Forecast-Discussion
000
FXUS65 KPSR 210903
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
203 AM MST MON MAY 21 2012
.SYNOPSIS...
A HIGH PRESSURE SYSTEM WILL AMPLIFY OVER THE REGION THROUGH THE
EARLY PART OF THIS WEEK...WITH AFTERNOON TEMPERATURES RISING SHARPLY
TODAY THROUGH TUESDAY. BY THE LATTER HALF OF THE WEEK...A SERIES OF
PACIFIC LOW PRESSURE SYSTEMS WILL MOVE INTO THE WESTERN
STATES...RESULTING IN COOLER TEMPERATURES WITH BREEZY AFTERNOONS.
OTHERWISE DRY WEATHER IS EXPECTED THROUGH EARLY NEXT WEEK.
&&
.DISCUSSION...
CLEAR SKIES ONCE AGAIN ACROSS THE REGION. EARLY MORNING SATELLITE
IMAGERY REVEALS A STRENGTHENING RIDGE ACROSS ARIZONA AND THE GULF OF
CALIFORNIA WITH ONLY A FEW HIGH CLOUDS ON THE NORTHERN PERIPHERY OF
THE RIDGE. AT THE SURFACE ACROSS SOUTH-CENTRAL ARIZONA AND SOUTHEAST
CALIFORNIA...TEMPS WERE GENERALLY IN THE MID TO UPPER 70S WITH LIGHT
WINDS.
WITH THE RIDGE FORECAST TO STRENGTHEN FURTHER TODAY...I EXPECT
TEMPERATURES TO RISE ABOUT 3-4 DEGREES FROM YESTERDAY AND THIS PUTS
MOST OF THE LOWER DESERTS INTO EXCESSIVE HEAT WARNING CRITERIA. FOR
WHAT ITS WORTH...THIS IS ALSO NEAR RECORD TERRITORY FOR MAY 21ST.
PREVIOUS SHIFT ISSUED A WARNING AND THIS STILL LOOKS REASONABLE...NO
CHANGES NECESSARY. IN ADDITION...BL TEMPS EXPECTED TO REMAIN NEARLY
IDENTICAL ON TUESDAY. THIS...ALONG WITH BREEZIER CONDITIONS...COULD
BE ENOUGH FOR US TO HIT EXCESSIVE HEAT CRITERIA AGAIN ON TUESDAY. I
WILL GO AHEAD AND ISSUE AN EXCESSIVE HEAT WATCH FOR TUESDAY
AFTERNOON. NEAR RECORD TEMPS ARE ALSO EXPECTED ON TUESDAY.
A WEAK TROUGH WILL MOVE THROUGH ON WEDNESDAY AND THIS WILL BEGIN A
GRADUAL LOWERING OF TEMPERATURES THAT WILL LAST THROUGH THE WEEKEND.
NO CHANCE OF PRECIP WITH THIS TROUGH BUT BL TEMPS SHOULD DROP ABOUT
2-3C PER DAY. MEANWHILE LOW PRESSURE WILL MOVE DOWN THE PACIFIC
COAST STARTING ON THURSDAY AND H5 HEIGHTS WILL DROP SUBSTANTIALLY
ACROSS THE DESERT SOUTHWEST BY THE TIME THE WEEKEND ARRIVES. WITH
850MB TEMPS EXPECTED TO BE AROUND 16C ON SATURDAY...THIS COULD
CONCEIVABLY RESULT IN DESERT HIGHS RIGHT AROUND 90 DEGREES. I
DECREASED HIGHS FOR FRIDAY AND SATURDAY SINCE THERE IS BETTER
AGREEMENT BETWEEN THE EUROPEAN AND GFS MODELS WITH RESPECT TO THIS
COOLDOWN. THE TROUGH WILL MOVE THROUGH ARIZONA ON SATURDAY BUT IT
STILL LOOKS LIKE IT WILL BE MOISTURE STARVED AND BASED ON TODAYS
00Z GUIDANCE...A LITTLE BIT FARTHER NORTH THAN PREVIOUS RUNS
INDICATED. BOTTOM LINE...MORE OF A WIND/FIRE WEATHER EVENT THAN
ANYTHING.
WEAK RIDGING RETURNS ON SUNDAY...CONSEQUENTLY TEMPERATURES WILL ONCE
AGAIN CLIMB BACK TO NEAR NORMAL VALUES IN THE UPPER 90S BY EARLY
NEXT WEEK.
&&
.AVIATION...
SOUTH CENTRAL ARIZONA INCLUDING KPHX...KIWA AND KSDL. SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH.
CLEAR SKIES WITH LIGHT WINDS FOLLOWING THE TYPICAL DIURNAL TRENDS
WILL LEAD TO NO AVIATION CONCERNS ACROSS THE REGION THROUGH MONDAY
EVENING. (PLEASE NOTE REDUCED VISIBILITY READINGS AT KIPL ARE
ERRONEOUS...AND TECHNICIANS HAVE BEEN DISPATCHED TO RECTIFY THIS
PROBLEM)
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
A LOW PRESSURE SYSTEM PASSING BY TO THE NORTH WEDNESDAY WILL LEAD TO
INCREASING WIND ACROSS THE AREA...ESPECIALLY THE CENTRAL ARIZONA
DESERTS AND HIGHER TERRAIN EAST OF PHOENIX. ABOVE NORMAL HIGH
TEMPERATURES AND SINGLE DIGIT MINIMUM HUMIDITIES WILL LEAD TO
DANGEROUS FIRE WEATHER CONDITIONS. A FIRE WEATHER WATCH MAY NEED TO
BE ISSUED FOR WEDNESDAY AFTERNOON AND EVENING FOR SOUTH CENTRAL
ARIZONA.
A BROAD AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE WESTERN
CONUS THURSDAY INTO THE WEEKEND. THIS WILL LEAD TO A COOLING
TREND...WITH HIGH TEMPERATURES TO FALL TO NEAR OR SLIGHTLY BELOW
SEASONAL NORMALS BY SATURDAY. EXPECT BREEZY TO WINDY CONDITIONS
DURING THE AFTERNOON AND EVENING HOURS EACH DAY...ESPECIALLY ON
FRIDAY. DESPITE THE COOLING TREND HUMIDITIES WILL REMAIN LOW EACH
DAY...MOSTLY IN THE SINGLE DIGITS TO AROUND 10 PERCENT. AS SUCH
THERE WILL BE A CONTINUED THREAT FOR HAZARDOUS FIRE WEATHER
CONDITIONS THROUGH THE PERIOD...MAINLY DURING AFTERNOON AND EVENING
HOURS. RECOVERIES WILL BE POOR TO MODERATE EACH NIGHT...WITH SOME
IMPROVEMENT TOWARDS THE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...EXCESSIVE HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM MST THIS
EVENING AZZ020>023-025>028.
EXCESSIVE HEAT WATCH FROM TUESDAY MORNING THROUGH TUESDAY
EVENING AZZ020>023-025>028.
CA...EXCESSIVE HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM PDT THIS
EVENING CAZ031>033.
EXCESSIVE HEAT WATCH FROM TUESDAY MORNING THROUGH TUESDAY
EVENING CAZ031>033.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...LEINS
AVIATION...MO
FIRE WEATHER...CB
NWS PSR Office Area Forecast Discussion
