Is the U.S. climate getting more extreme?
Is the world's climate getting more extreme, with hotter heat waves, colder cold events, heavier rains, and more extreme droughts? After seeing the unprecedented weather events of 2010 and the equally impressive floods of 2011, it's an important question to be asking. Unfortunately, it's an almost impossible question to answer objectively, because we simply don't have good enough long-term global weather records to do so. However, in the U.S., we do have good enough records to attempt this, and the NOAA National Climatic Data Center (NCDC) has developed a Climate Extremes Index to do so. For 2010, the Climate Extremes Index (CEI) showed that the U.S. had a near-average area experiencing extreme weather conditions. Averaged over decades-long time scales, the U.S. climate has been getting more extreme since 1970, but has not changed significantly over a century-long time scale. The Climate Extremes Index (CEI) is based upon three parameters:
1) Monthly maximum and minimum temperature
2) Daily precipitation
3) Monthly Palmer Drought Severity Index (PDSI)
The temperature data is taken from 1100 stations in the U.S. Historical Climatology Network (USHCN), a network of stations that have a long period of record, with little missing data. The temperature data is corrected for the Urban Heat Island effect, as well as for station and instrument changes. The precipitation data is taken from 1300 National Weather Service Cooperative stations. The Climate Extremes Index defines "much above normal" as the highest 10% of data, "much below normal" as the lowest 10%, and is the average of these five quantities:
1) The sum of: (a) the percentage of the United States with monthly maximum temperatures much below normal, and (b), the percentage of the United States with monthly maximum temperatures much above normal.
2) The sum of: (a) the percentage of the United States with monthly minimum temperatures much below normal, and (b), the percentage of the United States with monthly minimum temperatures much above normal.
3) The sum of: (a) the percentage of the United States in severe drought each month (equivalent to the lowest tenth percentile) based on the Palmer Drought Severity Index (PDSI), and (b), the percentage of the United States with severe moisture surplus (equivalent to the highest tenth percentile) based on the PDSI.
4) Twice the value of the percentage of the United States with a much greater than normal proportion of precipitation derived from extreme (equivalent to the highest tenth percentile) 1-day precipitation events.
5) The sum of: (a) percentage of the United States with a much greater than normal number of days with precipitation, and (b), percentage of the United States with a much greater than normal number of days without precipitation.
Figure 1. The Annual Climate Extremes Index (CEI), updated through 2010, shows that U.S. climate has generally been getting more extreme since the early 1970s, but that the 2010 climate was just slightly more extreme than average. On average since 1910, 21% of the U.S. has seen extreme conditions in a given year (thick black line), and in 2010 this number was about 24%. Image credit: National Climatic Data Center.
As summarized by Gleason et al. (2008), the National Climatic Data Center concludes that based on the Climate Extremes Index, the percentage of the U.S. seeing extreme temperatures and precipitation generally increased since the early 1970s. These increases were most pronounced in the summer. No trend in extremes were noted for winter. The annual CEI index plot averaged for all five temperature and precipitation indices (Figure 1) showed that four of the ten most extreme years on record occurred since 1996. However, some very extreme years also occurred in the 1910s through 1950s, in association with widespread extreme drought and above-average temperatures. The most extreme year in U.S. history was 1998, with 1934 a close second. The year 1998 was the hottest year in U.S. history, with a record 78% of the U.S. experiencing minimum temperatures much above normal. That year also had a record 23% of the U.S. with much greater than normal precipitation from extreme 1-day precipitation events. The 1934 extreme in CEI was due in large part because of the most widespread drought of the century--a full 52% of the U.S. was affected by severe or extreme drought conditions. That year also saw a record 64% of the U.S. with much above normal maximum temperatures.
Maximum and minimum temperatures
It is very interesting to look at the five separate indices that go into the Climate Extremes Index. Today I'll look at temperature, and focus on drought and precipitation in my next post. The portion of the U.S. experiencing month-long maximum or minimum temperatures either much above normal or much below normal has been about 10% over the past century (black lines in Figures 2 and 3.) However, over the past decade, about 20% of the U.S. has experienced monthly maximum temperatures much above normal, and less than 5% has experienced maximum temperatures much cooler than normal. Minimum temperatures show a similar behavior, but have increased more than the maximums (Figure 3). Climate models minimum temperatures should be rising faster than maximum temperatures if human-caused emissions of heat-trapping gases are responsible for global warming, which is in line with what we are seeing in the U.S. using the CEI.
While there have been a few years (1921, 1934) when the portion of the U.S. experiencing much above normal maximum temperatures was greater than anything observed in the past decade, the sustained lack of maximum temperatures much below normal over the past decade is unique. The behavior of minimum temperatures over the past decade is clearly unprecedented--both in the lack of minimum temperatures much below normal, and in the abnormal portion of the U.S. with much above normal minimum temperatures. Remember that these data ARE corrected for the Urban Heat Island effect, so we cannot blame increased urbanization for the increase in temperatures.
Figure 2. The Annual Climate Extremes Index (CEI) for maximum temperature, updated through 2010, shows that about 10% of U.S. had maximum temperatures much warmer than average during 2010. This was right near the average from the past 100 years (thick black line.) Image credit: National Climatic Data Center.
Figure 3. The Annual Climate Extremes Index (CEI) for minimum temperature, updated through 2010, shows that about 35% of U.S. had minimum temperatures much warmer than average during 2010. This was the 7th largest such area in the past 100 years. The mean area of the U.S. experiencing minimum temperatures much warmer than average over the past 100 years is about 10% (thick black line.) Image credit: National Climatic Data Center.
I'll have a new post on Tuesday, when I'll talk about how extremes of drought and precipitation have changed in the U.S. (I may talk instead about the developing winter storm for the Appalachians and Northeast coming Wednesday and Thursday this week, though.)
References
Gleason, K.L., J.H. Lawrimore, D.H. Levinson, T.R. Karl, and D.J. Karoly, 2008: "A Revised U.S. Climate Extremes Index", J. Climate, 21, 2124-2137.
The National Climatic Data Center has a more in-depth discussion of the Climate Extremes Index for the U.S. on a regional and seasonal basis during 2010. In some regions, such as the Southeast U.S., 2010 was a remarkably extreme year.
Jeff Masters
Reader Comments
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My goodness, I am seeing snow in the deep south?
I know you're right...lol..just wishful thinking..do love snow :)
i'am afraid we are only just seeing the extreme side of the weather as we progress along
we have seen nothing yet
I blame it on the Ancient Aliens...
FXUS62 KTBW 240754
AFDTBW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
254 AM EST MON JAN 24 2011
...STRONG THUNDERSTORMS AND HEAVY RAINFALL POSSIBLE TUESDAY
AFTERNOON THROUGH EARLY WEDNESDAY...
.SHORT TERM (TODAY-WEDNESDAY)...
THE FORECAST FOCUS FOR THIS PERIOD WILL BE ON THE APPROACHING
STORM SYSTEM ON TUESDAY AND THE POTENTIAL IMPACTS. FOR TODAY THE
FORECAST WILL BE FOR A QUIET DAY. A STRONG RIDGE OF HIGH PRESSURE
AT THE SURFACE WILL PUSH SOUTH OUT OF NEW ENGLAND AND INTO THE
ATLANTIC. A LOW PRESSURE TROUGH WILL DEVELOP ACROSS THE WESTERN
GULF OF MEXICO. THE COMBINATION OF THE TWO WILL CREATE AN EAST TO
SOUTHEAST FLOW TODAY WHICH WILL BRING WARM AND MOIST ADVECTION
BACK AT THE SURFACE. ALOFT THERE WILL BE A STRONG SHORTWAVE TROUGH
PUSHING OUT OF THE SOUTHERN ROCKIES AND INTO THE HIGH PLAINS. THIS
WILL HELP TO FORCE RISING HEIGHT ACROSS THE GULF AND FLORIDA. SO A
WARMER DAY IS EXPECTED TODAY BUT WITH LATE DAY INCREASING
CLOUDINESS. GUIDANCE WAS SLIGHTLY WARMER TODAY AND SO WENT CLOSE
TO IT WITH HIGHS TOPPING OUT IN THE MID 60S TO MID 70S. TONIGHT
THE SHORTWAVE WILL CARVE OUT SHARPLY IN THE 500 MB TROUGH OVER
WEST TEXAS. THIS WILL ALLOW FOR SURFACE CYCLOGENESIS TO TAKE PLACE
OVER THE NORTHWEST GULF BY 12Z TUESDAY. THIS WILL BRING ABUNDANT
CLOUDINESS AND STRENGTHEN THE WARM AND MOIST ADVECTION OVER
FLORIDA. LOW WILL BE CONSIDERABLY WARMER THAN THE PREVIOUS FEW
NIGHTS. THEN TUESDAY THE SURFACE LOW WILL MOVE EAST AS IT IS
FORCED BY A SHARP UPPER TROUGH PUSHING EAST. WITH A STRONG LEAD
VORT MAX MOVING OVER THE AREA ON TUESDAY AFTERNOON...WILL KEEP THE
HIGHEST POPS FOR THE AFTERNOON.
LATE TUESDAY AFTERNOON AND EVENING...THE STAGE LOOKS SET FOR A VERY
ACTIVE WEATHER EVENT. THE LOW WILL MOVE ACROSS NORTHERN FLORIDA.
THERE WILL BE A VERY HUMID AIRMASS ACROSS THE AREA AND THIS WILL
PUSH DEWPOINTS QUICKLY INTO THE MID 60S. PWATS OF 1.6-1.8 INCHES
OVER THE AREA ARE 2SD ABOVE NORMAL WHICH WILL MEAN A POTENTIAL FOR
HEAVY RAINFALL. THE SYSTEM WILL HAVE STRONG DYNAMIC FORCING WITH A
DEEP AND STRONG 500 MB LOW PUSHING THROUGH THE DEEP SOUTH. THE
WIND FIELDS ARE IMPRESSIVE WITH THIS SYSTEM...AND 0-6KM SHEAR OF
40 TO 50 KTS LATE TUESDAY AND OVERNIGHT IS SUPPORTIVE FOR
SUPERCELLULAR DEVELOPMENT. IN ADDITION TO THE SPEED
SHEAR...DIRECTIONAL SHEAR IS IMPRESSIVE AS WELL. THE 0-1KM SHEAR
VALUES ARE SUPPORTIVE OF A TORNADO THREAT. SO THIS EVENT APPEARS
PRIMED FOR POSSIBLE SEVERE WEATHER IN THE AREA...AND SPC HAS
HIGHLIGHTED THIS WITH A SLIGHT RISK FOR THE DAY.
TORNADO...STRAIGHT LINE WIND...AND VERY HEAVY RAINFALL ARE ALL
THREATS. WITH VERY COLD MID LEVEL TEMPERATURES...-13C AT 500
MB...LARGE HAIL IS ALSO A THREAT. THE LIMITING FACTOR WILL BE THE
PRESENCE OF LOW LEVEL INVERSION WHICH WILL BE STRONGEST IN THE
NORTH...AND THIS INVERSION COULD LIMIT THE DOWNWARD TRANSPORT OF
STRONG WINDS AND TORNADO THREAT.
BY WEDNESDAY THE LOW WILL RACE UP THE EASTERN SEABOARD AND STRONG
HIGH PRESSURE OUT OF THE ROCKIES WILL BUILD SOUTH TOWARDS THE GULF
OF MEXICO WITH COLD ADVECTION RETURNING.
.LONG TERM (WEDNESDAY NIGHT THROUGH SUNDAY)...WITH THE MID LEVEL
TROUGH EXITING INTO THE ATLANTIC A MORE ZONAL PATTERN WILL SET UP
FOR THE BEGINNING OF THE LONG TERM. A WEAK MID SHORT WAVE AXIS
EXPECTED TO SLIDE THROUGH THE EASTERN US BY FRIDAY BUT BUT A LACK OF
SURFACE DYNAMICS WILL KEEP CONVECTION LIMITED. AT THE SURFACE...HIGH
PRESSURE WILL BUILD IN FROM THE WESTERN GULF DRIFT EASTWARD THROUGH
THE PERIOD. PLENTY OF DRY AIR WILL LINGER OVER THE REGION HELPING TO
MAINTAIN MINIMAL POPS. MODEL SOUNDINGS INDICATE WEAK COLD AIR
ADVECTION FOR THE FIRST HALF OF THE PERIOD WITH NORTHERLY FLOW
THROUGH THE LOW LEVELS AND 850 TEMPS RANGING FROM 2-6C. MAY SEE FROM
FREEZING TEMPS IN PARTS OF THE NATURE COAST ON THURS AND FRI MORNING
BEFORE A GRADUAL WARMING TREND THROUGH THE WEEKEND.
&&
.AVIATION...VFR CONDITIONS EXPECTED THROUGH TODAY. MOISTURE IS
EXPECTED TO RETURN HELPING TO GRADUALLY INCREASE CLOUD COVER NORTH
TO SOUTH THROUGH EARLY TOMORROW MORNING.
&&
.MARINE...QUIET CONDITIONS THROUGH TONIGHT WILL BE REPLACED BY
INCREASING WINDS AND SEAS ON TUESDAY. LOW PRESSURE WILL DEVELOP
ACROSS THE NORTHWESTERN GULF AND MOVE THROUGH THE NORTHERN WATERS
LATE TUESDAY AND INTO EARLY WEDNESDAY. WINDS AND SEAS WILL
INCREASE AND ADVISORY CRITERIA CONDITIONS ARE LIKELY TO DEVELOP BY
EARLY WEDNESDAY. THUNDERSTORMS WILL MOVE ACROSS THE WATERS
THROUGH THE DAY ON TUESDAY AND INTO THE OVERNIGHT HOURS. HIGH
PRESSURE WILL BUILD IN BY THURSDAY AND INTO THE WEEKEND.
&&
.FIRE WEATHER...NO CONCERNS AS HIGH LOW LEVEL RELATIVE HUMIDITY
RETURNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 67 55 75 59 / 5 10 60 70
FMY 72 58 78 64 / 5 10 40 60
GIF 68 53 78 59 / 5 10 60 70
SRQ 68 56 75 61 / 5 10 50 70
BKV 68 48 74 57 / 5 10 60 70
SPG 65 57 74 59 / 5 10 60 70
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WARNING UNTIL 8 AM EST THIS MORNING FOR CITRUS-HERNANDO-
LEVY.
GULF WATERS...NONE.
&&
$$
SHORT TERM/MARINE/FIRE WEATHER...35/JOHNSON
LONG TERM/AVIATION...20/BARRON
But he is still a US Army Veteran.
I agree! The most likely cause would be the continuing effects of the massive amounts of flatulence they released into the atmosphere. Do to its foreign nature, I have evidence and graphs that prove it is warming the climate much more rapidly than human caused CO2 is.
In fact the impact on the atmosphere is at a yield of about 55% more at 3 PPM then human caused CO2 is.
Not only that, I have peer reviews from DR. John Doe, and Dr. Lady upperclass that prove how flatulence from ancient aliens could prove extremely dangerous for our planets future...
I will be releasing subsequent updates on this serious climate crisis in the near future.
Whatever the case, those who love to live on the side of anti-science will continue to be deniers, because anyone who disagrees with my theory is a denier of real science. How dare my knowledge of this subject be questioned...
my local NWS (KJAX) has been hem-hawin' over this...talkin about the negative tilt, low CAPE values, and low dewpoints during that time frame. THANK YOU for posting Tampa's discussion. It's really getting bad, our mets up here.
Had you not posted that, I never woulda looked at SPC. Thanks.
;)
Published: Monday, January 24, 2011, 9:12 AM
A explosion ripped through the arrivals hall at Moscow's busiest airport on Monday, killing 31 people and wounding about 130, Health Ministry officials said.
moscow-airport.JPGPavel Golovkin, The Associated Press A general view of the Domodedovo airport is seen in Moscow, Russia, on Dec. 26. An explosion ripped through the arrivals hall at Moscow's busiest airport on Monday, killing travellers and wounding others, Health Ministry officials said. The state RIA Novosti said the explosion may have been caused by a suicide bomber.
The state RIA Novosti said the explosion may have been caused by a suicide bomber.
The Russkaya Sluzhba Novostei radio station cited a traveler, identified as Viktor, as saying he heard the bang outside the airport, where he was waiting for a car.
"There was an explosion, a bang. Then I saw a policeman covered in fragments of flesh and all bloody. He was shouting 'I've survived! I've survived!'"
Domodedovo is generally regarded as Moscow's most up-to-date airport, but its security procedures have been called into question.
But most official and local rain gauges have recorded 4 to 8 inches of rain for January, and most fell in the last 2 weeks...
The system moving in tomorrow will be the strongest yet, and could even bring a tornado threat, and possibly another 2 to 4 inches of rain, which would be amazing for the dry season, but I'm not complaining! Lets just hope there won't be anyone hurt from severe weather. I don't think it will be like a spring outbreak in the plains or anything. But we can get some nasty little severe weather events in January and February here sometimes...
Whatever the case, thanks for the explanation about the change in rainfall likely being caused from the shift to NAO positive. That's what I suspected to be the cause of the more recent heavy rain pattern, but I wasn't really sure.
Lets hope this pattern continues! Less record cold and more rain to help the drought sounds good to me!
Anyway, good morning to all from a recently reformed lurker. Weather in Houston is yucky, but not cold.
Thanx for your service as well.
When Gore graduated in 1969, his student deferment ended and he immediately became eligible for the military draft. His father, a vocal anti-Vietnam War critic, was facing a tough reelection fight in 1970.
Gore eventually decided that the best way he could contribute to the anti-war effort was to enlist in the Army,which would improve his father's reelection prospects.
Although nearly all of his Harvard classmates avoided the draft and service in Vietnam, Gore believed if he found a way around military service, he would be handing an issue to his father's Republican opponent.
According to Gore's Senate biography, "He appeared in uniform in his father's campaign commercials, one of which ended with his father advising: 'Son, always love your country. Regardless, Al senior lost his seat.
Gore has said that his other reason for enlisting was that he did not want someone with fewer options than he to go in his place.
Actor Tommy Lee Jones, a former college housemate, recalled Gore saying that "if he found a fancy way of not going, someone else would have to go in his place." His Harvard advisor, Richard Neustadt, also stated that Gore decided, "that he would have to go as an enlisted man because, he said, 'In Tennessee, that's what most people have to do.'" In addition, Michael Roche, Gore's editor for The Castle Courier, stated that "anybody who knew Al Gore in Vietnam knows he could have sat on his butt and he didn't.
After enlisting in August 1969, Gore returned to the anti-war Harvard campus in his military uniform to say goodbye to his adviser and was "jeered" at by students. He later said he was astonished by the "emotional field of negativity and disapproval and piercing glances that ... certainly felt like real hatred".
Gore had basic training at Fort Dix from August to October, and then was assigned to be a journalist at Fort Rucker, Alabama. In April 1970, he was "Soldier of the Month".
Gore with the 20th Engineer Brigade in Bien Hoa as a journalist with the paper, The Castle Courier.
Al and Tipper Gore's wedding day, May 19, 1970 at the Washington National Cathedral
How weird! Well I don't know what they are smokin, cause forecasters here re basing on highly agreeing models and their consistent data.
Let met tell ya, this system will likely be very potent! Its probably not gonna be a widespread outbreak or anything, but I wouldn't be surprised if several warnings do get issued, and several inches of rain falls in some spots before all is said and done.
All my Marine friends assure me that the U.S.Navy is part of the Corps. So Semper Fi, Pat and thanks for your Veteren's Day posts. I read them with pleasure.
I am about to retire and hope to spend more time on WU.
Who could forget 1998 around here.. ECFL about burnt down.
Jedkins~ that set up looks somewhat favorable for an awakening of the I-4 tornado alley.
Climate change: Rising waters threaten North Carolina & national security
Must-read Hansen and Sato paper: We are at a climate tipping point that, once crossed, enables multi-meter sea level rise this century
Have you had college Chemistry for science majors yet? They wouldn't let me out of there til I knew what GHGs absorbed what wavelengths of IR photons & how long they lasted, the sorts of reactions to dismantle them, etc.. They are quite measurable & chemically explained. No big secret that WV is the most abundant GHG & without it our blue marble would be way too cold for us. I remember experiments..CO2 vs methane vs WV vs air vs vacuum in a double glass pane.. which heats up more & how much..use your volumes to workout nightmarish equations. That class started with some "deniers", didn't end with any. I was on a physics quest at the time. Does Met majors have to take the harder Chem for science majors?"
Hey SkyPony, yes unfortunately I do have to take some pretty serious chemistry, I need basic chem and 2 more chem classes after that require calculus to be completed. I have already completed the introductory class to chemistry, as well as the first calculus, this semester I am working on the harder stuff.
Honestly, I ended up finishing the last Chemistry course with an 85%, and I worked very hard to get that grade. I'm not sure why, but even though I'm pretty decent at math and I really love physics, Ive found I hate chemistry. For some reason the chemistry equations don't make any sense to me when the math is in chemistry form. My brain just doesn't work well with chemistry, just like some people just don't get how I love meteorology so darn much, lol.
Because I did work hard to earn that grade, I did learn quite a bit about the nature of gasses and how they interact though.
Ive yet to take the more difficult chemistry courses though, I'm not looking forward to them to say the least! lol
The only time I enjoyed chemistry at all was for the brief amount of time that we went over meteorology applications, which there weren't much of...
No severe, no Lady Lake, I'll be happy.
Yeah it does...
I'm just being optimistic and hoping this system just outputs a lot of rain and and exciting lightning and gusty wind event. I'm hoping damaging and destructive weather will be at a minimum.
Our one saving grace may be the cold water temps that will create as surface inversion as the NWS has been saying, however the cold water temps seem to be no match when strong dynamics and a significant low level jet are in place.
About 28 residences and a primary school were destroyed over the last weekend by the heavy rain that hit Ambriz district in northern Bengo Province. According to what Angop learnt, the rain also destroyed roads and other means of communication, a situation that hinders the inhabitants to go to agricultural fields. The affected people claimed for assistance of the local authorities in order to rebuild their houses.
"Unfortunately, it's an almost impossible question to answer objectively, because we simply don't have good enough long-term global weather records to do so"
But, you can absolutely say there is man-made global warming?
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CST MON JAN 24 2011
VALID 251200Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER MOST OF FL...
...SYNOPSIS...
MODEL CONSENSUS IS THAT VORT MAX NOW MOVING THROUGH SRN ROCKIES WILL
CONTINUE SEWD INTO BASE OF MEAN SYNOPTIC TROUGH...REACHING THE NWRN
GULF EARLY TUESDAY. THIS SHORTWAVE TROUGH WILL LIKELY BECOME
NEGATIVELY TILTED AS IT EJECTS ENEWD THROUGH THE NRN GULF AND SERN
STATES OVERNIGHT. ATTENDANT SURFACE LOW AND TRAILING COLD FRONT WILL
ADVANCE THROUGH THE GULF WHILE A WARM FRONT LIFTS NWD THROUGH THE FL
PENINSULA.
...FL...
WEAK SURFACE LOW ALREADY EVIDENT OVER THE WRN GULF SHOULD DEEPEN IN
RESPONSE TO INCREASING UPPER DIVERGENCE ASSOCIATED WITH THE
APPROACHING SHORTWAVE TROUGH. BOUNDARY LAYER OVER THE WRN GULF IS IN
THE PROCESS OF MODIFYING...AND FURTHER MODIFICATION WILL OCCUR
FARTHER EAST AS TRAJECTORIES BECOME MORE SLY. SECONDARY CYCLOGENESIS
IS FORECAST OFF THE GA COAST LATE TUESDAY AS ZONE OF DEEPER ASCENT
ACCOMPANYING THE SHORTWAVE TROUGH OVERTAKES THE GULF STREAM.
STRENGTHENING S-SWLY FLOW WILL ADVECT MID-UPPER 60S F DEWPOINTS
THROUGH SRN FL WITH LOW 60S MORE LIKELY FARTHER NORTH. LOW-LEVEL
THETA-E ADVECTION AND POTENTIAL FOR AT LEAST MODEST DIABATIC WARMING
WILL CONTRIBUTE TO DESTABILIZATION IN WARM SECTOR BY LATE
AFTERNOON...BUT MODEST LAPSE RATES SHOULD LIMIT MLCAPE TO 500-1000
J/KG OVER SRN FL AND BELOW 500 J/KG ACROSS NRN FL.
STORMS ARE EXPECTED TO INCREASE OVER THE CNTRL GULF WITHIN ZONE OF
INCREASING FORCING AND DESTABILIZATION ALONG AND AHEAD OF THE COLD
FRONT. ACTIVITY WILL ADVANCE EWD...LIKELY REACHING FL BY TUESDAY
EVENING INTO THE OVERNIGHT. EFFECTIVE VERTICAL SHEAR WILL INCREASE
TO 40-50 KT OVER THE PENINSULA AS THE SHORTWAVE THROUGH
APPROACHES...SUPPORTING ORGANIZED STORM STRUCTURES INCLUDING BOWING
SEGMENTS AND SUPERCELLS. DAMAGING WIND AND ISOLATED TORNADOES WILL
BE THE MAIN THREATS. WILL MAINTAIN 15% SEVERE PROBABILITIES AT THIS
TIME DUE MAINLY TO UNCERTAINTIES REGARDING THE EVOLUTION OF THE
THERMODYNAMIC ENVIRONMENT...BUT AN UPGRADE TO HIGHER PROBABILITIES
MIGHT BE NEEDED IN LATER OUTLOOKS
:)
Jedkins~ The trend lately hasn't been for these to be all that severe. Did have that tornado on the 17th though. MLB NWS caution concerning the event seems sensible. Toward the east coast it may come over in the night or early morning.
NOW IS THE TIME TO CHECK THAT YOUR NOAA WEATHER RADIO IS IN WORKING
ORDER. HAVING A NOAA WEATHER RADIO ALERT YOU OF AN APPROACHING
TORNADO...ESPECIALLY IN THE MIDDLE OF THE NIGHT...HAS SAVED LIVES.
.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.
...THREAT FOR DAMAGING WINDS AND TORNADOES LATE TUESDAY AND
TUESDAY NIGHT...
LOW PRESSURE IS FORECAST TO TRACK EAST NORTHEAST ACROSS THE
NORTHERN GULF OF MEXICO AND THE FLORIDA PANHANDLE TUESDAY AND
TUESDAY NIGHT. DEEP TROPICAL MOISTURE WILL SURGE NORTHWARD ACROSS
THE AREA AHEAD OF THIS SYSTEM. STRONG WIND FIELDS IN THE LOW AND
MID LEVELS OF THE ATMOSPHERE WILL PRODUCE A THREAT FOR SEVERE
STORMS CAPABLE OF PRODUCING DAMAGING WINDS AND LONG TRACK
TORNADOES. BASED ON CURRENT TIMING...SEVERE WEATHER IS POSSIBLE AS
EARLY AS TUESDAY AFTERNOON BUT MORE LIKELY TUESDAY NIGHT.
$$
KELLY
I would tend to believe the stable layer will lower the severe threat to a degree based on my observation of past severe weather events, but I do believe at least isolated tornados and damaging winds will materialize. Cold air aloft may support hail which is pretty rare in Florida, thanks to frequent arctic air masses cooling the upper layers.
What I'm most excited about with this system is the beneficial rains that it will likely bring. Conditions will support tropical cloud burst type rains, rain rates of 2 to 3 inches per hour will likely be common in thunderstorm cores. Strong to severe cells could have even higher rain rates.
Keep in mind though, the last few systems were actually downplayed around here. The last few rain events not only brought more rain than predicted, but the last 2 events we had massive amounts of lighting and gusty winds of 45 mph, which weren't in the forecast. The forecast called mainly for half inch amounts and maybe a rumble of thunder.
Of course, I'm not criticizing forecasters, I myself was shocked by how impressive the thunderstorm activity was with the last couple events here.
I believe they are probably right on target with the forecast this time.
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