Area Forecast Discussion
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FXUS61 KPBZ 281413 AAB
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
913 AM EST SUN DEC 28 2014

.SYNOPSIS...
A COLD FRONT WILL BE ACCOMPANIED BY SHOWERS THIS MORNING. A
RETURN TO BELOW-NORMAL TEMPERATURES WILL START MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
CHGS WERE MADE TO INCL RA/SN MIX GIVEN CURRENT OBS REFLECTING THIS
MIX AS COLD AIR INVADES. RDG ZONES WILL SEE A TRANSITION FROM SHRA
TO SHSN THRU THE DAY WITH ONSET OF COLDER AMS. PREV DISCUSSION
FOLLOWS...

FRONT WILL MOVE INTO THE MID-ATLANTIC REGION THIS MORNING AND
SHOWERS WILL END ACROSS MOST OF THE REGION EARLY THIS AFTERNOON. A
WEAK UPPER LEVEL WAVE WILL MOVE EASTWARD TO THE NORTH OF THE
SLOWING BOUNDARY AND WILL KEEP IN THE RISK FOR SHOWERS THROUGH THE
REST OF THE DAY IN THE FAR SOUTHEAST. CAA WILL TRAIL BEHIND THE
BOUNDARY...SO EXPECT STEADY OR SLOWLY FALLING TEMPS. THE COLDER
AIR WILL REACH THE SOUTHEASTERN RIDGES THIS AFTERNOON...WHICH WILL
ALLOW FOR A MIX OF RAIN AND SNOW OR ALL SNOW ACROSS THE RIDGE
TOPS.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
BROAD HIGH PRESSURE WILL BUILD INTO TONIGHT AND HOLD STEADY
THROUGH MONDAY. THE NEXT SHORTWAVE TROUGH ON MONDAY WILL PROVIDE
ANOTHER PUSH OF COLDER AIR. MODEST WIND FLOW ALOFT...WHICH WILL
VEER TO THE NORTHWEST WILL ACCOMPANY THE CAA...HOWEVER...STRONG
SUBSIDENCE FROM HIGH PRESSURE AND LOW INVERSIONS...WELL BELOW SNOW
GROWTH ZONE...SHOULD PREVENT ANY LAKE/OROGRAPHIC SNOW.

MODEL DIFFERENCES BEGIN TUESDAY...CONCERNING IMPACTS OF COASTAL
LOW. NAM/SREF REMAIN MOST AGGRESSIVE...SHOWING A MUCH MORE
ENERGETIC NORTHERN WAVE...SPREADING PRECIP FURTHER NORTH THEN
LATEST GFS/ECMWF/GEFS. LATEST RUN OF THE NAM HAS MOVED TOWARD THE
DRIER MODEL RUNS...LEADING ME TO BELIEVE THAT A DRIER FORECAST IS
THE WAY TO GO. WILL LEAVE IN SCHC/CHC POPS IN THE SOUTHEASTERN
RIDGES FOR SNOW SHOWERS.

A PUSH OF ARCTIC AIR WILL COMMENCE LATE TUESDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE EXTENDED WILL LARGELY BE DRY WITH A DECREASING TREND IN
TEMPERATURES AS A BROAD TROUGH IN THE LONGWAVE PATTERN SLOWLY SAGS
SOUTH ACROSS THE EASTERN CONUS.

POTENT SHRTWV TROF XPCD TO IMPACT FCST AREA FRI NGT AND SAT. BOTH
GFS AND ECMWF SHOW TEMPORAL CONSISTENCY...ALTHOUGH THE EXACT
TRACK OF THE SYSTEM DIFFERS. REGARDLESS...THE SFC FEATURE PASSES
TO THE NW OF THE FCST AREA...LEADING TO STRONG WARM AIR ADVCTN
THAT SHOULD KEEP PCPN LIQUID. ONLY CAVEAT WILL BE SUB-FREEZING
TEMPS AT ONSET...WHICH COULD SPELL A FRZG RAIN SCENARIO FOR AREAS
THAT TYPICALLY RETAIN COLD AIR...SPCLY SHELTERED VLLYS IN RDG
CNTYS AND NRN ZONES. POPS WERE INCRD DAY 7 GIVEN XPCD MEASURABLE
PCPN...BUT UNCERTAINTY RMNS IN PCPN TYPE.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
RAIN AND IFR CIGS WL GIVE WAY TO MVFR STRATOCU TDA...WITH EVENTUAL
VFR DVLP FM THE W WITH SBSDNC AND DRY ADVCTN. THE EXCEPTION WL BE
NRN TERMINALS WHERE COLD FLOW OVR THE LAKES IS EXPECTED TO CONT
FUELING MVFR STRATOCU INTO THE EVE.

OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
PERIODIC RESTRICTIONS CAN BE EXPECTED FOR THE FIRST HALF OF THE
WEEK WITH COLD ADVCTN AND CROSSING DISTURBANCES.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$

UPDATE...KRAMAR





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