Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KPHI 231535
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1135 AM EDT THU APR 23 2015

.SYNOPSIS...
A WEAKER SECONDARY COLD FRONT WILL CROSS THE AREA TODAY. A HIGH
PRESSURE SYSTEM WILL BRIEFLY BUILD OVER THE REGION FRIDAY INTO
EARLY SATURDAY. LOW PRESSURE IS THEN FORECAST TO PASS BY TO OUR
SOUTH FROM SATURDAY NIGHT INTO SUNDAY, TRACKING FROM AROUND THE
TENNESSEE VALLEY TO OFF THE CAROLINA COAST. ANOTHER HIGH PRESSURE
SYSTEM SHOULD BRIEFLY BUILD INTO THE AREA ON MONDAY AND TUESDAY.
THEN A LOW PRESSURE SYSTEM PREDICTED TO FORM IN THE GULF OF
MEXICO SHOULD REACH THE NORTH CAROLINA COASTAL WATERS ON
WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AN AREA OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY AND CONTINUE
TO SPIN ACROSS SOUTHEASTERN CANADA TODAY. STRONG WESTERLY AND
NORTHWESTERLY WINDS WILL CONTINUE THROUGH THE AFTERNOON AND INTO
THE EARLY EVENING, WITH GUSTS AROUND 30 MPH POSSIBLE THROUGH THIS
TIME. A WEAK COLD FRONT/SURFACE TROUGH IS EXPECTED TO SLIDE
ACROSS THE AREA THIS AFTERNOON. AS THIS HAPPENS, LOW-MID LEVEL
LAPSE RATES ARE FORECAST TO INCREASE AND THERE IS SOME MOISTURE
FORECAST TO MOVE ACROSS THE AREA. THIS COULD LEAD TO SOME ISOLATED
SHOWER ACTIVITY DEVELOPING TO OUR WEST AND MOVING INTO OUR AREA.
BASED ON UPSTREAM OBS, THESE SHOWERS COULD BE A RAIN/SNOW MIX FOR
MUCH OF SE PA AND CENTRAL AND NORTHERN NJ. FOR NOW, THE GREATEST
POSSIBILITY IS FOR OUR NORTHWESTERN THIRD OF THE AREA. ITS
POSSIBLE SOME SPRINKLES COULD MAKE IT DOWN INTO THE TIER OF
COUNTIES DOWN, SO WE`VE INCLUDED A CHANCE OF SPRINKLES THERE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
ANY SHOWERS AND/OR SPRINKLES ARE EXPECTED TO DISSIPATE BY THIS
EVENING AS DAYTIME INSTABILITY IS LOST AND THE SURFACE TROUGH MOVES
EASTWARD. SKIES WILL LIKELY REMAIN PRETTY CLOUDY FOR MUCH OF THE
NIGHT HOWEVER. WITH THE LOW REMAINING TO OUR NORTHEAST, THE PRESSURE
GRADIENT WILL REMAIN ACROSS THE AREA, KEEPING A STEADY BREEZE FOR
MUCH OF THE NIGHT. HOWEVER, WE STILL EXPECT COLD TEMPERATURES
TONIGHT AS COLD AIR ADVECTION WILL CONTINUE THROUGH THE NIGHT. WE`VE
ISSUED A FREEZE WARNING FOR AREAS WHERE WE ARE MOST CONFIDENT OF SUB-
FREEZING TEMPERATURES OCCURRING OVERNIGHT, AND A FREEZE WATCH FOR
THOSE AREAS WHERE WE ARE A LITTLE MORE UNCERTAIN. WITH THE BREEZE
EXPECTED, IT MAY BE HARD TO DEVELOP MUCH FROST, SO THAT`S WHY WE
HAVEN`T INCLUDED FRONT IS THE FORECAST OR ISSUED A FROST ADVISORY AT
THIS TIME.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE LONG TERM BEGINS WITH CONTINUED FROST/FREEZE CONCERNS BEFORE
SHIFTING FOCUS TO TWO DIFFERENT LOW PRESSURE SYSTEMS.

FRIDAY NIGHT...THE FREEZE WATCH CONTINUES FOR MOST OF OUR PA AND
NJ ZONES WHERE THE GROWING SEASON HAS STARTED. EXCEPTION IMMEDIATE
COAST AND PHL AREA. LESS CONFIDENCE IN DELMARVA ALTHOUGH THE SFC
HIGH PRESSURE SHOULD BE CLOSE ENOUGH TO DECOUPLE WINDS, RESULTING
IN PLENTY OF RADIATIONAL COOLING. ANOTHER SIGNAL IS THE WAA
PREDICTED ABOVE THE BOUNDARY LAYER. BECAUSE WINDS WILL BE LIGHTER,
WE HAVE INCLUDED FROST IN THE GRIDS. SLIGHTLY UNDERCUT GUIDANCE TO
ACCOUNT FOR RADIATIONAL COOLING WHICH ISN/T ALWAYS DEPICTED WELL
BY MODELS.

SATURDAY INTO SUNDAY...SURFACE LOW SHOULD CROSS FROM KS INTO THE
CAROLINAS. BY THE GFS THE BEST FORCING SHOULD BE WELL SOUTH OF OUR
REGION, OTHER THAN MID LEVEL QVEC CONVERGENCE. THEREFORE, AGREE
WITH THE PREVIOUS SHIFT THAT THE GFS IS TOO FAR NORTH WITH THE
QPF. DESPITE BEING ON THE NORTH SIDE OF THIS LOW, THE COMBINATION
OF DOWNSLOPING WINDS AND AIR MASS MODIFICATION SHOULD HELP TO KEEP
TEMPS NEAR OR JUST BELOW NORMAL BOTH DAYS.

THE CURRENT CLOSED LOW OVER ONTARIO THAT IS GOING TO HELP STEER THE
WEEKEND SFC SYSTEM WELL TO OUR SOUTH IS PREDICTED TO RETROGRADE
WESTWARD OR REMAIN NEARLY STATIONARY TO START NEXT WEEK. SOME
INSTABILITY SHOWERS ARE POSSIBLE UNDER THIS COLD POOL. BUT THE
THERMAL PROFILE CLOSER TO THE SURFACE WILL BE MILDER. SO WHILE
TEMPS SHOULD STILL BE BELOW NORMAL, THEY SHOULD BE A CATEGORY OR
TWO HIGHER THAN TODAY AND FRIDAY.

WE LEFT IN THE CHANCE FOR RAIN ON WEDNESDAY ASSOCIATED WITH THE NEXT
LOW PRESSURE SYSTEM/POSSIBLE NOR`EASTER. STILL CONSIDERABLE
UNCERTAINTY AND MODEL DIFFERENCES ON THIS SYSTEM, SO STAYED CLOSE
TO THE PREVIOUS FORECAST.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS WILL CONTINUE AT THE TAF SITES THROUGH THE PERIOD,
ALTHOUGH CLOUD COVER WILL INCREASE THIS AFTERNOON INTO TONIGHT. A
FEW VERY LIGHT RAIN SHOWERS/SPRINKLES WILL BE POSSIBLE THIS
AFTERNOON PRIMARILY FOR KTTN AND KABE. HOWEVER, VFR CONDITIONS ARE
EXPECTED TO CONTINUE EVEN UNDER THESE SHOWERS.

WINDS WILL BE THE MAIN CONCERN AS WIND GUSTS WILL INCREASE
THROUGH THE DAY AND WILL GUST AROUND 25 KNOTS AT TIMES TODAY. THE
SPEED OF THE GUSTS MAY DROP OFF A BIT THIS EVENING AND OVERNIGHT,
BUT WE COULD STILL GET SOME GUSTS ROUND 20 KNOTS THROUGH THE NIGHT
FOR MANY AREAS.

OUTLOOK...
FRIDAY...VFR CONDITIONS EXPECTED, GUSTY NORTHWESTERLY WINDS (UP TO
25 KT), ESPECIALLY LATE MORNING AND THROUGH THE AFTERNOON.

FRIDAY NIGHT...VFR CONDITIONS WITH LIGHTER WINDS.

SATURDAY AND SATURDAY NIGHT...MAINLY VFR CONDITIONS NORTHERN
AIRPORTS AND TERMINALS. SOME RAIN AND SUB-VFR CONDITIONS ARE
POSSIBLE, MAINLY SOUTH OF A KILG/KACY LINE.

SUNDAY THROUGH MONDAY...MAINLY VFR CONDITIONS ARE EXPECTED.

&&

.MARINE...
THE SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR TODAY AND TONIGHT AS
WINDS WILL REMAIN ELEVATED WITH THE PRESSURE GRADIENT REMAINING
ACROSS THE AREA AND SOME WINDS FROM ALOFT MIXING DOWN TO THE
SURFACE. WITH THE NORTHWEST FLOW, SEAS ARE NOT EXPECTED TO BUILD
SIGNIFICANTLY AND SHOULD BE AROUND 4-5 FEET.

OUTLOOK...
FRIDAY AND FRIDAY NIGHT...SCA CONDITIONS CONTINUE ON ALL WATERS
THROUGH THE DAY FRIDAY AND MAY LINGER INTO FRIDAY EVENING.

SATURDAY THROUGH SUNDAY...SUB SMALL CRAFT ADVISORY CONDITIONS
EXPECTED. THE LOW PRESSURE SYSTEM SHOULD PASS TOO FAR TO THE SOUTH
TO GENERATE HIGHER SEAS OR WINDS.

SUNDAY NIGHT THROUGH MONDAY...CONTINUED SUB-SCA CONDITIONS;
ALTHOUGH, SOME WIND GUSTS TO AROUND 20 KNOTS PLUS ARE POSSIBLE.

&&

.FIRE WEATHER...
DRY AND GUSTY CONDITIONS ARE EXPECTED TODAY WITH RH VALUES EXPECTED
TO DIP INTO THE MID/UPPER 20S AND WINDS GUSTING AROUND 25-30 MPH.
AFTER COORDINATION WITH THE STATE PARTNERS HAVE DECIDED TO ISSUE A
SPS FOR TODAY AS FINE FUELS ARE ALREADY BEGINNING TO DRY OUT. THE
SPS IS VALID THROUGH 7 PM EDT AS WE SHOULD SEE QUICK RH RECOVERY
EARLY THIS EVENING.

CONDITIONS MAY BE ENHANCED ON FRIDAY FOR THE POTENTIAL OF WILDFIRE
SPREAD ACROSS THE REGION. FRIDAY`S RELATIVE HUMIDITY VALUES ARE
PROGGED TO DROP BELOW 30 PERCENT FOR A TIME FROM LATE FRIDAY MORNING
AND THROUGH THE AFTERNOON TO EARLY EVENING. IN ADDITION, SUSTAINED
WEST-NORTHWEST WINDS BETWEEN 15 TO 20 MPH ARE FORECAST DURING THIS
TIMEFRAME, WITH GUSTS REACHING BETWEEN 25 TO 30 MPH AT TIMES. WE
WILL CONTINUE TO MONITOR THE LATEST GUIDANCE AND COORDINATE WITH OUR
FIRE WEATHER PARTNERS IF ANY ADDITIONAL PRODUCTS BECOME NECESSARY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING
     FOR PAZ060>062-101>106.
     FREEZE WARNING FROM 2 AM TO 9 AM EDT FRIDAY FOR PAZ061-062-105.
     FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR
     PAZ060-101>104-106.
NJ...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING
     FOR NJZ001-007>010-012-013-015>022-027.
     FREEZE WARNING FROM 2 AM TO 9 AM EDT FRIDAY FOR NJZ001-007>010.
     FREEZE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR
     NJZ012-013-015>022-027.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ430-431-
     450>455.

&&

$$
SYNOPSIS...GIGI/KLINE
NEAR TERM...JOHNSON/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...GIGI/JOHNSON
AVIATION...GIGI/JOHNSON/KLINE/ROBERTSON
MARINE...GIGI/JOHNSON/KLINE/ROBERTSON
FIRE WEATHER...JOHNSON/ROBERTSON/GIGI



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.