc
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1580. LargoFl
well thats it for me, time to do the weekend lawn cutting etc..have a great day folks..stay safe out there
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Quoting originalLT:
Kamanislander, is that scrappy, or crappy?:)(post 1563)


Scrappy is what you get when a system looks like crap and may be bound for the scrap heap LOL
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1578. Msdrown
Quoting LargoFl:
..yes i see that thanks..its all they posted so far down there


Yea, yesterday when I asked for the Cuba Radar and you sent me that and someone else gave me the link. I went there and brought up several different Radar sites and everyone of them were hours behind. They probably only post that short file once a day and its always old news. I was interested because you and me have been concerned about that almost stationary blob so I wanted to compare the closest radar with the satilites. Did't help so I made the comparison with your Miami radar and the satititles which showed me differences.
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1577. ncstorm
look at those blobs off the SE coast


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This HH mission is sure working hard trying to pin down a center, no question about that. It's going to be a real close call on this one. Circling around again.
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1575. LargoFl
..folks notice..off the east coast..more Blue today, we need to watch that area
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Kmanislander, is that scrappy, or crappy?:)(post 1563)
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1573. LargoFl
Quoting kmanislander:


I just pulled up Cuban radar and got a red "x".

Perhaps it is offline now
..yes same here all they have is yesterdays
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1572. LargoFl
Quoting Msdrown:


Hey Largo, how far off is 7 from Ernestos track, do you know???
so far looks pretty much the same at least for now, several models put it a tad more northward nearing cuba..we'll see
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T numbers are still running too high:


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 11 AUG 2012 Time : 124500 UTC
Lat : 14:05:52 N Lon : 57:26:32 W


CI# /Pressure/ Vmax
3.4 / 999.5mb/ 53.0kt


Final T# Adj T# Raw T#
3.2 2.8 2.3
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Quoting SFLWeatherman:
THX!:)


I just pulled up Cuban radar and got a red "x".

Perhaps it is offline now
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1569. LargoFl
Quoting Msdrown:


Thats from yesterday Largo, check the date and time.
..yes i see that thanks..its all they posted so far down there
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1568. Msdrown
Quoting LargoFl:


Hey Largo, how far off is 7 from Ernestos track, do you know???
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THX!:)
Quoting wunderkidcayman:

yes we do cuba had radar I'll get the link to you as soon as possible
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THX!:)
Quoting LargoFl:
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1565. LargoFl
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1564. Msdrown
Quoting LargoFl:


Thats from yesterday Largo, check the date and time.
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Quoting wunderkidcayman:


weak yeah open well don't know yet maybe maybe not hmm what if it opens and then closes back


A system can open and close several times.The infamous Dolly did that at least 3 times. It was clearly open around 0300 UTC last night and based upon what I am seeing now the NHC may downgrade soon.
It looks really scrappy on satellite.
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1562. LargoFl
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Quoting Abacosurf:
Hmmm. Well it is a low. Just at the wrong level.

lol yeah
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Quoting kmanislander:
That HH is sure searching around pretty hard near the original apparent center.


weak yeah open well don't know yet maybe maybe not hmm what if it opens and then closes back
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Quoting wunderkidcayman:

there is no low pressure system S of cuba the only thing a an ULL
Hmmm. Well it is a low. Just at the wrong level.
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Alright i shall be back later to entertain... for now i must eat and go for a boat ride.... horrible weather but who cares
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1557. LargoFl
pick your area for the forecast..................
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT SAT AUG 11 2012

VALID 111300Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

AN UPPER LOW OVER LOWER MI/ONTARIO WILL CONTINUE TO AFFECT THE
NORTHEAST STATES TODAY...WHILE A PROGRESSIVE SHORTWAVE TROUGH OVER
THE NORTHERN ROCKIES TURNS SOUTHEAST AND AFFECTS THE CENTRAL HIGH
PLAINS. WHILE THE THREAT OF ORGANIZED SEVERE STORMS APPEARS RATHER
LOW TODAY...SEVERAL AREAS MAY SEE LOCALLY STRONG TO SEVERE
THUNDERSTORMS THIS AFTERNOON AND EVENING.

...NORTHEAST...
MORNING VISIBLE SATELLITE IMAGERY SHOWS FEWER CLOUDS OVER THE
NORTHEAST STATES TODAY COMPARED TO YESTERDAY. THIS WILL INCREASE
THE LIKELIHOOD OF AT LEAST POCKETS OF STRONGER DAYTIME HEATING AND
DESTABILIZATION. MODEL SOUNDINGS FOR LATER TODAY SUGGEST EARLY
AFTERNOON MLCAPE VALUES OVER 1000 J/KG FROM CENTRAL/EASTERN NY INTO
WESTERN NEW ENGLAND. SCATTERED THUNDERSTORMS WILL LIKELY FORM ALONG
THIS CORRIDOR AS A MID LEVEL SHORTWAVE TROUGH OVER SOUTHEAST OH
APPROACHES THE REGION. MID LEVEL LAPSE RATES ARE MARGINAL FOR
ROBUST UPDRAFTS. HOWEVER...SUFFICIENT DEEP LAYER EFFECTIVE SHEAR
AND SOME DRY AIR ALOFT MAY POSE A RISK OF A LOCALLY GUSTY OR
DAMAGING WIND GUSTS IN THE STRONGEST STORMS. SMALL HAIL MAY ALSO
OCCUR OVER PARTS OF NY WHERE SLIGHTLY COOLER MID LEVEL TEMPERATURES
ARE EXPECTED.

...VA/CAROLINAS...
12Z RAOBS SHOW SUBSTANTIAL MOISTURE IN PLACE ACROSS MUCH OF THE
SOUTHEAST STATES INCLUDING SC/NC/VA. BROKEN CLOUDS WILL SLOW THE
DAYTIME HEATING PROCESS...BUT MODERATE INSTABILITY SHOULD DEVELOP BY
MID/LATE AFTERNOON WITH MLCAPE VALUES AROUND 2000 J/KG. FORCING FOR
ASCENT WILL BE RATHER WEAK...PROVIDING UNCERTAINTY REGARDING
COVERAGE/INTENSITY OF STORMS. HOWEVER...RATHER STRONG LOW/MID LEVEL
FLOW SUGGESTS SOME RISK OF GUSTY/DAMAGING WINDS IN THE STRONGER
CELLS TODAY. CLOUD TRENDS WILL BE MONITORED THROUGH THE MORNING FOR
GREATER DESTABILIZATION THAN CURRENTLY EXPECTED WHICH COULD WARRANT
AN UPGRADE TO SLIGHT RISK.

...CENTRAL HIGH PLAINS...
A RATHER STRONG AND PROGRESSIVE SHORTWAVE TROUGH OVER THE NORTHERN
ROCKIES IS FORECAST TO TRACK SOUTHEASTWARD AND AFFECT THE CENTRAL
HIGH PLAINS LATER TODAY. STRONG HEATING WILL OCCUR AHEAD OF THIS
FEATURE OVER PARTS OF SD/NEB/KS AND EASTERN CO...RESULTING IN STEEP
LOW LEVEL LAPSE RATES. LOW LEVEL MOISTURE WILL BE SOMEWHAT LIMITED
WITH AFTERNOON SURFACE DEWPOINTS LIKELY TO REMAIN IN THE 50S.
HIGH-BASED THUNDERSTORMS ARE EXPECTED TO FORM OVER PARTS OF EASTERN
WY/CO DURING THE AFTERNOON AND SPREAD INTO WESTERN SD/NEB/KS DURING
THE EVENING. MODEL SOLUTIONS ARE BECOMING MORE AGGRESSIVE WITH
THUNDERSTORM COVERAGE OVER THIS REGION. IF THIS TREND IS
CORRECT...THE THREAT OF COLD POOL DEVELOPMENT AND A MORE ORGANIZED
THREAT OF DAMAGING WINDS MAY ALSO MATERIALIZE. THIS AREA WILL ALSO
BE MONITORED IN LATER OUTLOOKS FOR POSSIBLE UPGRADE.

...SWRN AZ/SERN CA...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY OVER THE
MOUNTAINS OF SOUTHEAST AZ. RATHER STRONG EASTERLY FLOW ALOFT MAY
HELP A FEW OF THESE STORMS TO PROPAGATE WESTWARD INTO THE LOWER
DESERTS AFTER DARK. LOCALLY DAMAGING WINDS WOULD BE THE MAIN
THREAT.

..HART/DEAN.. 08/11/2012
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Quoting SFLWeatherman:
Do we have a Radar from cuba

yes we do cuba had radar I'll get the link to you as soon as possible
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That HH is sure searching around pretty hard near the original apparent center.
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Do we have a Radar from cuba
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Quoting SFLWeatherman:
The low pressure south of cuba is that what CMC had going up to S FL as TD or TS???

there is no low pressure system S of cuba the only thing a an ULL
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1552. LargoFl
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1551. LargoFl
............................we could use a few showers here by me, been very humid and Hot..but no rain
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Good morning. Another boringly normal day here. And that's ok with me. :)



Mostly Cloudy
81°
27°C
Humidity94%
Wind SpeedCalm
Barometer29.94 in
Dewpoint79°F (26°C)
Visibility7.00 mi
Heat Index89°F (32°C)

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Another sign of a system that is starting to open up.
The vort has now become very elongated to the SW

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Quoting LargoFl:
yes and more to come, stay safe over there folks, flooding is going to be a problem there


especially with the zmount of rain we have had the past twwo days
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Quoting RTSplayer:


Ok. 38kts is about 43mph, so that would make it a TS...if it's good data.



I wonder what's the deal with that big blob forming a good ways to the SW of the storm?

if anything I say still 35MPH

Quoting RTSplayer:
Storm is being robbed by the blob.

The blob has stronger convection than the TD.

nah I think that the blob SW of TD7 will soon shoot towards the TD giving it more convection

huh kinda reminds me of Ernesto when it was in that same place it had a little blob to its SW too and that blob was show a circulation for the blob and bearly anything for Ernesto but the blob got sucked into Ernesto before it entered the Caribbean I think the same maybe happening with TD7

Quoting SFLWeatherman:
What is that south of cuba???
Link


nothing just a blow up from the ULL
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1546. LargoFl
Quoting SFLWeatherman:
The low pressure south of cuba is that what CMC had going up to S FL as TD or TS???
it very well could be, we'll see
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Quoting Grothar:


Hello.


Mownin!
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather