How Dry Is It?

While most weather attention continues to be focused on the winter storm in the Northeast, we have remained very dry here in the Southwest. Nothing noted in my weather log, except morning low temperatures, since January 8th.

Jack Diebolt sent along the PW climo for Tucson soundings this morning (above) and noted the record dryness we've been enduring - itchy and dry skin time of year. The AFD from Phoenix NWS early this morning did note the dry soundings here in Tucson. That discussion was amazingly thorough and well-done; quite unusual and interesting to read (see below). At the very bottom are the GFS ensemble mean forecasts for 500 mb valid at 84-h (12 UTC 26 January) and at 168-h (00 UTC 30 January). These will help put the AFD in context, and also indicate that weather may return to our part of the country as the month comes to an end.
-------------------------------------------------------------------------------------------------------------

AREA FORECAST DISCUSSION

  NATIONAL WEATHER SERVICE PHOENIX AZ

  225 AM MST SAT JAN 23 2016

  

  .DISCUSSION...

  SOLID RIDGING ALOFT CONTINUES TO HOLD OVER THE REGION WITH NUMEROUS

  UPSTREAM SHORTWAVES ALIGNED ACROSS THE EAST PACIFIC BASIN POISED TO

  MOVE INLAND AND CREATE A SLIGHT PATTERN READJUSTMENT EARLY NEXT

  WEEK. THE LEAD WAVE WAS LIFTING NORTH INTO SRN OREGON EARLY THIS

  MORNING WITH AN ASSOCIATED JET STREAK AND SFC FRONT PUNCHING INTO

  CNTRL CALIFORNIA. MEANWHILE...A LOWER LATITUDE PV ANOMALY AND

  TRAILING JET SEGMENT (NEAR 27N 130W) WILL BE THE IMPETUS TO DISPLACE

  AND REALIGN THE SWRN CONUS RIDGE. SUBSEQUENT SHORTWAVES EMANATING

  FROM THE GULF OF ALASKA WILL PROPAGATE INTO THE GREAT BASIN MONDAY

  ALLOWING HIGH AMPLITUDE RIDING TO RETROGRADE AND ONCE AGAIN BECOME

  ESTABLISHED ALONG THE WEST COAST FOR THE BULK OF NEXT WEEK. 

  

  THROUGH LATE TONIGHT...INCREASINGLY THICK CIRRUS WILL SPILL INTO THE

  AREA AHEAD OF THE TROUGH AXIS AND AFOREMENTIONED LOWER LATITUDE

  SHORTWAVE. DESPITE THIS APPARENT INFUSION OF MOISTURE PER WV

  IMAGERY...THE VAST MAJORITY OF THE ATMOSPHERIC COLUMN REMAINS

  UNUSUALLY DRY PER REGIONAL INLAND SOUNDINGS. IN FACT...THE 00Z KTWC

  SAMPLED PWAT OF 0.12 INCHES SET A RECORD LOW FOR THE DATE WHILE THE

  COASTAL KNKX READING OF A PALTRY 0.36 INCHES FALLS IN THE LOWEST

  25TH PERCENTILE. THUS DESPITE FAIRLY ROBUST DYNAMICS AND DEFINED LOW

  LEVEL FRONTAL BOUNDARY...LITTLE MORE THAN VIRGA AND POTENTIALLY SOME

  SPRINKLES WOULD BE THE MOST LIKELY OUTCOME FROM THIS SYSTEM THIS

  EVENING AND OVERNIGHT. BOTH SREF AND NUMERICAL GUIDANCE

  PROBABILITIES BEAR THIS OUT AND WITH SUPPORT FROM HIGH RESOLUTION

  MODEL OUTPUT...LITTLE MORE THAN SINGLE DIGIT POPS ARE JUSTIFIED

  THROUGHOUT THE FORECAST AREA. 

  

  OTHERWISE...TEMPERATURE FORECASTS THROUGH SUNDAY MORNING CARRY MORE

  UNCERTAINTY GIVEN THE POTENTIAL INFLUENCE OF THICKER CLOUD COVER.

  WHILE THIS SHOULD LIMIT AFTERNOON NEAR SFC SUPER ADIABATIC

  WARMING...00Z KTWC SOUNDING DATA ONCE AGAIN SAMPLED MIDTROPOSPHERIC

  H5 HEIGHTS AND H9-H8 TEMPERATURES ABOVE THE 90TH

  PERCENTILE...SUGGESTING THAN ANY AMOUNT OF VERTICAL MIXING WILL

  YIELD READINGS IN AN ABOVE NORMAL RANGE ONCE AGAIN TODAY. WILL

  CONTINUE TO ADVERTISE HIGHS NEAR TO JUST BELOW PERSISTENCE THIS

  AFTERNOON...WITH OVERNIGHT LOWS NOT AS COOL AS COULD BE EXPECTED

  WITH FALLING HEIGHTS AND A COOLER POST FRONTAL AIRMASS. 

  

  HEIGHT FALLS WILL NOT BE PARTICULARLY AGGRESSIVE SUNDAY...THOUGH

  POST FRONTAL MOMENTUM TRANSFER MAY BE ABLE TO PARTIALLY TAP A BRIEF

  PERIOD OF STRONGER WINDS IN THE H8-H7 LAYER. WHILE THE PERIODIC WIND

  GUSTS WILL NOT BE UNUSUALLY STRONG FOR THE SEASON OR CREATE

  IMPACTS...IT WILL BE A SIGN OF COLD ADVECTION AND A CHANGING

  AIRMASS. A SECONDARY SHORTWAVE WILL SLIDE SOUTH THROUGH THE FORECAST

  AREA MONDAY...FORCING DEEPER NORTHERLY FLOW AND UPSTREAM SFC

  PRESSURE RISES CAPABLE OF UNLOCKING DRY CHILLY CONTINENTAL AIR DOWN

  INTO THE LOWER ELEVATIONS. MORE RECENT BEST PERFORMING GUIDANCE DOES

  NOT IMPLY TEMPERATURES AS COLD AS PREVIOUS ITERATIONS...THOUGH STILL

  FALLING IN A SLIGHTLY BELOW NORMAL CATEGORY.

  

  OPERATIONAL AND ENSEMBLE MEMBERS ARE IN FAIRLY GOOD AGREEMENT

  BUILDING RATHER SUBSTANTIAL HEIGHTS BACK INTO THE WRN CONUS DURING

  THE MIDDLE AND END OF NEXT WEEK...ALBEIT WITH THE CAVEAT OF A

  NOTABLE HEIGHT FIELD WEAKNESS AND SUBTROPICAL JET COMPONENT

  LINGERING OVER NRN MEXICO. WHILE THIS MAY MUTE MORE EXTREME WARMTH

  FOR THE SOUTHWEST...HEIGHT AND THICKNESS FIELDS STILL STRONGLY

  CONCUR THAT A RESUMPTION OF ABOVE AVERAGE TEMPERATURES WILL BE

  MANIFESTED. HAVE STILL HEDGED FORECASTS TOWARDS A CONSENSUS

  MEAN/MEDIAN VERSUS THE WARMEST GUIDANCE...THOUGH IT WOULD NOT BE OUT

  OF THE QUESTION (VIA THE PATTERN AND HISTORICAL CLIMATOLOGY) THAT A

  FEW LOCATIONS BREACH THE 80 DEGREE THRESHOLD AT SOME POINT. A LOOK

  AHEAD TOWARDS NEXT WEEKEND SHOWS GOOD PROMISE OF A MORE ACTIVE WET

  PATTERN...THOUGH NAEFS INDIVIDUAL MEMBER SPREAD DOES LIMIT A MORE

  CONFIDENT STATEMENT AT THIS POINT.

  ---------------------------------------------------------------------------------------