Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 230833
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
333 AM CDT WED APR 23 2014

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 330 AM CDT WED APR 23 2014

FORECAST CHALLENGE CONCERNS UPCOMING PCPN EVENT AND TEMPERATURES.
MODELS IN FAIR AGREEMENT THROUGH MOST OF THE PERIOD AND USED A
BLEND.

RAIN BAND GETTING ORGANIZED ACROSS THE SW FA AS UPPER WAVE
APPROACHES. GFS CURRENTLY A LITTLE TOO QUICK IN BRINGING DEEPER
MOISTURE NE THROUGH THE FA SO TRIMMED POPS ESPECIALLY ACROSS THE
NE FA WHICH WILL TAKE LONGEST TO MOISTEN UP. OTHERWISE CURRENT
POPS GOOD AS RAIN BAND LIFTS NE DURING THE DAY IN BROAD ZONE OF
IMPRESSIVE ISENTROPIC LIFT. ALTHOUGH MIXED LAYER SHALLOW TIGHT
SURFACE PRESSURE GRADIENT SETS UP WITH UP TO 35KTS THROUGH LAYER.
AS A RESULT HAVE ISSUED WIND ADVISORY ACROSS SW THIRD OF FA AND
LATER SHIFTS CAN MONITOR. AIRMASS REMAINS STABLE WITH UNFAVORABLE
LAPSE RATES SO TRIMMED T MENTION TODAY EXCEPT FOR THE FAR SOUTH
AND STILL THIS MARGINAL AT BEST.

RAIN WILL CONTINUE TO LIFT NE TONIGHT WITH BEST CHANCES ACROSS NE
HALF OF FA IN FAVORED ZONE OF ISENTROPIC LIFT AND LOWEST
CONDENSATION PRESSURE DEFICITS. SOME DRYING WORKS INTO THE WESTERN
FA LATE TONIGHT SO CHANCE POPS REASONABLE IN THIS AREA.

ALL MODELS BRINGING DRY SLOT INTO AREAS GENERALLY WEST OF THE
VALLEY. FROM VALLEY EAST RAIN BAND SHOULD SLOWLY SHIFT EAST WITH
UPPER LOW. TEMPERATURES WILL BE TRICKY DEPENDENT ON DEGREE OF
CLOUD COVER.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 330 AM CDT WED APR 23 2014

AS LOW EXITS COLDER AIR BEGINS TO FILTER SOUTHWARD THURSDAY NIGHT.
OVERALL PCPN CHANCES DO NOT LOOK GREAT. FAR NE CORNER OF FA THE
EXCEPTION AND COLUMN DOES SUPPORT SNOW SO THERE IS THE POTENTIAL
FOR SOME ACCUMULATIONS AND THIS WILL NEED TO BE MONITORED.

GFS MOST AGGRESSIVE IN DROPPING COLD AIR SOUTHWARD ON FRIDAY WHERE
AS ECMWF AND NAM WARMER. THIS WILL HAVE IMPACT ON BOTH
TEMPERATURES AND PHASE OF ANY PCPN WHICH OCCURS. WITH SIGNIFICANT
MODEL DIFFERENCES DID NOT MAKE MANY CHANGES THIS PERIOD.

FRIDAY TO MONDAY NIGHT...NORTHERN PLAINS STORMS SYSTEM MOVES INTO
THE GREAT LAKES REGION WITH EXITING DIFFUSE DEFZONE BAND OF RASN
SHOWERS DURING THE DAY FRIDAY. IN ITS WAKE CANADIAN SFC HIGH
PRESSURE AXIS WILL CREATE IDEAL DIURNAL COOLING AND SAT AM TEMPS
WILL BE SEASONALLY COOL WITH LOWS IN THE 20S AND 30S. FOG
DEVELOPMENT SAT MORNING MAY LIMIT TEMPS FROM BOTTOMING OUT. COOL DRY
EASTERLY WINDS ON SOUTHERN EDGE OF SFC HIGH AND A PSEUDO OMEGA BLOCK
DEVELOPS WITH RIDGING OVER THE UPPER MISS VALLEY LIMITING
PROGRESSION OF NEXT 500MB TROUGH. THUS DELAYING THE NEXT CHC OF PCPN
INTO MONDAY AND PROBABLY LONGER. THIS BLOCKING WILL KEEP THE
SEASONALLY COOL AIRMASS IN PLACE AND KEEP MAX TEMPS AROUND 10
DEGREES BELOW NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1141 PM CDT TUE APR 22 2014

VFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE NIGHT...WITH SOME
RAIN MOVING INTO THE SOUTH AND WESTERN PORTIONS OF THE FORECAST
AREA AND SPREADING TO THE NORTHERN AND EASTERN TAF SITES LATER IN
THE MORNING. RAIN COULD BRING VIS DOWN TO THE 2-5SM RANGE AT
TIMES...BUT THINK THAT CIGS WILL BE MOSTLY ABOVE 3000 FT. MODELS
SHOW A BIT MORE WIDESPREAD PRECIP DEVELOPING BEHIND THE FIRST BAND
TOMORROW AFTERNOON...SO WENT A BIT MORE BULLISH ON RAIN CONTINUING
THROUGH THE END OF THE PERIOD. WINDS WILL CONTINUE TO RAMP
UP...BLOWING FROM THE SOUTHEAST AT 20 TO 30 KTS WITH GUSTS AROUND
35 KTS BY MID MORNING. THE WINDS WILL DIMINISH A BIT BY WEDNESDAY
EVENING...AND CIGS WILL BEGIN TO DROP DOWN TO MVFR LEVELS.


&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR NDZ006-014-015-024-026-028-029-038-039-049-052-053.

MN...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM CDT THIS EVENING
     FOR MNZ003-029.

&&

$$

SHORT TERM...VOELKER
LONG TERM...JK/VOELKER
AVIATION...JR






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