901
FXUS61 KPBZ 162217
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
517 PM EST SAT NOV 16 2024
SYNOPSIS
DRY BUT DREARY WEATHER CONTINUES TODAY AS CLOUD COVER PERSISTS.
TEMPERATURES WILL WARM INTO EARLY NEXT WEEK. WIDESPREAD RAIN
CHANCES RETURN ON TUESDAY, WITH SEVERAL ADDITIONAL CHANCES FOR
PRECIPITATION THROUGH NEXT WEEKEND.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
KEY MESSAGES:
- DRY WEATHER CONTINUES THROUGH TONIGHT WITH PERSISTENT CLOUD
COVER.
------------------------------------------------------------------
OVERCAST STRATUS CONTINUES ACROSS THE AREA WITH NORTHWEST FLOW
AND SUBSTANTIAL BOUNDARY LAYER MOISTURE TRAPPED UNDER A STOUT
POST-FRONTAL INVERSION. RECENT PIT ACARS SOUNDINGS SHOW A
GRADUAL VEERING TREND TO MORE NORTHERLY BETWEEN 850-800 MB
WHICH EXPLAINS THE LOCALIZED BREAKS IN COVERAGE ESPECIALLY EAST
OF PITTSBURGH, BUT ANY BREAKS WILL BE FAIRLY SHORT-LIVED AND
GENERAL OVERCAST CONDITIONS WILL LIKELY CONTINUE INTO THE
OVERNIGHT. SOME GREATER ENSEMBLE SPREAD COMES INTO PLAY ACROSS
SOUTHEAST OHIO AND NORTHERN WEST VIRGINIA WHERE SOME WEAK WARM
ADVECTION ALOFT MAY ALLOW FOR MORE SCATTERED TO BROKEN COVERAGE
AS FLOW WEAKENS AND TURNS SOUTHERLY WITH A BUILDING RIDGE.
STILL, WITH GENERALLY BROKEN TO OVERCAST CONDITIONS CONTINUING
OVERNIGHT, LOWS WILL REMAIN JUST ABOVE-NORMAL. PATCHY FOG IS
POSSIBLE WITH LINGERING MOISTURE, ESPECIALLY ACROSS THE RIVER
VALLEYS.
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/
KEY MESSAGES:
- WARMING TREND THROUGH THE WEEKEND
- QUICK SHOWER CHANCE SUNDAY NIGHT INTO EARLY MONDAY
-------------------------------------------------------------------
THE UPPER RIDGE AXIS WILL SHIFT DIRECTLY OVERHEAD BY SUNDAY
MORNING AS HIGH PRESSURE CENTERED OVER THE SOUTHEAST BUILDS INTO
THE AREA. THIS WILL BACK FLOW MORE SOUTHWESTERLY, RESULTING IN
INCREASED WARM ADVECTION AND HELPING TO BREAK AND LIFT THE CLOUD
DECK THROUGH THE DAY. WARM ADVECTION WILL LEAD TO A 5-10 DEGREE
BOOST IN AFTERNOON HIGHS, WITH MUCH OF THE REGION IN THE
MID/UPPER 50S.
A QUICK-MOVING SHORTWAVE WILL CROSS WELL TO THE NORTH OF THE
AREA SUNDAY NIGHT INTO EARLY MONDAY AS A WEAK COLD FRONT CROSSES
THE OHIO VALLEY. THIS WILL ALLOW LIGHT SHOWERS TO DEVELOP
OVERNIGHT, PRIMARILY NORTH OF PITTSBURGH AND IN THE PA RIDGES,
BUT LOW-PROBABILITY CHANCES ELSEWHERE. LINGERING SHOWERS SHOULD
EXIT BY SUNRISE MONDAY.
DESPITE COOLING 850S, BETTER INSOLATION ON MONDAY AS CLOUD COVER
BREAKS WILL HELP HIGH TEMPERATURES GAIN ANOTHER ~5 DEGREES.
OTHERWISE, DRY WEATHER CONTINUES INTO MONDAY NIGHT.
LONG TERM /TUESDAY THROUGH SATURDAY/
KEY MESSAGES:
- RAIN RETURNS TUE/WED WITH ADDITIONAL CHANCES THROUGH LATE WEEK
- HIGH UNCERTAINTY REMAINS WITH A LATE WEEK SYSTEM
-------------------------------------------------------------------
ENSEMBLES SHOW FAIRLY HIGH CONSISTENCY THROUGH TUESDAY AS SFC
LOW PRESSURE COINCIDENT WITH A MID-LEVEL SHORTWAVE EJECTS OUT
OF THE SOUTHERN PLAINS MONDAY AND INTO THE GREAT LAKES ON
TUESDAY. THIS SHOULD BRING A ROUND OF RAINFALL AS EARLY AS
TUESDAY MORNING IN ADVANCE OF A CROSSING COLD FRONT. RAIN WILL
LIKELY LINGER INTO THE EVENING/OVERNIGHT PERIOD. HIGH
TEMPERATURES WILL ANOTHER FEW DEGREES ABOVE MONDAY (10-15
DEGREES ABOVE AVERAGE), PUTTING MUCH OF THE AREA IN THE LOWER
60S (UPPER 50S NORTH OF PITTSBURGH).
MORE SIGNIFICANT BREAKDOWN IN THE FORECAST OCCURS IN THE
WEDNESDAY THROUGH FRIDAY TIMEFRAME. GENERALLY, MODELS SHOW A
MORE POTENT WAVE/CLOSED LOW DEVELOPING OVER THE CENTRAL US BY
WEDNESDAY AND DIVING OVER THE EAST BY THURSDAY/FRIDAY.
STRENGTHENING LOW PRESSURE AT THE SURFACE WOULD BRING AN INITIAL
ROUND OF PRECIPITATION FOLLOWED BY WRAP-AROUND MOISTURE
COINCIDENT WITH SIGNIFICANT COLD AIR ADVECTION.
GREATEST UNCERTAINTY STEMS FROM THE TIMING, STRENGTH, AND
PLACEMENT OF THE TROUGH WHICH WILL DEPEND ON THE STRENGTH OF THE
DOWNSTREAM RIDGE OVER THE EAST COAST. TWO CLUSTERED SCENARIOS
REMAIN: A MORE AMPLIFIED RIDGE AND THEREFORE WEAKER/SLOWER
TROUGH PROGRESSION, OR LESS AMPLIFIED RIDGE WITH QUICKER,
DEEPER TROUGHING. HOWEVER, PROBABILITY FOR THE LATTER (AND
COLDER) SOLUTION IS INCREASING. THERE REMAINS A BIMODAL
DISTRIBUTION IN FORECAST ELEMENTS (YIELDING NON-
METEOROLOGICALLY SENSIBLE MEAN VALUES), BUT THE LEFT-MOST PEAK
(COLDER SOLUTION) CONTINUES TO GROW AT EXPENSE OF THE WARMER
SOLUTION.
GIVEN INCREASING CONFIDENCE, HAVE HEDGED TOWARD THE COLDER
SOLUTION. THIS DOES INCREASE THE POSSIBILITY OF SNOW FOR THE
THURSDAY/FRIDAY TIMEFRAME, BUT THIS WILL OBVIOUSLY BE
TEMPERATURE DEPENDENT. THE 25-75TH PERCENTILE SPREAD IN TEMPS
ON THURSDAY/FRIDAY IS ROUGHLY 20 DEGREES. STAY TUNED FOR MORE
DETAILS...
AVIATION /22Z SATURDAY THROUGH THURSDAY/
MVFR CEILINGS REMAIN LOCKED OVER THE REGION, AS MOISTURE REMAINS
TRAPPED UNDERNEATH A POST-FRONTAL INVERSION. THE MOISTURE LAYER
IS RELATIVELY THIN, AND SOME MODEST CLOUD BREAKUP IS ALREADY
OCCURRING NORTH OF PIT. IT STILL APPEARS THAT MIXING WILL
LIKELY BE INSUFFICIENT TO REMOVE CEILINGS IN MOST CASES TODAY
GIVEN THE STOUTNESS OF THE INVERSION. SUCH CEILINGS WILL LINGER
INTO THE EVENING AS WELL. INDEED, THE HREF SHOWS 50 TO 80
PERCENT PROBABILITY OF MVFR CEILINGS LINGERING THROUGH 06Z ACROSS
SOUTHWEST PA/NORTHERN WV. PROBABILITIES ARE A TOUCH LOWER IN
EASTERN OHIO. WILL ALLOW FOR A LOW VFR CEILING AT ZZV THIS
EVENING, BUT PLAN ON MAINTAINING MVFR CEILINGS INTO THE EVENING
AT MOST LOCATIONS.
HREF MEMBERS CONTINUE TO SHOW VARIANCE IN CLOUD COVERAGE AFTER
06Z, MAINLY SOUTH OF I-70, AS WARM ADVECTION TRIES TO EAT AWAY
AT THE LOW CLOUDS. THINK THAT AT LEAST ZZV AND MGW HAVE A
DECENT CHANCE OF SCATTERING OUT LATE TONIGHT - BUT DO NOT HAVE
ENOUGH CONFIDENCE TO GO FURTHER NORTH THAN THIS AT THE MOMENT.
ASSUMING THIS CLEARING DOES OCCUR, THERE IS A THREAT OF FOG
DEVELOPMENT DUE TO MOIST GROUNDS, LIGHT WINDS, AND POTENTIAL FOR
STRONG RADIATIONAL COOLING. HAVE INCLUDED TEMPO POSSIBILITIES
AT THE TWO SITES MENTIONED ABOVE.
THE DISSIPATION OF THE STRATOCUMULUS WILL CONTINUE PAST SUNRISE,
AIDED BY DAYTIME MIXING. EXPECT ALL SITES TO ACHIEVE VFR BY LATE
MORNING. AREAS THAT LOSE STRATOCUMULUS WILL STILL BE COVERED BY
A VEIL OF HIGHER CLOUDS, THANKS TO SOUTHWEST FLOW AHEAD OF A
GREAT LAKES SHORTWAVE.
NORTHWEST WIND WILL CONTINUE TODAY, GENERALLY AT 5 TO 10 KNOTS
OR SO, BEFORE DIMINISHING TONIGHT.
OUTLOOK....
ANY REMAINING STRATOCUMULUS WILL DISSIPATE SUNDAY AFTERNOON,
WITH CONTINUED VFR AND DRY CONDITIONS.
SUNDAY NIGHT, A WEAK SHORTWAVE AND SURFACE FRONT WILL SUPPORT
LOWER PROBABILITY RAIN CHANCES AND CEILING REDUCTIONS (FAVORING
NORTHWEST PA). VFR THEN LIKELY RETURNS ON MONDAY. THERE IS
INCREASING LIKELIHOOD FOR AN ACTIVE MID TO LATE WEEK WEATHER
PATTERN THAT LENDS TO MULTIPLE WAVES OF PRECIPITATION AND
PROLONGED RESTRICTIONS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...RACKLEY
NEAR TERM...RACKLEY/MLB
SHORT TERM...RACKLEY
LONG TERM...RACKLEY
AVIATION...CL
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page