Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 151707
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1000 AM MST FRI AUG 15 2014

.SYNOPSIS...
FOR TODAY...EXPECT ANOTHER ROUND OF SLOW MOVING SHOWERS AND
THUNDERSTORMS ACROSS MOST OF NORTHERN ARIZONA. FOR THE
WEEKEND...HIGH PRESSURE IN PLACE ACROSS THE STATE WILL DECREASE
THE CHANCES FOR PRECIPITATION AND WARM TEMPERATURES TO NEAR NORMAL
FOR THIS TIME OF YEAR. A LOW PRESSURE SYSTEM FORECAST TO DROP
SOUTH ALONG THE WEST COAST MAY INCREASE THE CHANCES FOR SHOWERS
AND THUNDERSTORMS BY THE MIDDLE OF THE NEXT WORK WEEK.

&&

.DISCUSSION...FORECASTS ARE IN GOOD SHAPE FOR TODAY WITH ONLY MINOR
UPDATES TO INCREASE STORM CHANCES A BIT MORE FOR SOME
AREAS...INCLUDING GILA COUNTY. STEERING FLOW WILL AGAIN BE
LIGHT...POSSIBLY A BIT MORE NORTHERLY THAN YESTERDAY AS THE
MID-LEVEL RIDGE CENTERS JUST TO OUR WEST. STORMS WILL BE SLOW MOVING
AGAIN TODAY WITH VERY LIGHT LOW AND MID LEVEL WINDS...BUT COULD BE MORE
PULSE TYPE CELLS AS THE JET-LEVEL WINDS HAVE DECREASED TODAY. SOME
STORMS YESTERDAY AFTN DUMPED 2.5 TO 3 INCHES OF RAIN OVER SMALL
AREAS...RESULTING IN LOCAL FLOODING.

.PREV DISCUSSION...(330 AM MST)...FOR TODAY...ATMOSPHERIC MOISTURE
IS A BIT HIGHER THIS MORNING THAN I ANTICIPATED YESTERDAY. DEW
POINTS ARE GENERALLY IN THE 50`S ACROSS NORTHERN ARIZONA THIS
MORNING...EXCEPT FOR FAR SOUTHWEST YAVAPAI COUNTY WHERE A FEW SITES
ARE REPORTING VALUES IN THE 60`S. GPS DERIVED PRECIPITABLE WATER
FOR FLAGSTAFF HAS ACTUALLY CLIMBED A LITTLE SINCE YESTERDAY
MORNING...AND IS HOVERING AROUND 0.9 INCHES.

NAM FORECAST SOUNDINGS...WHICH I THINK BETTER REPRESENT TODAY`S
BOUNDARY LAYER MOISTURE...FORECAST ENOUGH INSTABILITY FOR ANOTHER
CONVECTIVELY ACTIVE DAY. AS SUCH...I HAVE INCREASED THE CHANCES
FOR SHOWERS AND THUNDERSTORMS FOR TODAY COINCIDENT WITH DAYTIME
HEATING. SIMILAR TO YESTERDAY...0-6 KM WINDS ARE VERY
LIGHT...INDICATING LITTLE STORM MOTION AND ENHANCED POTENTIAL FOR
FLOODING FROM SLOW MOVING STORMS. WOULD NOT EXPECT SEVERE SIZED
HAIL GIVEN HAIL STONES WILL LIKELY FALL THROUGH THE STORMS
UPDRAFTS...BUT UP TO PENNY SIZED HAIL IS POSSIBLE.

SATURDAY THROUGH MONDAY...MODELS ARE IN FAIR AGREEMENT THAT A HIGH
PRESSURE CENTER WILL SET UP OVER/NEAR ARIZONA CAUSING DRYING
CONDITIONS AND PREVENTING NEW MOISTURE FROM MOVING INTO THE
REGION. THIS WILL REDUCE THE CHANCES FOR PRECIPITATION AND WILL
WARM TEMPERATURES TO NEAR NORMAL FOR THIS TIME OF YEAR.

TUESDAY ONWARD...LONGER TERM MODELS INDICATE A CLOSED LOW WILL DROP
SOUTHWARD ALONG THE WEST COAST DISPLACING THE SUB TROPICAL HIGH
CENTER EASTWARD. THE EXACT LOCATION OF THIS FEATURE WILL HAVE
SIGNIFICANT IMPACTS ON NORTHERN ARIZONA WEATHER AND CONSIDERABLE
UNCERTAINTY EXISTS WITH REGARDS TO WHERE THIS FEATURE WILL END UP.
FOR EXAMPLE...THE OPERATIONAL EUROPEAN FORECASTS THE CLOSED LOW
TO TRACK MUCH CLOSER TO ARIZONA SETTING UP SOUTHERLY FLOW AND
INCREASING LOW LEVEL MOISTURE ACROSS ARIZONA BY TUESDAY. THE
GFS ENSEMBLE AND MOST ENSEMBLE MEMBERS PREDICT THE LOW WILL SET
UP FURTHER WESTWARD....DELAYING THE INCREASE IN MOISTURE. AT THIS
POINT...I THINK A SLOW INCREASE IN THE CHANCES FOR SHOWERS AND
THUNDERSTORMS IS WARRANTED...WHICH IS MORE IN LINE WITH NAEFS
ENSEMBLE PRECIPITABLE WATER PREDICTIONS.

&&

.AVIATION...FOR THE 18Z PACKAGE...SCT -SHRA/TSRA TO REDEVELOP ALONG
THE HIGHEST TERRAIN FIRST AND SPREAD TO THE VALLEYS DURING THE
AFTERNOON. MVFR CIGS AND VSBYS PROBABLE IN THE STRONGEST STORMS.
PRECIP DECREASING AFT 03Z SAT. AVIATION DISCUSSION NOT UPDATED FOR
AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC.....JJ/RR
AVIATION...MAS

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF




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