Area Forecast Discussion
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FXUS61 KPBZ 041630 AAC
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
1230 PM EDT TUE AUG 4 2015

.SYNOPSIS...
GENERALLY DRY AND SUNNY CONDITIONS ARE EXPECTED THROUGH
WEDNESDAY. RAIN CHANCES INCREASE ON THURSDAY AS AN UPPER-LEVEL
DISTURBANCE APPROACHES THE REGION.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
A TROUGH AT H5 WILL LINGER OVER ERN CANADA TODAY...MAINTAINING
GENERAL WLY FLOW ALOFT IN THE GREAT LAKES REGION. HIGH PRESSURE AT
THE SURFACE WILL BUILD EWD FROM INDIANA/OHIO AND WILL AID IN
DRYING THE LOW LEVELS FOR MOST OF THE FORECAST AREA AND MOSTLY
SUNNY-PARTLY CLOUDY CONDITIONS FOR THE DAY.

THE PRIMARY EXCEPTION WILL BE IN THE NRN ZONES...WHERE A SECONDARY
FRONTAL SURGE OVERNIGHT WILL BE PRECEDED BY A PLUME OF ENHANCED
LOW-LEVEL MOISTURE...EVIDENT THIS AFTERNOON BY THE MORE ROBUST CU
FIELD PRESENT. IN THIS AREA...MODELS INDICATE EXISTENCE OF MODEST
INSTABILITY AND GENERATE LIGHT PRECIPITATION. WITH THE THREE
INGREDIENTS FOR CONVECTION PRESENT...POPS WERE INCREASED TO CHANCE
CATEGORY OVERNIGHT AS THE FRONTAL SURGE TRANSLATES SEWD.

AMID CONTINUED HIGH PRESSURE...WEDNESDAY WILL FEATURE CONSIDERABLE
SUN IN THE MORNING...GIVING WAY TO PARTLY CLOUDY CONDITIONS AS
COLD AIR ADVECTION AND STRONG HEATING YIELD A BROAD STRATOCU
FIELD. DRY AIR AND HIGH PRESSURE JUSTIFY ELIMINATING POPS ALMOST
EVERYWHERE WEDNESDAY AND WEDNESDAY NIGHT.

MAXIMA WILL BE SLIGHTLY BELOW NORMAL WITH THE PRESENCE OF THE
UNSEASONABLY COOL UPPER TROUGH...AND MINIMA ALSO BELOW NORMAL
OWING TO DRY AIR AND GENERALLY EFFICIENT RADIATIONAL COOLING.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
DEEP SHORTWAVE TROUGH WILL DIG INTO THE MIDWEST THURSDAY MORNING.
A SURFACE LOW WILL ACCOMPANY THE UPPER-LEVEL SYSTEM AND MOVE
ACROSS MISSOURI INTO ILLINOIS. THE EASTWARD MOVEMENT OF THE SYSTEM
HAS SLOWED FROM PREVIOUS RUNS...SO SHOWERS FROM THIS SYSTEM WILL
HOLD OFF UNTIL LATER IN THE DAY. MODELS STILL WRANGLING WITH THE
TRACK OF THE SURFACE LOW...STRENGTH OF THE UPPER-LEVEL WAVE...AND
IN TURN THE TIMING AND LOCATION OF SHOWERS. MODELS ARE IN MODERATE
AGREEMENT THAT THE SOUTHERN HALF OF THE AREA WILL SEE THE BEST
CHANCE FOR RAIN. THE MOST UNSTABLE ATMOSPHERE REMAINS TO THE SOUTH
OF THE SURFACE LOW...SO DO NOT EXPECT CONVECTION TO DEVELOP.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODELS STILL TRYING TO DETERMINE A SOLUTION FOR A SURFACE WAVE
WHICH WILL MOVE OUT OF THE MIDWEST AND CROSS THE MID-ATLANTIC LATE
THIS WEEK AND INTO THE FIRST HALF OF THE WEEKEND. AFTER THIS
POINT...A LOW CONFIDENCE FORECAST DUE TO MODEL DISCREPANCIES IN
TIMING OF SHORTWAVES IN THE NORTHWEST FLOW ALOFT.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE AT THE SURFACE WILL CONTINUE THE DRYING TREND
CURRENTLY OBSERVED AT ALL TERMINALS...LEADING TO A VFR FCST FOR
ALL TAFS. AMID DEEP MIXING...WNWLY WIND WILL INCREASE AND BECOME
GUSTY TO 15-20 KT THIS AFTERNOON.

A PLUME OF MOISTURE AHEAD OF A SECONDARY FRONTAL SURGE MAY
GENERATE SHOWERS AT KFKL/KDUJ OVERNIGHT TONIGHT...BUT VFR
CONDITIONS OTHERWISE ARE EXPECTED TO PERSIST THROUGH WEDNESDAY
NIGHT AT ALL TERMINALS.

OUTLOOK...THURSDAY THROUGH FRIDAY...
THE NEXT CHANCE FOR RESTRICTIONS IS EXPECTED WITH A THURSDAY
UPPER DISTURBANCE.

&&

.EQUIPMENT...
KPBZ RADAR REMAINS DOWN. TECHNICIANS ADVISE THAT A RETURN TO
SERVICE IS EXPECTED LATE THIS AFTERNOON.

GREGS KNOB NOAA WEATHER RADIO IS OFF THE AIR WITH A FAILED
TRANSMITTER.  RESTORATION IS EXPECTED WITHIN 24 HOURS.

&&

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

&&

$$

UPDATE...KRAMAR


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