Excessive Heat in Arizona, August 14 to 16, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
145 PM MST FRI AUG 14 2015

.SYNOPSIS...AN UPPER LEVEL AREA OF HIGH PRESSURE GRADUALLY MOVING
OVER THE AREA WILL CONTINUE TO BOOST TEMPERATURES TO NEAR OR ABOVE
RECORD LEVELS THIS WEEKEND.  EARLY NEXT WEEK THE HIGH WILL CONTINUE
MOVING SOUTHWEST ALLOWING TEMPERATURES TO COOL SOME BUT ALSO DRIVING
MUCH OF THE MONSOON MOISTURE OUT OF THE REGION.

&&

.DISCUSSION...WELL WE MANAGED TO TIE THE RECORD HIGH IN TUCSON
BEFORE THE CLOUDS ROLLED IN.  IT WILL BE A BIT OF A CHALLENGE TO
PUNCH IT MUCH HIGHER IF THE CLOUDS LINGER TOO LONG BUT WE STILL HAVE
SEVERAL HOURS OF HEATING LEFT.  JUST ENOUGH INSTABILITY FOR WIDELY
SCATTERED CONVECTION TO POP OFF THE LAST HOUR.  SOME OF IT IS A BIT
FURTHER NORTH THAN I WOULD HAVE INITIALLY EXPECTED LOOKING AT THE
MESOSCALE ANALYSIS.  THIS TYPE OF POPCORN CONVECTION WILL CONTINUE
INTO THE EVENING HOURS BEFORE SETTLING DOWN AFTER SUNSET AS THERE IS
NO SYNOPTIC OR SMALLER SCALE FEATURE TO DRIVE IT OTHER THAN SOLAR
HEATING.  CELL MOVEMENT IS TO THE NW AROUND 10 MPH.

FOR SATURDAY...EXPECTING LESS CONVECTION DUE TO A SOMEWHAT LESS
FAVORABLE ENVIRONMENT AS THE UPPER HIGH SETTLES IN OVERHEAD WITH THE
BEST SHOT AT CONVECTION ACROSS EASTERN AND SOUTHERN AREAS.  LOW
LEVEL THICKNESS LEVELS BUMP UP FURTHER FOR EVEN WARMER TEMPERATURES
AND WAS TEMPTED TO PUSH IT TO 111 AT TUCSON BUT HELD BACK JUST DUE
TO POTENTIAL FOR A FEW CLOUDS.  EITHER WAY WE ARE ALREADY
FORECASTING RECORD HIGHS AT MOST LOCATIONS IN SE AZ INCLUDING TUCSON
AS IT IS.  MUCH THE SAME FOR SUNDAY AS THICKNESS LEVELS VIRTUALLY
UNCHANGED.  CONVECTION WILL STILL STRUGGLE DUE TO THE PROXIMITY OF
THE UPPER HIGH WITH THE BEST CHANCES EAST AND SOUTH AGAIN.

AS WE TRANSITION TO MONDAY AND BEYOND...THE UPPER HIGH CONTINUES TO
DRIFT TO THE SOUTHWEST WHICH WILL ALLOW HIGH TEMPERATURES ACROSS THE
REGION TO BEGIN TO COOL OFF ALTHOUGH STILL REMAIN A BIT ABOVE
NORMAL.  SHOULD SEE ABOUT A FIVE DEGREE DROP FROM SUNDAY TO MONDAY
AND ANOTHER COUPLE OF DEGREES TUESDAY AND REMAIN FAIRLY STEADY STATE
THEREAFTER.  THE OTHER ASPECT OF THIS UPPER HIGH MOVEMENT IT THAT IT
PLACES THE HIGH IN A VERY UNFAVORABLE POSITION FOR US AS FAR AS
THUNDERSTORMS GO DUE TO THE DRYING WEST TO NORTHWEST FLOW THAT
DEVELOPS.  HAVE TRIMMED POPS FROM TUESDAY ONWARD A FAIR AMOUNT BUT
IF THE CURRENT RUNS WERE PERFECT PROGS...IT WOULDN'T BE ENOUGH.  EL
NINO EFFECT SHOWING ITS HAND?  WE WILL HAVE TO WAIT AND SEE JUST HOW
CLOSE TO PERFECT THEY END UP BEING AS WE GET CLOSER IN TIME.
CERNIGLIA

&&

.AVIATION...VALID THRU 15/23Z.
SCT CLOUDS...LOCALLY BKN...AT 10-14K FT AGL THRU 15/04Z. AFT
15/04Z...SKC-FEW CLOUDS AT 10-14K FT AGL. A SLIGHT CHANCE OF
-SHRA/-TSRA THRU 15/03Z. ISOLD -SHRA/-TSRA DEVELOPING AGAIN AFT
15/21Z. OUTSIDE OF ANY THUNDERSTORM WIND GUSTS...LIGHT SURFACE WIND
GENERALLY LESS THAN 12 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...STRONG HIGH PRESSURE ALOFT CENTERED OVER THE REGION
WILL RESULT IN WELL ABOVE NORMAL TEMPERATURES...WITH AFTERNOON HIGHS
TOPPING OUT AROUND OR ABOVE RECORD LEVELS THROUGH SUNDAY. THERE WILL
BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SATURDAY.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL THEN OCCUR IN
THE SUNDAY THROUGH WEDNESDAY TIME FRAME. ANOTHER DOWNTURN IN
THUNDERSTORM ACTIVITY IS EXPECTED LATE NEXT WEEK. OUTSIDE OF
THUNDERSTORM WIND GUSTS...20-FT WINDS WILL GENERALLY BE LESS THAN 15
MPH.

&&

.CLIMATE...WITH THE UPCOMING MID-AUGUST HEAT WAVE WE HAVE POSTED ON
OUR WEBSITE RECORD TEMPERATURE INFORMATION FOR PORTIONS OF SE AZ.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
  EXCESSIVE HEAT WARNING IN EFFECT FOR FRIDAY...SATURDAY AND SUNDAY
  AFTERNOON AND EVENING FOR AZZ501-502-504-505

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